/* منصة دوسية الطيف في الكيمياء — هوية الويب (من presentation-design-tokens) */
@font-face { font-family: 'Tajawal'; src: url('fonts/Tajawal-Regular.ttf') format('truetype'); font-weight: 400; font-display: swap; }
@font-face { font-family: 'Tajawal'; src: url('fonts/Tajawal-Medium.ttf') format('truetype'); font-weight: 500; font-display: swap; }
@font-face { font-family: 'Tajawal'; src: url('fonts/Tajawal-Bold.ttf') format('truetype'); font-weight: 700; font-display: swap; }
@font-face { font-family: 'Tajawal'; src: url('fonts/Tajawal-ExtraBold.ttf') format('truetype'); font-weight: 800; font-display: swap; }

:root {
  --bg: #05101F;
  --bg-alt: #0A1B33;
  --panel: #0E2440;
  --panel-light: #14305A;
  --line: #1D3A5F;
  --text: #ECF4FC;
  --strong: #FFFFFF;
  --muted: #93ADC6;
  --accent: #6FC7F2;
  --accent-soft: #3E86C0;
  --gold: #F2C14E;
  --gold-soft: rgba(242, 193, 78, 0.14);
  --radius: 16px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: 'Tajawal', Tahoma, 'Segoe UI', sans-serif;
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
.wrap { max-width: 1120px; margin-inline: auto; padding-inline: 24px; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---------- header ---------- */
.site-header {
  background: rgba(5, 16, 31, 0.92);
  border-bottom: 1px solid var(--line);
  position: sticky; top: 0; z-index: 20;
  backdrop-filter: blur(8px);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 16px; padding-block: 14px; flex-wrap: wrap; }
.brand { display: flex; align-items: center; gap: 12px; min-width: 0; }
.brand-logo { width: 42px; height: 42px; flex: none; }
.brand-name { font-weight: 800; font-size: 19px; color: var(--strong); letter-spacing: 0.2px; }
.brand-sub { font-size: 13px; color: var(--muted); }
.search-box {
  display: flex; align-items: center; gap: 8px;
  background: var(--panel); border: 1px solid var(--line);
  border-radius: 10px; padding: 8px 14px; color: var(--muted);
  min-width: 260px;
}
.search-box:focus-within { border-color: var(--accent); }
.search-box input {
  background: none; border: 0; outline: 0; color: var(--text);
  font: inherit; width: 100%;
}
.search-box input::placeholder { color: var(--muted); }

/* ---------- hero ---------- */
.hero { padding-block: 44px 8px; text-align: center; }
.hero h1 { font-size: 40px; line-height: 1.35; margin: 0 0 10px; color: var(--strong); font-weight: 800; }
.hero-accent { color: var(--gold); }
.hero-sub { color: var(--muted); margin: 0 auto; max-width: 560px; }

/* ---------- filters ---------- */
.filters { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; padding-block: 30px 10px; }
.u-chips { display: flex; gap: 8px; flex-wrap: wrap; }
.u-chip {
  font: inherit; font-size: 14px; cursor: pointer;
  color: var(--muted); background: var(--panel);
  border: 1px solid var(--line); border-radius: 999px;
  padding: 5px 16px; transition: border-color .15s, color .15s;
}
.u-chip:hover { color: var(--text); border-color: var(--accent-soft); }
.u-chip.is-active { color: #05101F; background: var(--accent); border-color: var(--accent); font-weight: 700; }
.sort-box { display: flex; align-items: center; gap: 8px; color: var(--muted); font-size: 14px; }
.sort-box select {
  font: inherit; font-size: 14px; color: var(--text);
  background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 6px 10px;
}
.count { color: var(--muted); font-size: 14px; margin: 4px 0 18px; }

/* ---------- grid & cards ---------- */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 22px;
  padding-bottom: 70px;
}
.lesson-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex; flex-direction: column;
  transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
}
.lesson-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-soft);
  box-shadow: 0 14px 34px rgba(0, 0, 0, 0.35);
}
.card-cover { display: block; aspect-ratio: 20 / 9; background: var(--bg-alt); }
.card-cover img, .card-motif { width: 100%; height: 100%; object-fit: cover; display: block; }
.card-body { padding: 18px 20px 20px; display: flex; flex-direction: column; gap: 8px; flex: 1; }
.card-chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  font-size: 13px; border-radius: 999px; padding: 2px 12px;
  background: var(--gold-soft); color: var(--gold); border: 1px solid rgba(242, 193, 78, 0.25);
}
.chip-meta { background: var(--bg-alt); color: var(--muted); border: 1px solid var(--line); }
.card-title { margin: 2px 0 0; font-size: 22px; font-weight: 800; line-height: 1.4; }
.card-title a { color: var(--strong); }
.card-subtitle { margin: 0; color: var(--accent); font-size: 15px; font-weight: 500; }
.card-desc {
  margin: 0; color: var(--muted); font-size: 14.5px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.card-foot { margin-top: auto; padding-top: 12px; display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.card-updated { font-size: 12.5px; color: var(--muted); }
.btn-start {
  display: inline-flex; align-items: center; gap: 7px;
  background: var(--accent); color: #05101F;
  font-weight: 800; font-size: 14.5px;
  border-radius: 10px; padding: 8px 18px;
  transition: background .15s;
  white-space: nowrap;
}
.btn-start:hover { background: var(--gold); text-decoration: none; }
.btn-start svg { transform: none; }

.empty { text-align: center; color: var(--muted); padding-block: 40px 80px; font-size: 18px; }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--line); background: var(--bg-alt); }
.footer-inner { display: flex; justify-content: space-between; gap: 10px; flex-wrap: wrap; padding-block: 20px; font-size: 13.5px; color: var(--muted); }
.footer-muted { opacity: 0.75; }

/* ---------- responsive ---------- */
@media (max-width: 720px) {
  .hero h1 { font-size: 30px; }
  .hero { padding-block: 30px 4px; }
  .header-inner { padding-block: 12px; }
  .search-box { min-width: 100%; order: 3; }
  .filters { padding-block: 22px 6px; }
  .grid { grid-template-columns: 1fr; gap: 16px; padding-bottom: 50px; }
}