/* --- 全局与基础样式 --- */
:root {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --primary-color: #b83b3b; /* 暗红色，用于强调 */
    --glass-bg: rgba(255, 255, 255, 0.1);
    --glass-border: rgba(255, 255, 255, 0.2);
    --font-serif: 'Noto Serif SC', serif;
}

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

html {
    scroll-behavior: smooth; /* 平滑滚动效果 */
}

body {
    font-family: var(--font-serif);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.8;
}

/* --- 首屏英雄区域 --- */
.hero-section {
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    text-align: center;
    background-image: linear-gradient(rgba(0, 0, 0, 0.7), rgba(0, 0, 0, 0.7)), url('bg.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed; /* 背景固定，产生视差效果 */
    position: relative;
    overflow: hidden;
}

.hero-content {
    animation: fadeInHeroContent 2s ease-out forwards;
}

.main-title {
    font-size: clamp(3rem, 15vw, 8rem); /* 响应式字体大小 */
    font-weight: 700;
    letter-spacing: 0.2em;
    text-shadow: 0 0 20px rgba(0, 0, 0, 0.5);
}

.subtitle {
    font-size: clamp(1rem, 4vw, 1.5rem);
    margin-top: 1rem;
    font-weight: 400;
    opacity: 0.8;
}

@keyframes fadeInHeroContent {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* --- 磨砂互动按钮 --- */
.button-group {
    margin-top: 3rem;
    display: flex;
    gap: 1.5rem;
    justify-content: center;
}

.glass-button {
    display: inline-block;
    padding: 12px 28px;
    border: 1px solid var(--glass-border);
    border-radius: 50px; /* 圆角 */
    background: var(--glass-bg);
    color: var(--text-color);
    text-decoration: none;
    font-size: 1rem;
    font-weight: 400;
    letter-spacing: 0.1em;
    
    /* 核心：磨砂玻璃效果 */
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px); /* 兼容Safari */

    /* 动效：舒适自然 */
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.glass-button:hover {
    background: rgba(255, 255, 255, 0.2);
    border-color: rgba(255, 255, 255, 0.4);
    transform: translateY(-5px); /* 悬浮时轻微上移 */
    box-shadow: 0 8px 15px rgba(0,0,0,0.2);
}

.glass-button:active {
    transform: translateY(-1px); /* 点击时下沉 */
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}


/* --- 向下滚动提示 --- */
.scroll-down-indicator {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    width: 24px;
    height: 40px;
    border: 2px solid var(--text-color);
    border-radius: 20px;
    opacity: 0.7;
}

.scroll-down-indicator span {
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 8px;
    background: var(--text-color);
    border-radius: 2px;
    animation: scroll-pulse 2s infinite;
}

@keyframes scroll-pulse {
    0% { transform: translate(-50%, 0); opacity: 1; }
    50% { transform: translate(-50%, 10px); opacity: 0; }
    100% { transform: translate(-50%, 0); opacity: 1; }
}


/* --- 主内容区域样式 --- */
main {
    padding: 6rem 2rem;
}

.content-section {
    max-width: 800px;
    margin: 0 auto 6rem auto;
    text-align: center;
}

.content-section h2 {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    position: relative;
    display: inline-block;
    color: var(--text-color);
}

/* 标题下划线装饰 */
.content-section h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 50px;
    height: 2px;
    background-color: var(--primary-color);
}

.content-section p {
    font-size: 1.1rem;
    text-align: justify; /* 两端对齐，更显庄重 */
    opacity: 0.9;
}

.strong-text {
    font-weight: 700;
    color: #fff;
    margin-top: 2rem;
    font-size: 1.2rem !important;
    text-align: center !important;
}

/* --- 时间轴样式 --- */
.timeline {
    position: relative;
    margin-top: 4rem;
}

/* 时间轴的中心线 */
.timeline::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 2px;
    height: 100%;
    background: rgba(255, 255, 255, 0.2);
}

.timeline-item {
    padding: 2rem 0;
    position: relative;
}

.timeline-content {
    background: rgba(0,0,0,0.2);
    padding: 1.5rem;
    border-radius: 8px;
    text-align: left;
    border: 1px solid var(--glass-border);
}

.timeline-content h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: #fff;
}

/* 时间轴上的圆点 */
.timeline-item::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 16px;
    height: 16px;
    background-color: var(--bg-color);
    border: 3px solid var(--primary-color);
    border-radius: 50%;
    z-index: 1;
}

/* --- JS滚动淡入效果 --- */
.fade-in {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

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


/* --- 页脚 --- */
footer {
    text-align: center;
    padding: 2rem;
    background: #111;
    font-size: 0.9rem;
    opacity: 0.7;
}


/* --- 响应式设计 --- */
@media (max-width: 768px) {
    main {
        padding: 4rem 1rem;
    }
    
    .content-section {
        margin-bottom: 4rem;
    }

    .content-section h2 {
        font-size: 2rem;
    }

    /* 在小屏幕上，时间轴变为单列布局 */
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item::after {
        left: 20px;
    }
    
    .timeline-content {
        margin-left: 50px;
    }
}