:root {
  --brand-from: #4f46e5;
  --brand-to: #1e293b;
  --bg-deep: #0b1220;
  --bg-panel: #111a2c;
  --border: rgba(148, 163, 184, 0.14);
}

* { scroll-behavior: smooth; }
body {
  font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg-deep);
  color: #e2e8f0;
  -webkit-font-smoothing: antialiased;
}

/* 渐变文字 */
.gradient-text {
  background: linear-gradient(90deg, #818cf8, #38bdf8);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* 网格背景 */
.bg-grid {
  background-image:
    linear-gradient(rgba(129, 140, 248, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(129, 140, 248, 0.07) 1px, transparent 1px);
  background-size: 44px 44px;
}

/* 滚动毛玻璃导航 */
.nav-blur {
  background: rgba(11, 18, 32, 0.82);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.45);
  border-bottom: 1px solid rgba(148, 163, 184, 0.10);
}

/* 卡片悬浮 */
.card-hover {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  transition: transform .3s ease, box-shadow .3s ease, border-color .3s ease;
}
.card-hover:hover {
  transform: translateY(-8px);
  border-color: rgba(99, 102, 241, 0.55);
  box-shadow: 0 22px 50px -20px rgba(79, 70, 229, 0.55);
}

/* 按钮发光 */
.btn-glow {
  box-shadow: 0 12px 34px -10px rgba(79, 70, 229, 0.65);
  transition: transform .25s ease, box-shadow .25s ease;
}
.btn-glow:hover {
  transform: translateY(-2px);
  box-shadow: 0 18px 44px -10px rgba(79, 70, 229, 0.8);
}

/* 入场动画 */
.fade-in {
  animation: fadeUp .8s ease both;
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

/* FAQ */
.faq-item {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  overflow: hidden;
  transition: box-shadow .3s ease, border-color .3s ease;
}
.faq-item.active {
  border-color: rgba(99, 102, 241, 0.5);
  box-shadow: 0 12px 34px -14px rgba(79, 70, 229, 0.5);
}
.faq-question {
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.1rem 1.3rem;
  font-weight: 600;
  color: #f1f5f9;
  user-select: none;
}
.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height .35s ease, padding .35s ease;
  color: #94a3b8;
  padding: 0 1.3rem;
}
.faq-item.active .faq-answer {
  max-height: 240px;
  padding: 0 1.3rem 1.2rem;
}
.faq-icon { transition: transform .3s ease; color: #818cf8; }
.faq-item.active .faq-icon { transform: rotate(180deg); }

/* 桌面显示器屏幕光效 */
.screen-glow {
  box-shadow: 0 0 60px -10px rgba(56, 189, 248, 0.45), 0 30px 70px -30px rgba(0, 0, 0, 0.8);
}