:root {
  --paper: #f5f3ed;
  --surface: #ffffff;
  --ink: #151515;
  --muted: #62645f;
  --line: #1c1c1c;
  --lime: #d7ff36;
  --cyan: #35d8ff;
  --coral: #ff6b62;
  --max: 1180px;
  --header-height: 70px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 84px;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "微软雅黑", Arial, Helvetica, sans-serif;
  font-size: 16px;
  line-height: 1.72;
}

body.menu-open {
  overflow: hidden;
}

img {
  display: block;
  max-width: 100%;
}

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

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button,
.button {
  font: inherit;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 200;
  padding: 8px 12px;
  background: var(--surface);
  border: 2px solid var(--ink);
  transform: translateY(-140%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: rgba(245, 243, 237, 0.96);
  border-bottom: 2px solid var(--ink);
}

.header-inner,
.hero-inner,
.section-inner,
.footer-inner {
  width: min(calc(100% - 40px), var(--max));
  margin-inline: auto;
}

.header-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: max-content;
  font-size: 19px;
  font-weight: 900;
}

.brand img {
  width: 38px;
  height: 38px;
  border: 2px solid var(--ink);
  border-radius: 5px;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 6px;
}

.site-nav a {
  padding: 8px 13px;
  border-bottom: 3px solid transparent;
  font-size: 14px;
  font-weight: 750;
}

.site-nav a:hover,
.site-nav a:focus-visible,
.site-nav a[aria-current="page"] {
  border-bottom-color: var(--ink);
}

.site-nav .nav-download {
  margin-left: 6px;
  color: var(--ink);
  background: var(--lime);
  border: 2px solid var(--ink);
  box-shadow: 3px 3px 0 var(--ink);
}

.menu-toggle {
  display: none;
  width: 42px;
  height: 42px;
  padding: 9px;
  background: var(--lime);
  border: 2px solid var(--ink);
  border-radius: 4px;
  cursor: pointer;
}

.menu-toggle span {
  display: block;
  height: 2px;
  margin: 4px 0;
  background: var(--ink);
  transition: transform 180ms ease, opacity 180ms ease;
}

.menu-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.menu-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.menu-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  padding: 10px 19px;
  color: var(--ink);
  background: var(--lime);
  border: 2px solid var(--ink);
  border-radius: 4px;
  box-shadow: 4px 4px 0 var(--ink);
  font-weight: 900;
  transition: transform 150ms ease, box-shadow 150ms ease;
}

.button:hover,
.button:focus-visible {
  transform: translate(2px, 2px);
  box-shadow: 2px 2px 0 var(--ink);
}

.button.secondary {
  background: var(--surface);
}

.hero {
  border-bottom: 2px solid var(--ink);
  background: var(--paper);
}

.hero-inner {
  min-height: 620px;
  display: grid;
  grid-template-columns: minmax(0, 1.03fr) minmax(420px, 0.97fr);
  align-items: center;
  gap: clamp(44px, 6vw, 86px);
  padding-block: 38px 32px;
}

.eyebrow,
.section-index,
.meter-label,
.image-label {
  margin: 0;
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0;
  text-transform: uppercase;
}

.eyebrow {
  display: inline-block;
  padding: 4px 8px;
  background: var(--cyan);
  border: 2px solid var(--ink);
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1,
h2,
h3 {
  letter-spacing: 0;
  line-height: 1.12;
}

h1 {
  max-width: 10em;
  margin: 18px 0 16px;
  font-size: clamp(40px, 4vw, 58px);
  font-weight: 950;
}

.hero-copy > p {
  max-width: 590px;
  margin-bottom: 20px;
  color: #373936;
  font-size: 18px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 13px;
}

.reading-meter {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  margin-top: 25px;
  border: 2px solid var(--ink);
}

.meter-item {
  min-width: 0;
  padding: 10px 12px;
  background: var(--surface);
  border-right: 1px solid var(--ink);
}

.meter-item:last-child {
  border-right: 0;
}

.meter-item strong,
.meter-item span {
  display: block;
}

.meter-item strong {
  font-size: 15px;
}

.meter-item span {
  color: var(--muted);
  font-size: 12px;
}

.hero-media {
  min-height: 492px;
  display: grid;
  grid-template-columns: 52px minmax(230px, 294px) 52px;
  align-items: center;
  justify-content: center;
  gap: 14px;
  position: relative;
}

.mode-strip {
  height: 335px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  padding: 12px 7px;
  background: var(--cyan);
  border: 2px solid var(--ink);
}

.mode-strip.right {
  background: var(--coral);
}

.mode-strip span {
  writing-mode: vertical-rl;
  font-size: 12px;
  font-weight: 900;
}

.mode-strip b {
  font-size: 18px;
}

.screen-well {
  position: relative;
  padding: 11px;
  background: var(--ink);
  border: 2px solid var(--ink);
  box-shadow: 10px 10px 0 var(--lime);
}

.screen-well img {
  width: 100%;
  height: auto;
  max-width: 399px;
  margin: auto;
}

.screen-readout {
  display: flex;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 4px 0;
  color: var(--surface);
  font-size: 11px;
  font-weight: 800;
}

.hero-media::after {
  content: "夜读亮度 / 阅读方向 / 章节定位";
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  padding-top: 8px;
  border-top: 2px solid var(--ink);
  text-align: center;
  font-size: 12px;
  font-weight: 900;
}

.band {
  border-bottom: 2px solid var(--ink);
}

.band.white {
  background: var(--surface);
}

.band.dark {
  color: var(--surface);
  background: var(--ink);
}

.band.lime {
  background: var(--lime);
}

.section-inner {
  padding-block: 68px;
}

.section-head {
  display: grid;
  grid-template-columns: 150px 1fr;
  gap: 30px;
  align-items: end;
  margin-bottom: 32px;
}

.section-index {
  color: var(--muted);
}

.band.dark .section-index {
  color: #b8bbb4;
}

h2 {
  margin-bottom: 0;
  font-size: clamp(30px, 3.5vw, 46px);
  font-weight: 950;
}

.section-lead {
  max-width: 760px;
  margin: -12px 0 32px 180px;
  color: var(--muted);
}

.band.dark .section-lead {
  color: #d8d9d5;
}

.context-matrix {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 2px solid var(--ink);
}

.context-cell {
  min-height: 145px;
  padding: 20px;
  background: var(--surface);
  border-right: 1px solid var(--ink);
}

.context-cell:nth-child(2) {
  background: var(--cyan);
}

.context-cell:nth-child(3) {
  background: var(--lime);
}

.context-cell:nth-child(4) {
  background: var(--coral);
  border-right: 0;
}

.context-cell strong {
  display: block;
  margin-bottom: 18px;
  font-size: 18px;
}

.context-cell p {
  margin-bottom: 0;
  font-size: 14px;
}

.gallery-grid {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr 0.92fr;
  gap: 22px;
  align-items: start;
}

.preview-figure {
  margin: 0;
}

.preview-frame {
  padding: 13px;
  background: #e8e7e1;
  border: 2px solid var(--ink);
}

.preview-frame.dark-frame {
  background: #252525;
}

.preview-frame.cyan-frame {
  background: var(--cyan);
}

.preview-figure img {
  width: 100%;
  height: auto;
  max-width: 399px;
  margin-inline: auto;
  border: 1px solid #777;
}

.preview-figure figcaption {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 12px;
  padding-top: 12px;
}

.image-label {
  padding-top: 2px;
  color: var(--coral);
}

.preview-figure p {
  margin: 0;
  font-size: 14px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.feature-card {
  min-height: 210px;
  padding: 24px;
  color: var(--ink);
  background: var(--surface);
  border: 2px solid var(--ink);
  border-radius: 6px;
}

.feature-card:nth-child(2),
.feature-card:nth-child(5) {
  background: var(--lime);
}

.feature-card:nth-child(3),
.feature-card:nth-child(4) {
  background: var(--cyan);
}

.feature-number {
  display: inline-block;
  margin-bottom: 22px;
  padding: 2px 7px;
  color: var(--surface);
  background: var(--ink);
  font-size: 12px;
  font-weight: 900;
}

.feature-card h3 {
  margin-bottom: 10px;
  font-size: 20px;
}

.feature-card p {
  margin-bottom: 0;
  font-size: 14px;
}

.setup-grid {
  display: grid;
  grid-template-columns: 0.92fr 1.08fr;
  gap: 46px;
  align-items: center;
}

.setup-image {
  padding: 14px;
  background: var(--surface);
  border: 2px solid var(--ink);
  box-shadow: 10px 10px 0 var(--cyan);
}

.setup-image img {
  width: min(100%, 399px);
  height: auto;
  margin: auto;
}

.setup-list {
  counter-reset: step;
  margin: 0;
  padding: 0;
  list-style: none;
}

.setup-list li {
  position: relative;
  padding: 17px 0 17px 62px;
  border-bottom: 1px solid var(--ink);
}

.setup-list li::before {
  counter-increment: step;
  content: "0" counter(step);
  position: absolute;
  top: 17px;
  left: 0;
  width: 44px;
  padding: 2px 0;
  background: var(--coral);
  border: 1px solid var(--ink);
  text-align: center;
  font-size: 12px;
  font-weight: 900;
}

.setup-list strong {
  display: block;
  margin-bottom: 4px;
}

.setup-list p {
  margin-bottom: 0;
  color: #3c3e3a;
  font-size: 14px;
}

.route-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
}

.route-link {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 20px;
  min-height: 180px;
  padding: 28px;
  background: var(--surface);
  border: 2px solid var(--ink);
}

.route-link:nth-child(2) {
  background: var(--cyan);
}

.route-link h3 {
  margin-bottom: 10px;
  font-size: 26px;
}

.route-link p {
  margin-bottom: 0;
  color: #40423e;
}

.route-arrow {
  align-self: end;
  font-size: 34px;
  font-weight: 900;
}

.download-band .section-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 30px;
  padding-block: 46px;
}

.download-band h2 {
  max-width: 700px;
  font-size: clamp(28px, 4vw, 48px);
}

.page-hero {
  border-bottom: 2px solid var(--ink);
}

.page-hero .section-inner {
  display: grid;
  grid-template-columns: 0.8fr 1.2fr;
  gap: 60px;
  align-items: end;
  padding-block: 70px 56px;
}

.page-hero h1 {
  max-width: 12em;
  margin-bottom: 0;
}

.page-hero-copy {
  padding: 24px;
  background: var(--cyan);
  border: 2px solid var(--ink);
}

.page-hero-copy p:last-child {
  margin-bottom: 0;
}

.guide-layout {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: 54px;
  align-items: start;
}

.guide-aside {
  position: sticky;
  top: 94px;
  padding: 20px;
  background: var(--lime);
  border: 2px solid var(--ink);
}

.guide-aside strong {
  display: block;
  margin-bottom: 10px;
}

.guide-aside a {
  display: block;
  padding: 9px 0;
  border-bottom: 1px solid var(--ink);
  font-size: 14px;
  font-weight: 800;
}

.guide-content section {
  padding: 0 0 48px;
  scroll-margin-top: 94px;
}

.guide-content section + section {
  padding-top: 48px;
  border-top: 2px solid var(--ink);
}

.guide-content h2 {
  margin-bottom: 24px;
  font-size: 34px;
}

.guide-content h3 {
  margin: 28px 0 10px;
  font-size: 21px;
}

.guide-content p,
.guide-content li {
  color: #353733;
}

.guide-content ol,
.guide-content ul {
  padding-left: 22px;
}

.note-block {
  margin: 24px 0;
  padding: 18px 20px;
  background: var(--cyan);
  border-left: 8px solid var(--ink);
}

.check-table {
  width: 100%;
  border-collapse: collapse;
  margin: 24px 0;
  background: var(--surface);
}

.check-table th,
.check-table td {
  padding: 13px 14px;
  border: 1px solid var(--ink);
  text-align: left;
  vertical-align: top;
}

.check-table th {
  background: var(--lime);
}

.faq-list {
  border-top: 2px solid var(--ink);
}

.faq-item {
  border-bottom: 2px solid var(--ink);
}

.faq-question {
  width: 100%;
  display: grid;
  grid-template-columns: 52px 1fr 24px;
  gap: 18px;
  align-items: center;
  padding: 20px 0;
  color: var(--ink);
  background: transparent;
  border: 0;
  text-align: left;
  cursor: pointer;
}

.faq-question span:first-child {
  color: var(--muted);
  font-size: 13px;
  font-weight: 900;
}

.faq-question strong {
  font-size: 19px;
}

.faq-icon {
  width: 22px;
  height: 22px;
  position: relative;
}

.faq-icon::before,
.faq-icon::after {
  content: "";
  position: absolute;
  top: 10px;
  left: 3px;
  width: 16px;
  height: 2px;
  background: var(--ink);
}

.faq-icon::after {
  transform: rotate(90deg);
  transition: transform 160ms ease;
}

.faq-question[aria-expanded="true"] .faq-icon::after {
  transform: rotate(0);
}

.faq-answer {
  max-width: 880px;
  padding: 0 44px 22px 70px;
}

.faq-answer[hidden] {
  display: none;
}

.faq-answer p:last-child {
  margin-bottom: 0;
}

.followup-link {
  margin-top: 24px;
}

.site-footer {
  color: var(--surface);
  background: var(--ink);
}

.footer-inner {
  padding-block: 34px;
  text-align: center;
}

.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
  font-weight: 900;
}

.footer-brand img {
  width: 34px;
  height: 34px;
  border: 1px solid var(--surface);
  border-radius: 4px;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 18px;
  margin-bottom: 16px;
  font-size: 14px;
}

.footer-inner p {
  max-width: 900px;
  margin: 6px auto 0;
  color: #d5d6d2;
  text-align: center;
  font-size: 13px;
}

@media (max-width: 900px) {
  :root {
    --header-height: 64px;
  }

  .header-inner,
  .hero-inner,
  .section-inner,
  .footer-inner {
    width: min(calc(100% - 28px), var(--max));
  }

  .menu-toggle {
    display: block;
  }

  .site-nav {
    position: fixed;
    top: var(--header-height);
    right: 0;
    left: 0;
    display: none;
    align-items: stretch;
    padding: 14px;
    background: var(--paper);
    border-bottom: 2px solid var(--ink);
  }

  .site-nav.open {
    display: grid;
  }

  .site-nav a {
    padding: 12px;
    border: 0;
    border-bottom: 1px solid var(--ink);
  }

  .site-nav .nav-download {
    margin: 8px 0 0;
    text-align: center;
  }

  .hero-inner {
    min-height: auto;
    grid-template-columns: 1fr;
    gap: 25px;
    padding-block: 28px 22px;
  }

  h1 {
    max-width: none;
    margin: 13px 0 11px;
    font-size: 38px;
  }

  .hero-copy > p {
    margin-bottom: 14px;
    font-size: 15px;
    line-height: 1.58;
  }

  .hero-actions {
    gap: 10px;
  }

  .button {
    min-height: 42px;
    padding: 8px 15px;
  }

  .reading-meter {
    margin-top: 17px;
  }

  .meter-item {
    padding: 7px 8px;
  }

  .meter-item strong {
    font-size: 13px;
  }

  .meter-item span {
    font-size: 10px;
  }

  .hero-media {
    min-height: 285px;
    grid-template-columns: 36px minmax(160px, 205px) 36px;
    gap: 8px;
  }

  .mode-strip {
    height: 210px;
    padding: 8px 4px;
  }

  .mode-strip span {
    font-size: 10px;
  }

  .screen-well {
    padding: 7px;
    box-shadow: 6px 6px 0 var(--lime);
  }

  .screen-readout {
    display: none;
  }

  .hero-media::after {
    padding-top: 5px;
    font-size: 10px;
  }

  .section-inner {
    padding-block: 48px;
  }

  .section-head {
    grid-template-columns: 1fr;
    gap: 8px;
    margin-bottom: 24px;
  }

  .section-lead {
    margin: -10px 0 24px;
  }

  .context-matrix,
  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .context-cell:nth-child(2) {
    border-right: 0;
  }

  .context-cell:nth-child(-n + 2) {
    border-bottom: 1px solid var(--ink);
  }

  .gallery-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
  }

  .preview-frame {
    padding: 6px;
  }

  .preview-figure figcaption {
    grid-template-columns: 1fr;
    gap: 3px;
  }

  .setup-grid,
  .page-hero .section-inner {
    grid-template-columns: 1fr;
  }

  .guide-layout {
    grid-template-columns: 1fr;
  }

  .guide-aside {
    position: static;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
  }

  .guide-aside strong {
    grid-column: 1 / -1;
  }

  .page-hero .section-inner {
    gap: 28px;
    padding-block: 52px 42px;
  }
}

@media (max-width: 620px) {
  .hero-inner {
    gap: 18px;
    padding-top: 22px;
  }

  h1 {
    font-size: 34px;
  }

  .eyebrow {
    font-size: 10px;
  }

  .reading-meter {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .hero-media {
    min-height: 264px;
    grid-template-columns: 30px minmax(150px, 184px) 30px;
  }

  .mode-strip {
    height: 190px;
  }

  .context-matrix,
  .feature-grid,
  .route-grid,
  .gallery-grid {
    grid-template-columns: 1fr;
  }

  .context-cell,
  .context-cell:nth-child(2),
  .context-cell:nth-child(3) {
    min-height: auto;
    border-right: 0;
    border-bottom: 1px solid var(--ink);
  }

  .gallery-grid {
    width: min(100%, 330px);
    margin-inline: auto;
  }

  .feature-card {
    min-height: auto;
  }

  .download-band .section-inner {
    display: grid;
  }

  .download-band .button {
    width: 100%;
  }

  .guide-aside {
    grid-template-columns: repeat(2, 1fr);
  }

  .check-table,
  .check-table tbody,
  .check-table tr,
  .check-table th,
  .check-table td {
    display: block;
  }

  .check-table tr + tr {
    margin-top: 12px;
  }

  .faq-question {
    grid-template-columns: 36px 1fr 22px;
    gap: 10px;
  }

  .faq-question strong {
    font-size: 17px;
  }

  .faq-answer {
    padding: 0 4px 20px 46px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition: none !important;
  }
}