/* ===========================
   Teach Me — Global Styles
   =========================== */

/* --- Theme variables (dark) --- */
:root[data-theme="dark"] {
  --accent: #61afef;
  --accent-hover: #8dd0ff;
  --bg: #1e2127;
  --bg-raised: #282c34;
  --bg-surface: #2c313a;
  --text: #e0e4eb;
  --text-heading: #fff;
  --text-h2: #e5c07b;
  --text-h3: #c678dd;
  --muted: #8b92a0;
  --border: #3e4451;
  --code-bg: #2c313a;
  --code-text: #98c379;
  --code-block-bg: #282c34;
  --code-block-text: #abb2bf;
  --code-block-border: #3e4451;
  --key-concept-bg: #2c313a;
  --demo-bg: #282c34;
  --demo-border: #4b5263;
  --quiz-bg: #282c34;
  --quiz-hover: #3e4451;
  --quiz-correct-bg: #2e4a35;
  --quiz-correct-border: #98c379;
  --quiz-correct-text: #98c379;
  --quiz-incorrect-bg: #4a2c2c;
  --quiz-incorrect-border: #e06c75;
  --quiz-incorrect-text: #e06c75;
  --recommended-bg: #2c313a;
  --recommended-border: #4b5263;
  --ask-bg: #2d2640;
  --ask-border: #4b3d6b;
  --ask-text: #c678dd;
  --copy-btn-bg: #3e4451;
  --copy-btn-text: #98c379;
  --copy-btn-hover-bg: #4b5263;
  --copy-btn-hover-text: #e5c07b;
  --toggle-bg: #3e4451;
  --warning-bg: #3d2e1e;
  --warning-border: #e5c07b;
  --warning-text: #e5c07b;
}

/* --- Theme variables (light) --- */
:root[data-theme="light"] {
  --accent: #1a73e8;
  --accent-hover: #1557b0;
  --bg: #fffff8;
  --bg-raised: #f9f8f3;
  --bg-surface: #f3f2ed;
  --text: #111;
  --text-heading: #111;
  --text-h2: #8b5e00;
  --text-h3: #6d28d9;
  --muted: #555;
  --border: #ddd;
  --code-bg: #f5f5f0;
  --code-text: #16803d;
  --code-block-bg: #1e293b;
  --code-block-text: #e2e8f0;
  --code-block-border: #334155;
  --key-concept-bg: #f5f3e8;
  --demo-bg: #f9f8f3;
  --demo-border: #d4d0c8;
  --quiz-bg: #f9f8f3;
  --quiz-hover: #eeece4;
  --quiz-correct-bg: #dcfce7;
  --quiz-correct-border: #16a34a;
  --quiz-correct-text: #15803d;
  --quiz-incorrect-bg: #fee2e2;
  --quiz-incorrect-border: #dc2626;
  --quiz-incorrect-text: #b91c1c;
  --recommended-bg: #fefce8;
  --recommended-border: #e8d44d;
  --ask-bg: #f8f5ff;
  --ask-border: #c4b5fd;
  --ask-text: #6d28d9;
  --copy-btn-bg: #334155;
  --copy-btn-text: #a7f3d0;
  --copy-btn-hover-bg: #475569;
  --copy-btn-hover-text: #fef08a;
  --toggle-bg: #eeece4;
  --warning-bg: #fef9e7;
  --warning-border: #d4a017;
  --warning-text: #92400e;
}

/* --- Progress bar (scroll-driven) --- */
@keyframes progress-fill { from { transform: scaleX(0); } to { transform: scaleX(1); } }
.progress-bar {
  position: fixed; top: 0; left: 0; right: 0; height: 4px;
  background: var(--accent); transform-origin: left;
  animation: progress-fill linear; animation-timeline: scroll();
  z-index: 9999;
}

/* --- Skip link (accessibility) --- */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--accent);
  color: #fff;
  padding: 0.5rem 1rem;
  z-index: 10000;
  font-size: 0.9rem;
  text-decoration: none;
  border-radius: 0 0 4px 0;
}
.skip-link:focus {
  top: 0;
}

/* --- Reset & base typography --- */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.7; color: var(--text); background: var(--bg);
  transition: background 0.3s, color 0.3s;
}
h1 { font-size: 2rem; margin-bottom: 0.3rem; color: var(--text-heading); }
h2 { font-size: 1.4rem; margin-top: 2.5rem; margin-bottom: 0.75rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; color: var(--text-h2); }
h3 { font-size: 1.1rem; margin-top: 1.8rem; margin-bottom: 0.5rem; color: var(--text-h3); }
p, ul, ol { margin-bottom: 1rem; }
ul, ol { padding-left: 1.5rem; }
li { margin-bottom: 0.4rem; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; color: var(--accent-hover); }
code { font-family: 'SF Mono', 'Fira Code', monospace; font-size: 0.88em; background: var(--code-bg); padding: 0.15em 0.4em; border-radius: 3px; color: var(--code-text); }
strong { color: var(--text-heading); }

/* --- Layout: sidebar + content --- */
.page-layout {
  display: flex;
  min-height: 100vh;
}
.sidebar {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: 260px;
  background: var(--bg-raised);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 1rem 0;
  z-index: 100;
  font-size: 0.82rem;
  transition: background 0.3s, border-color 0.3s;
}
.sidebar-header {
  padding: 0.5rem 1rem 1rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 0.75rem;
}
.sidebar-header a {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--text-heading);
  text-decoration: none;
}
.sidebar-header a:hover { color: var(--accent); }
.sidebar-section-title {
  padding: 0.5rem 1rem 0.3rem;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  font-weight: 600;
}
.sidebar ul { list-style: none; padding: 0; margin: 0; }
.sidebar li a {
  display: block;
  padding: 0.15rem 1rem;
  color: var(--muted);
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: background 0.15s, color 0.15s, border-color 0.15s;
}
.sidebar li a:hover {
  background: var(--bg-surface);
  color: var(--text);
}
.sidebar li a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: var(--bg-surface);
  font-weight: 600;
}
.sidebar li.current > a {
  color: var(--text-heading);
  font-weight: 700;
}
.sidebar .toc-list { margin-top: 0.5rem; }
.sidebar .toc-list li a { padding-left: 1.5rem; font-size: 0.78rem; }
.sidebar .toc-list li.toc-h2 { margin-top: 0.35rem; }
.sidebar .toc-list li.toc-h2:first-child { margin-top: 0; }
.sidebar .toc-list li.toc-h3 { margin-top: 0; }
.sidebar .toc-list li.toc-h3 a { padding-left: 2.8rem; font-size: 0.78rem; padding-top: 0; padding-bottom: 0; line-height: 1.3; opacity: 0.6; }
.sidebar .toc-list li a.toc-active {
  color: var(--accent);
  border-left-color: var(--accent);
}

.main-content {
  max-width: 800px;
  width: 100%;
  padding: 3rem 2rem 4rem;
  margin-left: calc(260px + max(2rem, (100vw - 260px - 800px - 200px) / 2));
  margin-right: 200px;
}

/* Narrow screens: hide sidebar, revert to centred single column */
@media (max-width: 1350px) {
  .main-content {
    margin-right: auto;
    margin-left: calc(260px + max(2rem, (100vw - 260px - 800px) / 2));
  }
}
@media (max-width: 1100px) {
  .sidebar { display: none; }
  .main-content {
    margin-left: 0;
    margin-right: auto;
    max-width: 900px;
    margin: 0 auto;
    padding: 3rem 1.5rem 4rem;
  }
}

/* --- Shared header (non-lesson pages) --- */
.site-header {
  border-bottom: 1px solid var(--border);
  padding: 1rem 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.site-header a {
  color: var(--text-heading);
  text-decoration: none;
  font-weight: 600;
  font-size: 1.25rem;
}
.site-header nav {
  display: flex;
  align-items: center;
}
.site-header nav a {
  font-size: 1rem;
  font-weight: 400;
  margin-left: 1.5rem;
  color: var(--accent);
}
.site-header nav a:hover {
  text-decoration: underline;
}

/* --- Shared footer --- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 2rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.875rem;
}
.site-footer a {
  color: var(--accent);
  text-decoration: none;
}
.site-footer a:hover {
  text-decoration: underline;
}

/* --- Page content (non-lesson pages) --- */
.page-content {
  flex: 1;
  max-width: 720px;
  margin: 4rem auto;
  padding: 0 2rem;
}
.page-content h1 { margin-bottom: 0.5rem; }
.page-content .tagline {
  color: var(--muted);
  font-size: 1.125rem;
  margin-bottom: 3rem;
}
.page-content h2 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
  margin-top: 2.5rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border-bottom: none;
  padding-bottom: 0;
}
.page-content h2:first-of-type { margin-top: 0; }

/* --- Course list (root index) --- */
.course-list { list-style: none; padding-left: 0; }
.course-list li { margin-bottom: 1.5rem; }
.course-list a { color: var(--accent); text-decoration: none; font-size: 1.25rem; font-weight: 500; }
.course-list a:hover { text-decoration: underline; }
.course-list .description { color: var(--muted); font-size: 0.95rem; margin-top: 0.25rem; }

/* --- Lesson list (course index) --- */
.lesson-list { list-style: none; padding-left: 0; counter-reset: lesson; }
.lesson-list li { margin-bottom: 0.75rem; }
.lesson-list a { color: var(--accent); text-decoration: none; font-size: 1.1rem; }
.lesson-list a:hover { text-decoration: underline; }
.lesson-number { color: var(--muted); font-size: 0.9rem; display: inline-block; width: 2rem; }

/* --- Reference list (course index) --- */
.reference-list { list-style: none; padding-left: 0; }
.reference-list li { margin-bottom: 0.75rem; }
.reference-list a { color: var(--accent); text-decoration: none; font-size: 1.1rem; }
.reference-list a:hover { text-decoration: underline; }

/* --- Lesson chrome --- */
.back-link { display: inline-block; margin-bottom: 1.5rem; font-size: 0.9rem; }
.lesson-num { color: var(--muted); font-size: 0.9rem; text-transform: uppercase; letter-spacing: 0.05em; }

/* --- Key concept & warning callouts --- */
.key-concept { background: var(--key-concept-bg); border-left: 4px solid var(--accent); padding: 1rem 1.2rem; margin: 1.5rem 0; border-radius: 0 4px 4px 0; }
.key-concept > strong:first-child { display: block; margin-bottom: 0.3rem; color: var(--text-h2); }
.key-concept p { margin-top: 0.5rem; margin-bottom: 0; }
.key-concept ul, .key-concept ol { margin-top: 0.4rem; margin-bottom: 0; padding-left: 1.3rem; }
.warning { background: var(--warning-bg); border-left: 4px solid var(--warning-border); padding: 1rem 1.2rem; margin: 1.5rem 0; border-radius: 0 4px 4px 0; }
.warning > strong:first-child { display: block; margin-bottom: 0.3rem; color: var(--warning-text); }
.warning p { margin-top: 0.5rem; margin-bottom: 0; }

/* --- Code blocks with copy button --- */
.code-wrapper { position: relative; margin: 1.2rem 0; }
.code-wrapper pre {
  background: var(--code-block-bg); color: var(--code-block-text); padding: 1.2rem 1.4rem;
  border-radius: 6px; overflow-x: auto; font-size: 0.85rem; line-height: 1.6;
  border: 1px solid var(--code-block-border);
}
.code-wrapper pre code { background: none; padding: 0; border-radius: 0; color: inherit; font-size: inherit; }
.copy-btn {
  position: absolute; top: 0.6rem; right: 0.6rem;
  background: var(--copy-btn-bg); color: var(--copy-btn-text); border: none; padding: 0.3rem 0.6rem;
  border-radius: 4px; font-size: 0.75rem; cursor: pointer; opacity: 0; transition: opacity 0.2s;
}
.code-wrapper:hover .copy-btn { opacity: 1; }
.copy-btn:hover { background: var(--copy-btn-hover-bg); color: var(--copy-btn-hover-text); }
.copy-btn.copied { background: #16a34a; color: #fff; }

/* --- Demo area --- */
.demo { border: 1px solid var(--border); border-radius: 6px; padding: 1.5rem; margin: 1.5rem 0; background: var(--demo-bg); }
.demo svg { display: block; margin: 0 auto; }
.demo svg.bordered { border: 1px dashed var(--demo-border); border-radius: 4px; }
.demo-caption { text-align: center; font-size: 0.85rem; color: var(--muted); margin-top: 0.8rem; }
.demo-controls { display: flex; gap: 1rem; flex-wrap: wrap; margin-top: 1rem; align-items: center; justify-content: center; }
.demo-controls label { font-size: 0.85rem; color: var(--muted); }
.demo-controls input[type="range"] { width: 120px; }
.demo-controls button, .demo-btn {
  padding: 0.4rem 1rem;
  border-radius: 4px;
  border: 1px solid var(--border);
  background: var(--bg-surface);
  color: var(--text);
  cursor: pointer;
  font-size: 0.85rem;
}
.demo-controls button:hover, .demo-btn:hover {
  background: var(--bg-raised);
}

/* --- Quiz --- */
.quiz { background: var(--quiz-bg); border: 1px solid var(--border); border-radius: 6px; padding: 1.5rem; margin: 2rem 0; }
.quiz h3 { margin-top: 0; color: var(--text); }
.quiz-option { display: block; margin: 0.5rem 0; padding: 0.6rem 1rem; border: 1px solid var(--border); border-radius: 4px; cursor: pointer; transition: background 0.15s; color: var(--text); }
.quiz-option:hover { background: var(--quiz-hover); }
.quiz-option.correct { background: var(--quiz-correct-bg); border-color: var(--quiz-correct-border); color: var(--quiz-correct-text); }
.quiz-option.incorrect { background: var(--quiz-incorrect-bg); border-color: var(--quiz-incorrect-border); color: var(--quiz-incorrect-text); }
.quiz-feedback { margin-top: 0.8rem; font-size: 0.9rem; min-height: 1.4rem; }

/* --- Footer nav (lesson pages) --- */
.footer-nav { margin-top: 3rem; padding-top: 1.5rem; border-top: 1px solid var(--border); display: flex; justify-content: space-between; font-size: 0.9rem; }
.recommended { background: var(--recommended-bg); border: 1px solid var(--recommended-border); border-radius: 6px; padding: 1rem 1.2rem; margin: 1.5rem 0; }
.recommended > strong:first-child { display: block; margin-bottom: 0.3rem; color: var(--text-h2); }
.ask-kiro { background: var(--ask-bg); border: 1px solid var(--ask-border); border-radius: 6px; padding: 1rem 1.2rem; margin: 1.5rem 0; font-size: 0.9rem; color: var(--ask-text); }

/* --- Theme toggle --- */
.theme-toggle {
  background: var(--toggle-bg); border: 1px solid var(--border);
  border-radius: 50%; width: 2.2rem; height: 2.2rem;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer; font-size: 1rem; z-index: 9999;
  transition: background 0.3s, border-color 0.3s;
  margin-left: 1rem;
}
.theme-toggle:hover { transform: scale(1.1); }

/* --- Tables --- */
table { width: 100%; border-collapse: collapse; font-size: 0.88em; margin: 1rem 0; }
th, td { text-align: left; padding: 0.5rem 0.7rem; border-bottom: 1px solid var(--border); }
th { color: var(--text-heading); font-weight: 600; }

/* --- Auto-linked reference links on code elements --- */
a.ref-link { text-decoration: none; border-bottom: 1px dotted var(--accent); }
a.ref-link:hover { border-bottom-style: solid; }
a.ref-link code { color: var(--code-text); }
a.ref-link:hover code { color: var(--accent); }

/* --- Reference doc element entries --- */
.element-entry strong.example-label { font-size: 0.82rem; color: var(--muted); }
.element-entry pre { background: var(--code-block-bg); color: var(--code-block-text); padding: 0.8rem 1rem; border-radius: 5px; overflow-x: auto; font-size: 0.8rem; line-height: 1.5; margin-top: 0.3rem; }

/* --- Ad placeholders (CLS-compliant) --- */
.ad-sidebar {
  position: fixed;
  top: 5rem;
  right: 1.5rem;
  width: 160px;
  min-height: 600px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  z-index: 50;
}

.ad-inline {
  width: 100%;
  min-height: 90px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  margin: 2.5rem 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.ad-footer {
  width: 100%;
  min-height: 90px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  margin: 2rem 0 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Hide sidebar ad on screens too narrow to fit it */
@media (max-width: 1350px) {
  .ad-sidebar { display: none; }
}

/* Hide all ad placeholders on mobile */
@media (max-width: 1100px) {
  .ad-sidebar { display: none; }
  .ad-inline { display: none; }
  .ad-footer { display: none; }
}