/* ==========================================================================
   AI 趋势观察 · 2025–2026
   设计系统：Linear 工程冷峻风
   ========================================================================== */

:root {
  /* 色彩令牌 */
  --bg: #08090B;
  --bg-elevated: #0E0F12;
  --bg-footer: #0A0B0E;
  --border: rgba(255, 255, 255, 0.08);
  --border-soft: rgba(255, 255, 255, 0.07);
  --primary: #5E6AD2;
  --primary-soft: #8B93E8;
  --text-primary: #EDEEF0;
  --text-secondary: #9BA0A6;
  --text-muted: #5E6269;
  --green: #4CB782;
  --amber: #D9A441;
  --gray: #7A7F87;

  /* 字体令牌 */
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
  --font-cn: "Sarasa Gothic SC", "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Source Han Sans SC", sans-serif;

  /* 布局令牌 */
  --max-width: 1344px;
  --gutter: 48px;
  --radius: 12px;
}

/* ---------- 基础重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-cn);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, p { margin: 0; }
a { color: inherit; text-decoration: none; }
ul { margin: 0; padding: 0; list-style: none; }
svg { display: block; }

/* ==========================================================================
   顶部导航
   ========================================================================== */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg);
}

.navbar-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  padding: 0 var(--gutter);
  max-width: calc(var(--max-width) + var(--gutter) * 2);
  margin: 0 auto;
}

.nav-hairline {
  height: 1px;
  background: var(--border-soft);
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo { width: 22px; height: 22px; }
.logo svg { width: 100%; height: 100%; }

.wordmark {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.01em;
}

.tag {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

.nav-right {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-link {
  font-size: 13px;
  color: var(--text-secondary);
  transition: color 0.15s ease;
}
.nav-link:hover { color: var(--text-primary); }
.nav-link.active { color: var(--text-primary); }

.pill {
  font-size: 12px;
  font-weight: 600;
  color: var(--primary-soft);
  padding: 8px 14px;
  border: 1px solid rgba(94, 106, 210, 0.5);
  border-radius: 20px;
  transition: background 0.15s ease;
}
.pill:hover { background: rgba(94, 106, 210, 0.1); }

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}
.menu-toggle span {
  width: 20px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 1px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

/* ==========================================================================
   Hero 首屏
   ========================================================================== */
.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 22px;
  padding: 104px var(--gutter) 88px;
  background: linear-gradient(180deg, #0F0F1A 0%, #08080A 100%);
}

.kicker {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  color: var(--primary-soft);
  letter-spacing: 0.23em;
}

.headline {
  font-size: 64px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

.subheadline {
  font-size: 17px;
  line-height: 1.75;
  color: var(--text-secondary);
  max-width: 760px;
}

.accent-bar {
  width: 44px;
  height: 3px;
  border-radius: 2px;
  background: var(--primary);
}

.source-line {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

/* ==========================================================================
   通用区块
   ========================================================================== */
.section {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 72px var(--gutter);
}

.section-head {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 34px;
}

.section-kicker {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 600;
  color: var(--primary-soft);
  letter-spacing: 0.23em;
}

.section-title {
  font-size: 30px;
  font-weight: 700;
}

/* ==========================================================================
   关键数据卡片
   ========================================================================== */
.cards-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 28px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.card-label {
  font-family: var(--font-sans);
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.16em;
}

.card-value {
  font-family: var(--font-sans);
  font-size: 46px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
}

.card-sub {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-secondary);
}

.card-delta {
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 600;
  color: var(--green);
}

.card-foot {
  font-size: 12px;
  line-height: 1.65;
  color: var(--text-muted);
}

/* ==========================================================================
   六大核心切片
   ========================================================================== */
.slices-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.slice {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 28px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.slice-num {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  color: var(--primary-soft);
  letter-spacing: 0.06em;
}

.slice-title {
  font-size: 19px;
  font-weight: 700;
}

.slice-desc {
  font-size: 14px;
  line-height: 1.65;
  color: var(--text-secondary);
}

.slice-stat {
  margin-top: auto;
  font-size: 12px;
  font-weight: 600;
  color: var(--primary-soft);
}

/* ==========================================================================
   中美欧三极格局
   ========================================================================== */
.poles-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.pole {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 28px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.pole-name {
  font-size: 20px;
  font-weight: 700;
}

.pole-tag {
  align-self: flex-start;
  font-size: 12px;
  font-weight: 600;
  color: var(--primary-soft);
}

.pole-value {
  font-family: var(--font-sans);
  font-size: 40px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
}

.pole-biglab {
  font-size: 12px;
  color: var(--text-muted);
}

.pole-lab {
  font-size: 12px;
  color: var(--text-muted);
}

.pole-val {
  font-family: var(--font-sans);
  font-size: 16px;
  font-weight: 600;
}

.pole-feat {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
}

.track {
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--border-soft);
  overflow: hidden;
  margin-top: auto;
}

.bar {
  display: block;
  height: 100%;
  width: 0;
  border-radius: 3px;
  background: var(--primary);
  transition: width 1s cubic-bezier(0.22, 1, 0.36, 1);
}

.pole-note {
  margin-top: 16px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-muted);
}

/* ==========================================================================
   2026 预测
   ========================================================================== */
.pred-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.pred {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 20px 24px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.conf {
  flex-shrink: 0;
  font-size: 12px;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 12px;
  white-space: nowrap;
}

.conf-high { color: var(--green); background: rgba(76, 183, 130, 0.13); border: 1px solid rgba(76, 183, 130, 0.5); }
.conf-mid  { color: var(--amber); background: rgba(217, 164, 65, 0.13); border: 1px solid rgba(217, 164, 65, 0.5); }
.conf-low  { color: var(--gray);  background: rgba(122, 127, 135, 0.13); border: 1px solid rgba(122, 127, 135, 0.5); }

.pred-body { display: flex; flex-direction: column; gap: 4px; }

.pred-txt {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.6;
}

.pred-src {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
}

/* ==========================================================================
   页脚
   ========================================================================== */
.footer {
  background: var(--bg-footer);
  padding: 56px var(--gutter) 40px;
}

.foot-hair {
  height: 1px;
  background: var(--border-soft);
  max-width: var(--max-width);
  margin: 0 auto 26px;
}

.brand-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto 26px;
}

.brand-left { display: flex; align-items: center; gap: 10px; }
.brand-left .logo { width: 20px; height: 20px; }

.brand-right {
  font-size: 12px;
  color: var(--text-muted);
}

.src-label {
  font-family: var(--font-sans);
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.16em;
  max-width: var(--max-width);
  margin: 0 auto 16px;
}

.src-wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  max-width: var(--max-width);
  margin: 0 auto 34px;
}

.src-wrap li {
  font-size: 13px;
  color: var(--text-secondary);
}

.bottom-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
}

.copy-l {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 500;
  color: var(--text-muted);
}

.copy-r {
  font-size: 12px;
  color: var(--text-muted);
}

.icp-bar {
  max-width: var(--max-width);
  margin: 18px auto 0;
  text-align: center;
}

.icp-link {
  font-size: 12px;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s ease;
}

.icp-link:hover {
  color: var(--text-secondary);
}

/* ==========================================================================
   滚动入场动画
   ========================================================================== */
.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s cubic-bezier(0.22, 1, 0.36, 1);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .bar { transition: none; }
}

/* ==========================================================================
   响应式
   ========================================================================== */
@media (max-width: 1024px) {
  .cards-row, .slices-grid, .poles-row {
    grid-template-columns: repeat(2, 1fr);
  }
  .headline { font-size: 52px; }
}

@media (max-width: 760px) {
  :root { --gutter: 24px; }

  .nav-right {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 16px 24px;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease;
  }
  .nav-right.open {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
  }
  .menu-toggle { display: flex; }

  .hero { padding: 72px var(--gutter) 64px; }
  .headline { font-size: 38px; }
  .subheadline { font-size: 15px; }

  .cards-row, .slices-grid, .poles-row {
    grid-template-columns: 1fr;
  }
  .section { padding: 56px var(--gutter); }
  .pred { flex-direction: column; align-items: flex-start; }

  .brand-row, .bottom-bar { flex-direction: column; align-items: flex-start; gap: 12px; }
}