:root {
  /* === 基础色阶 === */
  --bg-light:     #EFEFEF;
  --bg-white:     #FAFAFA;
  --bg-dark:      #0F1012;
  --bg-deep:      #08090A;

  /* === 墨色阶 === */
  --ink:          #0F1012;
  --ink-light:    #FAFAFA;
  --muted:        #8F8F8F;
  --faint:        rgba(15, 16, 18, 0.12);

  /* === 强调色 === */
  --accent:       #0071E3;
  --accent-hover: #0062CC;
  --accent-dim:   rgba(0, 113, 227, 0.12);
  --accent-soft:  rgba(0, 113, 227, 0.06);

  /* === 功能色 === */
  --success:      #34C759;
  --warning:      #FF9500;

  /* === 线条 === */
  --line:         rgba(15, 16, 18, 0.08);
  --line-dark:    rgba(255, 255, 255, 0.08);

  /* === 排版 === */
  --font-sans:    "Inter", "SF Pro Display", "Segoe UI Variable",
                  "Microsoft YaHei UI", "PingFang SC", sans-serif;
  --font-mono:    "JetBrains Mono", "Cascadia Code", "Bahnschrift",
                  "Segoe UI Variable Display", monospace;

  --text-hero:    clamp(48px, 8vw, 96px);
  --text-h1:      clamp(32px, 5vw, 56px);
  --text-h2:      clamp(24px, 3vw, 36px);
  --text-h3:      18px;
  --text-body:    15px;
  --text-small:   12px;
  --text-caption: 10px;

  --w-light:      300;
  --w-regular:    400;
  --w-medium:     500;
  --w-semibold:   600;

  --lh-tight:     1.05;
  --lh-heading:   1.2;
  --lh-body:      1.65;
  --lh-loose:     1.9;

  /* === 间距 === */
  --space-xs:     4px;
  --space-sm:     8px;
  --space-md:     16px;
  --space-lg:     24px;
  --space-xl:     48px;
  --space-2xl:    80px;
  --space-3xl:    120px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--bg-light);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: var(--text-body);
  font-weight: var(--w-regular);
  line-height: var(--lh-body);
  letter-spacing: 0;
  text-rendering: geometricPrecision;
  -webkit-font-smoothing: antialiased;
}

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

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

/* ===== 导航 ===== */

.site-nav {
  position: fixed;
  top: 24px;
  left: 50%;
  z-index: 20;
  width: min(1080px, calc(100vw - 48px));
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  background: var(--bg-white);
  border: 1px solid var(--line);
  border-radius: 10px;
  transform: translateX(-50%);
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: var(--w-semibold);
  letter-spacing: -0.02em;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: var(--w-semibold);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-links a {
  font-family: var(--font-mono);
  font-size: var(--text-small);
  font-weight: var(--w-medium);
  letter-spacing: 0.04em;
  color: var(--muted);
  transition: color 180ms ease;
}

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

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 32px;
  padding: 0 18px;
  border-radius: 26px;
  background: var(--accent);
  color: #fff;
  font-family: var(--font-mono);
  font-size: var(--text-small);
  font-weight: var(--w-semibold);
  letter-spacing: 0.02em;
  transition: background 180ms ease;
}

.nav-cta:hover {
  background: var(--accent-hover);
}

/* ===== Section 1: Hero ===== */

.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-3xl) 7vw;
}

.hero-copy {
  max-width: 720px;
}

.eyebrow {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: var(--space-lg);
  color: var(--muted);
}

.eyebrow strong {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
}

.eyebrow span {
  font-size: var(--text-small);
  font-weight: var(--w-regular);
}

h1 {
  margin-bottom: var(--space-lg);
  font-family: var(--font-sans);
  font-size: var(--text-hero);
  font-weight: var(--w-light);
  line-height: var(--lh-tight);
  letter-spacing: -0.02em;
}

.hero-signature {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: var(--space-md);
  color: var(--muted);
  line-height: var(--lh-heading);
}

.hero-signature strong {
  font-family: var(--font-mono);
  font-size: var(--text-h2);
  font-weight: var(--w-medium);
  letter-spacing: -0.01em;
}

.hero-signature span {
  font-size: var(--text-body);
  font-weight: var(--w-light);
}

.hero-line {
  max-width: 560px;
  margin: 0 auto var(--space-xl);
  color: var(--muted);
  font-size: var(--text-body);
  font-weight: var(--w-regular);
  line-height: var(--lh-body);
}

.product-links {
  display: flex;
  gap: var(--space-sm);
  justify-content: center;
  flex-wrap: wrap;
}

.product-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 24px;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: transparent;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: var(--text-small);
  font-weight: var(--w-medium);
  letter-spacing: 0.02em;
  transition: border-color 180ms ease, background 180ms ease;
}

.product-links a:first-child {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.product-links a:hover {
  border-color: var(--accent);
}

.product-links a:first-child:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
}

.hero-version {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: var(--space-lg);
  padding: 4px 14px;
  border-radius: 26px;
  background: var(--accent-dim);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
}

/* ===== Section 2: Statement (深色) ===== */

.statement-section {
  min-height: 80vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-3xl) 7vw;
  background: var(--bg-dark);
  color: var(--ink-light);
  text-align: center;
}

.statement-section h2 {
  max-width: 900px;
  font-family: var(--font-sans);
  font-size: var(--text-h1);
  font-weight: var(--w-light);
  line-height: var(--lh-heading);
  letter-spacing: -0.01em;
}

/* ===== Section 3: Features ===== */

.features-section {
  padding: var(--space-3xl) 7vw;
}

.features-section .section-index {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: var(--space-xl);
  color: var(--muted);
}

.features-section .section-index strong {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
}

.features-section .section-index span {
  font-size: var(--text-small);
}

.feature-strip {
  display: flex;
  gap: 1px;
}

.feature-strip article {
  flex: 1;
  min-height: 240px;
  padding: var(--space-lg);
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--bg-white);
  transition: border-color 180ms ease;
}

.feature-strip article:hover {
  border-color: var(--accent);
}

.feature-strip article + article {
  margin-left: var(--space-sm);
}

.feature-strip .tag {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  border-radius: 26px;
  background: var(--accent-dim);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
}

.feature-strip h3 {
  margin: var(--space-lg) 0 var(--space-sm);
  font-family: var(--font-sans);
  font-size: var(--text-h3);
  font-weight: var(--w-medium);
}

.feature-strip p {
  color: var(--muted);
  font-size: var(--text-small);
  line-height: var(--lh-body);
}

/* ===== Section 4: Safety (深色) ===== */

.safety-section {
  min-height: 60vh;
  display: grid;
  grid-template-columns: 0.38fr 1fr;
  gap: 4vw;
  align-items: center;
  padding: var(--space-3xl) 7vw;
  background: var(--bg-dark);
  color: var(--ink-light);
}

.safety-section .section-index {
  display: flex;
  flex-direction: column;
  gap: 4px;
  color: var(--muted);
}

.safety-section .section-index strong {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
  color: var(--muted);
}

.safety-section .section-index span {
  font-size: var(--text-small);
  color: rgba(255, 255, 255, 0.4);
}

.safety-section h2 {
  max-width: 800px;
  margin-bottom: var(--space-md);
  font-family: var(--font-sans);
  font-size: var(--text-h1);
  font-weight: var(--w-light);
  line-height: var(--lh-heading);
}

.safety-section p {
  max-width: 640px;
  color: var(--muted);
  font-size: var(--text-body);
  line-height: var(--lh-body);
}

/* ===== Section 5: Download (蓝色) ===== */

.download-section {
  min-height: 70vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-3xl) 7vw;
  background: var(--accent);
  color: #fff;
  text-align: center;
}

.download-section .section-index {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: var(--space-lg);
  color: rgba(255, 255, 255, 0.7);
}

.download-section .section-index strong {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
}

.download-section .section-index span {
  font-size: var(--text-small);
}

.download-section h2 {
  margin-bottom: var(--space-sm);
  font-family: var(--font-mono);
  font-size: var(--text-h1);
  font-weight: var(--w-light);
  letter-spacing: -0.02em;
}

.download-version {
  display: inline-flex;
  align-items: center;
  padding: 4px 14px;
  border-radius: 26px;
  background: rgba(255, 255, 255, 0.16);
  color: rgba(255, 255, 255, 0.9);
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
  margin-bottom: var(--space-xl);
}

.download-changelog {
  max-width: 480px;
  margin-bottom: var(--space-xl);
  text-align: left;
}

.download-changelog h4 {
  margin-bottom: var(--space-sm);
  font-family: var(--font-mono);
  font-size: var(--text-small);
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
  color: rgba(255, 255, 255, 0.7);
}

.download-changelog ul {
  margin: 0;
  padding-left: var(--space-md);
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--text-small);
  line-height: var(--lh-body);
}

.download-changelog li + li {
  margin-top: var(--space-xs);
}

.download-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  min-height: 52px;
  padding: 0 36px;
  border-radius: 26px;
  background: #fff;
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 15px;
  font-weight: var(--w-semibold);
  letter-spacing: 0.02em;
  transition: background 180ms ease, transform 180ms ease;
}

.download-btn:hover {
  background: #f0f0f0;
  transform: translateY(-1px);
}

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

.download-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 24px;
  margin-top: var(--space-md);
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: 26px;
  background: transparent;
  color: rgba(255, 255, 255, 0.85);
  font-family: var(--font-mono);
  font-size: var(--text-small);
  font-weight: var(--w-medium);
  transition: border-color 180ms ease;
}

.download-secondary:hover {
  border-color: #fff;
  color: #fff;
}

.download-requirements {
  margin-top: var(--space-xl);
  color: rgba(255, 255, 255, 0.55);
  font-size: var(--text-caption);
  line-height: var(--lh-body);
}

/* ===== Section 6: Footer ===== */

.site-footer {
  padding: var(--space-2xl) 7vw var(--space-xl);
  background: var(--bg-dark);
  color: var(--ink-light);
  border-top: 1px solid var(--line-dark);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: var(--space-2xl);
  max-width: 1080px;
  margin: 0 auto;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.footer-brand-name {
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: var(--w-semibold);
  letter-spacing: -0.02em;
}

.footer-brand-copy {
  color: var(--muted);
  font-size: var(--text-caption);
}

.footer-nav {
  display: flex;
  gap: var(--space-2xl);
}

.footer-nav-col {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer-nav-col strong {
  font-family: var(--font-mono);
  font-size: var(--text-caption);
  font-weight: var(--w-semibold);
  letter-spacing: 0.04em;
  color: var(--muted);
  text-transform: uppercase;
  margin-bottom: var(--space-xs);
}

.footer-nav-col a {
  color: rgba(255, 255, 255, 0.6);
  font-size: var(--text-small);
  transition: color 180ms ease;
}

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

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1080px;
  margin: var(--space-xl) auto 0;
  padding-top: var(--space-md);
  border-top: 1px solid var(--line-dark);
  color: var(--muted);
  font-size: var(--text-caption);
}

.footer-bottom a + a {
  margin-left: var(--space-md);
}

.footer-bottom a:hover {
  color: var(--ink-light);
}

/* ===== 响应式 ===== */

@media (max-width: 1080px) {
  .feature-strip {
    flex-direction: column;
  }

  .feature-strip article + article {
    margin-left: 0;
    margin-top: var(--space-sm);
  }

  .safety-section {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .site-nav {
    top: 12px;
    width: calc(100vw - 24px);
    padding: 0 var(--space-md);
  }

  .nav-links {
    display: none;
  }

  .hero {
    min-height: 100svh;
    padding: 104px 7vw 82px;
  }

  h1 {
    font-size: clamp(40px, 12vw, 72px);
  }

  .product-links {
    flex-direction: column;
    align-items: center;
  }

  .product-links a {
    width: 100%;
    max-width: 280px;
  }

  .safety-section {
    min-height: auto;
    padding: var(--space-2xl) 7vw;
  }

  .download-section {
    min-height: auto;
    padding: var(--space-2xl) 7vw;
  }

  .footer-inner {
    flex-direction: column;
    gap: var(--space-lg);
  }

  .footer-nav {
    gap: var(--space-lg);
  }

  .footer-bottom {
    flex-direction: column;
    gap: var(--space-sm);
    text-align: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 1ms !important;
    animation-iteration-count: 1 !important;
    scroll-behavior: auto !important;
    transition-duration: 1ms !important;
  }
}