:root {
  --bg: #f4f6fb;
  --surface: #ffffff;
  --text: #101828;
  --text-2: #667085;
  --line: rgba(16, 24, 40, 0.08);
  --brand: #1a8cff;
  --brand-deep: #0b5fff;
  --ink: #0b1220;
  --radius: 16px;
  --shadow: 0 24px 80px rgba(16, 40, 80, 0.12);
  --font-display: "Noto Sans SC", "Manrope", "Segoe UI", sans-serif;
  --font-body: "Noto Sans SC", "Manrope", "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  background: var(--bg);
  font-family: var(--font-body);
  overflow-x: hidden;
}

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

.bg-glow {
  position: fixed;
  inset: -20% -10% auto;
  height: 70vh;
  background:
    radial-gradient(40% 50% at 20% 20%, rgba(26, 140, 255, 0.18), transparent 70%),
    radial-gradient(35% 45% at 80% 10%, rgba(11, 95, 255, 0.12), transparent 70%),
    radial-gradient(30% 40% at 55% 45%, rgba(80, 200, 255, 0.1), transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.bg-grid {
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(16, 24, 40, 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(16, 24, 40, 0.035) 1px, transparent 1px);
  background-size: 56px 56px;
  mask-image: radial-gradient(circle at 50% 20%, black, transparent 72%);
  pointer-events: none;
  z-index: 0;
}

.nav,
.hero,
.section,
.footer {
  position: relative;
  z-index: 1;
}

.nav {
  max-width: 1120px;
  margin: 0 auto;
  padding: 18px 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-brand {
  display: flex;
  align-items: center;
}

.nav-logo {
  height: 28px;
  width: auto;
  display: block;
}

.nav-links {
  display: flex;
  gap: 8px;
  margin-left: 18px;
  color: var(--text-2);
  font-size: 14px;
  font-weight: 500;
}

.nav-links a {
  padding: 8px 12px;
  border-radius: 999px;
  letter-spacing: 0.02em;
  transition: color 0.18s ease, background 0.18s ease;
}

.nav-links a:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.7);
}

.nav-actions {
  margin-left: auto;
  display: flex;
  gap: 10px;
  align-items: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 999px;
  padding: 10px 16px;
  font-size: 14px;
  font-weight: 600;
  border: 1px solid transparent;
  transition: transform 0.18s ease, background 0.18s ease, box-shadow 0.18s ease;
  cursor: pointer;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-solid {
  background: var(--ink);
  color: #fff;
  box-shadow: 0 10px 24px rgba(11, 18, 32, 0.18);
}

.btn-solid:hover {
  background: #162033;
}

.btn-outline {
  background: rgba(255, 255, 255, 0.72);
  border-color: var(--line);
  color: var(--text);
  backdrop-filter: blur(8px);
}

.btn-ghost {
  background: transparent;
  color: var(--text-2);
}

.btn-ghost:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.55);
}

.btn-lg {
  padding: 14px 22px;
  font-size: 15px;
}

.hero {
  max-width: 980px;
  margin: 0 auto;
  padding: 48px 24px 24px;
  text-align: center;
}

.hero-brand {
  height: 42px;
  width: auto;
  margin: 0 auto 22px;
  display: block;
  animation: rise 0.7s ease both;
}

.hero-title {
  margin: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.08em;
  font-family: var(--font-display);
  font-size: clamp(2.35rem, 5.4vw, 3.75rem);
  line-height: 1.18;
  letter-spacing: 0.06em;
  font-weight: 900;
  color: #0f172a;
  animation: rise 0.75s ease 0.05s both;
}

.hero-line {
  display: block;
}

.hero-line-accent {
  position: relative;
  color: #0b5fff;
  letter-spacing: 0.08em;
}

.hero-line-accent::after {
  content: "";
  position: absolute;
  left: 12%;
  right: 12%;
  bottom: 0.08em;
  height: 0.18em;
  border-radius: 999px;
  background: linear-gradient(
    90deg,
    rgba(26, 140, 255, 0) 0%,
    rgba(26, 140, 255, 0.22) 35%,
    rgba(120, 200, 255, 0.28) 65%,
    rgba(26, 140, 255, 0) 100%
  );
  z-index: -1;
}

.hero-sub {
  max-width: 620px;
  margin: 18px auto 0;
  color: var(--text-2);
  font-size: 17px;
  line-height: 1.65;
  animation: rise 0.75s ease 0.1s both;
}

.hero-cta {
  margin-top: 28px;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  animation: rise 0.75s ease 0.15s both;
}

.hero-meta {
  margin-top: 14px;
  color: var(--text-2);
  font-size: 13px;
  animation: rise 0.75s ease 0.18s both;
}

.product-frame {
  margin: 48px auto 0;
  max-width: 920px;
  border-radius: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  overflow: hidden;
  text-align: left;
  animation: rise 0.85s ease 0.22s both;
}

.product-chrome {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
  background: #fbfcfe;
}

.product-chrome span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: #d0d5dd;
}

.product-chrome span:nth-child(1) { background: #ff5f57; }
.product-chrome span:nth-child(2) { background: #febc2e; }
.product-chrome span:nth-child(3) { background: #28c840; }

.product-chrome-title {
  margin-left: 8px;
  font-size: 12px;
  color: var(--text-2);
  font-weight: 600;
  letter-spacing: 0.08em;
}

.product-body {
  display: grid;
  grid-template-columns: 140px 1fr;
  min-height: 320px;
}

.product-side {
  padding: 16px 12px;
  background: #f3f5f9;
  border-right: 1px solid var(--line);
}

.side-item {
  padding: 10px 12px;
  border-radius: 10px;
  color: var(--text-2);
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 6px;
}

.side-item.active {
  background: #fff;
  color: var(--text);
  box-shadow: 0 1px 2px rgba(16, 24, 40, 0.06);
}

.product-main {
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.tunnel-card {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 4px 16px;
  align-items: center;
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: #fff;
}

.tunnel-card strong {
  font-size: 14px;
}

.tag {
  margin-left: 8px;
  font-size: 10px;
  font-weight: 700;
  color: var(--brand-deep);
  background: rgba(26, 140, 255, 0.12);
  border-radius: 999px;
  padding: 2px 8px;
}

.route {
  grid-column: 1;
  font-size: 12px;
  color: var(--text-2);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

.switch {
  grid-row: 1 / span 2;
  width: 42px;
  height: 26px;
  border-radius: 999px;
  background: #e5e7eb;
  position: relative;
}

.switch::after {
  content: "";
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

.switch.on {
  background: #34c759;
}

.switch.on::after {
  left: 19px;
}

.product-note {
  margin-top: 6px;
  color: var(--text-2);
  font-size: 12px;
}

.section {
  max-width: 1120px;
  margin: 0 auto;
  padding: 72px 24px 24px;
}

.section-head {
  max-width: 640px;
  margin-bottom: 28px;
}

.section-head h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  letter-spacing: -0.02em;
}

.section-head p {
  margin: 10px 0 0;
  color: var(--text-2);
  line-height: 1.6;
}

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

.feature {
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 18px;
  backdrop-filter: blur(8px);
}

.feature h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-family: var(--font-display);
}

.feature p {
  margin: 0;
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.6;
}

.download-card {
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 28px;
  border-radius: 22px;
  color: var(--text);
  border: 1px solid rgba(16, 24, 40, 0.06);
  box-shadow: 0 10px 40px rgba(16, 40, 80, 0.06);
  isolation: isolate;
  /* 整卡平滑过渡：白 → 淡青 → 淡紫 → 淡粉，避免半边硬切 */
  background:
    linear-gradient(
      135deg,
      #ffffff 0%,
      #f8fbff 22%,
      #eef6ff 48%,
      #f3effc 72%,
      #fff3f8 100%
    );
}

.download-card::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    115deg,
    rgba(255, 255, 255, 0.35) 0%,
    rgba(255, 255, 255, 0.08) 45%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
  z-index: 0;
}

.download-card > * {
  position: relative;
  z-index: 1;
}

.download-card h2 {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.55rem;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--text);
}

.download-card p {
  margin: 8px 0 0;
  color: var(--text-2);
  line-height: 1.55;
}

.download-card .btn-solid {
  background: var(--ink);
  color: #fff;
  flex-shrink: 0;
}

.update-box {
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid var(--line);
  border-radius: 18px;
  padding: 22px;
}

.update-box h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.update-box .muted {
  color: var(--text-2);
}

.update-box .md {
  color: var(--text-2);
  font-size: 14px;
  line-height: 1.65;
  white-space: pre-wrap;
}

.footer {
  max-width: 1120px;
  margin: 48px auto 0;
  padding: 28px 24px 48px;
  display: flex;
  align-items: center;
  gap: 18px;
  border-top: 1px solid var(--line);
  color: var(--text-2);
  font-size: 13px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 600;
}

.footer-brand img {
  height: 20px;
}

.footer-links {
  display: flex;
  gap: 16px;
}

.footer-copy {
  margin-left: auto;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(14px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .nav-links {
    display: none;
  }

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

  .product-body {
    grid-template-columns: 1fr;
  }

  .product-side {
    display: flex;
    gap: 8px;
    border-right: none;
    border-bottom: 1px solid var(--line);
  }

  .side-item {
    margin: 0;
  }

  .download-card {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 560px) {
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .nav-actions .btn-ghost {
    display: none;
  }

  .footer {
    flex-wrap: wrap;
  }

  .footer-copy {
    margin-left: 0;
    width: 100%;
  }
}