/* Core Theme */
:root {
  --bg: #0b1016;
  --bg-soft: #121923;
  --text: #e6edf3;
  --muted: #a9b3be;
  --primary: #7c3aed;
  --primary-600: #6d28d9;
  --card: #0f1621;
  --border: #1f2a37;
  --success: #10b981;
  --warn: #f59e0b;
  --danger: #ef4444;
}

html[data-theme="light"] {
  --bg: #f7f8fb;
  --bg-soft: #ffffff;
  --text: #0b1220;
  --muted: #5b6573;
  --primary: #6d28d9;
  --primary-600: #5b21b6;
  --card: #ffffff;
  --border: #e5e7eb;
}

* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font:
    15px/1.6 system-ui,
    -apple-system,
    Segoe UI,
    Roboto,
    Ubuntu,
    Cantarell,
    Noto Sans,
    Helvetica,
    Arial,
    "Apple Color Emoji",
    "Segoe UI Emoji";
  padding-top: 56px;
}

/* Layout */
.container {
  width: 100%;
  max-width: none;
  margin: 9px 0;
  padding: 0 16px;
}
header.site {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background: var(--bg-soft);
  border-bottom: 1px solid var(--border);
  padding: 0px;
}
.navbar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 16px;
}
/* Reduced vertical padding by half */
.navbar {
  padding: 3px 6px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
}
.brand .logo {
  width: 28px;
  height: 28px;
}
.navlinks {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}
.navlinks a {
  color: var(--muted);
  text-decoration: none;
  padding: 6px 10px;
  border-radius: 8px;
}
.navlinks a.active,
.navlinks a:hover {
  color: var(--text);
  background: rgba(124, 58, 237, 0.12);
}
.grow {
  flex: 1;
}
.theme-toggle {
  background: transparent;
  color: var(--text);
  border:none;
  padding: 0;
  cursor: pointer;
  width: 38px;
  height: 38px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}
.theme-toggle .icon {
  position: absolute;
  opacity: 0;
  transform: scale(0.7) rotate(-90deg);
  transition: opacity 180ms ease, transform 360ms ease;
}
html[data-theme="light"] .theme-toggle .sun {
  opacity: 1;
  transform: scale(1) rotate(0deg);
  color: var(--warn);
}
html[data-theme="dark"] .theme-toggle .moon {
  opacity: 1;
  transform: scale(1) rotate(0deg);
}
.theme-toggle.spin {
  animation: theme-spin 360ms ease;
}
@keyframes theme-spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(180deg); }
}

footer.site {
  border-top: 1px solid var(--border);
  background: var(--bg-soft);
  color: var(--muted);
}
footer.site .content {
  display: flex;
  gap: 14px;
  padding: 14px 16px;
  justify-content: space-between;
  flex-wrap: wrap;
}

/* Components */
.hero {
  background: linear-gradient(180deg, rgba(124, 58, 237, 0.16), transparent);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 24px;
}
.hero h1 {
  margin: 0 0 8px;
}
.cta {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 24px 0;
}
.card {
  border: 1px solid var(--border);
  background: var(--card);
  padding: 16px;
  border-radius: 14px;
  color: inherit;
  text-decoration: none;
}
.card:hover {
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.12);
  transform: translateY(-1px);
  transition: 160ms;
}

.panel {
  border: 1px solid var(--border);
  background: var(--bg-soft);
  border-radius: 14px;
  padding: 16px;
}
.panel h2 {
  margin-top: 0;
}

.btn {
  border: 1px solid var(--border);
  background: var(--bg-soft);
  color: var(--text);
  padding: 10px 14px;
  border-radius: 10px;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.btn.primary {
  background: var(--primary);
  border-color: var(--primary-600);
}
.btn.success {
  background: var(--success);
  border-color: #0ea271;
}
.btn.warn {
  background: var(--warn);
  border-color: #d97706;
  color: #111;
}
.btn:hover {
  filter: brightness(1.05);
}

.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 999px;
  background: rgba(124, 58, 237, 0.16);
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 12px;
}

/* Forms */
.input,
select,
textarea {
  background: var(--bg-soft);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
}
label {
  display: block;
  font-weight: 600;
  margin: 8px 0 6px;
}

/* Tables */
table {
  width: 100%;
  border-collapse: collapse;
}
th,
td {
  border-bottom: 1px solid var(--border);
  padding: 10px;
  text-align: left;
}

/* Quiz */
.quiz-controls {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
  margin-bottom: 12px;
}
.question {
  border: 1px solid var(--border);
  background: var(--card);
  padding: 14px;
  border-radius: 12px;
  margin: 12px 0;
}
.options {
  display: grid;
  gap: 8px;
  margin-top: 8px;
}
.option {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px;
  display: flex;
  gap: 10px;
  align-items: start;
}
.option.correct {
  border-color: var(--success);
  background: rgba(16, 185, 129, 0.1);
}
.option.wrong {
  border-color: var(--danger);
  background: rgba(239, 68, 68, 0.1);
}
.explain {
  color: var(--muted);
  margin-top: 6px;
  font-size: 0.95em;
}

.progress {
  height: 10px;
  background: var(--border);
  border-radius: 999px;
  overflow: hidden;
}
.progress > span {
  display: block;
  height: 100%;
  background: var(--primary);
  width: 0%;
  transition: width 240ms ease;
}

/* Utility */
.mono {
  font-family:
    ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    "Courier New", monospace;
}
.small {
  font-size: 12px;
  color: var(--muted);
}
.center {
  display: grid;
  place-items: center;
}
.hidden {
  display: none !important;
}

/* Subject Layout */
.layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 16px;
  align-items: start;
}
@media (max-width: 900px) {
  .layout {
    grid-template-columns: 1fr;
  }
}
.sidebar {
  position: sticky;
  top: 64px;
  max-height: calc(100vh - 80px);
  overflow: auto;
  border: 1px solid var(--border);
  background: var(--bg-soft);
  border-radius: 12px;
  padding: 12px;
}
.content {
  display: grid;
  gap: 12px;
}

/* Tree */
.tree-title {
  font-weight: 700;
  margin: 8px 0 6px;
}
.tree-subtitle {
  font-weight: 600;
  margin: 6px 0 4px;
  color: var(--muted);
}
.tree-list {
  list-style: none;
  padding: 0 0 0 8px;
  margin: 0;
  display: grid;
  gap: 4px;
}
.tree-list a {
  display: block;
  padding: 6px 8px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text);
  border: 1px solid transparent;
}
.tree-list a:hover {
  background: rgba(124, 58, 237, 0.08);
  border-color: var(--border);
}
.tree-list a.active {
  background: rgba(124, 58, 237, 0.16);
  border-color: var(--primary-600);
}