/* ============================================
   base.css — CSS Variables, Reset, Typography, Utilities
   ============================================ */

:root {
    --primary-blue: #0066cc;
    --secondary-blue: #4a90e2;
    --dark-blue: #1a1a2e;
    --gray-light: #f5f7fa;
    --gray-medium: #e2e8f0;
    --gray-dark: #4a5568;
    --text-primary: #1a1a2e;
    --text-secondary: #718096;
    --white: #ffffff;
    --shadow-light: 0 4px 15px rgba(0, 0, 0, 0.08);
    --shadow-medium: 0 10px 30px rgba(0, 0, 0, 0.12);
    --shadow-heavy: 0 15px 40px rgba(0, 0, 0, 0.15);
    --font-primary: 'Microsoft YaHei', 'PingFang SC', sans-serif;
    --border-color: #e0e0e0;
    --footer-bg: #1a1a2e;
}

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

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

body {
    font-family: var(--font-primary, 'Microsoft YaHei', 'PingFang SC', sans-serif);
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary, #333);
    background: var(--white, #fff);
    overflow-x: hidden;
}

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

ul, ol {
    list-style: none;
}

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

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

/* ---- Utility Classes ---- */

/* Text align center */
.tac {
    text-align: center;
}

/* Secondary text color */
.text-secondary {
    color: var(--text-secondary, #999);
}

/* Hide on small screens (< 576px) */
@media (max-width: 576px) {
    .hidden-sm {
        display: none !important;
    }
}