/* Shared with course index.html — student area shell */
:root {
  --ink: #000000;
  --paper: #f6fbff;
  --muted: rgba(0, 0, 0, 0.72);
  --card: rgba(255, 255, 255, 0.72);
  --stroke: rgba(0, 0, 0, 0.12);
  --shadow: 0 16px 60px rgba(0, 0, 0, 0.16);
  --border: 1.5px;
  --blue: #0b2a55;
  --turq: #22d3c5;
  --radius: 22px;
}

:root[data-theme="dark"] {
  --ink: #f2f5f8;
  --paper: #050b14;
  --muted: rgba(242, 245, 248, 0.74);
  --card: rgba(11, 22, 40, 0.62);
  --stroke: rgba(234, 243, 255, 0.12);
  --shadow: 0 18px 70px rgba(0, 0, 0, 0.55);
  --border: 2px;
}

* {
  box-sizing: border-box;
}
html,
body {
  height: 100%;
}
body {
  margin: 0;
  color: var(--ink);
  background: radial-gradient(
      1200px 700px at 18% 12%,
      rgba(34, 211, 197, 0.18),
      transparent 60%
    ),
    radial-gradient(
      1100px 720px at 84% 18%,
      rgba(11, 42, 85, 0.24),
      transparent 65%
    ),
    radial-gradient(
      900px 650px at 55% 88%,
      rgba(0, 188, 212, 0.14),
      transparent 60%
    ),
    linear-gradient(180deg, var(--paper), var(--paper));
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto,
    Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  overflow-x: hidden;
}
a {
  color: inherit;
  text-decoration: none;
}

.wrap {
  max-width: 1100px;
  margin: 0 auto;
  padding: 28px 18px 48px;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 4px 18px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
  flex: 1 1 auto;
}

.brand > div:last-child {
  min-width: 0;
}

.brand:focus-visible {
  outline: 2px solid var(--turq);
  outline-offset: 3px;
  border-radius: 14px;
}
.mark {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--blue), var(--turq));
  box-shadow: 0 10px 26px rgba(11, 42, 85, 0.25);
  position: relative;
  overflow: hidden;
}
.mark::after {
  content: "";
  position: absolute;
  inset: -40% -20% auto auto;
  width: 120%;
  height: 120%;
  background: radial-gradient(
    closest-side,
    rgba(255, 255, 255, 0.48),
    transparent 65%
  );
  transform: rotate(20deg);
}
.brand .title {
  margin: 0;
  font-weight: 780;
  letter-spacing: -0.02em;
  font-size: 18px;
  color: var(--ink);
}
.brand .subtitle {
  margin: 0;
  font-size: 14px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

header > .pill {
  flex-shrink: 0;
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border: var(--border) solid var(--stroke);
  background: var(--card);
  border-radius: 999px;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.06);
  backdrop-filter: blur(10px);
}

.toggle {
  display: inline-flex;
  align-items: center;
  cursor: pointer;
  user-select: none;
  position: relative;
}

.toggle-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  cursor: pointer;
  z-index: 2;
}

.toggle-rail {
  --rail-w: 54px;
  --rail-h: 30px;
  --rail-pad: 3px;
  --knob-size: 22px;
  position: relative;
  display: block;
  width: var(--rail-w);
  height: var(--rail-h);
  border-radius: 999px;
  background: linear-gradient(
    165deg,
    #eef5fb 0%,
    #e2ecf6 100%
  );
  box-shadow: inset 0 1px 4px rgba(11, 42, 85, 0.12);
  border: var(--border) solid rgba(11, 42, 85, 0.1);
  transition: background 0.25s ease, box-shadow 0.25s ease,
    border-color 0.25s ease;
}

.toggle-input:checked + .toggle-rail {
  background: linear-gradient(
    165deg,
    #132a45 0%,
    #071426 100%
  );
  box-shadow: inset 0 2px 6px rgba(0, 0, 0, 0.55);
  border-color: rgba(0, 0, 0, 0.35);
}

.toggle-knob {
  position: absolute;
  top: var(--rail-pad);
  left: var(--rail-pad);
  width: var(--knob-size);
  height: var(--knob-size);
  border-radius: 50%;
  z-index: 1;
  transition: transform 0.22s ease, background 0.22s ease,
    box-shadow 0.22s ease;
}

.toggle-input:checked + .toggle-rail .toggle-knob {
  transform: translateX(0);
  background: #f2f6fc;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.28);
}

.toggle-input:not(:checked) + .toggle-rail .toggle-knob {
  transform: translateX(
    calc(
      var(--rail-w) - var(--knob-size) - var(--rail-pad) * 2
    )
  );
  background: #0b2a55;
  box-shadow: 0 2px 8px rgba(11, 42, 85, 0.35);
}

.toggle-sun,
.toggle-moon {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
  z-index: 0;
}

.toggle-sun {
  left: 6px;
  color: var(--blue);
}

.toggle-moon {
  right: 5px;
  color: #dff9f6;
}

.toggle-sun svg,
.toggle-moon svg {
  width: 14px;
  height: 14px;
  display: block;
}

.panel {
  border: var(--border) solid var(--stroke);
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  backdrop-filter: blur(12px);
  overflow: hidden;
}

.hero {
  padding: 22px 22px 18px;
}
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: 999px;
  border: var(--border) solid var(--stroke);
  background: rgba(255, 255, 255, 0.35);
  color: var(--muted);
  font-size: 13px;
}
:root[data-theme="dark"] .kicker {
  background: rgba(5, 11, 20, 0.35);
}
.kdot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--turq);
  box-shadow: 0 0 0 6px rgba(34, 211, 197, 0.14);
}
h1 {
  margin: 14px 0 8px;
  font-size: clamp(24px, 3.2vw, 36px);
  line-height: 1.08;
  letter-spacing: -0.04em;
}
.course-hint {
  margin: -2px 0 14px;
  font-size: 15px;
  color: var(--muted);
  font-weight: 600;
}
.hero p {
  margin: 0;
  color: var(--muted);
  font-size: 15.5px;
  line-height: 1.55;
}
.hero p + p {
  margin-top: 12px;
}

.hero a {
  color: var(--turq);
  text-decoration: underline;
  text-underline-offset: 3px;
}
.hero a:hover {
  filter: brightness(0.95);
}
:root[data-theme="dark"] .hero a {
  color: #5eead4;
}

.section-title {
  margin: 14px 0 8px;
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.grid {
  margin-top: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
}

.archive {
  opacity: 0.92;
}

:root[data-theme="dark"] .archive {
  opacity: 0.88;
}

.archive .cardlink {
  box-shadow: none;
}

.archive .cardlink:hover {
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.12);
}

.cardlink {
  display: grid;
  gap: 8px;
  padding: 16px 16px;
  border-radius: 18px;
  border: var(--border) solid var(--stroke);
  background: rgba(255, 255, 255, 0.35);
  transition: transform 120ms ease, border-color 120ms ease,
    box-shadow 120ms ease;
}

:root[data-theme="dark"] .cardlink {
  background: rgba(26, 40, 70, 0.5);
}

.cardlink:hover {
  transform: translateY(-1px);
  border-color: rgba(0, 188, 212, 0.35);
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.14);
}

.cardlink .name {
  font-weight: 780;
  letter-spacing: -0.02em;
  font-size: 16px;
  line-height: 1.2;
  color: var(--ink);
  word-break: break-word;
}

.cardlink .hint {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.25;
}

footer {
  margin-top: 18px;
  text-align: center;
  color: var(--muted);
  font-size: 13px;
  padding: 6px 4px 0;
}

@media (max-width: 640px) {
  .wrap {
    padding-left: 14px;
    padding-right: 14px;
  }

  header {
    flex-wrap: nowrap;
    align-items: center;
    gap: 8px;
  }

  .brand {
    gap: 8px;
  }

  .mark {
    width: 36px;
    height: 36px;
    flex-shrink: 0;
  }

  .brand .title {
    font-size: 16px;
  }

  .brand .subtitle {
    font-size: 11px;
    letter-spacing: 0.12em;
  }

  .pill {
    padding: 8px 10px;
  }

  .toggle-rail {
    --rail-w: 46px;
    --rail-h: 26px;
    --rail-pad: 2px;
    --knob-size: 18px;
  }

  .toggle-sun svg,
  .toggle-moon svg {
    width: 12px;
    height: 12px;
  }

  .toggle-sun {
    left: 5px;
  }

  .toggle-moon {
    right: 4px;
  }
}

@media (max-width: 520px) {
  .grid {
    grid-template-columns: 1fr;
  }
}