/* ========== 全局变量 ========== */
:root {
  --color-primary: #2563eb;      /* 主蓝色 */
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #eef2ff;
  --color-text: #1d1d1f;
  --color-text-light: #6e6e73;
  --color-bg: #f5f5f7;
  --color-white: #ffffff;
  --color-border: #e5e7eb;
  --radius: 12px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

/* ========== 基础重置 ========== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ========== 排版 ========== */
h1 { font-size: 2rem; font-weight: 700; }
h2 { font-size: 1.4rem; font-weight: 600; }
h3 { font-size: 1.2rem; font-weight: 600; }
p  { color: var(--color-text-light); }

a {
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.15s;
}
a:hover { color: var(--color-primary-dark); }

/* ========== 布局容器 ========== */
.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ========== 导航栏 ========== */
.navbar {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border);
  padding: 16px 0;
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(8px);
  background: rgba(255,255,255,0.9);
}
.navbar .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.navbar .logo {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: 8px;
}
.navbar .logo span {
  color: var(--color-primary);
}
.nav-links {
  display: flex;
  gap: 24px;
  list-style: none;
}
.nav-links a {
  color: var(--color-text-light);
  font-weight: 500;
  font-size: 0.95rem;
}
.nav-links a:hover { color: var(--color-text); }

/* ========== 主内容区 ========== */
.hero {
  text-align: center;
  padding: 60px 0 40px;
}
.hero h1 {
  margin-bottom: 12px;
  background: linear-gradient(135deg, #1e3a5f, #2563eb);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.1rem;
  max-width: 500px;
  margin: 0 auto;
}

/* ========== 卡片 ========== */
.card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.2s, transform 0.2s;
}
.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

/* ========== 按钮 ========== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 40px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: background 0.15s, box-shadow 0.15s;
  font-family: var(--font-sans);
}
.btn-primary {
  background: var(--color-primary);
  color: #fff;
}
.btn-primary:hover {
  background: var(--color-primary-dark);
  box-shadow: 0 4px 12px rgba(37,99,235,0.3);
}
.btn-secondary {
  background: #f3f4f6;
  color: var(--color-text);
}
.btn-secondary:hover { background: #e5e7eb; }

/* ========== 工具列表 ========== */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  margin: 32px 0;
}
.tool-card h2 {
  font-size: 1.2rem;
  margin-bottom: 6px;
}
.tool-card p {
  font-size: 0.9rem;
}

/* ========== 页脚 ========== */
.footer {
  margin-top: 60px;
  padding: 24px 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-light);
  border-top: 1px solid var(--color-border);
}
.footer a { margin: 0 8px; }

/* ========== 响应式 ========== */
@media (max-width: 600px) {
  .hero { padding: 40px 0 24px; }
  .navbar .container { flex-direction: column; gap: 8px; }
}