:root {
  --blue: #1a73e8;
  --blue-deep: #174ea6;
  --blue-soft: #e8f0fe;
  --ink: #202124;
  --mute: #5f6368;
  --paper: #ffffff;
  --wash: #f8f9fa;
  --line: #dadce0;
  --ok: #188038;
  --radius: 10px;
  --shadow: 0 1px 2px rgba(32, 33, 36, 0.08), 0 2px 8px rgba(32, 33, 36, 0.06);
  --max: 1120px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.75;
}

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

a {
  color: var(--blue);
  text-decoration: none;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease;
}

a:hover {
  color: var(--blue-deep);
  text-decoration: underline;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.nav-bar {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.02em;
  text-decoration: none;
}

.brand:hover {
  color: var(--blue);
  text-decoration: none;
}

.brand svg {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  display: inline-flex;
  align-items: center;
  padding: 8px 14px;
  border-radius: 999px;
  color: var(--mute);
  font-size: 14px;
  font-weight: 600;
  text-decoration: none;
}

.nav-links a:hover {
  color: var(--blue);
  background: var(--blue-soft);
  text-decoration: none;
}

.nav-links a.is-now {
  color: var(--blue);
  background: var(--blue-soft);
  box-shadow: inset 0 -2px 0 var(--blue);
}

.hero {
  background: var(--blue-soft);
  border-bottom: 1px solid #d2e3fc;
}

.hero-inner,
.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 56px 24px;
}

.hero-inner {
  padding-top: 64px;
  padding-bottom: 64px;
}

.kicker {
  display: inline-block;
  margin-bottom: 12px;
  color: var(--blue);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0 0 20px;
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: -0.03em;
}

h2 {
  margin: 0 0 16px;
  font-size: clamp(22px, 3vw, 28px);
  line-height: 1.35;
  letter-spacing: -0.02em;
}

h3 {
  margin: 0 0 10px;
  font-size: 18px;
  line-height: 1.4;
}

p {
  margin: 0 0 16px;
  color: var(--ink);
}

.lead,
.hero p {
  font-size: 17px;
  max-width: 820px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 10px 20px;
  border-radius: 6px;
  font-weight: 600;
  font-size: 15px;
  text-decoration: none;
  border: 1px solid transparent;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: var(--blue);
  color: #fff;
}

.btn-primary:hover {
  background: var(--blue-deep);
  color: #fff;
  text-decoration: none;
  box-shadow: 0 1px 3px rgba(26, 115, 232, 0.35);
}

.btn-ghost {
  background: var(--paper);
  color: var(--blue);
  border-color: #c5d7f5;
}

.btn-ghost:hover {
  background: #f3f8ff;
  color: var(--blue-deep);
  text-decoration: none;
}

.section {
  background: var(--paper);
}

.section-alt {
  background: var(--wash);
}

.section-head {
  max-width: 760px;
  margin-bottom: 28px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  align-items: start;
}

.card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 22px 18px;
  box-shadow: var(--shadow);
}

.card p:last-child,
.quote p:last-child,
.faq-item p:last-child {
  margin-bottom: 0;
}

.icon-round {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--blue-soft);
  color: var(--blue);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 14px;
}

.icon-round svg {
  width: 22px;
  height: 22px;
}

.split {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 36px;
  align-items: center;
}

.split.reverse {
  grid-template-columns: 0.95fr 1.05fr;
}

.split.reverse .split-copy {
  order: 2;
}

.split.reverse .split-visual {
  order: 1;
}

.split-visual {
  background: var(--blue-soft);
  border: 1px solid #d2e3fc;
  border-radius: 14px;
  padding: 28px;
  min-height: 220px;
}

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

.checklist li {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin-bottom: 12px;
  color: var(--ink);
}

.checklist svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  margin-top: 4px;
  color: var(--ok);
}

.os-card .os-name {
  font-weight: 700;
  margin-bottom: 8px;
}

.os-card .os-meta {
  color: var(--mute);
  font-size: 14px;
  margin-bottom: 16px;
}

.quote {
  background: var(--paper);
  border: 1px solid var(--line);
  border-left: 4px solid var(--blue);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 20px 22px;
}

.quote-meta {
  margin-top: 14px;
  font-size: 14px;
  color: var(--mute);
  font-weight: 600;
}

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

.stat {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
}

.stat b {
  display: block;
  font-size: 28px;
  color: var(--blue);
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 6px;
}

.stat span {
  color: var(--mute);
  font-size: 14px;
}

.compare {
  width: 100%;
  border-collapse: collapse;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.compare th,
.compare td {
  text-align: left;
  padding: 14px 16px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.compare th {
  background: var(--blue-soft);
  color: var(--ink);
  font-size: 14px;
}

.compare tr:last-child td {
  border-bottom: 0;
}

.compare td:first-child {
  font-weight: 600;
  width: 22%;
}

.faq-list {
  display: grid;
  gap: 14px;
}

.faq-item {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
}

.faq-item h3 {
  color: var(--ink);
}

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

.steps li {
  position: relative;
  padding: 0 0 24px 56px;
  border-left: 2px solid #d2e3fc;
  margin-left: 16px;
}

.steps li:last-child {
  border-left-color: transparent;
  padding-bottom: 0;
}

.steps li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: -15px;
  top: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--blue);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.dl-panel {
  background: var(--paper);
  border: 1px solid #c5d7f5;
  border-radius: 14px;
  padding: 28px;
  box-shadow: var(--shadow);
}

.dl-panel h3 {
  margin-bottom: 8px;
}

.muted {
  color: var(--mute);
}

.site-footer {
  background: var(--ink);
  color: #e8eaed;
  padding: 40px 24px 32px;
}

.footer-inner {
  max-width: var(--max);
  margin: 0 auto;
}

.site-footer p {
  color: #e8eaed;
  font-size: 14px;
  line-height: 1.7;
}

.site-footer a {
  color: #8ab4f8;
}

.site-footer a:hover {
  color: #fff;
}

.footer-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin: 0 0 20px;
  padding: 0;
  list-style: none;
}

.footer-nav a {
  font-weight: 600;
  text-decoration: none;
}

.footer-nav a.is-now {
  color: #fff;
  border-bottom: 2px solid #8ab4f8;
}

@media (max-width: 960px) {
  .grid-3,
  .grid-4,
  .stat-row,
  .split,
  .split.reverse,
  .grid-2 {
    grid-template-columns: 1fr;
  }

  .split.reverse .split-copy,
  .split.reverse .split-visual {
    order: unset;
  }
}

@media (max-width: 720px) {
  .nav-bar {
    flex-direction: column;
    align-items: flex-start;
    padding: 12px 16px 10px;
    gap: 8px;
  }

  .hero-inner,
  .wrap {
    padding: 36px 16px;
  }

  .grid-4 {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 520px) {
  .grid-4 {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }
}