:root {
  --reader-font-size: 20px;
  --brand: #f05a1a;
  --ink: #172033;
  --muted: #667085;
  --line: #d7dce3;
  --paper: #ffffff;
  --canvas: #eef1f4;
}

* {
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 168px;
}

body {
  margin: 0;
  background: var(--canvas);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: var(--reader-font-size);
  line-height: 1.65;
}

body.reader-large {
  --reader-font-size: 22px;
}

body.reader-xlarge {
  --reader-font-size: 25px;
}

button,
a {
  font: inherit;
}

a {
  color: inherit;
  text-decoration: none;
}

.reader-header {
  position: sticky;
  z-index: 50;
  top: 0;
  display: grid;
  grid-template-columns: minmax(190px, 1fr) auto auto;
  align-items: center;
  min-height: 82px;
  padding: 12px clamp(18px, 3vw, 44px);
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.98);
}

.home-logo {
  display: inline-flex;
  align-items: center;
  width: fit-content;
  min-height: 52px;
  padding: 4px 8px;
}

.home-logo img {
  display: block;
  width: 176px;
  height: 48px;
  object-fit: contain;
}

.reader-tools {
  display: flex;
  align-items: center;
  gap: 14px;
}

.font-switch {
  display: grid;
  grid-template-columns: repeat(3, 52px);
  overflow: hidden;
  border: 1px solid #b8c0cc;
  border-radius: 8px;
  background: #fff;
}

.font-switch button {
  min-width: 52px;
  min-height: 48px;
  border: 0;
  border-right: 1px solid #b8c0cc;
  background: #fff;
  color: #344054;
  font-weight: 800;
  cursor: pointer;
}

.font-switch button:last-child {
  border-right: 0;
}

.font-switch button[aria-pressed="true"] {
  background: var(--ink);
  color: #fff;
}

.back-button,
.bottom-back {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 52px;
  padding: 0 20px;
  border-radius: 8px;
  background: var(--brand);
  color: #fff;
  font-weight: 900;
}

.section-nav {
  position: sticky;
  z-index: 40;
  top: 82px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 10px clamp(18px, 3vw, 44px);
  border-bottom: 1px solid var(--line);
  background: #f8fafc;
  scrollbar-width: none;
}

.section-nav::-webkit-scrollbar {
  display: none;
}

.section-nav a {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 18px;
  border: 1px solid #cbd2dc;
  border-radius: 8px;
  background: #fff;
  font-size: 17px;
  font-weight: 800;
}

.page-shell {
  width: min(100%, 1760px);
  margin: 0 auto;
  background: var(--paper);
}

.model-hero {
  display: grid;
  grid-template-columns: minmax(300px, 1.1fr) minmax(420px, 1.9fr);
  gap: clamp(24px, 4vw, 64px);
  align-items: center;
  padding: clamp(30px, 5vw, 72px) clamp(22px, 5vw, 72px);
  background: #172033;
  color: #fff;
}

.eyebrow {
  margin: 0 0 10px;
  color: #ffb28f;
  font-size: 0.9em;
  font-weight: 900;
}

.model-hero h1 {
  margin: 0;
  font-size: clamp(34px, 4vw, 58px);
  line-height: 1.14;
}

.model-hero .subtitle {
  margin: 18px 0 0;
  color: #d8dee9;
  font-size: 1.05em;
  font-weight: 700;
}

.highlights {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.highlight {
  min-height: 88px;
  padding: 16px 18px;
  border-left: 5px solid var(--brand);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
}

.highlight strong {
  display: block;
  font-size: 1.08em;
  line-height: 1.3;
}

.highlight span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.82em;
  font-weight: 700;
}

.content-area {
  padding: 28px clamp(22px, 5vw, 72px) 56px;
}

.intro-note {
  margin: 0 0 24px;
  padding: 18px 20px;
  border-left: 5px solid #1476d4;
  background: #edf6ff;
  color: #19466f;
  font-weight: 750;
}

.spec-section {
  padding: 30px 0 24px;
  border-bottom: 2px solid #e5e9ef;
}

.spec-section:last-child {
  border-bottom: 0;
}

.section-title {
  display: flex;
  align-items: center;
  gap: 14px;
  margin: 0 0 16px;
  font-size: clamp(28px, 2.6vw, 38px);
  line-height: 1.25;
}

.section-title::before {
  width: 8px;
  height: 34px;
  border-radius: 4px;
  background: var(--brand);
  content: "";
}

.spec-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 32px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.spec-item {
  position: relative;
  min-height: 66px;
  padding: 13px 12px 13px 32px;
  border-bottom: 1px solid var(--line);
  font-weight: 700;
}

.spec-item::before {
  position: absolute;
  top: 23px;
  left: 8px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--brand);
  content: "";
}

.options-section {
  margin-top: 34px;
  padding: 30px clamp(18px, 3vw, 38px);
  border: 2px solid #e7b14f;
  border-radius: 8px;
  background: #fff8e8;
}

.options-section .section-title::before {
  background: #d79000;
}

.option-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.option-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  gap: 18px;
  padding: 12px 16px;
  border: 1px solid #e8ca8d;
  border-radius: 6px;
  background: #fff;
  font-weight: 800;
}

.option-price {
  flex: 0 0 auto;
  color: #b54a00;
  font-weight: 950;
}

.page-actions {
  display: flex;
  justify-content: center;
  padding: 38px 0 12px;
}

.bottom-back {
  min-width: 280px;
  min-height: 60px;
  font-size: 1.05em;
}

.reader-footer {
  padding: 24px;
  background: #172033;
  color: #cbd5e1;
  text-align: center;
  font-size: 16px;
  font-weight: 700;
}

@media (max-width: 1199px) {
  .model-hero {
    grid-template-columns: 1fr;
  }

  .reader-header {
    grid-template-columns: 1fr auto;
  }

  .reader-tools {
    gap: 8px;
  }

  .back-button {
    padding: 0 14px;
  }
}

@media (max-width: 767px), (orientation: portrait) and (max-width: 1100px) {
  html {
    scroll-padding-top: 225px;
  }

  .reader-header {
    grid-template-columns: 1fr;
    gap: 8px;
    padding: 10px 16px;
  }

  .home-logo {
    margin: 0 auto;
  }

  .reader-tools {
    width: 100%;
    justify-content: space-between;
  }

  .section-nav {
    top: 128px;
    padding-inline: 14px;
  }

  .highlights,
  .spec-grid,
  .option-list {
    grid-template-columns: 1fr;
  }

  .model-hero,
  .content-area {
    padding-inline: 18px;
  }

  .model-hero h1 {
    font-size: 34px;
  }
}

@media print {
  .reader-header,
  .section-nav,
  .page-actions {
    display: none;
  }

  body {
    background: #fff;
  }

  .page-shell {
    width: 100%;
  }

  .spec-section,
  .options-section {
    break-inside: avoid;
  }
}