/* 重置 & 全新高级色盘 —— 深邃、洁净、专业 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-color: var(--bg);
    color: var(--text-primary);
    font-family: "Inter", "Microsoft YaHei", system-ui, sans-serif;
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* 平滑滚动 */
html {
    scroll-behavior: smooth;
    scroll-padding-top: 90px;
}

a {
    text-decoration: none;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 clamp(1.2rem, 4vw, 2.5rem);
}

/* 高级排版 */
.h1 {
    font-size: clamp(2rem, 4vw, 2.5rem);
    font-weight: 600;
    line-height: 1.2;
    letter-spacing: -0.02em;
    color: var(--text-primary);
}

.h2 {
    font-size: clamp(1.8rem, 4vw, 2.5rem);
    font-weight: 600;
    letter-spacing: -0.015em;
    line-height: 1.25;
}

.h3 {
    font-size: clamp(1.25rem, 2.5vw, 1.0rem);
    font-weight: 600;
    line-height: 1.4;
    letter-spacing: -0.01em;
}

.body-lg {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.body {
    font-size: 1rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.section {
    padding: var(--section-padding);
    position: relative;
}

/* section头部 start*/
.section-header {
    text-align: center;
    max-width: 720px;
    margin: 0 auto clamp(3rem, 5vw, 4rem);
}

.section-title {
    font-size: clamp(1.8rem, 4vw, 2.0rem);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    display: inline-block;
    position: relative;
}

.section-title::after {
    content: "";
    position: absolute;
    bottom: -0.5rem;
    left: 50%;
    transform: translateX(-50%);
    width: 64px;
    height: 3px;
    background: var(--primary);
    border-radius: 2px;
}

.section-desc {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* section头部 end*/

/* 卡片全面升级 start*/
.card {
    background: var(--surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: clamp(1.8rem, 3vw, 2.5rem);
    transition: var(--transition);
    border: 1px solid var(--border-light);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-soft);
    transform: translateY(-3px);
}

/* 卡片全面升级 end*/

/* 按钮 — 极简但精致 start*/
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 2rem;
    font-weight: 500;
    font-size: 1rem;
    border-radius: 40px; /* 现代圆角 */
    border: none;
    cursor: pointer;
    transition: var(--transition);
    gap: 0.5rem;
    white-space: nowrap;
    background: transparent;
    border: 1px solid transparent;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background-color: #0A5A3F;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    border-color: var(--border-light);
    background: var(--surface);
    color: var(--text-primary);
}

.btn-outline:hover {
    border-color: var(--primary);
    background: var(--primary-light);
    color: var(--primary);
    transform: translateY(-2px);
}

/* 按钮 — 极简但精致 end*/

/*尾部结论及内容 start*/
.body-sm {
    font-size: 0.875rem;
    color: var(--text-tertiary);
}

/*尾部结论及内容 end*/

/* 回到顶部按钮 start*/
#backToTop {
    position: fixed;
    bottom: 32px;
    right: 32px;
    background-color: var(--color-primary);
    color: #fff;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-default);
    cursor: pointer;
    border: none;
    font-size: 20px;
}

#backToTop:hover {
    background-color: rgba(13, 148, 136, 0.9);
}

#backToTop.show {
    opacity: 1;
    visibility: visible;
}

/* 回到顶部按钮 end*/

/* 渐入动画增强 start*/
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.7s cubic-bezier(0.2, 0, 0, 1), transform 0.7s cubic-bezier(0.2, 0, 0, 1);
}

.fade-in.active {
    opacity: 1;
    transform: translateY(0);
}

/* 渐入动画增强 end*/