/* ============================================
   Base Styles — 重置与基础排版
   ============================================ */

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

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

body {
    font-family: var(--font-family);
    font-size: var(--text-base);
    line-height: var(--leading-normal);
    color: var(--color-text-primary);
    background-color: var(--color-bg-light);
    overflow-x: hidden;
}

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

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

a:hover {
    color: var(--color-primary-light);
}

ul, ol {
    list-style: none;
}

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

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

h1, h2, h3, h4, h5, h6 {
    font-weight: var(--font-bold);
    line-height: var(--leading-tight);
    color: var(--color-text-primary);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-4xl); }
h3 { font-size: var(--text-2xl); }
h4 { font-size: var(--text-xl); }
h5 { font-size: var(--text-lg); }

.section-dark h1,
.section-dark h2,
.section-dark h3,
.section-dark h4,
.section-dark h5,
.section-dark h6 {
    color: var(--color-text-light);
}

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

.section-dark p {
    color: var(--color-text-light-2);
}

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

.container-wide {
    max-width: var(--container-wide);
}

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

/* 滚动动画 */
.reveal {
    opacity: 0;
    transform: translateY(32px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
    opacity: 1;
    transform: translateY(0);
}

/* 响应式断点混入通过媒体查询实现 */
@media (max-width: 1024px) {
    h1 { font-size: var(--text-4xl); }
    h2 { font-size: var(--text-3xl); }
    h3 { font-size: var(--text-xl); }
    .container { padding: 0 var(--space-lg); }
}

@media (max-width: 768px) {
    html { font-size: 15px; }
    h1 { font-size: var(--text-3xl); }
    h2 { font-size: var(--text-2xl); }
    .container { padding: 0 var(--space-md); }
}