:root {
  /* 品牌主色（蓝） */
  --brand-blue-50: #f4f9ff;
  --brand-blue-100: #ebf3ff;
  --brand-blue-300: #a0cfff;
  --brand-blue-500: #3976fa;
  --brand-blue-600: #409eff;
  --brand-blue-800: #1b3a5b;

  /* 品牌辅色 */
  --brand-cyan-400: #01c0f9;
  --brand-cyan-500: #00d4ff;
  --brand-purple-500: #7c3aed;
  --brand-indigo-500: #6366f1;

  /* 中性色 */
  --neutral-white: #ffffff;
  --neutral-50: #f8faff;
  --neutral-100: #f0f4ff;
  --neutral-200: #e8edf5;
  --neutral-300: #d0d7e0;
  --neutral-500: #8b95a5;
  --neutral-700: #4a5568;
  --neutral-900: #1a202c;

  /* 渐变（克制使用） */
  --gradient-brand: linear-gradient(
    135deg,
    #01c0f9 0%,
    #00d4ff 20%,
    #0041c2 50%,
    #3d2eb8 70%,
    #532ece 100%
  );
  --gradient-ai-text: linear-gradient(90deg, #01c0f9 0%, #00d4ff 40%, #01c0f9 100%);
  --gradient-plat-text: linear-gradient(90deg, #0041c2 0%, #3d4bc2 40%, #532ece 100%);
  --gradient-card-soft: linear-gradient(
    135deg,
    rgba(1, 192, 249, 0.05) 0%,
    rgba(0, 65, 194, 0.04) 50%,
    rgba(83, 46, 206, 0.03) 100%
  );

  /* 字体（Fallback 带 size-adjust，减轻 webfont 替换时的缩放感） */
  --font-display: "YouSheBiaoTiHei-2", "Inter", "Inter Fallback", "Noto Sans SC", "Noto Sans SC Fallback",
    sans-serif;
  --font-body: "Inter", "Inter Fallback", "Noto Sans SC", "Noto Sans SC Fallback", -apple-system,
    BlinkMacSystemFont, "Segoe UI", sans-serif;

  /* 字号层级（主次分明：一眼看到标题） */
  --text-display: clamp(3.6rem, 8vw, 6.4rem);
  --text-h1: clamp(2.25rem, 4.2vw, 3.15rem);
  --text-h2: clamp(2rem, 3.6vw, 2.85rem);
  --text-h3: clamp(1.35rem, 2vw, 1.65rem);
  --text-lead: clamp(1.15rem, 1.8vw, 1.35rem);
  --text-body: 1.0625rem;
  --text-body-sm: 0.9375rem;
  --text-caption: 0.8125rem;

  /* 布局 */
  --container: 1200px;
  --nav-h: 72px;
  --radius-lg: 20px;
  --radius-card: 16px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --shadow-soft: 0 12px 40px rgba(26, 32, 44, 0.06);
  --shadow-card: 0 10px 28px rgba(27, 58, 91, 0.05);
  --shadow-card-hover: 0 16px 36px rgba(57, 118, 250, 0.12);
  --shadow-btn: 0 10px 28px rgba(57, 118, 250, 0.32);
  --shadow-hero: 0 28px 80px rgba(27, 58, 91, 0.12);
  --transition: 0.28s cubic-bezier(0.22, 1, 0.36, 1);
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);

  /* 语义 */
  --bg-page: var(--neutral-white);
  --bg-muted: var(--neutral-50);
  --bg-card: linear-gradient(180deg, #ffffff 0%, var(--neutral-50) 100%);
  --text-primary: var(--neutral-900);
  --text-secondary: var(--neutral-700);
  --text-muted: var(--neutral-500);
  --text-subtle: #94a3b8;
  --border: var(--neutral-200);
  --border-accent: rgba(160, 207, 255, 0.45);
  --border-card: rgba(208, 215, 224, 0.85);
  --font-semibold: 600;
  --font-bold: 700;
}