/* study-engine portal — landing styles.
   Dark by default (dev tool, late-night usage). Light via prefers-color-scheme.
   CSS variable naming mirrors engine/templates/course.html.j2 where possible
   so the landing feels consistent with individual course shells. */

:root {
  --bg: #f6f4fb;
  --bg-elev: #ffffff;
  --bg-soft: #efeaf7;
  --fg: #191428;
  --fg-dim: #5a5273;
  --muted: #8b859d;
  --border: #e3dcf1;
  --border-hi: #c9bfe2;
  --card: #ffffff;
  --card-hover: #fbf8ff;
  --accent: #6441cc;
  --accent-soft: rgba(100, 65, 204, 0.12);
  --accent-ink: #ffffff;
  --mark-bg: rgba(100, 65, 204, 0.22);
  --mark-fg: #1a0e3b;
  --danger: #ff3b30;
  --radius: 12px;
  --radius-sm: 8px;
  --radius-lg: 18px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --shadow-sm: 0 1px 2px rgba(30, 20, 60, 0.06);
  --shadow-md: 0 6px 18px rgba(30, 20, 60, 0.08);
  --shadow-lg: 0 20px 44px rgba(30, 20, 60, 0.14);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "JetBrains Mono", Menlo, Consolas, monospace;
  --course-accent: var(--accent);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
a { color: var(--accent); text-decoration: none; }
a:hover, a:focus-visible { text-decoration: underline; }
code {
  font-family: var(--font-mono);
  font-size: 0.9em;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  padding: 1px 6px;
  border-radius: 4px;
}
.skip-link { position: absolute; left: -9999px; top: auto; }
.skip-link:focus {
  left: var(--space-4); top: var(--space-4);
  background: var(--accent); color: var(--accent-ink);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm); z-index: 100;
}

/* ───── Header ───── */
.site-header {
  display: flex; flex-wrap: wrap; gap: var(--space-4);
  align-items: center; justify-content: space-between;
  padding: var(--space-5) var(--space-6);
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--bg-elev) 0%, var(--bg) 100%);
  position: sticky; top: 0; z-index: 10;
  backdrop-filter: blur(8px);
}
.brand { display: flex; align-items: center; gap: var(--space-3); }
.brand-mark {
  width: 44px; height: 44px;
  border-radius: var(--radius);
  background: var(--accent); color: var(--accent-ink);
  display: grid; place-items: center;
  font-weight: 700; font-size: 20px;
  box-shadow: var(--shadow-sm);
}
.brand-title { margin: 0; font-size: 20px; font-weight: 700; letter-spacing: -0.01em; }
.brand-subtitle { margin: 0; font-size: 13px; color: var(--fg-dim); }
.site-nav {
  flex: 1 1 320px; min-width: 260px;
  display: flex; justify-content: flex-end;
}

/* ───── Search ───── */
.search { position: relative; width: 100%; max-width: 480px; }
.search-label { position: absolute; left: -9999px; }
#search-input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--fg);
  font: inherit; outline: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}
#search-input::placeholder { color: var(--muted); }
#search-input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
.search-hint {
  position: absolute; top: calc(100% + var(--space-2)); left: 0; right: 0;
  padding: var(--space-2) var(--space-3);
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--fg-dim); font-size: 13px;
  box-shadow: var(--shadow-md);
}
.search-results {
  position: absolute; top: calc(100% + var(--space-2)); left: 0; right: 0;
  max-height: 60vh; overflow-y: auto;
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow-lg);
  padding: var(--space-2); z-index: 20;
}
.search-result {
  display: block; padding: var(--space-3);
  border-radius: var(--radius-sm);
  color: inherit; text-decoration: none;
  border: 1px solid transparent; cursor: pointer;
}
.search-result + .search-result { margin-top: 2px; }
.search-result:hover,
.search-result:focus-visible,
.search-result.is-active {
  background: var(--accent-soft);
  border-color: var(--border-hi);
  text-decoration: none;
}
.search-result-head {
  display: flex; gap: var(--space-2); align-items: center;
  margin-bottom: var(--space-1);
  font-size: 12px; color: var(--fg-dim);
}
.search-result-kind {
  display: inline-block; padding: 1px 6px;
  border-radius: 999px;
  background: var(--bg-soft); border: 1px solid var(--border);
  text-transform: uppercase; letter-spacing: 0.05em;
  font-size: 10px;
}
.search-result-course { font-weight: 600; color: var(--fg); }
.search-result-title { font-weight: 600; color: var(--fg); margin-bottom: 2px; }
.search-result-snippet {
  font-size: 13px; color: var(--fg-dim); line-height: 1.4;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical;
  overflow: hidden;
}
.search-result mark,
.search-result-snippet mark {
  background: var(--mark-bg); color: var(--mark-fg);
  padding: 0 2px; border-radius: 2px;
}
.search-empty {
  padding: var(--space-4); text-align: center;
  color: var(--fg-dim); font-size: 14px;
}

/* ───── Main / cards ───── */
.site-main {
  padding: var(--space-6);
  max-width: 1280px; width: 100%; margin: 0 auto;
}
.section-head {
  display: flex; align-items: baseline; justify-content: space-between;
  gap: var(--space-4); margin-bottom: var(--space-5);
}
.section-title {
  margin: 0; font-size: 18px; font-weight: 600;
  color: var(--fg-dim); text-transform: uppercase; letter-spacing: 0.08em;
}
.section-meta { margin: 0; font-size: 13px; color: var(--muted); }
.courses-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-5);
}
.courses-loading {
  grid-column: 1 / -1; padding: var(--space-7);
  text-align: center; color: var(--fg-dim);
}
.course-card {
  position: relative;
  display: flex; flex-direction: column; gap: var(--space-3);
  padding: var(--space-5);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  color: inherit; text-decoration: none;
  transition: transform 0.18s ease, box-shadow 0.18s ease,
              border-color 0.18s ease, background 0.18s ease;
  overflow: hidden;
}
.course-card::before {
  content: "";
  position: absolute; inset: 0 0 auto 0; height: 3px;
  background: var(--course-accent, var(--accent));
  opacity: 0.85;
}
.course-card.is-visible { animation: card-in 0.35s ease forwards; }
@keyframes card-in {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
.course-card:hover,
.course-card:focus-visible {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: var(--border-hi);
  background: var(--card-hover);
  text-decoration: none; outline: none;
}
.course-card-head {
  display: flex; justify-content: space-between; align-items: flex-start;
  gap: var(--space-3);
}
.course-title {
  margin: 0; font-size: 18px; font-weight: 700;
  line-height: 1.25; color: var(--fg);
}
.course-lang {
  flex-shrink: 0; font-size: 10px;
  text-transform: uppercase; letter-spacing: 0.08em;
  padding: 3px 8px; border-radius: 999px;
  background: var(--course-accent, var(--accent));
  color: var(--accent-ink); font-weight: 700;
}
.course-subtitle { margin: 0; font-size: 14px; color: var(--fg-dim); line-height: 1.4; }
.course-lecturer { margin: 0; font-size: 13px; color: var(--muted); font-style: italic; }
.course-meta {
  display: flex; flex-wrap: wrap; gap: var(--space-2) var(--space-4);
  font-size: 12px; color: var(--fg-dim);
}
.course-meta-item { display: inline-flex; align-items: center; gap: var(--space-1); }
.course-build { opacity: 0.6; font-size: 11px; font-variant-numeric: tabular-nums; }
.course-features { display: flex; gap: var(--space-2); flex-wrap: wrap; }
.feature-badge {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 3px 8px; border-radius: 999px;
  background: var(--bg-soft); border: 1px solid var(--border);
  font-size: 11px; color: var(--fg-dim); text-transform: lowercase;
}
.feature-badge[data-feature="chat"]    { color: #1a8a3e; }
.feature-badge[data-feature="podcast"] { color: #b07818; }
.feature-badge[data-feature="search"]  { color: #2a6cb5; }
.course-tags { display: flex; flex-wrap: wrap; gap: var(--space-1); margin-top: auto; }
.course-tag {
  font-size: 11px; padding: 2px 8px; border-radius: 999px;
  background: var(--accent-soft);
  color: var(--course-accent, var(--accent));
  border: 1px solid transparent;
}
.course-progress {
  font-size: 12px; color: var(--fg-dim);
  padding-top: var(--space-2); border-top: 1px dashed var(--border);
}
.course-progress-bar {
  display: block; height: 4px;
  background: var(--bg-soft); border-radius: 999px;
  overflow: hidden; margin-top: var(--space-1);
}
.course-progress-bar > span {
  display: block; height: 100%;
  background: var(--course-accent, var(--accent));
  transition: width 0.4s ease;
}

/* ───── Empty state ───── */
.empty-state {
  grid-column: 1 / -1;
  padding: var(--space-7); text-align: center;
  background: var(--card);
  border: 1px dashed var(--border-hi);
  border-radius: var(--radius-lg);
}
.empty-state h3 { margin: 0 0 var(--space-2) 0; font-size: 18px; }
.empty-state p { margin: 0; color: var(--fg-dim); font-size: 14px; }

/* ───── Footer ───── */
.site-footer {
  border-top: 1px solid var(--border);
  padding: var(--space-4) var(--space-6);
  display: flex; flex-wrap: wrap; gap: var(--space-2) var(--space-3);
  align-items: center; font-size: 12px; color: var(--fg-dim);
}
.footer-item { color: inherit; }
.footer-sep { color: var(--muted); }

/* ───── Responsive ───── */
@media (max-width: 640px) {
  .site-header { padding: var(--space-4); flex-direction: column; align-items: stretch; }
  .site-nav { flex: 0 1 auto; justify-content: stretch; min-width: 0; }
  .search { max-width: 100%; }
  .site-main { padding: var(--space-4); }
  .courses-grid { grid-template-columns: 1fr; gap: var(--space-4); }
  .site-footer { padding: var(--space-4); }
}
@media (prefers-reduced-motion: reduce) {
  .course-card,
  .course-card.is-visible {
    animation: none !important;
    transform: none !important;
    opacity: 1 !important;
    transition: none !important;
  }
}