/* ==========================================================================
   Oh My Learning — site styles
   Light + dark themes. Dark is applied via prefers-color-scheme OR an explicit
   [data-theme="dark"] on <html> (the toggle); [data-theme="light"] forces light.
   ========================================================================== */

:root {
  /* Light theme (default) */
  --bg: #f7f8fa;
  --bg-elevated: #ffffff;
  --surface: #ffffff;
  --surface-2: #f0f2f6;
  --surface-3: #e7eaf0;
  --text: #1a1d24;
  --text-soft: #454b57;
  --text-muted: #6b7280;
  --border: #e2e6ec;
  --border-strong: #d0d5de;
  --accent: #4f46e5;
  --accent-strong: #4338ca;
  --accent-soft: rgba(79, 70, 229, 0.1);
  --accent-contrast: #ffffff;
  --shadow-sm: 0 1px 2px rgba(16, 24, 40, 0.06), 0 1px 3px rgba(16, 24, 40, 0.08);
  --shadow-md: 0 4px 12px rgba(16, 24, 40, 0.08), 0 2px 4px rgba(16, 24, 40, 0.05);
  --shadow-lg: 0 12px 32px rgba(16, 24, 40, 0.12);

  --junior: #16a34a;
  --mid: #2563eb;
  --senior: #9333ea;
  --staff: #d97706;
  --principal: #dc2626;

  --solid: #16a34a;
  --partial: #65a30d;
  --shaky: #d97706;
  --not-yet: #dc2626;

  --radius: 12px;
  --radius-sm: 8px;
  --radius-pill: 999px;
  --content-width: 1180px;
  --reading-width: 760px;
  --sidebar-width: 268px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
    "Helvetica Neue", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Monaco, Consolas,
    "Liberation Mono", monospace;
}

/* Dark palette shared by auto + explicit toggle */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0d1017;
    --bg-elevated: #141821;
    --surface: #161b25;
    --surface-2: #1d2430;
    --surface-3: #262f3d;
    --text: #e6e9ef;
    --text-soft: #b9c0cc;
    --text-muted: #8b94a3;
    --border: #262d3a;
    --border-strong: #333c4c;
    --accent: #818cf8;
    --accent-strong: #a5b0ff;
    --accent-soft: rgba(129, 140, 248, 0.14);
    --accent-contrast: #0d1017;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-md: 0 6px 18px rgba(0, 0, 0, 0.45);
    --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.55);

    --junior: #4ade80;
    --mid: #60a5fa;
    --senior: #c084fc;
    --staff: #fbbf24;
    --principal: #f87171;

    --solid: #4ade80;
    --partial: #a3e635;
    --shaky: #fbbf24;
    --not-yet: #f87171;
  }
}

/* Explicit dark toggle wins regardless of OS preference */
:root[data-theme="dark"] {
  --bg: #0d1017;
  --bg-elevated: #141821;
  --surface: #161b25;
  --surface-2: #1d2430;
  --surface-3: #262f3d;
  --text: #e6e9ef;
  --text-soft: #b9c0cc;
  --text-muted: #8b94a3;
  --border: #262d3a;
  --border-strong: #333c4c;
  --accent: #818cf8;
  --accent-strong: #a5b0ff;
  --accent-soft: rgba(129, 140, 248, 0.14);
  --accent-contrast: #0d1017;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 6px 18px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.55);

  --junior: #4ade80;
  --mid: #60a5fa;
  --senior: #c084fc;
  --staff: #fbbf24;
  --principal: #f87171;

  --solid: #4ade80;
  --partial: #a3e635;
  --shaky: #fbbf24;
  --not-yet: #f87171;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 24px; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

h1, h2, h3, h4 { line-height: 1.25; letter-spacing: -0.01em; }

/* ---------- Layout ---------- */

.layout { display: flex; min-height: 100vh; align-items: stretch; }

.sidebar {
  width: var(--sidebar-width);
  flex-shrink: 0;
  background: var(--bg-elevated);
  border-right: 1px solid var(--border);
  padding: 22px 16px 32px;
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
}

.sidebar-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 26px;
  padding: 0 6px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
}
.brand:hover { color: var(--text); }
.brand-mark {
  color: var(--accent);
  font-size: 0.95rem;
  transform: translateY(-1px);
}

.theme-btn {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-2);
  color: var(--text-soft);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.theme-btn:hover { background: var(--surface-3); color: var(--text); border-color: var(--border-strong); }
.theme-icon { grid-area: 1 / 1; transition: opacity 0.2s ease, transform 0.2s ease; }
.theme-icon-sun { opacity: 0; transform: rotate(-40deg) scale(0.6); }
.theme-icon-moon { opacity: 1; }
:root[data-theme="dark"] .theme-icon-sun { opacity: 1; transform: none; }
:root[data-theme="dark"] .theme-icon-moon { opacity: 0; transform: rotate(40deg) scale(0.6); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-icon-sun { opacity: 1; transform: none; }
  :root:not([data-theme="light"]) .theme-icon-moon { opacity: 0; transform: rotate(40deg) scale(0.6); }
}

.nav { margin-bottom: 24px; }
.nav-section {
  font-size: 0.68rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--text-muted);
  margin: 0 0 8px;
  padding: 0 10px;
}
.nav ul { list-style: none; margin: 0; padding: 0; }
.nav li { margin: 2px 0; }
.nav-link {
  display: block;
  padding: 7px 11px;
  border-radius: var(--radius-sm);
  color: var(--text-soft);
  font-size: 0.92rem;
  font-weight: 500;
  transition: background 0.12s ease, color 0.12s ease;
}
.nav-link:hover { background: var(--surface-2); color: var(--text); }
.nav-link.active {
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-weight: 600;
}

.main-col { flex: 1; min-width: 0; display: flex; flex-direction: column; }

.topbar {
  display: none;
  align-items: center;
  gap: 14px;
  padding: 12px 18px;
  background: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 20;
}
.topbar-brand { font-weight: 700; color: var(--text); letter-spacing: -0.02em; }
.nav-burger {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 34px;
  height: 34px;
  padding: 8px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-2);
  cursor: pointer;
}
.nav-burger span { display: block; height: 2px; background: var(--text-soft); border-radius: 2px; }

.content {
  flex: 1;
  width: 100%;
  max-width: var(--content-width);
  margin: 0 auto;
  padding: 44px 48px 80px;
}

/* ---------- Hero / headers ---------- */

.hero { margin-bottom: 40px; }
.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 0 10px;
}
.hero h1 {
  font-size: clamp(2rem, 4vw, 2.9rem);
  margin: 0 0 14px;
  font-weight: 800;
}
.lead {
  color: var(--text-soft);
  font-size: 1.12rem;
  max-width: 62ch;
  margin: 0;
}

.stat-row {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 28px;
}
.stat {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 14px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 92px;
  box-shadow: var(--shadow-sm);
}
.stat-value { font-size: 1.6rem; font-weight: 800; color: var(--text); letter-spacing: -0.02em; }
.stat-label { font-size: 0.78rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.05em; }

.page-header { margin-bottom: 34px; }
.page-header h1 { font-size: clamp(1.7rem, 3vw, 2.3rem); margin: 10px 0 12px; font-weight: 800; }

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  font-size: 0.85rem;
  margin: 0 0 4px;
}
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb .sep { opacity: 0.5; }

/* ---------- Cards ---------- */

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 20px;
}
.card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  color: var(--text);
  box-shadow: var(--shadow-sm);
  transition: transform 0.16s ease, border-color 0.16s ease, box-shadow 0.16s ease;
}
.card:hover {
  transform: translateY(-3px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-lg);
  color: var(--text);
}
.card-body { flex: 1; }
.card-body h2 { margin: 0 0 8px; font-size: 1.22rem; font-weight: 700; }
.card-body p { margin: 0 0 12px; color: var(--text-muted); font-size: 0.92rem; }
.card-footer { margin-top: 18px; }

/* ---------- Progress ---------- */

.progress {
  height: 7px;
  background: var(--surface-3);
  border-radius: var(--radius-pill);
  overflow: hidden;
}
.progress-lg { height: 9px; max-width: 420px; margin-top: 6px; }
.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
  border-radius: var(--radius-pill);
  transition: width 0.4s ease;
}
.progress-meta {
  display: flex;
  justify-content: space-between;
  margin-top: 8px;
  font-size: 0.78rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* ---------- Badges ---------- */

.badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  border: 1px solid transparent;
  white-space: nowrap;
}
.badge-status { background: var(--surface-2); color: var(--text-muted); border-color: var(--border); }
.badge-id {
  background: var(--surface-2);
  color: var(--text-soft);
  border-color: var(--border);
  font-family: var(--font-mono);
  text-transform: none;
  letter-spacing: 0;
}
.badge-prereq {
  background: var(--accent-soft);
  color: var(--accent-strong);
  border-color: transparent;
  text-transform: none;
  font-family: var(--font-mono);
  letter-spacing: 0;
}

.badge-seniority-junior { background: color-mix(in srgb, var(--junior) 14%, transparent); color: var(--junior); border-color: color-mix(in srgb, var(--junior) 32%, transparent); }
.badge-seniority-mid { background: color-mix(in srgb, var(--mid) 14%, transparent); color: var(--mid); border-color: color-mix(in srgb, var(--mid) 32%, transparent); }
.badge-seniority-senior { background: color-mix(in srgb, var(--senior) 14%, transparent); color: var(--senior); border-color: color-mix(in srgb, var(--senior) 32%, transparent); }
.badge-seniority-staff { background: color-mix(in srgb, var(--staff) 14%, transparent); color: var(--staff); border-color: color-mix(in srgb, var(--staff) 32%, transparent); }
.badge-seniority-principal { background: color-mix(in srgb, var(--principal) 14%, transparent); color: var(--principal); border-color: color-mix(in srgb, var(--principal) 32%, transparent); }

.badge-mastery-solid { background: color-mix(in srgb, var(--solid) 14%, transparent); color: var(--solid); border-color: color-mix(in srgb, var(--solid) 32%, transparent); }
.badge-mastery-partial { background: color-mix(in srgb, var(--partial) 14%, transparent); color: var(--partial); border-color: color-mix(in srgb, var(--partial) 32%, transparent); }
.badge-mastery-shaky { background: color-mix(in srgb, var(--shaky) 14%, transparent); color: var(--shaky); border-color: color-mix(in srgb, var(--shaky) 32%, transparent); }
.badge-mastery-not-yet { background: color-mix(in srgb, var(--not-yet) 14%, transparent); color: var(--not-yet); border-color: color-mix(in srgb, var(--not-yet) 32%, transparent); }
.badge-mastery-discussed { background: var(--accent-soft); color: var(--accent-strong); border-color: transparent; }

/* ---------- Lesson list ---------- */

.lesson-list { display: flex; flex-direction: column; gap: 8px; }
.lesson-row {
  display: flex;
  align-items: center;
  gap: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 15px 20px;
  color: var(--text);
  box-shadow: var(--shadow-sm);
  transition: transform 0.14s ease, border-color 0.14s ease, box-shadow 0.14s ease;
}
.lesson-row:hover {
  transform: translateX(3px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
  color: var(--text);
}
.lesson-row.is-done { border-left: 3px solid var(--solid); }
.lesson-number {
  font-family: var(--font-mono);
  color: var(--text-muted);
  font-size: 0.88rem;
  min-width: 26px;
  font-weight: 600;
}
.lesson-main { flex: 1; display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.lesson-title { font-weight: 600; font-size: 1rem; }
.lesson-read { font-size: 0.76rem; color: var(--text-muted); }
.lesson-badges { display: flex; gap: 8px; flex-wrap: wrap; justify-content: flex-end; }

/* ---------- Lesson page ---------- */

.lesson { max-width: 100%; }
.lesson-header { margin-bottom: 32px; padding-bottom: 24px; border-bottom: 1px solid var(--border); }
.lesson-header h1 { font-size: clamp(1.8rem, 3.4vw, 2.5rem); margin: 12px 0 18px; font-weight: 800; }
.lesson-meta { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.meta-dot { color: var(--text-muted); }
.meta-read { color: var(--text-muted); font-size: 0.9rem; }
.meta-source { color: var(--text-muted); font-size: 0.9rem; margin: 14px 0 0; font-style: italic; }
.lesson-prereqs { margin-top: 16px; display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.prereq-label { font-size: 0.82rem; font-weight: 600; color: var(--text-soft); text-transform: uppercase; letter-spacing: 0.04em; }

.lesson-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 220px;
  gap: 48px;
  align-items: start;
}

.lesson-toc {
  position: sticky;
  top: 24px;
  font-size: 0.88rem;
  border-left: 1px solid var(--border);
  padding-left: 18px;
}
.toc-title {
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 700;
  color: var(--text-muted);
  margin: 0 0 10px;
}
.lesson-toc ul { list-style: none; margin: 0; padding: 0; }
.lesson-toc > .toc ul ul { padding-left: 12px; }
.lesson-toc li { margin: 3px 0; }
.lesson-toc a {
  display: block;
  color: var(--text-muted);
  padding: 3px 0;
  line-height: 1.4;
  border-left: 2px solid transparent;
  transition: color 0.12s ease;
}
.lesson-toc a:hover { color: var(--accent); }

/* ---------- Reading typography ---------- */

.markdown-body {
  color: var(--text);
  font-size: 1.05rem;
  max-width: var(--reading-width);
}
.markdown-body > *:first-child { margin-top: 0; }
.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4 {
  margin-top: 2.2em;
  margin-bottom: 0.6em;
  color: var(--text);
  scroll-margin-top: 24px;
}
.markdown-body h2 {
  font-size: 1.55rem;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
  font-weight: 700;
}
.markdown-body h3 { font-size: 1.25rem; font-weight: 700; }
.markdown-body h4 { font-size: 1.05rem; font-weight: 700; }
.markdown-body p { margin: 0 0 18px; }
.markdown-body ul, .markdown-body ol { margin: 0 0 18px; padding-left: 26px; }
.markdown-body li { margin-bottom: 7px; }
.markdown-body li::marker { color: var(--text-muted); }
.markdown-body a { color: var(--accent); text-decoration: underline; text-underline-offset: 2px; text-decoration-thickness: 1px; }
.markdown-body a:hover { color: var(--accent-strong); }
.markdown-body strong { font-weight: 700; color: var(--text); }
.markdown-body hr { border: none; border-top: 1px solid var(--border); margin: 32px 0; }

/* Heading permalinks from the toc extension */
.markdown-body .headerlink {
  opacity: 0;
  margin-left: 8px;
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 400;
}
.markdown-body h2:hover .headerlink,
.markdown-body h3:hover .headerlink,
.markdown-body h4:hover .headerlink { opacity: 1; }

.markdown-body code {
  font-family: var(--font-mono);
  background: var(--surface-2);
  padding: 0.15em 0.4em;
  border-radius: 5px;
  font-size: 0.88em;
  border: 1px solid var(--border);
}
.markdown-body pre {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  overflow-x: auto;
  margin: 0 0 22px;
  box-shadow: var(--shadow-sm);
  line-height: 1.55;
}
.markdown-body pre code {
  background: transparent;
  padding: 0;
  border: none;
  font-size: 0.86rem;
}
.markdown-body .highlight { margin: 0 0 22px; }
.markdown-body .highlight pre { margin: 0; }

.markdown-body table {
  width: 100%;
  border-collapse: collapse;
  margin: 0 0 22px;
  font-size: 0.95rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.markdown-body th, .markdown-body td {
  border-bottom: 1px solid var(--border);
  padding: 11px 15px;
  text-align: left;
}
.markdown-body th { background: var(--surface-2); font-weight: 700; }
.markdown-body tbody tr:last-child td { border-bottom: none; }
.markdown-body tbody tr:hover { background: var(--surface-2); }

.markdown-body blockquote {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  margin: 0 0 22px;
  padding: 12px 20px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-soft);
}
.markdown-body blockquote p:last-child { margin-bottom: 0; }

/* ---------- Prev / next ---------- */

.lesson-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 52px;
  padding-top: 28px;
  border-top: 1px solid var(--border);
}
.lesson-nav-link {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 16px 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  color: var(--text);
  transition: border-color 0.14s ease, box-shadow 0.14s ease, transform 0.14s ease;
}
.lesson-nav-link:hover { border-color: var(--border-strong); box-shadow: var(--shadow-md); transform: translateY(-2px); color: var(--text); }
.lesson-nav-link.next { text-align: right; align-items: flex-end; }
.lesson-nav-link .dir { font-size: 0.78rem; color: var(--accent); font-weight: 600; }
.lesson-nav-link .lbl { font-weight: 600; }

/* ---------- Responsive ---------- */

.nav-toggle:checked ~ .layout .sidebar { display: block; }

@media (max-width: 960px) {
  .layout { flex-direction: column; }
  .topbar { display: flex; }
  .sidebar {
    display: none;
    width: 100%;
    height: auto;
    position: static;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }
  .sidebar-head .theme-btn { display: none; }
  .content { padding: 28px 22px 64px; }
  .lesson-layout { grid-template-columns: 1fr; gap: 0; }
  .lesson-toc { display: none; }
}

@media (max-width: 560px) {
  .lesson-row { flex-wrap: wrap; gap: 10px; }
  .lesson-badges { justify-content: flex-start; width: 100%; }
  .lesson-nav { grid-template-columns: 1fr; }
  .lesson-nav-link.next { text-align: left; align-items: flex-start; }
  .stat { flex: 1; min-width: 0; }
}