:root {
  color-scheme: light;
  --ink: #050505;
  --muted: #666;
  --line: #dedede;
  --paper: #fff;
  --soft: #f7f7f7;
  --radius: 18px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  letter-spacing: 0;
}

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

.page {
  min-height: 100vh;
}

.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 68px;
  padding: 0 28px;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 17px;
  font-weight: 720;
  white-space: nowrap;
}

.mark {
  position: relative;
  width: 34px;
  height: 34px;
}

.mark-sheet {
  position: absolute;
  left: 4px;
  bottom: 3px;
  width: 25px;
  height: 25px;
  border: 1.4px solid var(--ink);
  border-radius: 8px;
  transform: rotate(-5deg);
}

.mark-sheet::before,
.mark-sheet::after {
  content: "";
  position: absolute;
  left: 6px;
  height: 1.4px;
  border-radius: 99px;
  background: var(--ink);
}

.mark-sheet::before {
  bottom: 8px;
  width: 12px;
}

.mark-sheet::after {
  bottom: 4px;
  width: 8px;
}

.mark-flash {
  position: absolute;
  right: 1px;
  top: 1px;
  display: grid;
  place-items: center;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: var(--paper);
  color: var(--ink);
  font-size: 12px;
  line-height: 1;
  border: 1.4px solid var(--ink);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 22px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
}

.nav-links a:hover {
  color: var(--ink);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 360px;
  align-items: center;
  gap: 64px;
  width: min(1120px, calc(100% - 48px));
  min-height: calc(100vh - 68px);
  margin: 0 auto;
  padding: 54px 0 72px;
}

.hero-copy {
  max-width: 620px;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--muted);
  font-size: 15px;
  font-weight: 750;
}

h1 {
  margin: 0;
  font-size: clamp(52px, 8vw, 96px);
  line-height: 1;
  font-weight: 760;
}

.lead {
  max-width: 540px;
  margin: 24px 0 0;
  color: #2f2f2f;
  font-size: 21px;
  line-height: 1.68;
  font-weight: 650;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin-top: 34px;
}

.button,
.ghost-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  border-radius: 999px;
  padding: 0 20px;
  font-size: 15px;
  font-weight: 760;
}

.button {
  background: var(--ink);
  color: var(--paper);
}

.ghost-button {
  border: 1px solid var(--line);
}

.hero-note {
  margin-top: 18px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 620;
}

.phone {
  position: relative;
  width: 320px;
  height: 652px;
  margin-left: auto;
  border: 12px solid var(--ink);
  border-radius: 48px;
  background: var(--paper);
  overflow: hidden;
}

.phone::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 11px;
  width: 116px;
  height: 34px;
  border-radius: 999px;
  background: var(--ink);
  transform: translateX(-50%);
}

.phone-screen {
  height: 100%;
  padding: 72px 20px 28px;
}

.phone-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 28px;
}

.phone-title {
  font-size: 34px;
  line-height: 1;
  font-weight: 850;
}

.phone-icon {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--soft);
  font-size: 22px;
}

.task {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.check {
  width: 24px;
  height: 24px;
  border: 2px solid var(--ink);
  border-radius: 50%;
  margin-top: 2px;
}

.task-title {
  margin: 0;
  font-size: 18px;
  line-height: 1.35;
  font-weight: 780;
}

.task-meta {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 14px;
  font-weight: 680;
}

.tabbar {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  padding: 12px 12px 18px;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  background: var(--paper);
  color: var(--muted);
  font-size: 12px;
  font-weight: 780;
  text-align: center;
}

.tabbar span:first-child {
  color: var(--ink);
}

.section {
  width: min(1040px, calc(100% - 48px));
  margin: 0 auto;
  padding: 74px 0;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.section h2 {
  max-width: 680px;
  margin: 0;
  font-size: clamp(32px, 5vw, 54px);
  line-height: 1.08;
  font-weight: 850;
}

.section-lead {
  max-width: 680px;
  margin: 18px 0 0;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.7;
  font-weight: 620;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
  margin-top: 34px;
}

.feature {
  min-height: 190px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
}

.feature strong {
  display: block;
  margin-bottom: 12px;
  font-size: 20px;
}

.feature p {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.7;
  font-weight: 560;
}

.privacy-band {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  align-items: start;
}

.privacy-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.privacy-list li {
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
  color: #222;
  font-size: 17px;
  line-height: 1.6;
  font-weight: 650;
}

.footer {
  width: min(1040px, calc(100% - 48px));
  margin: 0 auto;
  padding: 34px 0 48px;
  border-top: 1px solid rgba(0, 0, 0, 0.08);
  color: var(--muted);
  font-size: 13px;
  font-weight: 620;
}

.footer a {
  color: var(--ink);
  font-weight: 760;
}

.doc {
  width: min(760px, calc(100% - 48px));
  margin: 0 auto;
  padding: 58px 0 82px;
}

.doc h1 {
  font-size: clamp(38px, 7vw, 64px);
}

.doc .updated {
  margin: 16px 0 34px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 650;
}

.doc h2 {
  margin: 34px 0 10px;
  font-size: 22px;
}

.doc p,
.doc li {
  color: #333;
  font-size: 17px;
  line-height: 1.85;
  font-weight: 560;
}

.doc ul {
  padding-left: 22px;
}

@media (max-width: 860px) {
  .nav {
    padding: 0 20px;
  }

  .nav-links {
    gap: 14px;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-top: 54px;
  }

  .phone {
    width: min(320px, 100%);
    height: 620px;
    margin: 0 auto;
  }

  .feature-grid,
  .privacy-band {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .nav-links a:first-child {
    display: none;
  }

  .hero,
  .section,
  .footer,
  .doc {
    width: min(100% - 36px, 1040px);
  }

  .lead {
    font-size: 18px;
  }

  .phone {
    height: 560px;
    border-width: 10px;
    border-radius: 42px;
  }
}