/* ============================
   base.css - 字体、重置、变量、工具类
   ============================ */

/* --- MiSans 字体定义 --- */
@font-face {
  font-family: 'MiSans';
  src: url('../fonts/MiSans-Regular.woff2') format('woff2');
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'MiSans';
  src: url('../fonts/MiSans-Medium.woff2') format('woff2');
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'MiSans';
  src: url('../fonts/MiSans-Semibold.woff2') format('woff2');
  font-weight: 600;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'MiSans';
  src: url('../fonts/MiSans-Bold.woff2') format('woff2');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}

/* --- CSS 变量 --- */
:root {
  --primary: #1a56db;
  --primary-dark: #0f3a8e;
  --primary-light: #e8f0fe;
  --primary-gradient: linear-gradient(135deg, #0f3a8e 0%, #1a56db 50%, #00b4d8 100%);
  --accent: #00b4d8;
  --accent-light: #e0f7fa;

  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-light: #9ca3af;
  --text-white: #ffffff;

  --bg-white: #ffffff;
  --bg-gray: #f8fafc;
  --bg-dark: #0f172a;
  --border: #e5e7eb;
  --border-light: #f3f4f6;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --font-family: 'MiSans', system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --transition: 0.3s ease;
  --transition-fast: 0.15s ease;
  --container-max: 1200px;
  --nav-height: 72px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  color: var(--text-primary);
  background-color: var(--bg-white);
  line-height: 1.6;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition-fast);
}

ul, ol {
  list-style: none;
}

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

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

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

h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
}

/* --- 工具类 --- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
}

.section-gray {
  background-color: var(--bg-gray);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.section-subtitle {
  font-size: 1.125rem;
  text-align: center;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto 48px;
  line-height: 1.7;
}

.text-center { text-align: center; }
.text-primary { color: var(--primary); }
.text-accent { color: var(--accent); }

/* 滚动入场动画 */
.fade-up {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 按钮基础 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 0.95rem;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn-primary {
  background: var(--primary);
  color: var(--text-white);
}
.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 2px solid var(--primary);
}
.btn-outline:hover {
  background: var(--primary);
  color: var(--text-white);
}

.btn-white {
  background: var(--bg-white);
  color: var(--primary);
}
.btn-white:hover {
  background: var(--primary-light);
  transform: translateY(-1px);
}

.btn-accent {
  background: var(--accent);
  color: var(--text-white);
}
.btn-accent:hover {
  background: #009db8;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

/* 标签 */
.tag {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 100px;
  font-size: 0.75rem;
  font-weight: 500;
  background: var(--primary-light);
  color: var(--primary);
}

.tag-accent {
  background: var(--accent-light);
  color: #0077b6;
}