:root {
  color-scheme: light;
  --bg: #f6f8fb;
  --ink: #17202a;
  --muted: #5e6b7a;
  --line: #d7dee8;
  --surface: #ffffff;
  --surface-strong: #edf3f8;
  --accent: #136f63;
  --accent-strong: #0f5b51;
  --gold: #c7922d;
  --blue: #2569a8;
  --shadow: 0 18px 50px rgba(32, 47, 66, 0.12);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.8), rgba(246, 248, 251, 1) 520px),
    var(--bg);
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 18px clamp(20px, 5vw, 72px);
  border-bottom: 1px solid rgba(215, 222, 232, 0.78);
  background: rgba(246, 248, 251, 0.9);
  backdrop-filter: blur(18px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  min-width: 210px;
}

.brand-mark {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: 8px;
  color: white;
  background: var(--accent);
  font-weight: 800;
}

.brand strong,
.brand small {
  display: block;
}

.brand small {
  margin-top: 2px;
  color: var(--muted);
  font-size: 12px;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 18px;
  color: var(--muted);
  font-size: 14px;
}

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

main {
  overflow: hidden;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 460px);
  gap: clamp(28px, 6vw, 78px);
  align-items: center;
  min-height: calc(100vh - 86px);
  padding: clamp(42px, 8vw, 100px) clamp(20px, 5vw, 72px) 44px;
}

.hero-copy {
  max-width: 760px;
}

.eyebrow {
  margin: 0 0 12px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

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

h1 {
  max-width: 920px;
  margin-bottom: 22px;
  font-size: clamp(38px, 7vw, 76px);
  line-height: 1.02;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 14px;
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.1;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 10px;
  font-size: 21px;
  line-height: 1.28;
}

.hero-text,
.section p,
.post-card p,
.timeline p {
  color: var(--muted);
  line-height: 1.75;
}

.hero-text {
  max-width: 680px;
  margin-bottom: 30px;
  font-size: 18px;
}

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

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 8px;
  font-weight: 700;
}

.button.primary {
  color: white;
  background: var(--accent);
}

.button.primary:hover {
  background: var(--accent-strong);
}

.button.secondary {
  border: 1px solid var(--line);
  background: white;
}

.network-panel {
  position: relative;
  min-height: 520px;
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(rgba(19, 111, 99, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(19, 111, 99, 0.08) 1px, transparent 1px),
    var(--surface);
  background-size: 32px 32px;
  box-shadow: var(--shadow);
}

.topology {
  position: relative;
  height: 340px;
}

.node,
.line {
  position: absolute;
}

.node {
  z-index: 2;
  display: grid;
  width: 78px;
  height: 78px;
  place-items: center;
  border: 2px solid currentColor;
  border-radius: 8px;
  background: white;
  font-weight: 800;
  box-shadow: 0 10px 25px rgba(23, 32, 42, 0.08);
}

.core {
  top: 18px;
  left: 50%;
  color: var(--accent);
  transform: translateX(-50%);
}

.switch {
  top: 144px;
  left: 50%;
  color: var(--blue);
  transform: translateX(-50%);
}

.router {
  top: 136px;
  left: 24px;
  color: var(--gold);
}

.server {
  right: 24px;
  bottom: 28px;
  color: #7b557c;
}

.client {
  bottom: 22px;
  left: 44px;
  color: #41536b;
}

.line {
  z-index: 1;
  height: 2px;
  background: #9cb0c5;
  transform-origin: left center;
}

.l1 {
  top: 116px;
  left: 50%;
  width: 104px;
  transform: rotate(90deg);
}

.l2 {
  top: 178px;
  left: 102px;
  width: 130px;
}

.l3 {
  top: 250px;
  left: 104px;
  width: 165px;
  transform: rotate(-22deg);
}

.l4 {
  top: 238px;
  right: 88px;
  width: 126px;
  transform: rotate(36deg);
}

.status-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin: 0;
}

.status-grid div {
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.78);
}

.status-grid dt {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.status-grid dd {
  margin: 5px 0 0;
  font-weight: 800;
}

.section {
  padding: 78px clamp(20px, 5vw, 72px);
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 24px;
}

.post-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.post-card {
  min-height: 250px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.post-card h3 a:hover {
  color: var(--accent);
}

.post-card .tag {
  display: inline-flex;
  margin-bottom: 24px;
  padding: 5px 9px;
  border-radius: 6px;
  color: var(--accent-strong);
  background: #dcefe9;
  font-size: 12px;
  font-weight: 800;
}

.post-card time {
  display: block;
  margin-top: 28px;
  color: var(--muted);
  font-size: 13px;
}

.post-card.muted {
  background: var(--surface-strong);
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(280px, 1fr);
  gap: clamp(28px, 5vw, 60px);
  align-items: start;
  background: #eaf0f5;
}

.lab-list {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: lab;
}

.lab-list li {
  counter-increment: lab;
  display: flex;
  gap: 14px;
  align-items: center;
  padding: 16px 18px;
  border: 1px solid #cfd9e4;
  border-radius: 8px;
  background: white;
  font-weight: 700;
}

.lab-list li::before {
  content: counter(lab, decimal-leading-zero);
  color: var(--gold);
  font-weight: 900;
}

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

.timeline div {
  padding: 22px;
  border-top: 3px solid var(--accent);
  background: white;
}

.timeline span {
  color: var(--gold);
  font-weight: 900;
}

.timeline h3 {
  margin-top: 18px;
}

.about {
  max-width: 880px;
}

.footer {
  padding: 28px clamp(20px, 5vw, 72px);
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 14px;
}

@media (max-width: 980px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .nav {
    justify-content: flex-start;
  }

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

  .network-panel {
    min-height: 470px;
  }

  .post-grid,
  .timeline,
  .split {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 620px) {
  .site-header {
    position: static;
  }

  .hero {
    min-height: auto;
    padding-top: 44px;
  }

  h1 {
    font-size: 40px;
  }

  .network-panel {
    min-height: 420px;
    padding: 16px;
  }

  .topology {
    height: 280px;
  }

  .node {
    width: 64px;
    height: 64px;
    font-size: 14px;
  }

  .router {
    left: 8px;
  }

  .server {
    right: 8px;
  }

  .client {
    left: 14px;
  }

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