/* ===== 文档 / PPT 模式切换 ===== */
.view-switch {
  display: inline-flex;
  align-items: center;
  padding: 2px;
  margin-right: 10px;
  border: 1px solid var(--c-border, #eaecef);
  border-radius: 8px;
  background: #f6f8fb;
  gap: 2px;
}
.view-switch[hidden] { display: none !important; }
.view-btn {
  min-width: 48px;
  padding: 4px 10px;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: var(--c-text-soft, #4a5b6d);
  font-family: inherit;
  font-size: 13px;
  line-height: 1.5;
  cursor: pointer;
  white-space: nowrap;
  transition: background .15s, color .15s, box-shadow .15s;
}
.view-btn:hover { color: var(--c-accent, #3eaf7c); }
.view-btn.is-active {
  background: #fff;
  color: var(--c-text, #2c3e50);
  box-shadow: 0 1px 3px rgba(15, 23, 42, .12);
  font-weight: 600;
}
.md-download {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 30px;
  padding: 0 10px;
  margin-right: 10px;
  border: 1px solid var(--c-border, #eaecef);
  border-radius: 7px;
  background: #fff;
  color: var(--c-text-soft, #4a5b6d);
  font-family: inherit;
  font-size: 12.5px;
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
}
.md-download[hidden] { display: none !important; }
.md-download:hover {
  border-color: var(--c-accent, #3eaf7c);
  color: var(--c-accent, #3eaf7c);
}

/* ===== PPT 模式 ===== */
body.ppt-mode { overflow: hidden; }
body.ppt-mode > .navbar,
body.ppt-mode > .layout { display: none !important; }

.ppt-stage {
  --ppt-w: 1280px;
  --ppt-h: 720px;
  position: fixed;
  inset: 0;
  z-index: 3000;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  color: #203040;
  background:
    radial-gradient(1100px 620px at 82% -10%, rgba(74, 114, 173, .16), transparent 62%),
    radial-gradient(900px 560px at 8% 108%, rgba(62, 175, 124, .12), transparent 60%),
    #eef3f9;
  font-family: var(--font-sans);
}
.ppt-stage:fullscreen { background: #fff; }
.ppt-stage:fullscreen .ppt-bar { display: none; }
.ppt-stage:fullscreen .ppt-viewport {
  padding: 0;
}
.ppt-stage:fullscreen .ppt-slide {
  border: 0;
  border-radius: 0;
  box-shadow: none;
}
.ppt-stage:fullscreen .ppt-nav { opacity: 0; }
.ppt-stage:fullscreen .ppt-viewport:hover .ppt-nav { opacity: .9; }
.ppt-stage:focus { outline: none; }

.ppt-bar {
  flex: 0 0 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 20px;
  background: rgba(255, 255, 255, .78);
  border-bottom: 1px solid rgba(74, 114, 173, .14);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}
.ppt-brand {
  display: flex;
  align-items: center;
  gap: 9px;
  color: #43566f;
  font-size: 21px;
  font-weight: 700;
  letter-spacing: .03em;
  white-space: nowrap;
}
.ppt-brand-dot {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: #4a72ad;
  box-shadow: 0 0 0 4px rgba(74, 114, 173, .14);
}
.ppt-actions { display: flex; align-items: center; gap: 10px; }
.ppt-actions .view-switch { margin-right: 2px; background: #edf2f8; }
.ppt-actions .view-btn {
  min-width: 64px;
  padding: 6px 14px;
  font-size: 21px;
}
.ppt-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 38px;
  padding: 0 14px;
  border: 1px solid rgba(74, 114, 173, .22);
  border-radius: 7px;
  background: #fff;
  color: #43566f;
  font-family: inherit;
  font-size: 21px;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
}
.ppt-btn:hover { border-color: #4a72ad; color: #315b94; }
.ppt-btn-primary {
  border-color: #4a72ad;
  background: #4a72ad;
  color: #fff;
}
.ppt-btn-primary:hover { background: #3d6298; color: #fff; }

.ppt-viewport {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px 76px 30px;
}
.ppt-slides {
  position: relative;
  flex: 0 0 auto;
  width: var(--ppt-w);
  height: var(--ppt-h);
  container-type: size;
  transform: scale(var(--ppt-scale, 1));
  transform-origin: center center;
}
.ppt-measure {
  position: absolute;
  top: 0;
  left: -100000px;
  width: var(--ppt-w);
  height: var(--ppt-h);
  container-type: size;
  visibility: hidden;
  pointer-events: none;
}
.ppt-measure .ppt-slide {
  position: absolute;
  inset: 0;
  opacity: 1;
  transform: none;
}
.ppt-slide {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  width: 100%;
  height: 100%;
  padding: clamp(24px, 3.1cqh, 42px) clamp(34px, 4.4cqw, 70px) clamp(16px, 2.2cqh, 28px);
  overflow: hidden;
  background: #fff;
  border: 1px solid rgba(74, 114, 173, .16);
  border-radius: 14px;
  box-shadow: 0 24px 80px rgba(23, 43, 77, .20), 0 2px 8px rgba(23, 43, 77, .06);
  opacity: 0;
  transform: translateY(8px) scale(.995);
  pointer-events: none;
  transition: opacity .18s ease, transform .18s ease;
}
.ppt-slide.is-active {
  opacity: 1;
  transform: none;
  pointer-events: auto;
}
.ppt-slide::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 6px;
  background: linear-gradient(90deg, #4a72ad, #7aa7dc 55%, #6fbf9a);
}

.ppt-head {
  flex: 0 0 auto;
  padding-bottom: 10px;
  margin-bottom: 12px;
  border-bottom: 1px solid #e6eef8;
}
.ppt-kicker {
  margin-bottom: 2px;
  color: #6b83a3;
  font-size: 21px;
  font-weight: 600;
  letter-spacing: .02em;
}
.ppt-head h2 {
  margin: 0;
  color: #1d334d;
  font-size: clamp(30px, 1.9cqw + 13px, 44px);
  line-height: 1.22;
  font-weight: 700;
  letter-spacing: -.01em;
}
.ppt-body {
  flex: 1 1 auto;
  min-height: 0;
  overflow: hidden;
  color: #26384d;
  font-size: clamp(22px, 1.05cqw + 10px, 30px);
  line-height: 1.56;
  word-break: break-word;
}
.ppt-body.ppt-scroll {
  overflow-y: auto;
  padding-right: 8px;
}
.ppt-body.ppt-tight p { margin: .22em 0; }
.ppt-body.ppt-tight ul,
.ppt-body.ppt-tight ol { margin: .24em 0; }
.ppt-body.ppt-tight li { margin: .12em 0; }
.ppt-body.ppt-tight pre { margin: .3em 0; padding: 9px 13px; }
.ppt-body.ppt-tight pre code { line-height: 1.4; }
.ppt-body.ppt-tight .block { margin: .3em 0; padding: 9px 13px; }
.ppt-body.ppt-tight h3 { margin: .3em 0 .18em; }
.ppt-body.ppt-tight blockquote { margin: .3em 0; padding: 7px 13px; }
.ppt-body.ppt-tight th,
.ppt-body.ppt-tight td { padding: 5px 9px; }
.ppt-body.ppt-scroll::-webkit-scrollbar { width: 8px; }
.ppt-body.ppt-scroll::-webkit-scrollbar-thumb {
  background: #c8d6e8;
  border-radius: 4px;
}
.ppt-body > :first-child { margin-top: 0; }
.ppt-body > :last-child { margin-bottom: 0; }
.ppt-content .ppt-body { display: flex; flex-direction: column; }
.ppt-content .ppt-body > :first-child { margin-top: auto; }
.ppt-content .ppt-body > :last-child { margin-bottom: auto; }
.ppt-body p { margin: .48em 0; }
.ppt-body ul,
.ppt-body ol { margin: .5em 0; padding-left: 1.35em; }
.ppt-body li { margin: .28em 0; }
.ppt-body h3 {
  margin: .55em 0 .3em;
  color: #315b94;
  font-size: clamp(25px, 1.15cqw + 12px, 34px);
  line-height: 1.3;
}
.ppt-body h4 {
  margin: .55em 0 .25em;
  color: #315b94;
  font-size: 24px;
  line-height: 1.3;
}
.ppt-body strong { color: #173b63; }
.ppt-body a { color: #2f6fb5; text-decoration: none; }
.ppt-body blockquote {
  margin: .55em 0;
  padding: 10px 18px;
  border-left: 5px solid #4a72ad;
  border-radius: 0 8px 8px 0;
  background: #f3f7fd;
  color: #3d5674;
}
.ppt-body blockquote p { margin: .25em 0; }

.ppt-body .block {
  margin: .55em 0;
  padding: 13px 18px;
  border-left: 6px solid #9aa7b4;
  border-radius: 0 9px 9px 0;
  background: #f7f9fc;
}
.ppt-body .block-title {
  margin: 0 0 6px;
  font-size: 22px;
  font-weight: 700;
}
.ppt-body .block-tip { border-color: #42b983; background: #f3f9f6; }
.ppt-body .block-tip .block-title { color: #2f8f65; }
.ppt-body .block-warning { border-color: #d9b400; background: #fffbea; }
.ppt-body .block-warning .block-title { color: #9a7c00; }
.ppt-body .block-info { border-color: #3e8ed0; background: #f1f7fd; }
.ppt-body .block-info .block-title { color: #2d6fa8; }
.ppt-body .block-note { border-color: #9aa7b4; background: #f6f7f8; }
.ppt-body .block-danger { border-color: #c00; background: #fff2f2; }
.ppt-body .block-danger .block-title { color: #b00000; }
.ppt-body .block > :last-child { margin-bottom: 0; }

.ppt-body pre {
  margin: .55em 0;
  padding: 12px 16px;
  overflow: hidden;
  border-radius: 10px;
  background: #282c34;
}
.ppt-body pre code {
  display: block;
  padding: 0;
  overflow: visible;
  background: transparent;
  color: #abb2bf;
  font-family: var(--font-mono);
  font-size: 21px;
  line-height: 1.4;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  tab-size: 4;
}
.ppt-body pre code .hljs-comment,
.ppt-body pre code .hljs-quote { color: #8b98a8; }
.ppt-body :not(pre) > code {
  padding: 2px 7px;
  border-radius: 5px;
  background: #edf3fa;
  color: #24527f;
  font-family: var(--font-mono);
  font-size: 22px;
}
.ppt-body pre.mermaid {
  background: #f7f9fc;
  text-align: center;
}
.ppt-body pre.mermaid svg {
  max-width: 100%;
  height: auto;
  max-height: 48cqh;
}

.ppt-body table {
  width: 100%;
  margin: .5em 0;
  border-collapse: collapse;
  font-size: 22px;
  line-height: 1.4;
}
.ppt-body th,
.ppt-body td {
  padding: 9px 13px;
  border: 1px solid #dce6f2;
  text-align: left;
  vertical-align: top;
}
.ppt-body th { background: #f1f6fc; font-weight: 700; }
.ppt-body tr:nth-child(even) td { background: #fafcff; }

.ppt-body img {
  display: block;
  max-width: 100%;
  max-height: 46cqh;
  margin: .5em auto;
  object-fit: contain;
}
.ppt-body details {
  margin: .5em 0;
  padding: 8px 14px;
  border: 1px solid #dce6f2;
  border-radius: 8px;
  background: #f8fbfe;
}
.ppt-body summary {
  font-size: 22px;
  font-weight: 600;
  cursor: default;
}
.ppt-body .katex { font-size: 1.06em; }
.ppt-body .katex-display { margin: .5em 0; overflow: hidden; }
.ppt-body hr { display: none; }

.ppt-foot {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-top: 9px;
  border-top: 1px solid #edf2f8;
  color: #8494a9;
  font-size: 22px;
  line-height: 1.2;
}
.ppt-page { color: #6b83a3; font-weight: 600; font-variant-numeric: tabular-nums; }

/* 标题页 */
.ppt-title {
  justify-content: center;
  align-items: center;
  padding: clamp(34px, 5cqh, 70px) clamp(44px, 6cqw, 100px);
  text-align: center;
}
.ppt-title::before { height: 8px; }
.ppt-title-main { max-width: 92%; }
.ppt-title-kicker {
  margin-bottom: 20px;
  color: #4a72ad;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: .16em;
}
.ppt-title h1 {
  margin: 0;
  color: #17345a;
  font-size: clamp(42px, 3.1cqw + 20px, 70px);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -.025em;
}
.ppt-title .ppt-sub {
  max-width: 920px;
  margin: 26px auto 0;
  color: #56708f;
  font-size: clamp(22px, 1.15cqw + 10px, 30px);
  line-height: 1.55;
}
.ppt-title .ppt-sub p { margin: .2em 0; }
.ppt-title .ppt-sub strong { color: #315b94; }
.ppt-title .ppt-foot {
  position: absolute;
  left: clamp(34px, 4.4cqw, 70px);
  right: clamp(34px, 4.4cqw, 70px);
  bottom: clamp(16px, 2.2cqh, 28px);
  width: auto;
}

/* ===== 讲解型 PPT（slides.json） ===== */
.ppt-cover {
  justify-content: center;
  align-items: center;
  text-align: center;
  background: linear-gradient(135deg, #f8fbff 0%, #eef4fb 55%, #eaf3f0 100%);
}
.ppt-cover::before { height: 9px; background: linear-gradient(90deg, #4a72ad, #7aa7dc 55%, #6fbf9a); }
.ppt-cover-main { max-width: 92%; }
.ppt-cover-kicker {
  margin-bottom: 22px;
  color: #4a72ad;
  font-size: 22px;
  font-weight: 800;
  letter-spacing: .16em;
}
.ppt-cover h1 {
  margin: 0;
  color: #17345a;
  font-size: clamp(42px, 3.1cqw + 20px, 70px);
  line-height: 1.16;
  font-weight: 800;
  letter-spacing: -.025em;
}
.ppt-cover-sub {
  max-width: 980px;
  margin: 24px auto 0;
  color: #3d5674;
  font-size: clamp(24px, 1.2cqw + 12px, 32px);
  line-height: 1.5;
}
.ppt-cover-meta {
  margin-top: 18px;
  color: #6b83a3;
  font-size: 22px;
}
.ppt-cover .ppt-foot {
  position: absolute;
  left: clamp(34px, 4.4cqw, 70px);
  right: clamp(34px, 4.4cqw, 70px);
  bottom: clamp(16px, 2.2cqh, 28px);
  width: auto;
}

.ppt-section {
  justify-content: center;
  text-align: left;
  background: linear-gradient(135deg, #17345a 0%, #2c5a8e 58%, #3d7d9c 100%);
  color: #fff;
}
.ppt-section::before { height: 9px; background: linear-gradient(90deg, #7aa7dc, #6fbf9a); }
.ppt-section-index {
  color: rgba(255, 255, 255, .16);
  font-size: clamp(64px, 7cqw, 118px);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -.04em;
}
.ppt-section h2 {
  margin: 6px 0 0;
  color: #fff;
  font-size: clamp(38px, 2.9cqw + 18px, 58px);
  line-height: 1.2;
}
.ppt-section-sub {
  margin: 18px 0 0;
  color: rgba(255, 255, 255, .82);
  font-size: clamp(24px, 1.2cqw + 12px, 32px);
  line-height: 1.5;
}
.ppt-section .ppt-foot {
  position: absolute;
  left: clamp(34px, 4.4cqw, 70px);
  right: clamp(34px, 4.4cqw, 70px);
  bottom: clamp(16px, 2.2cqh, 28px);
  width: auto;
  border-top-color: rgba(255, 255, 255, .18);
  color: rgba(255, 255, 255, .62);
}
.ppt-section .ppt-page { color: rgba(255, 255, 255, .78); }

.ppt-quote {
  justify-content: center;
  align-items: center;
  text-align: center;
  background: linear-gradient(135deg, #f8fbff, #eef4fb);
}
.ppt-quote blockquote {
  margin: 0;
  padding: 0 clamp(30px, 5cqw, 80px);
  border: 0;
  background: transparent;
  color: #17345a;
  font-size: clamp(34px, 2.5cqw + 14px, 52px);
  line-height: 1.34;
  font-weight: 700;
}
.ppt-quote-source {
  margin-top: 26px;
  color: #6b83a3;
  font-size: 22px;
}
.ppt-quote .ppt-foot {
  position: absolute;
  left: clamp(34px, 4.4cqw, 70px);
  right: clamp(34px, 4.4cqw, 70px);
  bottom: clamp(16px, 2.2cqh, 28px);
  width: auto;
}

.ppt-loading { justify-content: center; align-items: center; text-align: center; }
.ppt-loading-box { display: flex; flex-direction: column; align-items: center; gap: 18px; }
.ppt-loading-box p { margin: 0; color: #4a72ad; font-size: 24px; font-weight: 600; }
.ppt-spinner {
  width: 44px;
  height: 44px;
  border: 5px solid rgba(74, 114, 173, .2);
  border-top-color: #4a72ad;
  border-radius: 50%;
  animation: ppt-spin .8s linear infinite;
}
@keyframes ppt-spin { to { transform: rotate(360deg); } }

/* ===== 教学型版式 ===== */
.ppt-head-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 2px;
}
.ppt-head-top .ppt-kicker { margin-bottom: 0; }
.ppt-phase {
  flex: 0 0 auto;
  padding: 3px 12px;
  border-radius: 999px;
  background: #edf3fb;
  color: #4a72ad;
  font-size: 21px;
  font-weight: 700;
  letter-spacing: .04em;
}

.ppt-takeaway {
  flex: 0 0 auto;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin: 12px 0 10px;
  padding: 10px 16px;
  border-left: 5px solid #4a72ad;
  border-radius: 0 10px 10px 0;
  background: #eef5fb;
  color: #315b94;
  font-size: 22px;
  line-height: 1.4;
}
.ppt-takeaway span {
  flex: 0 0 auto;
  padding: 2px 8px;
  border-radius: 6px;
  background: #4a72ad;
  color: #fff;
  font-size: 21px;
  font-weight: 700;
}
.ppt-takeaway em { font-style: normal; font-weight: 600; }

.ppt-cover.has-side {
  flex-direction: row;
  align-items: stretch;
  gap: 0;
  text-align: left;
}
.ppt-cover.has-side .ppt-cover-main {
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-width: 0;
  padding-right: 36px;
}
.ppt-cover.has-side h1 { font-size: clamp(40px, 2.9cqw + 18px, 62px); }
.ppt-cover.has-side .ppt-cover-sub { margin-left: 0; margin-right: 0; }
.ppt-cover-side {
  flex: 0 0 280px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding-left: 34px;
  border-left: 1px solid #dbe6f3;
}
.ppt-cover-no {
  color: #dce9f8;
  font-size: 116px;
  font-weight: 800;
  line-height: .9;
  letter-spacing: -.06em;
}
.ppt-cover-points { list-style: none; margin: 18px 0 0; padding: 0; }
.ppt-cover-points li {
  position: relative;
  margin: .45em 0;
  padding-left: 1.35em;
  color: #315b94;
  font-size: 23px;
  font-weight: 600;
}
.ppt-cover-points li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: #6fbf9a;
  font-weight: 800;
}

.ppt-problem-scenario {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 16px 20px;
  border: 1px solid #e2ebf6;
  border-radius: 12px;
  background: #f7faff;
  color: #33465c;
  font-size: 23px;
  line-height: 1.5;
}
.ppt-problem-label {
  flex: 0 0 auto;
  padding: 2px 10px;
  border-radius: 6px;
  background: #4a72ad;
  color: #fff;
  font-size: 21px;
  font-weight: 700;
}
.ppt-problem-scenario p { margin: 0; }
.ppt-problem-question {
  margin: 20px 0 18px;
  padding-left: 18px;
  border-left: 6px solid #6fbf9a;
  color: #17345a;
  font-size: 30px;
  font-weight: 800;
  line-height: 1.4;
}
.ppt-problem-points {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}
.ppt-problem-point {
  position: relative;
  padding: 16px 16px 14px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: #fff;
}
.ppt-problem-no {
  position: absolute;
  top: 10px;
  right: 13px;
  color: #dce9f8;
  font-size: 38px;
  font-weight: 800;
  line-height: 1;
}
.ppt-problem-point h3 { margin: 0 0 6px; color: #315b94; font-size: 23px; }
.ppt-problem-point p { margin: 0; color: #3d5674; font-size: 21px; line-height: 1.45; }

.ppt-objective-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}
.ppt-objective {
  padding: 13px 16px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: linear-gradient(180deg, #f8fbff, #fff);
}
.ppt-objective-tag {
  display: inline-block;
  padding: 2px 9px;
  border-radius: 999px;
  background: #e8f5ee;
  color: #2f8f65;
  font-size: 21px;
  font-weight: 700;
}
.ppt-objective-tag.tag-skill { background: #eaf1fb; color: #315b94; }
.ppt-objective-tag.tag-quality { background: #fff6e6; color: #9a6a00; }
.ppt-objective h3 { margin: 6px 0 3px; color: #17345a; font-size: 23px; }
.ppt-objective p { margin: 0; color: #3d5674; font-size: 21px; line-height: 1.4; }

.ppt-agenda {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}
.ppt-agenda-item {
  min-height: 190px;
  padding: 18px 16px;
  border: 1px solid #dfe8f4;
  border-top: 5px solid #4a72ad;
  border-radius: 12px;
  background: #f8fbff;
}
.ppt-agenda-item:nth-child(2) { border-top-color: #6fbf9a; }
.ppt-agenda-item:nth-child(3) { border-top-color: #d9a441; }
.ppt-agenda-item:nth-child(4) { border-top-color: #8d7ac8; }
.ppt-agenda-no {
  display: block;
  color: #4a72ad;
  font-size: 34px;
  font-weight: 800;
  line-height: 1;
}
.ppt-agenda-item h3 { margin: 14px 0 8px; color: #17345a; font-size: 24px; }
.ppt-agenda-item p { margin: 0; color: #3d5674; font-size: 21px; line-height: 1.45; }
.ppt-agenda-note {
  margin-top: 14px;
  padding: 12px 16px;
  border-radius: 10px;
  background: #eef5fb;
  color: #315b94;
  font-size: 22px;
  line-height: 1.45;
}

.ppt-flow { display: flex; align-items: stretch; gap: 8px; }
.ppt-flow-node {
  flex: 1 1 0;
  min-width: 0;
  min-height: 180px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 16px 14px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: #f8fbff;
}
.ppt-flow-label {
  margin-bottom: 8px;
  color: #6b83a3;
  font-size: 21px;
  font-weight: 700;
  letter-spacing: .04em;
}
.ppt-flow-node strong { display: block; color: #17345a; font-size: 24px; line-height: 1.3; }
.ppt-flow-node p { margin: 8px 0 0; color: #3d5674; font-size: 21px; line-height: 1.45; }
.ppt-flow-arrow {
  flex: 0 0 auto;
  align-self: center;
  color: #6fbf9a;
  font-size: 34px;
  font-weight: 800;
}
.ppt-flow-note {
  margin-top: 14px;
  padding: 12px 16px;
  border-radius: 10px;
  background: #eef5fb;
  color: #315b94;
  font-size: 22px;
  line-height: 1.45;
}

.ppt-split {
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  align-items: center;
  gap: 16px;
  min-height: 0;
  height: 100%;
}
.ppt-pane { display: flex; flex-direction: column; min-width: 0; min-height: 0; }
.ppt-pane-title { margin-bottom: 6px; color: #4a72ad; font-size: 22px; font-weight: 700; }
.ppt-pane pre { margin: 0; }
.ppt-pane-list { margin: 0; padding-left: 1.15em; }
.ppt-pane-list li { margin: .4em 0; color: #33465c; font-size: 22px; line-height: 1.45; }
.ppt-pane-note {
  margin-top: 12px;
  padding: 10px 14px;
  border-radius: 9px;
  background: #eef5fb;
  color: #315b94;
  font-size: 21px;
  line-height: 1.4;
}
.ppt-terminal { overflow: hidden; border-radius: 12px; background: #282c34; }
.ppt-terminal-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 12px;
  background: #21252b;
}
.ppt-terminal-bar i { width: 10px; height: 10px; border-radius: 50%; background: #e06c75; }
.ppt-terminal-bar i:nth-child(2) { background: #e5c07b; }
.ppt-terminal-bar i:nth-child(3) { background: #98c379; }
.ppt-terminal-bar em { margin-left: 8px; color: #8b98a8; font-size: 21px; font-style: normal; }
.ppt-terminal pre { margin: 0; border-radius: 0; background: transparent; }

.ppt-task-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}
.ppt-task {
  padding: 16px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: #f8fbff;
}
.ppt-task-check {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: #6fbf9a;
  color: #fff;
  font-size: 21px;
  font-weight: 800;
}
.ppt-task h3 { margin: 10px 0 6px; color: #17345a; font-size: 23px; }
.ppt-task p { margin: 0; color: #3d5674; font-size: 21px; line-height: 1.45; }
.ppt-task-hint {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px dashed #d9e4f1;
  color: #6b83a3;
  font-size: 21px;
  line-height: 1.4;
}

.ppt-lead {
  margin: 0 0 16px;
  color: #315b94;
  font-size: clamp(25px, 1.1cqw + 13px, 31px);
  font-weight: 700;
  line-height: 1.45;
}

.ppt-bullets { list-style: none; margin: 0; padding: 0; }
.ppt-bullets li {
  position: relative;
  margin: .62em 0;
  padding-left: 1.2em;
  font-size: clamp(25px, 1.15cqw + 12px, 32px);
  line-height: 1.5;
}
.ppt-bullets li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .62em;
  width: .42em;
  height: .42em;
  border-radius: 50%;
  background: #4a72ad;
}

.ppt-cards {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}
.ppt-cards.cols-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.ppt-cards.cols-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.ppt-card {
  display: flex;
  flex-direction: column;
  justify-content: center;
  min-height: 180px;
  padding: 24px;
  border: 1px solid #dfe8f4;
  border-top: 5px solid #4a72ad;
  border-radius: 12px;
  background: linear-gradient(180deg, #f7faff, #fff);
}
.ppt-card:nth-child(2) { border-top-color: #6fbf9a; }
.ppt-card:nth-child(3) { border-top-color: #d9a441; }
.ppt-card:nth-child(4) { border-top-color: #8d7ac8; }
.ppt-card h3 {
  margin: 0 0 10px;
  color: #315b94;
  font-size: 28px;
  line-height: 1.3;
}
.ppt-card p {
  margin: 0;
  color: #3d5674;
  font-size: 23px;
  line-height: 1.5;
}

.ppt-compare { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.ppt-compare-col {
  min-height: 210px;
  padding: 20px 24px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: #f7faff;
}
.ppt-compare-left { border-color: #efd3d3; background: #fff8f8; }
.ppt-compare-right { border-color: #cfe9dc; background: #f4fbf7; }
.ppt-compare-col h3 {
  margin: 0 0 10px;
  color: #315b94;
  font-size: 28px;
  line-height: 1.3;
}
.ppt-compare-list { margin: 0; padding-left: 1.1em; }
.ppt-compare-list li {
  margin: .4em 0;
  color: #33465c;
  font-size: 23px;
  line-height: 1.45;
}

.ppt-code-wrap {
  display: flex;
  flex-direction: column;
  min-height: 0;
}
.ppt-code-wrap pre { flex: 0 0 auto; margin: 0; overflow: auto; }
.ppt-caption {
  margin-top: 8px;
  color: #6b83a3;
  font-size: 22px;
  line-height: 1.4;
}

.ppt-code-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  min-height: 0;
  align-items: start;
}
.ppt-code-pane { display: flex; flex-direction: column; min-height: 0; }
.ppt-code-label {
  margin-bottom: 6px;
  color: #4a72ad;
  font-size: 22px;
  font-weight: 700;
}
.ppt-code-pane pre { flex: 1 1 auto; min-height: 0; margin: 0; overflow: auto; }
.ppt-code-pane pre code { font-size: 21px; }

.ppt-steps {
  counter-reset: ppt-step;
  list-style: none;
  margin: 0;
  padding: 0;
}
.ppt-steps li {
  counter-increment: ppt-step;
  position: relative;
  margin: .55em 0;
  padding-left: 3.1em;
  font-size: 24px;
  line-height: 1.42;
}
.ppt-steps li::before {
  content: counter(ppt-step);
  position: absolute;
  left: 0;
  top: .02em;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.9em;
  height: 1.9em;
  border-radius: 50%;
  background: #4a72ad;
  color: #fff;
  font-size: .92em;
  font-weight: 700;
}
.ppt-steps li strong { display: block; color: #315b94; font-size: 24px; }
.ppt-steps li span { display: block; margin-top: 2px; color: #3d5674; }

.ppt-table { width: 100%; border-collapse: collapse; font-size: 22px; }

.ppt-callout {
  padding: 22px 26px;
  border-left: 8px solid #9aa7b4;
  border-radius: 0 14px 14px 0;
  background: #f6f8fb;
}
.ppt-callout-tip { border-color: #42b983; background: #f2faf6; }
.ppt-callout-warning { border-color: #d9b400; background: #fffbea; }
.ppt-callout-danger { border-color: #c0392b; background: #fff4f2; }
.ppt-callout-info { border-color: #3e8ed0; background: #f2f8fe; }
.ppt-callout-label {
  margin-bottom: 10px;
  color: #6b7a8c;
  font-size: 22px;
  font-weight: 800;
  letter-spacing: .08em;
}
.ppt-callout-tip .ppt-callout-label { color: #2f8f65; }
.ppt-callout-warning .ppt-callout-label { color: #9a7c00; }
.ppt-callout-danger .ppt-callout-label { color: #b00000; }
.ppt-callout-info .ppt-callout-label { color: #2d6fa8; }
.ppt-callout-text {
  color: #26384d;
  font-size: clamp(24px, 1.2cqw + 12px, 31px);
  font-weight: 600;
  line-height: 1.5;
}
.ppt-callout-list { margin: 12px 0 0; padding-left: 1.2em; }
.ppt-callout-list li { margin: .25em 0; font-size: 22px; line-height: 1.45; }

.ppt-quiz { display: flex; flex-direction: column; gap: 14px; }
.ppt-question {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 14px 18px;
  border: 1px solid #dfe8f4;
  border-radius: 12px;
  background: #f7faff;
}
.ppt-q-num {
  flex: 0 0 auto;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: #4a72ad;
  color: #fff;
  font-size: 22px;
  font-weight: 700;
}
.ppt-q-text { color: #26384d; font-size: 26px; line-height: 1.45; }
.ppt-q-main { min-width: 0; }
.ppt-q-hint { margin-top: 6px; color: #6b83a3; font-size: 22px; }

.ppt-summary { list-style: none; margin: 0; padding: 0; }
.ppt-summary li {
  position: relative;
  margin: .42em 0;
  padding-left: 1.55em;
  color: #26384d;
  font-size: 26px;
  line-height: 1.45;
}
.ppt-summary li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #2f8f65;
  font-weight: 800;
}
.ppt-next {
  margin-top: 20px;
  padding: 14px 18px;
  border-radius: 12px;
  background: #eef4fb;
  color: #315b94;
  font-size: 23px;
  line-height: 1.45;
}
.ppt-next span { margin-right: 10px; font-weight: 800; }

/* 翻页按钮与页码 */
.ppt-nav {
  position: absolute;
  top: 50%;
  z-index: 5;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  margin-top: -26px;
  border: 1px solid rgba(74, 114, 173, .18);
  border-radius: 50%;
  background: rgba(255, 255, 255, .88);
  color: #4a72ad;
  font-family: inherit;
  font-size: 34px;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(23, 43, 77, .10);
  transition: background .15s, color .15s, opacity .15s;
}
.ppt-nav:hover { background: #4a72ad; color: #fff; }
.ppt-nav:disabled { opacity: .28; cursor: default; }
.ppt-nav:disabled:hover { background: rgba(255, 255, 255, .88); color: #4a72ad; }
.ppt-prev { left: 12px; }
.ppt-next { right: 12px; }

/* 隐藏滚动条但保留滚动 */
.ppt-stage ::-webkit-scrollbar { width: 8px; height: 8px; }
.ppt-stage ::-webkit-scrollbar-thumb { background: #c8d6e8; border-radius: 4px; }

@media (max-width: 900px) {
  .view-switch { margin-right: 6px; }
  .view-btn { min-width: 42px; padding: 4px 7px; font-size: 12px; }
  .md-download { display: none; }
  .ppt-bar { padding: 0 10px; }
  .ppt-brand { font-size: 12px; }
  .ppt-btn { height: 30px; padding: 0 8px; font-size: 12px; }
  .ppt-viewport { padding: 8px 44px 24px; }
  .ppt-nav { width: 42px; height: 42px; margin-top: -21px; font-size: 28px; }
}