:root {
  --bg: #f4f5f7;
  --surface: #ffffff;
  --ink: #111827;
  --muted: #6b7280;
  --line: #e5e7eb;
  --line-strong: #d1d5db;
  --accent: #0f766e;
  --accent-deep: #0b5f58;
  --accent-soft: rgba(15, 118, 110, 0.1);
  --easy: #15803d;
  --easy-bg: rgba(21, 128, 61, 0.08);
  --medium: #b45309;
  --medium-bg: rgba(180, 83, 9, 0.1);
  --hard: #b91c1c;
  --hard-bg: rgba(185, 28, 28, 0.08);
  --danger: #9f1239;
  --ok: #0f766e;
  --info: #1d4ed8;
  --radius-lg: 14px;
  --radius: 12px;
  --radius-sm: 10px;
  --shadow: 0 1px 2px rgba(17, 24, 39, 0.04);
  --font: "Outfit", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, monospace;
  --ease: 150ms ease;
  --header-h: 56px;
}

*,
*::before,
*::after { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent-deep); text-decoration: none; }
a:hover { text-decoration: underline; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.icon {
  width: 16px;
  height: 16px;
  stroke-width: 1.75;
  flex-shrink: 0;
}

.section-label {
  margin: 0 0 0.45rem;
  font-size: 11px;
  font-weight: 650;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.muted { color: var(--muted); }
.mono { font-family: var(--mono); font-size: 12px; }

/* ---------- Header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: var(--header-h);
  padding: 0.65rem 1.25rem;
  border-bottom: 1px solid var(--line);
  background: rgba(244, 245, 247, 0.92);
  backdrop-filter: blur(8px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  color: var(--ink);
  text-decoration: none;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand:hover { text-decoration: none; }

.brand-mark {
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
}

.brand-mark .icon { width: 15px; height: 15px; }

.brand-text { font-size: 15px; }

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: var(--surface);
  border-radius: var(--radius-sm);
  padding: 0.4rem;
  cursor: pointer;
}

.nav-link,
.nav-user {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.4rem 0.65rem;
  border-radius: var(--radius-sm);
  color: var(--muted);
  text-decoration: none;
  font-size: 13.5px;
  font-weight: 550;
  transition: background var(--ease), color var(--ease);
}

.nav-link .icon { width: 18px; height: 18px; }

.nav-link:hover {
  background: rgba(17, 24, 39, 0.04);
  color: var(--ink);
  text-decoration: none;
}

.nav-link.is-active {
  background: var(--accent-soft);
  color: var(--accent-deep);
}

.nav-link.is-active .icon { color: var(--accent); }

.nav-user {
  color: var(--muted);
  font-family: var(--mono);
  font-size: 12px;
}

.site-main {
  width: min(1280px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 1.5rem 0 3rem;
}

.toast-stack {
  position: fixed;
  top: calc(var(--header-h) + 0.75rem);
  right: 1rem;
  z-index: 80;
  display: grid;
  gap: 0.55rem;
  width: min(360px, calc(100vw - 1.5rem));
  pointer-events: none;
}

.toast {
  pointer-events: auto;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: start;
  gap: 0.55rem;
  padding: 0.8rem 0.75rem 0.8rem 0.85rem;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--surface);
  box-shadow: 0 10px 30px rgba(17, 24, 39, 0.1);
  font-size: 14px;
  color: var(--ink);
  opacity: 0;
  transform: translateY(-8px);
  transition: opacity 160ms ease, transform 160ms ease;
}

.toast.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.toast.is-leaving {
  opacity: 0;
  transform: translateY(-6px);
}

.toast .icon {
  width: 16px;
  height: 16px;
  margin-top: 0.1rem;
}

.toast-message {
  line-height: 1.4;
  padding-top: 0.05rem;
}

.toast-dismiss {
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  padding: 0.1rem;
  border-radius: 6px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: color var(--ease), background var(--ease);
}

.toast-dismiss:hover {
  color: var(--ink);
  background: rgba(17, 24, 39, 0.05);
}

.toast-dismiss .icon {
  width: 14px;
  height: 14px;
  margin-top: 0;
}

.toast-success {
  border-color: rgba(15, 118, 110, 0.28);
  background: #f3faf9;
}
.toast-success .icon:first-child { color: var(--ok); }

.toast-error {
  border-color: rgba(159, 18, 57, 0.28);
  background: #fff5f7;
}
.toast-error .icon:first-child { color: var(--danger); }

.toast-info {
  border-color: rgba(29, 78, 216, 0.22);
  background: #f5f8ff;
}
.toast-info .icon:first-child { color: var(--info); }

h1 {
  margin: 0;
  font-size: clamp(1.7rem, 2.4vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

h2 {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 650;
  letter-spacing: -0.02em;
}

.lede {
  margin: 0.5rem 0 0;
  color: var(--muted);
  font-size: 14px;
  max-width: 52ch;
}

/* ---------- Buttons / inputs ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  padding: 0.55rem 0.9rem;
  font: inherit;
  font-size: 13.5px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: background var(--ease), border-color var(--ease), color var(--ease);
}

.btn:hover { text-decoration: none; }
.btn:focus-visible,
.nav-link:focus-visible,
.sidebar-link:focus-visible,
.problem-row:focus-visible,
.roadmap-node:focus-visible,
.star-btn:focus-visible,
select:focus-visible,
input:focus-visible,
textarea:focus-visible,
.modal-close:focus-visible,
.roadmap-ctrl:focus-visible {
  outline: 2px solid rgba(15, 118, 110, 0.45);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover { background: var(--accent-deep); color: #fff; }

.btn-ghost {
  background: transparent;
  border-color: var(--line);
  color: var(--ink);
}

.btn-ghost:hover { background: rgba(17, 24, 39, 0.03); }

.btn-icon,
.label-with-icon,
.back-link,
.meta-link,
.empty {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

label {
  display: grid;
  gap: 0.3rem;
  font-size: 13px;
  font-weight: 550;
}

input[type="text"],
input[type="password"],
input[type="search"],
input[type="url"],
select,
textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.75rem;
  font: inherit;
  font-size: 14px;
  background: var(--surface);
  color: var(--ink);
  appearance: none;
  -webkit-appearance: none;
}

input:focus,
select:focus,
textarea:focus {
  border-color: var(--accent);
}

/* ---------- Dashboard layout ---------- */
.dash-layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 1.5rem;
  align-items: start;
}

.sidebar-toggle { display: none; margin-bottom: 0.75rem; }

.category-sidebar {
  position: sticky;
  top: calc(var(--header-h) + 0.75rem);
  max-height: calc(100vh - var(--header-h) - 1.5rem);
  overflow: auto;
  padding-right: 0.25rem;
}

.sidebar-head { margin-bottom: 0.85rem; }

.sidebar-all,
.sidebar-link {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.15rem 0.5rem;
  align-items: center;
  padding: 0.5rem 0.55rem;
  border-radius: var(--radius-sm);
  color: var(--ink);
  text-decoration: none;
  border: 1px solid transparent;
  transition: background var(--ease), border-color var(--ease);
}

.sidebar-all { margin-bottom: 0.35rem; font-weight: 600; }

.sidebar-link-text {
  font-size: 13.5px;
  font-weight: 550;
  line-height: 1.25;
}

.sidebar-count {
  color: var(--muted);
  font-size: 11.5px;
}

.sidebar-bar {
  grid-column: 1 / -1;
  height: 3px;
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.06);
  overflow: hidden;
}

.sidebar-bar-fill {
  display: block;
  height: 100%;
  background: var(--accent);
  border-radius: inherit;
}

.sidebar-all:hover,
.sidebar-link:hover {
  background: rgba(17, 24, 39, 0.035);
  text-decoration: none;
}

.sidebar-all.is-active,
.sidebar-link.is-active {
  background: var(--accent-soft);
  border-color: rgba(15, 118, 110, 0.18);
  color: var(--accent-deep);
}

.sidebar-backdrop { display: none; }

.dash-main { min-width: 0; }

/* ---------- Hero ---------- */
.dash-hero {
  display: flex;
  justify-content: space-between;
  align-items: stretch;
  gap: 1.25rem;
  margin-bottom: 1.1rem;
  padding-bottom: 1.1rem;
  border-bottom: 1px solid var(--line);
}

.dash-hero-category { align-items: flex-end; }

.hero-progress-text {
  margin: 0.55rem 0 0.7rem;
  font-size: 15px;
  color: var(--muted);
}

.hero-progress-text strong {
  color: var(--ink);
  font-size: 1.35rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.hero-bar {
  width: min(360px, 100%);
  height: 6px;
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.08);
  overflow: hidden;
}

.hero-bar-fill {
  height: 100%;
  background: var(--accent);
  border-radius: inherit;
}

.continue-card {
  width: min(300px, 100%);
  padding: 0.9rem 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow);
  display: grid;
  gap: 0.45rem;
  align-content: start;
}

.continue-title {
  color: var(--ink);
  font-size: 16px;
  font-weight: 650;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.continue-title:hover { color: var(--accent-deep); }

.continue-meta {
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  color: var(--muted);
  font-size: 13px;
}

.continue-card .btn { justify-self: start; margin-top: 0.25rem; }

/* ---------- Stats ---------- */
.overview-page {
  width: min(1080px, 100%);
  margin: 0 auto;
}

.overview-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}

.dash-split {
  display: grid;
  gap: 1rem;
  margin: 0 0 1.25rem;
  align-items: stretch;
}

.dash-split.has-both {
  grid-template-columns: minmax(0, 1.45fr) minmax(260px, 0.9fr);
}

.dash-split.has-chart-only,
.dash-split.has-contests-only {
  grid-template-columns: 1fr;
}

.progress-chart-card,
.dash-split .contest-preview {
  margin: 0;
  height: 100%;
}

.progress-chart-card {
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.dash-split .contest-preview {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.dash-split .contest-preview-list {
  flex: 1;
}

.progress-chart-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.range-tabs {
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  padding: 0.2rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.02);
}

.range-tab {
  min-width: 2.4rem;
  padding: 0.3rem 0.55rem;
  border-radius: 999px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 650;
  text-align: center;
  text-decoration: none;
  transition: background var(--ease), color var(--ease);
}

.range-tab:hover {
  color: var(--ink);
  text-decoration: none;
}

.range-tab.is-active {
  background: var(--surface);
  color: var(--accent-deep);
  box-shadow: var(--shadow);
}

.progress-chart-wrap {
  height: 180px;
  min-height: 160px;
  flex: 1;
  position: relative;
}

.progress-chart-legend {
  display: flex;
  gap: 0.9rem;
  margin-top: 0.65rem;
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--muted);
}

.legend-item::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 999px;
}

.legend-attempted::before { background: var(--medium); }
.legend-done::before { background: var(--accent); }

.stat-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.stat {
  padding: 0.85rem 0.95rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.stat strong {
  display: block;
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.stat-label {
  display: block;
  margin-top: 0.25rem;
  color: var(--muted);
  font-size: 12.5px;
  font-weight: 550;
}

/* ---------- Filters ---------- */
.filters {
  display: grid;
  grid-template-columns: minmax(180px, 1.4fr) 140px 140px auto;
  gap: 0.6rem;
  align-items: center;
  margin-bottom: 1.25rem;
}

.filter-search { position: relative; }

.filter-search-icon {
  position: absolute;
  left: 0.7rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  pointer-events: none;
  display: inline-flex;
}

.filter-search input { padding-left: 2.1rem; }

.filter-actions {
  display: flex;
  gap: 0.45rem;
  align-items: center;
  justify-content: flex-end;
}

/* ---------- Problem list ---------- */
.category-group { margin-bottom: 1.35rem; }

.category-group-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.55rem;
}

.problem-list {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  overflow: hidden;
}

.problem-row {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.7rem 0.85rem;
  border-bottom: 1px solid var(--line);
  cursor: pointer;
  transition: background var(--ease);
}

.problem-row-star,
.problem-row .status-badge {
  flex: 0 0 auto;
}

.problem-row-lc {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 auto;
}

.problem-row:last-child { border-bottom: 0; }

.problem-row:hover,
.problem-row:focus-visible {
  background: rgba(15, 118, 110, 0.04);
}

.problem-row:hover .row-chevron,
.problem-row:focus-visible .row-chevron {
  opacity: 1;
  transform: translateX(2px);
  color: var(--accent);
}

.problem-name {
  flex: 0 1 auto;
  min-width: 0;
  max-width: min(34rem, 48%);
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: -0.01em;
  text-decoration: none;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.problem-name:hover { color: var(--accent-deep); }

.problem-row-end {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  margin-left: auto;
  flex: 0 0 auto;
}

.row-chevron {
  display: inline-flex;
  color: var(--muted);
  opacity: 0.35;
  transition: opacity var(--ease), transform var(--ease), color var(--ease);
}

.diff {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 4.2rem;
  padding: 0.18rem 0.5rem;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
  background: rgba(17, 24, 39, 0.04);
  color: var(--muted);
}

.diff-easy { color: var(--easy); background: var(--easy-bg); }
.diff-medium { color: var(--medium); background: var(--medium-bg); }
.diff-hard { color: var(--hard); background: var(--hard-bg); }

.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--muted);
}

.status-badge .status-icon {
  width: 14px;
  height: 14px;
}

.status-badge-icon {
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: rgba(17, 24, 39, 0.04);
}

.status-badge-icon .status-icon {
  width: 16px;
  height: 16px;
}

.status-badge-todo { color: #6b7280; }
.status-badge-attempted { color: var(--medium); }
.status-badge-done { color: var(--accent); }

.status-badge-icon.status-badge-todo { background: rgba(107, 114, 128, 0.1); }
.status-badge-icon.status-badge-attempted { background: var(--medium-bg); }
.status-badge-icon.status-badge-done { background: var(--accent-soft); }

.star-btn {
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  padding: 0.3rem;
  border-radius: 8px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: color var(--ease), background var(--ease);
}

.star-btn .icon-star { width: 16px; height: 16px; }
.star-btn:hover,
.star-btn.is-on { color: #b45309; }
.star-btn .icon-star.is-filled,
.star-btn.is-on .icon-star { fill: currentColor; }

.star-btn-lg {
  gap: 0.35rem;
  border: 1px solid var(--line);
  background: var(--surface);
  font-size: 13.5px;
  font-family: var(--font);
  font-weight: 600;
  padding: 0.5rem 0.75rem;
  color: var(--ink);
}

.star-btn-lg.is-on {
  background: rgba(180, 83, 9, 0.08);
  border-color: rgba(180, 83, 9, 0.28);
  color: #b45309;
}

.leetcode-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: rgba(231, 164, 31, 0.1);
  transition: background var(--ease);
}

.leetcode-link:hover {
  background: rgba(231, 164, 31, 0.18);
  text-decoration: none;
}

.leetcode-icon {
  width: 16px;
  height: 16px;
  display: block;
  object-fit: contain;
}

.empty-panel,
.problem-table-wrap {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.empty {
  margin: 0;
  padding: 1.5rem;
  justify-content: center;
  color: var(--muted);
  font-size: 14px;
}

/* Legacy table pages (bookmarks/aging) */
.problem-table-wrap { overflow-x: auto; margin-bottom: 1rem; }

.problem-table {
  width: 100%;
  border-collapse: collapse;
  table-layout: fixed;
  min-width: 640px;
}

.problem-table th,
.problem-table td {
  padding: 0.75rem 0.85rem;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: middle;
  font-size: 14px;
}

.problem-table th {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  background: #fafafa;
}

.problem-table tr:last-child td { border-bottom: 0; }
.problem-table tbody tr:hover { background: rgba(15, 118, 110, 0.035); }
.problem-table .col-star { width: 48px; text-align: center; }
.problem-table .col-problem { width: 34%; }
.problem-table .col-diff { width: 100px; text-align: right; }
.problem-table .col-status { width: 64px; text-align: center; }
.problem-table .col-category { width: 20%; }
.problem-table .col-lc { width: 48px; text-align: center; }
.problem-table .col-age { width: 90px; }
.problem-table .col-solves { width: 90px; }

.aging-preview,
.contest-preview {
  margin: 0 0 1.25rem;
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.contest-preview-list {
  display: grid;
  gap: 0.45rem;
}

.contest-preview-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.7rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: inherit;
  transition: background var(--ease), border-color var(--ease);
}

.contest-preview-item:hover {
  background: rgba(15, 118, 110, 0.04);
  border-color: rgba(15, 118, 110, 0.28);
}

.contest-preview-link {
  min-width: 0;
  color: inherit;
  text-decoration: none;
}

.contest-preview-link:hover {
  text-decoration: none;
}

.contest-preview-link:hover strong { color: var(--accent-deep); }

.contest-preview-meta {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  flex-shrink: 0;
}

.contest-card-actions {
  margin-top: 0.65rem;
}

.cal-menu {
  position: relative;
  display: inline-block;
}

.cal-menu summary {
  list-style: none;
  cursor: pointer;
}

.cal-menu summary::-webkit-details-marker { display: none; }

.cal-menu-trigger {
  font-size: 13px;
}

.cal-menu-compact .cal-menu-trigger {
  padding: 0.35rem;
  min-width: 32px;
  justify-content: center;
}

.cal-menu-panel {
  position: absolute;
  top: calc(100% + 0.35rem);
  left: 0;
  z-index: 20;
  min-width: 190px;
  padding: 0.35rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: 0 10px 28px rgba(17, 24, 39, 0.12);
  display: grid;
  gap: 0.15rem;
}

.cal-menu-compact .cal-menu-panel {
  left: auto;
  right: 0;
}

.cal-menu-item {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.5rem 0.6rem;
  border-radius: 8px;
  color: var(--ink);
  font-size: 13px;
  font-weight: 550;
  text-decoration: none;
}

.cal-menu-item:hover {
  background: rgba(15, 118, 110, 0.06);
  text-decoration: none;
}

.cal-menu-item .icon {
  width: 15px;
  height: 15px;
  color: var(--muted);
}

.contest-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-bottom: 1rem;
}

.contest-column {
  padding: 1rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.contest-column-head {
  margin-bottom: 0.85rem;
}

.contest-column-head h2 {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 1.15rem;
}

.contest-column-head p { margin: 0.25rem 0 0; font-size: 13px; }

.contest-list {
  display: grid;
  gap: 0.55rem;
}

.contest-card {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.85rem;
  padding: 0.8rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fcfcfd;
}

.contest-card.is-live {
  border-color: rgba(15, 118, 110, 0.35);
  background: rgba(15, 118, 110, 0.04);
}

.contest-card-main { min-width: 0; }

.contest-kind {
  margin: 0 0 0.2rem;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.contest-card h3 {
  margin: 0;
  font-size: 15px;
  font-weight: 650;
}

.contest-card h3 a {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  color: var(--ink);
  text-decoration: none;
}

.contest-card h3 a:hover { color: var(--accent-deep); }
.contest-card h3 .icon { width: 14px; height: 14px; color: var(--muted); }

.contest-when {
  margin: 0.35rem 0 0.15rem;
  font-size: 13.5px;
  font-weight: 600;
}

.contest-relative {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-size: 12.5px;
  font-weight: 650;
  white-space: nowrap;
}

.contest-relative.is-live {
  background: rgba(15, 118, 110, 0.14);
}

.contest-fetched,
.contest-stale-note {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 12.5px;
  margin: 0.25rem 0 0;
}

.aging-preview-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.aging-preview-sub {
  margin: 0.2rem 0 0;
  font-size: 13px;
}

.aging-preview-list {
  display: grid;
  gap: 0.45rem;
}

.aging-preview-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.7rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: inherit;
  text-decoration: none;
  transition: background var(--ease), border-color var(--ease);
}

.aging-preview-item:hover {
  background: rgba(15, 118, 110, 0.04);
  border-color: rgba(15, 118, 110, 0.28);
  text-decoration: none;
}

.aging-preview-main {
  display: grid;
  gap: 0.15rem;
  min-width: 0;
}

.aging-preview-main strong {
  font-size: 14.5px;
  font-weight: 650;
  letter-spacing: -0.01em;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.aging-preview-main .muted { font-size: 12.5px; }

.reset-progress-form {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.65rem 1rem;
  margin-top: 1.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
}

.reset-progress-hint {
  margin: 0;
  font-size: 12.5px;
}

.btn-danger-ghost {
  background: transparent;
  border-color: rgba(159, 18, 57, 0.28);
  color: var(--danger);
}

.btn-danger-ghost:hover {
  background: rgba(159, 18, 57, 0.06);
  color: var(--danger);
}

.age-pill,
.practice-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  flex-shrink: 0;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
  font-size: 12.5px;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  background: var(--medium-bg);
  color: var(--medium);
}

.age-pill .icon,
.practice-chip .icon {
  width: 14px;
  height: 14px;
}

.practice-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin-top: 0.75rem;
}

.practice-chip {
  background: var(--accent-soft);
  color: var(--accent-deep);
}

/* ---------- Modal ---------- */
.modal {
  border: 0;
  padding: 0;
  background: transparent;
  width: min(720px, calc(100vw - 2rem));
  max-width: calc(100vw - 2rem);
}

.modal::backdrop {
  background: rgba(17, 24, 39, 0.4);
}

.modal-card {
  width: 100%;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.9rem 1rem;
  border-bottom: 1px solid var(--line);
}

.modal-head h2 {
  margin: 0;
  font-size: 1.05rem;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.modal-close {
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  padding: 0.3rem;
  border-radius: 8px;
}

.modal-close:hover { background: rgba(17, 24, 39, 0.05); color: var(--ink); }

.modal-body {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  padding: 1rem;
}

.modal-body label:first-child,
.modal-body label:nth-child(4) { grid-column: 1 / -1; }

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.45rem;
  padding: 0 1rem 1rem;
}

/* ---------- Auth / detail ---------- */
.auth-panel {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 2rem;
  align-items: center;
  min-height: calc(100vh - 8rem);
}

.auth-form {
  padding: 1.25rem;
  display: grid;
  gap: 0.85rem;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
}

.auth-alt { margin: 0; color: var(--muted); font-size: 14px; }
.checkbox { display: flex; align-items: center; gap: 0.45rem; font-weight: 400; }

body:has(.problem-shell) .site-main {
  width: min(1480px, calc(100% - 2rem));
}

.problem-shell {
  --ai-panel-width: clamp(360px, 28vw, 400px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--ai-panel-width);
  gap: 1.25rem;
  align-items: start;
}

.problem-shell.is-ai-collapsed {
  grid-template-columns: minmax(0, 1fr);
}

.problem-workspace {
  width: 100%;
  min-width: 0;
  max-width: 1100px;
}

.problem-shell.is-ai-collapsed .problem-workspace {
  max-width: none;
}

.ai-chat {
  position: sticky;
  top: calc(var(--header-h) + 0.85rem);
  height: calc(100vh - var(--header-h) - 1.7rem);
  width: 100%;
  display: flex;
  flex-direction: column;
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  overflow: hidden;
}

.problem-shell.is-ai-collapsed .ai-chat {
  display: none;
}

.ai-chat-header {
  flex: 0 0 auto;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.85rem 0.9rem;
  border-bottom: 1px solid var(--line);
  background: #fafafa;
}

.ai-chat-title {
  display: flex;
  align-items: flex-start;
  gap: 0.65rem;
  min-width: 0;
}

.ai-chat-heading {
  min-width: 0;
}

.ai-chat-heading strong {
  display: block;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.ai-chat-context {
  margin: 0.15rem 0 0;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--ink);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.ai-chat-meta {
  margin: 0.2rem 0 0;
  font-size: 11.5px;
  line-height: 1.4;
}

.ai-chat-model {
  font-family: var(--mono);
  font-size: 11px;
}

.ai-chat-mark {
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  flex-shrink: 0;
}

.ai-chat-mark .icon { width: 15px; height: 15px; }

.ai-chat-header-actions {
  display: inline-flex;
  gap: 0.1rem;
  flex-shrink: 0;
}

.ai-chat-messages {
  flex: 1 1 auto;
  min-height: 0;
  overflow-x: hidden;
  overflow-y: auto;
  padding: 0.85rem 0.9rem;
  display: grid;
  gap: 0.9rem;
  align-content: start;
  background: #fff;
}

.ai-msg {
  display: grid;
  gap: 0.25rem;
  min-width: 0;
  max-width: 100%;
}

.ai-msg-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  min-height: 22px;
}

.ai-msg-label {
  font-size: 11px;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}

.ai-copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.28rem;
  border: 0;
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 0.15rem 0.3rem;
  border-radius: 6px;
  cursor: pointer;
}

.ai-copy-btn:hover {
  color: var(--accent-deep);
  background: var(--accent-soft);
}

.ai-copy-btn.is-copied { color: var(--accent); }
.ai-copy-btn .icon { width: 13px; height: 13px; }

.ai-msg-body {
  position: relative;
  min-width: 0;
  max-width: 100%;
  padding: 0;
  border: 0;
  background: transparent;
  font-size: 14px;
  line-height: 1.55;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.ai-msg-user .ai-msg-body {
  padding: 0.65rem 0.75rem;
  border-radius: 10px;
  border: 1px solid rgba(15, 118, 110, 0.16);
  background: rgba(15, 118, 110, 0.05);
}

.ai-msg-system .ai-msg-body,
.ai-msg.is-error .ai-msg-body {
  padding: 0.65rem 0.75rem;
  border-radius: 10px;
  border: 1px solid rgba(185, 28, 28, 0.16);
  background: rgba(185, 28, 28, 0.04);
}

.ai-msg.is-pending .ai-msg-body {
  color: var(--muted);
  padding: 0.35rem 0;
}

.ai-error-actions {
  margin-top: 0.55rem;
}

.ai-retry-btn {
  font-size: 12.5px;
}

.ai-code-block {
  position: relative;
  max-width: 100%;
  margin: 0.65rem 0;
  border-radius: 8px;
  overflow: hidden;
  background: #0d1117;
}

.ai-code-block pre {
  margin: 0 !important;
  max-width: 100%;
  overflow-x: auto;
  border-radius: 0 !important;
  background: transparent !important;
}

.ai-code-block pre code,
.ai-code-block pre code.hljs {
  padding: 0.7rem 0.8rem;
  padding-right: 4.25rem;
  font-size: 12.5px;
  line-height: 1.5;
}

.ai-copy-code {
  position: absolute;
  top: 0.4rem;
  right: 0.4rem;
  z-index: 2;
  background: rgba(17, 24, 39, 0.82);
  color: #e5e7eb;
  border-radius: 7px;
  padding: 0.25rem 0.4rem;
}

.ai-copy-code:hover {
  background: rgba(15, 118, 110, 0.92);
  color: #fff;
}

.ai-copy-code.is-copied {
  background: rgba(15, 118, 110, 0.95);
  color: #fff;
}

.ai-thinking {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  margin: 0;
  font-style: normal;
  font-weight: 550;
}

.ai-thinking-label { color: var(--muted); }

.ai-thinking-dots {
  display: inline-flex;
  align-items: center;
  gap: 0.22rem;
}

.ai-thinking-dots span {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0.35;
  animation: ai-think-bounce 1.15s ease-in-out infinite;
}

.ai-thinking-dots span:nth-child(2) { animation-delay: 0.15s; }
.ai-thinking-dots span:nth-child(3) { animation-delay: 0.3s; }

@keyframes ai-think-bounce {
  0%, 70%, 100% {
    opacity: 0.3;
    transform: translateY(0) scale(0.9);
  }
  35% {
    opacity: 1;
    transform: translateY(-3px) scale(1);
  }
}

.ai-msg-body.markdown-body > :first-child { margin-top: 0; }
.ai-msg-body.markdown-body > :last-child { margin-bottom: 0; }
.ai-msg-body.markdown-body p { margin: 0.45rem 0; }
.ai-msg-body.markdown-body h1,
.ai-msg-body.markdown-body h2,
.ai-msg-body.markdown-body h3,
.ai-msg-body.markdown-body h4 {
  margin: 0.85rem 0 0.4rem;
  font-size: 14.5px;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.35;
}
.ai-msg-body.markdown-body h1 { font-size: 16px; }
.ai-msg-body.markdown-body h2 { font-size: 15px; }
.ai-msg-body.markdown-body ul,
.ai-msg-body.markdown-body ol {
  margin: 0.4rem 0;
  padding-left: 1.15rem;
}
.ai-msg-body.markdown-body li { margin: 0.2rem 0; }
.ai-msg-body.markdown-body code {
  overflow-wrap: anywhere;
  word-break: break-word;
}
.ai-msg-body.markdown-body pre {
  margin: 0;
  max-width: 100%;
}
.ai-msg-body.markdown-body table {
  display: block;
  max-width: 100%;
  overflow-x: auto;
}

.ai-chat-suggestions {
  flex: 0 0 auto;
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  padding: 0.55rem 0.85rem;
  border-top: 1px solid var(--line);
  background: #fafafa;
}

.ai-chip {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--ink);
  border-radius: 999px;
  padding: 0.24rem 0.6rem;
  font: inherit;
  font-size: 12px;
  font-weight: 550;
  cursor: pointer;
  transition: background var(--ease), border-color var(--ease), color var(--ease);
}

.ai-chip:hover:not(:disabled) {
  background: var(--accent-soft);
  border-color: rgba(15, 118, 110, 0.35);
  color: var(--accent-deep);
}

.ai-chip-primary {
  border-color: rgba(15, 118, 110, 0.35);
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-weight: 650;
}

.ai-chip:disabled { opacity: 0.55; cursor: not-allowed; }

.ai-chat-composer {
  flex: 0 0 auto;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 0.45rem;
  align-items: end;
  padding: 0.7rem 0.75rem;
  border-top: 1px solid var(--line);
  background: #fff;
}

.ai-chat-composer textarea {
  width: 100%;
  min-height: 40px;
  max-height: 120px;
  resize: none;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0.55rem 0.7rem;
  font: inherit;
  font-size: 13.5px;
  line-height: 1.4;
  background: #fcfcfd;
  overflow-y: auto;
}

.ai-chat-composer textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.12);
}

.ai-chat-send {
  width: 36px;
  height: 36px;
  padding: 0;
  justify-content: center;
  border-radius: 10px;
}

.ai-chat-send.is-loading { opacity: 0.7; }

.ai-chat-rail,
.ai-chat-fab {
  display: none;
}

.ai-chat-rail {
  position: sticky;
  top: calc(var(--header-h) + 0.85rem);
  align-self: start;
  width: 44px;
  margin-left: auto;
  flex-direction: column;
  align-items: center;
  gap: 0.35rem;
  padding: 0.7rem 0.35rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  color: var(--accent-deep);
  font: inherit;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.04em;
  cursor: pointer;
}

.ai-chat-rail:hover {
  background: var(--accent-soft);
  border-color: rgba(15, 118, 110, 0.35);
}

.problem-shell.is-ai-collapsed .ai-chat-rail {
  display: inline-flex;
}

.ai-chat-fab {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  z-index: 45;
  align-items: center;
  gap: 0.4rem;
  padding: 0.7rem 0.95rem;
  border: 1px solid rgba(15, 118, 110, 0.28);
  border-radius: 999px;
  background: var(--surface);
  color: var(--accent-deep);
  font: inherit;
  font-size: 13px;
  font-weight: 650;
  box-shadow: 0 8px 24px rgba(17, 24, 39, 0.12);
  cursor: pointer;
}

.ai-chat-fab:hover {
  background: var(--accent-soft);
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin-bottom: 1.25rem;
  color: var(--muted);
  font-weight: 550;
  font-size: 13.5px;
  text-decoration: none;
  transition: color var(--ease);
}

.back-link:hover {
  color: var(--ink);
  text-decoration: none;
}

.problem-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.5rem;
  margin-bottom: 1.75rem;
  padding-bottom: 1.35rem;
  border-bottom: 1px solid var(--line);
}

.problem-category {
  margin: 0 0 0.35rem;
  font-size: 13px;
  font-weight: 550;
  color: var(--muted);
}

.problem-title {
  margin: 0;
  font-size: clamp(1.9rem, 3vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
}

.problem-meta-line {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem;
  margin-top: 0.75rem;
  font-size: 13.5px;
}

.meta-sep { color: var(--line-strong); }

.problem-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: flex-end;
  flex-shrink: 0;
}

.problem-leetcode-btn {
  border-color: rgba(15, 118, 110, 0.35);
  color: var(--accent-deep);
}

.problem-leetcode-btn:hover {
  background: var(--accent-soft);
  border-color: rgba(15, 118, 110, 0.5);
  color: var(--accent-deep);
}

.problem-form { display: grid; gap: 1.5rem; }

.status-panel {
  display: grid;
  gap: 0.5rem;
  max-width: 280px;
}

.status-control {
  position: relative;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 0.45rem;
  padding: 0.15rem 0.65rem 0.15rem 0.7rem;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition: border-color var(--ease), background var(--ease);
}

.status-control:hover { border-color: var(--line-strong); }

.status-control:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.12);
}

.status-control-todo { color: #6b7280; }
.status-control-attempted {
  color: var(--medium);
  border-color: rgba(180, 83, 9, 0.28);
  background: rgba(180, 83, 9, 0.04);
}
.status-control-done {
  color: var(--accent);
  border-color: rgba(15, 118, 110, 0.28);
  background: rgba(15, 118, 110, 0.04);
}

.status-control select {
  border: 0;
  background: transparent;
  padding: 0.55rem 0;
  font-weight: 650;
  font-size: 14px;
  color: inherit;
  cursor: pointer;
  width: auto;
  min-width: 0;
}

.status-control select:focus {
  outline: none;
  border: 0;
  box-shadow: none;
}

.status-control-icon,
.status-chevron {
  display: inline-flex;
  pointer-events: none;
}

.status-control .icon { width: 16px; height: 16px; }

.status-hint {
  margin: 0;
  font-size: 12.5px;
}

.notes-panel { display: grid; gap: 0.75rem; }

.notes-field-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

.notes-hint {
  margin: 0.2rem 0 0;
  font-size: 12.5px;
  font-weight: 400;
}

.notes-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.notes-footer-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.save-state {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 13px;
}

.save-state.is-dirty { color: var(--medium); }

#save-notes-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.problem-pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
}

.pager-link {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  max-width: min(420px, 48%);
  padding: 0.75rem 0.85rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  color: var(--ink);
  text-decoration: none;
  transition: background var(--ease), border-color var(--ease);
}

.pager-link:hover {
  background: var(--surface);
  border-color: var(--line);
  text-decoration: none;
}

.pager-link span { display: grid; gap: 0.1rem; min-width: 0; }
.pager-link small {
  font-size: 11px;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--muted);
}
.pager-link strong {
  font-size: 14px;
  font-weight: 600;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.pager-link-next { text-align: right; margin-left: auto; }

.md-editor {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface);
}

.md-editor.is-view .md-toolbar,
.md-editor.is-view .md-pane-write,
.md-editor.is-view .md-preview-label { display: none; }

.md-editor.is-view .md-panes,
.md-editor.is-view[data-mode="preview"] .md-panes { grid-template-columns: 1fr; }

.md-empty-state {
  display: grid;
  gap: 0.35rem;
  padding: 0.35rem 0;
  color: var(--muted);
}

.md-empty-state p { margin: 0; font-size: 14px; }

.md-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem;
  align-items: center;
  padding: 0.45rem 0.55rem;
  border-bottom: 1px solid var(--line);
  background: #fafafa;
}

.md-toolbar-group {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 0.2rem;
  padding-right: 0.4rem;
  margin-right: 0.15rem;
  border-right: 1px solid var(--line);
}

.md-toolbar-group:last-child {
  border-right: 0;
  margin-left: auto;
  padding-right: 0;
}

.md-btn {
  border: 1px solid transparent;
  background: transparent;
  color: var(--ink);
  border-radius: 8px;
  padding: 0.35rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.md-btn:hover { background: rgba(17, 24, 39, 0.05); }
.md-btn.is-active { background: var(--accent-soft); color: var(--accent-deep); }
.md-btn .icon { width: 16px; height: 16px; }

.md-panes {
  display: grid;
  grid-template-columns: 1fr 1fr;
  height: clamp(300px, 42vh, 520px);
  min-height: 0;
}

.md-editor[data-mode="write"] .md-panes,
.md-editor[data-mode="preview"] .md-panes { grid-template-columns: 1fr; }
.md-editor[data-mode="write"] .md-pane-preview,
.md-editor[data-mode="preview"] .md-pane-write { display: none; }

.md-pane-write {
  border-right: 1px solid var(--line);
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.md-editor[data-mode="write"] .md-pane-write { border-right: 0; }

.md-input {
  width: 100%;
  flex: 1 1 auto;
  min-height: 0 !important;
  height: 100%;
  border: 0 !important;
  border-radius: 0 !important;
  outline: none !important;
  resize: none;
  padding: 0.9rem 1rem !important;
  font-family: var(--mono) !important;
  font-size: 13px !important;
  line-height: 1.6 !important;
  background: #fcfcfd !important;
}

.md-pane-preview {
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: #fff;
}

.md-preview-label {
  flex: 0 0 auto;
  padding: 0.5rem 1rem 0;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted);
  font-weight: 650;
}

.md-preview {
  flex: 1 1 auto;
  min-height: 0;
  padding: 0.7rem 1rem 1.1rem;
  overflow: auto;
}

/* Reading mode: let notes grow with content */
.md-editor.is-view .md-panes {
  height: auto;
  min-height: clamp(220px, 32vh, 420px);
}

.md-editor.is-view .md-pane-preview,
.md-editor.is-view .md-preview {
  overflow: visible;
}

.md-editor.is-view .md-preview {
  min-height: clamp(220px, 32vh, 420px);
}

.markdown-body {
  color: var(--ink);
  font-size: 0.96rem;
  line-height: 1.65;
}

.markdown-body > :first-child { margin-top: 0; }
.markdown-body h1,
.markdown-body h2,
.markdown-body h3 {
  margin: 1.1rem 0 0.5rem;
  letter-spacing: -0.02em;
}
.markdown-body code {
  font-family: var(--mono);
  font-size: 0.88em;
  background: rgba(17, 24, 39, 0.05);
  padding: 0.1rem 0.3rem;
  border-radius: 5px;
}
.markdown-body pre {
  background: #0d1117;
  color: #e6edf3;
  padding: 0;
  border-radius: 10px;
  overflow: hidden;
}
.markdown-body pre code,
.markdown-body pre code.hljs {
  display: block;
  background: transparent;
  padding: 0.85rem 0.95rem;
  overflow-x: auto;
  font-size: 0.86em;
  line-height: 1.55;
}
/* Keep token colors even if the theme stylesheet is slow/blocked */
.markdown-body pre code .hljs-keyword,
.markdown-body pre code .hljs-selector-tag,
.markdown-body pre code .hljs-title.function_ { color: #ff7b72; }
.markdown-body pre code .hljs-string,
.markdown-body pre code .hljs-attr { color: #a5d6ff; }
.markdown-body pre code .hljs-number,
.markdown-body pre code .hljs-literal { color: #79c0ff; }
.markdown-body pre code .hljs-comment { color: #8b949e; font-style: italic; }
.markdown-body pre code .hljs-built_in,
.markdown-body pre code .hljs-type { color: #ffa657; }
.markdown-body pre code .hljs-title,
.markdown-body pre code .hljs-title.class_ { color: #d2a8ff; }
.markdown-body table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
.markdown-body th,
.markdown-body td { border: 1px solid var(--line); padding: 0.4rem 0.55rem; }
.markdown-body blockquote {
  border-left: 3px solid var(--accent);
  margin: 0.7rem 0;
  padding-left: 0.8rem;
  color: var(--muted);
}

/* ---------- Roadmap ---------- */
.roadmap-page { width: min(1100px, 100%); margin: 0 auto; }

.roadmap-hero {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 1rem;
  margin-bottom: 1rem;
}

.roadmap-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  color: var(--muted);
  font-size: 12.5px;
  font-weight: 550;
}

.roadmap-legend span {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.legend-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  display: inline-block;
  background: #cbd5e1;
}

.legend-complete { background: var(--accent); }
.legend-current { background: #0ea5a0; box-shadow: 0 0 0 3px rgba(14, 165, 160, 0.18); }
.legend-upcoming { background: #d1d5db; }

.roadmap-board-wrap {
  position: relative;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    radial-gradient(circle, rgba(17, 24, 39, 0.05) 0.8px, transparent 0.8px) 0 0 / 20px 20px,
    #f8f9fb;
  min-height: 420px;
}

.roadmap-board {
  position: relative;
  width: 1000px;
  height: 1200px;
  margin: 0 auto;
}

.roadmap-edges {
  position: absolute;
  inset: 0;
  width: 1000px;
  height: 1200px;
  pointer-events: none;
}

.roadmap-edge {
  fill: none;
  stroke: #c5ccd6;
  stroke-width: 2;
  stroke-linecap: round;
  transition: stroke var(--ease), stroke-width var(--ease), opacity var(--ease);
}

.roadmap-board.is-tracing .roadmap-edge { opacity: 0.18; }

.roadmap-edge.is-on-path {
  opacity: 1 !important;
  stroke: var(--accent);
  stroke-width: 2.8;
}

@keyframes roadmap-draw {
  to { stroke-dashoffset: 0; }
}

.roadmap-node {
  position: absolute;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.2rem;
  padding: 0.65rem 0.75rem 0.55rem;
  border-radius: 13px;
  border: 1px solid var(--line-strong);
  background: #f3f4f6;
  color: var(--ink);
  text-decoration: none;
  box-shadow: none;
  transition: border-color var(--ease), background var(--ease), transform var(--ease);
  z-index: 1;
}

.roadmap-node:hover {
  transform: translateY(-1px);
  border-color: #9ca3af;
  text-decoration: none;
  color: var(--ink);
}

.roadmap-node.is-upcoming {
  opacity: 0.72;
  background: #f3f4f6;
}

.roadmap-node.is-current,
.roadmap-node.is-here {
  opacity: 1;
  background: #fff;
  border-color: rgba(15, 118, 110, 0.55);
  box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.1);
}

.roadmap-node.is-complete {
  opacity: 1;
  background: #ecf8f5;
  border-color: rgba(15, 118, 110, 0.35);
}

.roadmap-board.is-tracing .roadmap-node { opacity: 0.28; }
.roadmap-board.is-tracing .roadmap-node.is-on-path { opacity: 1; }

.roadmap-node-state {
  position: absolute;
  top: 8px;
  right: 8px;
  color: var(--muted);
  display: inline-flex;
}

.roadmap-node.is-complete .roadmap-node-state { color: var(--accent); }
.roadmap-node.is-here .roadmap-node-state { color: var(--accent); }

.roadmap-node-title {
  font-size: 13px;
  font-weight: 650;
  line-height: 1.2;
  letter-spacing: -0.01em;
  padding-right: 1.1rem;
}

.roadmap-node-meta {
  font-size: 11.5px;
  color: var(--muted);
}

.roadmap-node-bar {
  display: block;
  height: 4px;
  border-radius: 999px;
  background: rgba(17, 24, 39, 0.08);
  overflow: hidden;
  margin-top: 0.15rem;
}

.roadmap-node-bar-fill {
  display: block;
  height: 100%;
  background: var(--accent);
  border-radius: inherit;
}

.roadmap-here-label {
  margin-top: 0.1rem;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
}

.roadmap-controls {
  position: sticky;
  bottom: 12px;
  float: right;
  margin: -52px 12px 12px 0;
  display: inline-flex;
  gap: 0.3rem;
  padding: 0.3rem;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.95);
  box-shadow: var(--shadow);
  z-index: 5;
}

.roadmap-ctrl {
  width: 32px;
  height: 32px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.roadmap-ctrl:hover { background: rgba(17, 24, 39, 0.05); }

/* ---------- Responsive ---------- */
@media (max-width: 1100px) {
  .dash-layout { grid-template-columns: 220px minmax(0, 1fr); }
  .filters { grid-template-columns: 1fr 1fr; }
  .filter-actions { grid-column: 1 / -1; justify-content: flex-start; }
}

@media (max-width: 1100px) {
  .dash-split.has-both {
    grid-template-columns: 1fr;
  }

  body:has(.problem-shell) .site-main {
    width: min(1080px, calc(100% - 2rem));
  }

  .problem-shell,
  .problem-shell.is-ai-collapsed {
    grid-template-columns: 1fr;
  }

  .problem-workspace { max-width: none; }

  .ai-chat-rail { display: none !important; }
  .ai-chat-fab { display: inline-flex; }
  body.is-ai-chat-open .ai-chat-fab { display: none; }

  .ai-chat,
  .problem-shell.is-ai-collapsed .ai-chat {
    display: flex;
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 60;
    width: min(400px, 100vw);
    height: 100vh;
    border-radius: 0;
    border: 0;
    border-left: 1px solid var(--line);
    transform: translateX(105%);
    transition: transform 180ms ease;
    box-shadow: -10px 0 28px rgba(17, 24, 39, 0.12);
  }

  .ai-chat.is-open { transform: translateX(0); }

  body.is-ai-chat-open::before {
    content: "";
    position: fixed;
    inset: 0;
    z-index: 55;
    background: rgba(17, 24, 39, 0.35);
  }
}

@media (max-width: 640px) {
  .ai-chat,
  .problem-shell.is-ai-collapsed .ai-chat {
    width: 100vw;
    border-left: 0;
  }
}

@media (max-width: 900px) {
  .auth-panel,
  .dash-layout,
  .stat-row,
  .dash-hero,
  .modal-body,
  .contest-grid {
    grid-template-columns: 1fr;
    display: grid;
  }

  .dash-hero { display: grid; }

  .sidebar-toggle { display: inline-flex; }

  .category-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: min(300px, 86vw);
    z-index: 50;
    max-height: none;
    padding: 1rem;
    background: var(--surface);
    border-right: 1px solid var(--line);
    transform: translateX(-105%);
    transition: transform 160ms ease;
  }

  .category-sidebar.is-open { transform: translateX(0); }

  .sidebar-backdrop {
    display: block;
    position: fixed;
    inset: 0;
    z-index: 45;
    background: rgba(17, 24, 39, 0.35);
  }

  .sidebar-backdrop[hidden] { display: none; }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    display: none;
    position: absolute;
    top: calc(var(--header-h) - 2px);
    right: 0.75rem;
    left: 0.75rem;
    flex-direction: column;
    align-items: stretch;
    gap: 0.2rem;
    padding: 0.55rem;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--surface);
    box-shadow: var(--shadow);
  }

  .site-nav.is-open { display: flex; }

  .aging-preview-item {
    flex-direction: column;
    align-items: flex-start;
  }

  .md-panes,
  .md-editor[data-mode="split"] .md-panes { grid-template-columns: 1fr; }
  .md-editor.is-editing[data-mode="split"] .md-panes {
    height: auto;
  }
  .md-editor.is-editing[data-mode="split"] .md-pane-write,
  .md-editor.is-editing[data-mode="split"] .md-pane-preview {
    height: clamp(240px, 36vh, 420px);
  }
  .md-pane-write { border-right: 0; border-bottom: 1px solid var(--line); }
  .md-toolbar-group:last-child { margin-left: 0; }

  .problem-header {
    flex-direction: column;
    align-items: stretch;
    gap: 1rem;
  }

  .problem-actions {
    justify-content: flex-start;
    width: 100%;
  }

  .problem-actions .bookmark-form,
  .problem-actions .btn,
  .problem-actions .star-btn-lg {
    flex: 1 1 auto;
  }

  .problem-actions .star-btn-lg,
  .problem-actions .btn {
    width: 100%;
    justify-content: center;
  }

  .status-panel { max-width: none; }

  .notes-footer {
    flex-direction: column;
    align-items: stretch;
  }

  .notes-footer-actions {
    justify-content: flex-end;
  }

  .problem-pager {
    flex-direction: column;
  }

  .pager-link,
  .pager-link-next {
    max-width: none;
    margin-left: 0;
    text-align: left;
  }

  .roadmap-hero { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 640px) {
  .site-main {
    width: min(100% - 1.1rem, 1280px);
  }

  .progress-chart-head {
    flex-direction: column;
    align-items: stretch;
  }

  .range-tabs { align-self: flex-start; }

  .toast-stack {
    top: calc(var(--header-h) + 0.5rem);
    right: 0.65rem;
    width: min(360px, calc(100vw - 1.3rem));
  }

  .filters { grid-template-columns: 1fr; }
  .continue-card { width: 100%; }
  .stat strong { font-size: 1.4rem; }

  .problem-row {
    flex-wrap: wrap;
    row-gap: 0.4rem;
  }

  .problem-name {
    flex: 1 1 12rem;
    max-width: none;
    white-space: normal;
  }

  .problem-row-end {
    margin-left: 0;
    width: 100%;
    padding-left: 4.1rem;
    justify-content: flex-start;
  }

  .problem-actions {
    flex-direction: column;
  }

  .problem-title {
    font-size: 1.75rem;
  }

  .notes-field-head {
    flex-direction: column;
    align-items: stretch;
  }

  .notes-field-head .btn {
    align-self: flex-start;
  }
}