/* ==========================================================
   CYBER GOMOKU 官网 v2 — 纯 CSS 霓虹棋盘视觉（无图片）
   ========================================================== */

:root {
  --bg: #05060f;
  --bg2: #0a0c1c;
  --cyan: #00f0ff;
  --magenta: #ff2ecc;
  --gold: #ffd700;
  --text: #e8f4ff;
  --text-dim: #8fa3c0;
  --panel: rgba(10, 14, 32, 0.72);
  --line: rgba(0, 240, 255, 0.25);
  --glow-cyan: 0 0 12px rgba(0, 240, 255, 0.6);
  --font-display: 'Orbitron', 'Noto Sans SC', sans-serif;
  --font-body: 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body::before {
  content: '';
  position: fixed; inset: 0; z-index: -1;
  background:
    radial-gradient(ellipse at 15% -5%, rgba(0, 240, 255, 0.1), transparent 45%),
    radial-gradient(ellipse at 90% 5%, rgba(255, 46, 204, 0.08), transparent 40%),
    radial-gradient(ellipse at 50% 110%, rgba(0, 240, 255, 0.06), transparent 50%),
    var(--bg);
}

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

/* ---------------- 导航 ---------------- */
.site-nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  height: 58px;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 24px;
  background: rgba(5, 6, 15, 0.82);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}
.brand {
  font-family: var(--font-display);
  font-weight: 900;
  letter-spacing: 2px;
  color: var(--cyan);
  text-shadow: var(--glow-cyan);
}
.brand span { color: var(--magenta); text-shadow: 0 0 12px rgba(255, 46, 204, 0.6); }
.site-nav-links { display: flex; gap: 22px; }
.site-nav-links a {
  font-size: 0.9rem;
  color: var(--text-dim);
  transition: color 0.2s;
}
.site-nav-links a:hover { color: var(--cyan); }

/* CTA（统一措辞：立即游玩） */
.cta {
  display: inline-block;
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: 2px;
  padding: 11px 26px;
  border-radius: 10px;
  border: 1px solid var(--cyan);
  color: var(--cyan);
  background: rgba(0, 240, 255, 0.06);
  box-shadow: inset 0 0 14px rgba(0, 240, 255, 0.1), var(--glow-cyan);
  transition: all 0.2s ease;
}
.cta:hover { color: #04121a; background: var(--cyan); box-shadow: 0 0 24px rgba(0, 240, 255, 0.9); }
.cta-primary {
  color: var(--magenta);
  border-color: var(--magenta);
  background: rgba(255, 46, 204, 0.07);
  box-shadow: inset 0 0 14px rgba(255, 46, 204, 0.12), 0 0 12px rgba(255, 46, 204, 0.5);
}
.cta-primary:hover { color: #1a0310; background: var(--magenta); box-shadow: 0 0 26px rgba(255, 46, 204, 0.95); }
.cta-ghost { background: transparent; box-shadow: none; }
.cta-nav { padding: 8px 18px; font-size: 0.82rem; }

/* 汉堡菜单 */
.nav-toggle {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  width: 38px; height: 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
}
.nav-toggle span {
  width: 18px; height: 2px;
  background: var(--cyan);
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ---------------- 英雄区 ---------------- */
.hero {
  min-height: 100vh;
  display: flex; align-items: center;
  padding: 120px 24px 60px;
}
.hero-inner {
  max-width: 1120px;
  margin: 0 auto;
  width: 100%;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 48px;
  align-items: center;
}
.hero-copy { text-align: left; }
.hero-chip {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 0.72rem;
  letter-spacing: 4px;
  color: var(--gold);
  border: 1px solid rgba(255, 215, 0, 0.5);
  padding: 4px 14px;
  border-radius: 6px;
  margin-bottom: 20px;
  background: rgba(255, 215, 0, 0.06);
}
.hero-title {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(2.4rem, 6.5vw, 4.4rem);
  letter-spacing: 0.08em;
  color: var(--cyan);
  text-shadow: 0 0 30px rgba(0, 240, 255, 0.8), 0 0 80px rgba(0, 240, 255, 0.4);
}
.hero-sub {
  font-family: var(--font-display);
  font-size: clamp(0.9rem, 2.4vw, 1.25rem);
  letter-spacing: 0.4em;
  color: var(--magenta);
  text-shadow: 0 0 14px rgba(255, 46, 204, 0.6);
  margin-top: 12px;
}
.hero-desc {
  max-width: 540px;
  margin: 22px 0 30px;
  color: var(--text-dim);
  font-size: 1.02rem;
}
.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }

/* ---- 纯 CSS 霓虹棋盘 ---- */
.hero-board {
  position: relative;
  width: min(400px, 42vw);
  aspect-ratio: 1;
  margin: 0 auto;
  border: 2px solid rgba(0, 240, 255, 0.5);
  border-radius: 14px;
  box-shadow: 0 0 60px rgba(0, 240, 255, 0.25), inset 0 0 40px rgba(0, 240, 255, 0.06);
  background: rgba(6, 8, 20, 0.85);
  overflow: hidden;
}
.hero-board::before {
  content: '';
  position: absolute; inset: 0;
  background: repeating-linear-gradient(to bottom, transparent 0 3px, rgba(0, 240, 255, 0.03) 3px 4px);
  pointer-events: none;
}
.board-grid {
  position: absolute; inset: 8%;
  background:
    repeating-linear-gradient(to right, rgba(0, 240, 255, 0.35) 0 1px, transparent 1px 6.5%),
    repeating-linear-gradient(to bottom, rgba(0, 240, 255, 0.35) 0 1px, transparent 1px 6.5%);
}
.board-star {
  position: absolute;
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 8px var(--cyan);
}
.st1 { left: 31%; top: 31%; }
.st2 { left: 31%; top: 62%; }
.st3 { left: 62%; top: 31%; }
.st4 { left: 62%; top: 62%; }
.st5 { left: 46.5%; top: 46.5%; }
/* 棋子：黑四连斜线 + 白防守 */
.stone {
  position: absolute;
  width: 6.8%;
  aspect-ratio: 1;
  border-radius: 50%;
  z-index: 2;
}
.stone.b {
  background: radial-gradient(circle at 32% 30%, #3a4152, #0a0a0f 70%);
  box-shadow: 0 0 10px rgba(0, 240, 255, 0.7);
}
.stone.w {
  background: radial-gradient(circle at 32% 30%, #ffffff, #9fb0e0 70%);
  box-shadow: 0 0 10px rgba(255, 46, 204, 0.7);
}
/* 黑子斜四连 */
.s-a { left: 20%; top: 20%; }
.s-b { left: 27%; top: 27%; }
.s-c { left: 34%; top: 34%; }
.s-d { left: 41%; top: 41%; }
/* 白子防守 */
.s-e { left: 48%; top: 34%; }
.s-f { left: 27%; top: 48%; }
/* 收官子 */
.s-g { left: 41%; top: 27%; }
/* 连五高亮线 */
.board-win {
  position: absolute;
  left: 18.5%; top: 26.6%;
  width: 33%; height: 2.5px;
  background: linear-gradient(90deg, var(--gold), #fff, var(--gold));
  box-shadow: 0 0 12px var(--gold);
  transform: rotate(45deg);
  transform-origin: left center;
  z-index: 1;
  animation: winPulse 2s ease-in-out infinite;
}
@keyframes winPulse {
  0%, 100% { opacity: 0.5; }
  50% { opacity: 1; }
}

/* ---------------- 数据带 ---------------- */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  max-width: 1080px;
  margin: 0 auto;
  padding: 40px 24px 64px;
}
.stat {
  text-align: center;
  padding: 26px 12px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--panel);
}
.stat b {
  display: block;
  font-family: var(--font-display);
  font-size: 2.6rem;
  color: var(--cyan);
  text-shadow: var(--glow-cyan);
}
.stat span { color: var(--text-dim); font-size: 0.9rem; }

/* ---------------- 区块通用 ---------------- */
.section { max-width: 1080px; margin: 0 auto; padding: 80px 24px; }
.section-head { text-align: center; margin-bottom: 52px; }
.section-head h2 {
  font-family: var(--font-display);
  font-size: clamp(1.4rem, 3.4vw, 2.2rem);
  letter-spacing: 0.12em;
  color: var(--cyan);
  text-shadow: var(--glow-cyan);
}
.section-head p { color: var(--text-dim); margin-top: 12px; }

/* ---------------- 游戏模式 ---------------- */
.modes {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.mode {
  padding: 34px 24px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--panel);
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
}
.mode:hover { transform: translateY(-4px); box-shadow: 0 0 24px rgba(0, 240, 255, 0.2); }
.mode-badge {
  display: inline-grid;
  place-items: center;
  width: 62px; height: 62px;
  margin-bottom: 18px;
  border-radius: 50%;
  font-family: var(--font-display);
  font-weight: 900;
  letter-spacing: 2px;
  color: var(--cyan);
  border: 1px solid var(--cyan);
  background: rgba(0, 240, 255, 0.06);
  box-shadow: var(--glow-cyan);
}
.mode:nth-child(2) .mode-badge { color: var(--magenta); border-color: var(--magenta); box-shadow: 0 0 12px rgba(255, 46, 204, 0.5); }
.mode:nth-child(3) .mode-badge { color: var(--green); border-color: var(--green); box-shadow: 0 0 12px rgba(57, 255, 20, 0.4); }
.mode h3 { font-family: var(--font-display); font-size: 1.1rem; margin-bottom: 10px; letter-spacing: 0.06em; }
.mode p { color: var(--text-dim); font-size: 0.92rem; }

/* ---------------- 玩法 ---------------- */
.steps {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  counter-reset: step;
}
.step {
  padding: 30px 22px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--panel);
  transition: transform 0.2s, box-shadow 0.2s;
}
.step:hover { transform: translateY(-4px); box-shadow: 0 0 24px rgba(0, 240, 255, 0.2); }
.step b {
  font-family: var(--font-display);
  font-size: 1.6rem;
  color: var(--gold);
  text-shadow: 0 0 12px rgba(255, 215, 0, 0.5);
}
.step h3 { font-family: var(--font-display); font-size: 1.05rem; margin: 10px 0 8px; letter-spacing: 0.06em; }
.step p { color: var(--text-dim); font-size: 0.92rem; }

/* ---------------- 系统亮点 ---------------- */
.sys-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}
.sys-item {
  padding: 24px 26px;
  border-radius: 14px;
  border: 1px solid rgba(143, 163, 192, 0.2);
  background: rgba(10, 14, 32, 0.45);
}
.sys-num {
  font-family: var(--font-display);
  font-size: 1rem;
  color: var(--magenta);
  text-shadow: 0 0 10px rgba(255, 46, 204, 0.5);
}
.sys-item h3 { font-family: var(--font-display); font-size: 1.05rem; margin: 8px 0 6px; letter-spacing: 0.05em; }
.sys-item p { color: var(--text-dim); font-size: 0.9rem; }

/* ---------------- FAQ ---------------- */
.faq { max-width: 760px; }
.faq-item {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel);
  margin-bottom: 12px;
  overflow: hidden;
}
.faq-item summary {
  cursor: pointer;
  padding: 16px 20px;
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  list-style: none;
  position: relative;
}
.faq-item summary::after {
  content: '+';
  position: absolute; right: 18px; top: 50%;
  transform: translateY(-50%);
  color: var(--cyan);
  font-family: var(--font-display);
}
.faq-item[open] summary::after { content: '−'; }
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item p { padding: 0 20px 16px; color: var(--text-dim); font-size: 0.92rem; }

/* ---------------- 最终 CTA ---------------- */
.final-cta {
  position: relative;
  text-align: center;
  padding: 90px 24px;
  overflow: hidden;
  background: radial-gradient(ellipse at center, rgba(255, 46, 204, 0.08), transparent 60%);
}
.final-board {
  position: absolute;
  inset: 0;
  background:
    repeating-linear-gradient(to right, rgba(0, 240, 255, 0.05) 0 1px, transparent 1px 6.5%),
    repeating-linear-gradient(to bottom, rgba(0, 240, 255, 0.05) 0 1px, transparent 1px 6.5%);
  pointer-events: none;
  mask-image: radial-gradient(ellipse at center, #000 0%, transparent 70%);
}
.final-cta h2 {
  position: relative;
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 4vw, 2.4rem);
  letter-spacing: 0.1em;
  color: var(--cyan);
  text-shadow: var(--glow-cyan);
}
.final-cta p { position: relative; color: var(--text-dim); margin: 14px 0 28px; }
.final-cta .cta { position: relative; }

/* ---------------- 页脚 ---------------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 40px 24px 48px;
  text-align: center;
}
.footer-brand {
  font-family: var(--font-display);
  letter-spacing: 2px;
  color: var(--cyan);
}
.footer-links { display: flex; gap: 20px; justify-content: center; margin: 16px 0; flex-wrap: wrap; }
.footer-links a { color: var(--text-dim); font-size: 0.85rem; transition: color 0.2s; }
.footer-links a:hover { color: var(--cyan); }
.footer-note { color: rgba(143, 163, 192, 0.6); font-size: 0.78rem; }

/* ---------------- 滚动揭示（fail-open） ---------------- */
.reveal { opacity: 1; transform: none; }
.js .reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.js .reveal.in { opacity: 1; transform: none; }

/* ---------------- 响应式（多屏幕） ---------------- */
@media (max-width: 1024px) {
  .hero-inner { grid-template-columns: 1fr; gap: 40px; text-align: center; }
  .hero-copy { text-align: center; }
  .hero-desc { margin-left: auto; margin-right: auto; }
  .hero-actions { justify-content: center; }
  .hero-board { width: min(380px, 72vw); }
  .section { padding: 68px 24px; }
}
@media (max-width: 900px) {
  .steps { grid-template-columns: repeat(2, 1fr); }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .modes { grid-template-columns: 1fr; }
  .site-nav { padding: 0 18px; }
}
@media (max-width: 640px) {
  .site-nav { padding: 0 14px; height: 54px; }
  .nav-toggle { display: flex; }
  .site-nav-links {
    position: fixed;
    top: 54px; left: 0; right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(5, 6, 15, 0.98);
    border-bottom: 1px solid var(--line);
    padding: 6px 20px 10px;
    display: none;
  }
  .site-nav-links.open { display: flex; }
  .site-nav-links a {
    padding: 13px 0;
    font-size: 1rem;
    border-bottom: 1px solid rgba(0, 240, 255, 0.08);
  }
  .site-nav-links a:last-child { border-bottom: none; }
  .hero { min-height: auto; padding: 100px 18px 48px; }
  .hero-desc { font-size: 0.95rem; }
  .hero-board { width: min(340px, 82vw); margin-top: 6px; }
  .stats { gap: 10px; padding-bottom: 40px; }
  .section { padding: 56px 16px; }
  .cta { padding: 12px 22px; }
  .cta-nav { padding: 7px 14px; }
  .hero-actions { gap: 12px; }
  .sys-grid { grid-template-columns: 1fr; }
}
@media (max-width: 420px) {
  .hero { padding-top: 92px; }
  .hero-actions .cta { width: 100%; text-align: center; }
  .hero-title { letter-spacing: 0.04em; }
  .stat { padding: 18px 8px; }
  .stat b { font-size: 2rem; }
  .steps { grid-template-columns: 1fr; }
}
@media (max-height: 560px) and (min-width: 641px) {
  .hero { min-height: auto; padding-top: 84px; padding-bottom: 44px; }
  .hero-board { width: min(300px, 36vw); }
}
@media (min-width: 1440px) {
  .hero-inner { max-width: 1200px; }
  .section { max-width: 1200px; }
  body { font-size: 1.05rem; }
}

/* 偏好减少动效 */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .js .reveal { opacity: 1; transform: none; transition: none; }
  .board-win { animation: none; }
}