/* === AtlasAI — Apple/Google 风格落地页 === */

:root {
  --blue: #0071e3;
  --blue-hover: #0077ed;
  --blue-light: #e8f0fe;
  --dark: #1d1d1f;
  --gray-100: #f5f5f7;
  --gray-200: #e8e8ed;
  --gray-300: #d2d2d7;
  --gray-500: #86868b;
  --gray-600: #6e6e73;
  --gray-800: #424245;
  --white: #ffffff;
  --radius: 12px;
  --radius-lg: 18px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--dark);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
  line-height: 1.5;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
h1, h2, h3, p { margin: 0; }

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 40px;
  padding: 0 20px;
  border-radius: 980px;
  font-size: 14px;
  font-weight: 600;
  transition: all 0.2s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--blue);
  color: var(--white);
}
.btn-primary:hover { background: var(--blue-hover); }

.btn-secondary {
  background: var(--gray-100);
  color: var(--dark);
  border: 1px solid var(--gray-300);
}
.btn-secondary:hover { background: var(--gray-200); }

.btn-ghost {
  background: transparent;
  color: var(--blue);
}
.btn-ghost:hover { background: var(--blue-light); }

.btn-large {
  height: 48px;
  padding: 0 28px;
  font-size: 16px;
}

/* ===== Header ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0,0,0,0.06);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 700;
  color: var(--dark);
}

.nav-links {
  display: flex;
  gap: 28px;
  font-size: 13px;
  font-weight: 500;
  color: var(--gray-600);
}
.nav-links a:hover { color: var(--dark); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ===== 语言切换器 ===== */
.lang-switcher { position: relative; }
.lang-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 32px;
  padding: 0 10px;
  border-radius: 980px;
  border: 1px solid var(--gray-300);
  background: var(--white);
  font-size: 12px;
  font-weight: 500;
  color: var(--gray-600);
  cursor: pointer;
  transition: all 0.2s;
}
.lang-btn:hover { border-color: var(--blue); color: var(--blue); }
.lang-dropdown {
  display: none;
  position: absolute;
  top: 100%;
  right: 0;
  margin-top: 4px;
  min-width: 160px;
  border-radius: var(--radius);
  border: 1px solid var(--gray-200);
  background: var(--white);
  box-shadow: 0 8px 30px rgba(0,0,0,0.1);
  overflow: hidden;
  z-index: 10;
}
.lang-switcher.open .lang-dropdown { display: block; }
.lang-option {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  padding: 10px 14px;
  border: none;
  background: transparent;
  font-size: 13px;
  cursor: pointer;
  text-align: left;
  color: var(--dark);
}
.lang-option:hover { background: var(--gray-100); }
.lang-option.active { background: var(--blue-light); color: var(--blue); font-weight: 600; }

/* ===== Hero ===== */
.hero {
  padding: 120px 0 80px;
  background: linear-gradient(180deg, #fafbfc 0%, var(--white) 100%);
  overflow: hidden;
}
.hero .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 60px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 28px;
  padding: 0 12px;
  border-radius: 980px;
  background: var(--blue-light);
  color: var(--blue);
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 20px;
}
.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--blue);
}

.hero-title {
  font-size: clamp(40px, 5vw, 64px);
  font-weight: 800;
  line-height: 1.05;
  letter-spacing: -0.03em;
  color: var(--dark);
  margin-bottom: 20px;
}

.hero-lede {
  font-size: clamp(16px, 1.4vw, 20px);
  line-height: 1.6;
  color: var(--gray-600);
  margin-bottom: 32px;
  max-width: 540px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.hero-metrics {
  display: flex;
  gap: 40px;
}
.metric-item { display: flex; flex-direction: column; gap: 4px; }
.metric-value {
  font-size: 32px;
  font-weight: 800;
  color: var(--dark);
  letter-spacing: -0.02em;
}
.metric-label {
  font-size: 13px;
  color: var(--gray-500);
}

/* Hero 卡片 */
.hero-visual {
  position: relative;
}
.hero-card {
  border-radius: var(--radius-lg);
  border: 1px solid var(--gray-200);
  background: var(--white);
  box-shadow: 0 20px 60px rgba(0,0,0,0.08);
  overflow: hidden;
}
.hero-card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  background: var(--gray-100);
  border-bottom: 1px solid var(--gray-200);
  font-size: 12px;
  font-weight: 600;
  color: var(--gray-600);
}
.card-dots { display: flex; gap: 6px; }
.card-dots span {
  width: 10px; height: 10px; border-radius: 50%;
}
.card-dots span:nth-child(1) { background: #ff5f57; }
.card-dots span:nth-child(2) { background: #febc2e; }
.card-dots span:nth-child(3) { background: #28c840; }

.hero-card-body {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.analysis-line {
  display: flex;
  gap: 8px;
  font-size: 13px;
  line-height: 1.5;
}
.analysis-line .label {
  color: var(--gray-500);
  min-width: 70px;
  flex-shrink: 0;
}
.analysis-line .value { color: var(--dark); }
.analysis-line .score-high { color: #16a34a; font-weight: 600; }

/* ===== Sections ===== */
.section {
  padding: 100px 0;
}

.section-heading {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 56px;
}
.section-heading h2 {
  font-size: clamp(32px, 3.5vw, 48px);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
  color: var(--dark);
}
.section-heading p {
  font-size: 18px;
  color: var(--gray-600);
  line-height: 1.6;
}

/* ===== Sources ===== */
.section-sources {
  background: var(--gray-100);
}

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

.source-card {
  border-radius: var(--radius);
  background: var(--white);
  padding: 32px 24px;
  border: 1px solid var(--gray-200);
  transition: all 0.2s;
}
.source-card:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.06);
  transform: translateY(-2px);
}
.source-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius);
  display: grid;
  place-items: center;
  font-size: 18px;
  font-weight: 800;
  margin-bottom: 20px;
}
.source-card h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--dark);
}
.source-card p {
  font-size: 14px;
  line-height: 1.6;
  color: var(--gray-600);
}

/* ===== Workflow ===== */
.workflow-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
  align-items: center;
  gap: 0;
}

.workflow-step {
  text-align: center;
  padding: 32px 20px;
  border-radius: var(--radius);
  background: var(--white);
  border: 1px solid var(--gray-200);
  transition: all 0.2s;
}
.workflow-step:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.06);
}

.step-number {
  font-size: 14px;
  font-weight: 800;
  color: var(--blue);
  margin-bottom: 14px;
  letter-spacing: 0.05em;
}
.workflow-step h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
}
.workflow-step p {
  font-size: 14px;
  color: var(--gray-600);
  line-height: 1.6;
}

.workflow-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 8px;
}

/* ===== Features ===== */
.section-features {
  background: var(--white);
}

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

.feature-card {
  padding: 32px 24px;
  border-radius: var(--radius);
  border: 1px solid var(--gray-200);
  transition: all 0.2s;
}
.feature-card:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.06);
  transform: translateY(-2px);
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius);
  background: var(--blue-light);
  display: grid;
  place-items: center;
  margin-bottom: 20px;
}
.feature-card h3 {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--dark);
}
.feature-card p {
  font-size: 14px;
  line-height: 1.6;
  color: var(--gray-600);
}

/* ===== CTA ===== */
.section-cta {
  padding: 60px 0 100px;
}

.cta-card {
  text-align: center;
  padding: 64px 32px;
  border-radius: 20px;
  background: linear-gradient(135deg, #f5f7fa 0%, #e8f0fe 100%);
  border: 1px solid var(--gray-200);
}
.cta-card h2 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}
.cta-card p {
  font-size: 18px;
  color: var(--gray-600);
  margin-bottom: 32px;
}

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--gray-200);
  padding: 40px 0;
  background: var(--gray-100);
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  text-align: center;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 16px;
}

.footer-tagline {
  font-size: 13px;
  color: var(--gray-600);
}

.footer-links {
  display: flex;
  gap: 24px;
  font-size: 13px;
  color: var(--gray-500);
}
.footer-links a:hover { color: var(--blue); }

.footer-copy {
  font-size: 12px;
  color: var(--gray-500);
}

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .hero .container {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .nav-links { display: none; }
  .sources-grid, .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .workflow-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .workflow-arrow { display: none; }
}

@media (max-width: 640px) {
  .hero { padding: 100px 0 60px; }
  .section { padding: 60px 0; }
  .sources-grid, .features-grid {
    grid-template-columns: 1fr;
  }
  .hero-metrics { gap: 24px; }
  .metric-value { font-size: 24px; }
}