/* ===== CSS Variables ===== */
:root {
  --color-primary: #1a5276;
  --color-primary-light: #2980b9;
  --color-accent: #3498db;
  --color-accent-hover: #2471a3;
  --color-white: #ffffff;
  --color-off-white: #f4f7fa;
  --color-bg: #f8f9fb;
  --color-text: #2c3e50;
  --color-text-light: #95a5a6;
  --color-text-muted: #bdc3c7;
  --color-border: #dce1e6;
  --color-success: #27ae60;
  --color-error: #e74c3c;
  --font-main: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --max-width: 1200px;
  --banner-height: 64px;
  --breadcrumb-height: 44px;
  --transition: 0.25s ease;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.12);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.16);
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-main);
  color: var(--color-text);
  background: var(--color-white);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  font-size: inherit;
}

img {
  max-width: 100%;
  display: block;
}

ul, ol {
  list-style: none;
}

input {
  font-family: inherit;
  font-size: inherit;
}

/* ===== Utility ===== */
.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

/* ===== Typography ===== */
h1 { font-size: 2rem; font-weight: 700; margin-bottom: 1rem; color: var(--color-primary); }
h2 { font-size: 1.5rem; font-weight: 600; margin-bottom: 0.75rem; color: var(--color-primary); }
h3 { font-size: 1.25rem; font-weight: 500; margin-bottom: 0.5rem; }
p { margin-bottom: 1rem; }

/* ===== Page Content Default Styles ===== */
.page-content {
  animation: fadeIn 0.3s ease;
}

.page-content[data-lang] {
  display: none;
}

.page-content[data-lang].active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}