/* ==========================================================================
   数字化与人工智能课程 · 通过 LLM-Wiki 搭建个人知识库
   手绘黑板风深色主题 · 16:9 课程画幅（图上文下）
   ========================================================================== */

:root {
  --bg:           #161821;
  --bg-elev:      #1d2029;
  --bg-card:      #20242f;
  --bg-inset:     #11131a;

  --text:         #e8e6e1;
  --text-soft:    #b8b5ac;
  --text-mute:    #7d7a72;

  --accent:       #f0a040;
  --accent-soft:  #c97a28;
  --raw:          #4a90b8;
  --wiki:         #5fa872;
  --schema:       #9a7ec0;
  --good:         #5fa872;
  --bad:          #c97070;

  --line:         #2d313d;
  --line-soft:    #262933;

  --maxw:         1200px;
  --radius:       14px;
  --radius-sm:    8px;

  --font: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei",
          "Source Han Sans SC", "Noto Sans CJK SC", -apple-system,
          "Segoe UI", system-ui, sans-serif;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 40px; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  font-size: 17px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: var(--accent); text-decoration: none; transition: color .2s; }
a:hover { color: #ffc070; }
::selection { background: var(--accent); color: var(--bg); }
code {
  font-family: "JetBrains Mono", "Cascadia Code", "Consolas", monospace;
  background: var(--bg-inset);
  padding: 2px 8px;
  border-radius: 5px;
  font-size: .85em;
  color: var(--accent);
  border: 1px solid var(--line);
}

/* ===== Hero ===== */
.hero {
  min-height: 100svh;
  display: flex; flex-direction: column;
  justify-content: center;
  position: relative;
  padding: 72px 28px 92px;
  background:
    radial-gradient(ellipse 80% 50% at 20% 30%, rgba(240,160,64,.08), transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 70%, rgba(154,126,192,.08), transparent 60%),
    var(--bg);
}

.hero-brand {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 24px;
  margin-bottom: 42px;
}
.hero-logo {
  width: 104px; height: 104px;
  object-fit: contain;
  flex-shrink: 0;
}
.hero-brand-text {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.hero-brand-name {
  font-size: 1.55rem;
  font-weight: 800;
  color: var(--text);
  letter-spacing: 2px;
}
.hero-brand-org {
  font-size: .96rem;
  color: var(--text-mute);
  letter-spacing: .5px;
}

.hero-content {
  max-width: var(--maxw);
  margin: 0 auto;
  width: 100%;
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(380px, .92fr);
  gap: 68px;
  align-items: center;
}
.hero-title {
  font-size: clamp(2.4rem, 5vw, 3.8rem);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: 1px;
  margin-bottom: 28px;
}
.accent { color: var(--accent); }
.hero-desc {
  font-size: 1.15rem;
  color: var(--text-soft);
  margin-bottom: 40px;
  max-width: 500px;
}
.hero-cta { display: flex; gap: 16px; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center;
  padding: 14px 36px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  transition: all .25s;
  border: 1px solid transparent;
}
.btn-primary { background: var(--accent); color: var(--bg); }
.btn-primary:hover { background: #ffb55a; color: var(--bg); transform: translateY(-2px); }

.hero-figure {
  width: min(100%, 520px);
  justify-self: end;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
  background: var(--bg-card);
  box-shadow: 0 30px 80px rgba(0,0,0,.5);
  cursor: zoom-in;
  transition: transform .3s;
}
.hero-figure:hover { transform: translateY(-4px); }
.hero-figure img {
  width: 100%;
  aspect-ratio: 2 / 3;
  object-fit: cover;
}
.hero-figure figcaption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--text-mute);
  text-align: center;
  border-top: 1px solid var(--line-soft);
}

.scroll-hint {
  position: absolute;
  bottom: 32px; left: 50%;
  transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center;
  gap: 6px;
  color: var(--text-mute);
  font-size: 12px;
  letter-spacing: 2px;
  animation: bob 2s ease-in-out infinite;
}
.scroll-hint .arrow { font-size: 20px; }
@keyframes bob { 0%,100%{transform:translateX(-50%) translateY(0)} 50%{transform:translateX(-50%) translateY(8px)} }

/* ===== 内容区 + 弱分割 ===== */
.content {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 28px 60px;
}
.sec { padding: 28px 0; }
.sec-title {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 800;
  margin-bottom: 14px;
  line-height: 1.3;
}
.sec-intro {
  color: var(--text-soft);
  font-size: 1.05rem;
  max-width: none;
  margin-bottom: 36px;
}
.divider {
  border: none;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--line) 20%, var(--line) 80%, transparent);
  margin: 12px 0;
}

/* ===== 卡片：16:9 图片在上，课程说明在下 ===== */
.cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 56px;
}
.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--line);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  min-height: 0;
  transition: transform .3s, border-color .3s, box-shadow .3s;
}
.card:hover {
  transform: translateY(-3px);
  border-color: var(--accent-soft);
  box-shadow: 0 18px 48px rgba(0,0,0,.42);
}

/* 上方图片区 —— 严格保持课件原生 16:9 画幅 */
.card-fig {
  position: relative;
  flex: none;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--bg-inset);
  border-bottom: 1px solid var(--line-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: zoom-in;
  overflow: hidden;
  padding: 0;
}
.card-fig img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  transition: transform .4s;
}
.card:hover .card-fig img { transform: scale(1.03); }

.slide-no {
  position: absolute;
  top: 18px; right: 18px;
  z-index: 2;
  background: rgba(22, 24, 33, .88);
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 1px;
  padding: 5px 12px;
  border-radius: 6px;
  border: 1px solid var(--accent-soft);
  backdrop-filter: blur(4px);
}

/* 下方文字区：桌面端用 grid 双列，行1只取标题高度、行2占剩余空间，
   配合 points 跨行，从根本上消除「h3 被右侧撑高留白」的问题 */
.card-body {
  padding: 32px 40px 38px;
  display: grid;
  grid-template-columns: minmax(0, .92fr) minmax(0, 1.08fr);
  grid-template-rows: auto 1fr;   /* 关键：行1=标题高度，行2=剩余空间 */
  column-gap: 48px;
  align-items: start;
  min-height: 230px;
}
/* 标题固定在左上格（行1列1），行1高度只由它决定，不再被 points 撑高 */
.card-body h3 {
  grid-column: 1;
  grid-row: 1;
  font-size: 1.55rem;
  font-weight: 800;
  margin-bottom: 20px;
  line-height: 1.4;
}
/* 段落固定在左下格（行2列1），紧贴标题下方，无留白 */
.card-body > p {
  grid-column: 1;
  grid-row: 2;
  color: var(--text-soft);
  font-size: 1rem;
  margin-bottom: 0;
  line-height: 1.85;
}
.card-body > p:last-child { margin-bottom: 0; }

/* 要点独占右列、跨全部行，从标题同一行（右上角）开始向下排列 */
.points {
  list-style: none;
  margin: 0;
  grid-column: 2;
  grid-row: 1 / -1;
}
.points li {
  position: relative;
  padding: 6px 0 6px 22px;
  color: var(--text-soft);
  font-size: .96rem;
  line-height: 1.7;
}
.points li::before {
  content: '';
  position: absolute;
  left: 0; top: 16px;
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--accent);
}
.points li b { color: var(--text); }

.c-raw    { color: var(--raw); }
.c-wiki   { color: var(--wiki); }
.c-schema { color: var(--schema); }
.c-good   { color: var(--good); }
.c-bad    { color: var(--bad); }

.verse {
  grid-column: 1 / -1;
  font-size: 2.4rem;
  line-height: 2;
  text-align: center;
  color: var(--accent);
  margin: 10px 0 14px;
  font-weight: 500;
  letter-spacing: 1px;
  border-left: none;
  padding-left: 0;
}

/* ===== 页脚 ===== */
.footer {
  border-top: 1px solid var(--line);
  background: var(--bg-inset);
  padding: 48px 28px;
  margin-top: 60px;
}
.footer-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
  text-align: center;
}
.footer-brand {
  display: flex; align-items: center; gap: 12px;
  color: var(--text-soft);
  font-size: .95rem;
}
.footer-logo {
  width: 28px; height: 28px;
  object-fit: contain;
  border-radius: 5px;
}
.back-top {
  font-size: .9rem;
  color: var(--text-soft);
  padding: 9px 24px;
  border: 1px solid var(--line);
  border-radius: 999px;
}
.back-top:hover { border-color: var(--accent); color: var(--accent); }

/* ===== 图片灯箱 ===== */
.lightbox {
  position: fixed; inset: 0;
  z-index: 1000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 72px 96px 88px;
  background: rgba(6, 8, 12, .96);
  opacity: 0;
  pointer-events: none;
}
.lightbox.open {
  display: flex;
  opacity: 1;
  pointer-events: auto;
}
.lightbox img {
  max-width: calc(100vw - 192px);
  max-height: calc(100vh - 160px);
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: 0 24px 80px rgba(0, 0, 0, .7);
}
.lb-close,
.lb-prev,
.lb-next {
  position: absolute;
  z-index: 2;
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border: 1px solid rgba(255, 255, 255, .16);
  border-radius: 50%;
  background: rgba(32, 36, 47, .86);
  color: var(--text);
  font-family: var(--font);
  line-height: 1;
  cursor: pointer;
  transition: color .2s, border-color .2s, background .2s, transform .2s;
}
.lb-close:hover,
.lb-prev:hover,
.lb-next:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(32, 36, 47, 1);
}
.lb-close {
  top: 22px;
  right: 26px;
  font-size: 24px;
}
.lb-prev,
.lb-next {
  top: 50%;
  transform: translateY(-50%);
  font-size: 38px;
  padding-bottom: 4px;
}
.lb-prev:hover,
.lb-next:hover { transform: translateY(-50%) scale(1.06); }
.lb-prev { left: 26px; }
.lb-next { right: 26px; }
.lb-caption {
  position: absolute;
  left: 88px;
  right: 88px;
  bottom: 24px;
  color: var(--text-soft);
  font-size: 15px;
  line-height: 1.5;
  text-align: center;
}

/* ===== 响应式 ===== */
@media (max-width: 980px) {
  .hero {
    min-height: auto;
    padding-top: 56px;
  }
  .hero-content {
    grid-template-columns: 1fr;
    gap: 48px;
    max-width: 760px;
  }
  .hero-figure {
    width: min(100%, 560px);
    justify-self: center;
  }
  .hero-desc { max-width: 680px; }
  .scroll-hint { display: none; }
}

@media (max-width: 720px) {
  body { font-size: 16px; }
  .hero { padding: 42px 20px 64px; }
  .hero-brand {
    gap: 16px;
    margin-bottom: 32px;
  }
  .hero-logo { width: 78px; height: 78px; }
  .hero-brand-name { font-size: 1.15rem; letter-spacing: 1px; }
  .hero-brand-org { font-size: .76rem; }
  .hero-title { font-size: clamp(2.2rem, 12vw, 3.25rem); }
  .hero-desc { font-size: 1rem; }

  .content { padding: 28px 18px 48px; }
  .sec { padding: 24px 0; }
  .sec-intro { margin-bottom: 28px; }
  .cards { gap: 34px; }
  .card-body {
    grid-template-columns: 1fr;
    grid-template-rows: auto;   /* 单列布局，行高自适应 */
    row-gap: 0;
    min-height: 0;
    padding: 24px 24px 28px;
  }
  /* 窄屏：强制垂直顺序 h3 → p → points，覆盖桌面端的跨行/跨列规则 */
  .card-body > * { grid-column: 1; grid-row: auto; }
  .card-body h3 { order: 1; }
  .card-body > p { order: 2; }
  .card-body > .points { order: 3; }
  .card-body h3 { font-size: 1.35rem; margin-bottom: 14px; }
  .points,
  .verse { margin-top: 18px; }
  .slide-no { top: 10px; right: 10px; }

  .footer { padding: 38px 20px; }
  .footer-brand { flex-direction: column; }

  .lightbox { padding: 64px 14px 82px; }
  .lightbox img {
    max-width: calc(100vw - 28px);
    max-height: calc(100vh - 150px);
  }
  .lb-close { top: 12px; right: 14px; }
  .lb-prev,
  .lb-next {
    top: auto;
    bottom: 16px;
    transform: none;
  }
  .lb-prev:hover,
  .lb-next:hover { transform: scale(1.06); }
  .lb-prev { left: 16px; }
  .lb-next { right: 16px; }
  .lb-caption { left: 72px; right: 72px; bottom: 27px; font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}