/* ===== CSS 变量 ===== */
:root {
  /* 颜色 */
  --color-bg-start: #1a1a4e;
  --color-bg-mid: #2d1b69;
  --color-bg-end: #0d3b6e;
  --color-glass-bg: rgba(255, 255, 255, 0.12);
  --color-glass-bg-hover: rgba(255, 255, 255, 0.18);
  --color-glass-border: rgba(255, 255, 255, 0.25);
  --color-glass-border-hover: rgba(255, 255, 255, 0.45);
  --color-text-primary: rgba(255, 255, 255, 0.95);
  --color-text-secondary: rgba(255, 255, 255, 0.65);
  --color-text-muted: rgba(255, 255, 255, 0.4);
  --color-accent: #a78bfa;
  --color-accent-light: #c4b5fd;
  --color-accent-dark: #7c3aed;
  --color-success: #34d399;
  --color-warning: #fbbf24;
  --color-error: #f87171;
  --color-option-selected: rgba(167, 139, 250, 0.25);
  --color-option-selected-border: rgba(167, 139, 250, 0.7);

  /* 圆角 */
  --radius-card: 20px;
  --radius-btn: 12px;
  --radius-sm: 8px;
  --radius-xs: 6px;
  --radius-pill: 999px;

  /* 阴影 */
  --shadow-card: 0 8px 32px rgba(0, 0, 0, 0.18);
  --shadow-card-hover: 0 12px 40px rgba(0, 0, 0, 0.28);
  --shadow-btn: 0 4px 16px rgba(124, 58, 237, 0.35);
  --shadow-btn-hover: 0 6px 24px rgba(124, 58, 237, 0.5);

  /* 毛玻璃 */
  --blur-glass: blur(20px);
  --blur-glass-heavy: blur(32px);

  /* 间距 */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;

  /* 字体 */
  --font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Segoe UI', system-ui, sans-serif;
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 22px;
  --font-size-2xl: 28px;
  --font-size-3xl: 36px;

  /* 动效 */
  --transition-fast: all 0.15s ease;
  --transition-base: all 0.25s ease;
  --transition-slow: all 0.4s ease;
}

/* ===== 全局重置 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: var(--font-size-base);
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  color: var(--color-text-primary);
  min-height: 100vh;
  background: linear-gradient(135deg, var(--color-bg-start) 0%, var(--color-bg-mid) 50%, var(--color-bg-end) 100%);
  background-attachment: fixed;
  overflow-x: hidden;
  line-height: 1.6;
}

/* 背景装饰光晕 */
body::before,
body::after {
  content: '';
  position: fixed;
  border-radius: 50%;
  filter: blur(80px);
  pointer-events: none;
  z-index: 0;
}

body::before {
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(124, 58, 237, 0.25) 0%, transparent 70%);
  top: -200px;
  right: -100px;
}

body::after {
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(59, 130, 246, 0.2) 0%, transparent 70%);
  bottom: -150px;
  left: -100px;
}

/* ===== 毛玻璃基础样式 ===== */
.glass {
  background: var(--color-glass-bg);
  backdrop-filter: var(--blur-glass);
  -webkit-backdrop-filter: var(--blur-glass);
  border: 1px solid var(--color-glass-border);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
  transition: var(--transition-base);
}

.glass:hover {
  background: var(--color-glass-bg-hover);
  border-color: var(--color-glass-border-hover);
  box-shadow: var(--shadow-card-hover);
}

.glass-heavy {
  background: rgba(255, 255, 255, 0.08);
  backdrop-filter: var(--blur-glass-heavy);
  -webkit-backdrop-filter: var(--blur-glass-heavy);
  border: 1px solid var(--color-glass-border);
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
}

/* ===== 排版 ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-text-primary);
}

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }
h4 { font-size: var(--font-size-lg); }

p {
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ===== 应用容器 ===== */
#app {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  padding: var(--spacing-lg);
}

/* ===== 页面切换 ===== */
.page {
  display: none;
  width: 100%;
  max-width: 720px;
  animation: fadeInUp 0.4s ease;
}

.page.active {
  display: flex;
  flex-direction: column;
  align-items: center;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== 滚动条 ===== */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-pill);
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.35);
}

/* ===== 工具类 ===== */
.text-center { text-align: center; }
.text-muted { color: var(--color-text-muted); }
.text-accent { color: var(--color-accent); }
.mt-sm { margin-top: var(--spacing-sm); }
.mt-md { margin-top: var(--spacing-md); }
.mt-lg { margin-top: var(--spacing-lg); }
.mt-xl { margin-top: var(--spacing-xl); }
.mb-sm { margin-bottom: var(--spacing-sm); }
.mb-md { margin-bottom: var(--spacing-md); }
.mb-lg { margin-bottom: var(--spacing-lg); }
.hidden { display: none !important; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}