/* ==================== 基础变量与容器 ==================== */
:root {
    --rf-red: #8B0000;
    --rf-dark: #111111;
    --rf-gray: #666666;
    --rf-light: #f8f9fa;
    --rf-border: #EAEAEA;
    --rf-white: #ffffff;
    --rf-text-light: rgba(255, 255, 255, 0.8);
}

.rf-container {
    max-width: 1440px;
    margin: 0 auto;
    padding: 0 40px;
    box-sizing: border-box;
}

/* ==================== 1. 沉浸式 Banner ==================== */
.rf-cases-header {
    background-color: var(--rf-dark);
}

.header-banner {
    position: relative;
    height: 480px;
    display: flex;
    align-items: center;
    overflow: hidden;
}

.banner-bg {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: url('../images/cases_banner.jpg') center/cover no-repeat; /* 请替换为您的图片 */
    transform: scale(1.05);
    transition: transform 3s ease;
}

.rf-cases-header:hover .banner-bg {
    transform: scale(1);
}

.banner-overlay {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: linear-gradient(90deg, rgba(17,17,17,0.9) 0%, rgba(17,17,17,0.4) 100%);
    z-index: 1;
}

.banner-content {
    position: relative;
    z-index: 2;
    max-width: 600px;
    margin-top: 60px;
}

.page-title .en-title {
    display: block;
    font-size: 14px;
    color: var(--rf-red);
    font-weight: 700;
    letter-spacing: 6px;
    margin-bottom: 15px;
    text-transform: uppercase;
}

.page-title .zh-title {
    font-size: 56px;
    color: var(--rf-white);
    font-weight: 700;
    letter-spacing: 2px;
    margin-bottom: 20px;
    display: block;
}

.banner-desc {
    color: var(--rf-text-light);
    font-size: 18px;
    line-height: 1.8;
}

/* ==================== 2. 分类筛选器 ==================== */
.case-filter-bar {
    background: var(--rf-white);
    padding: 30px 0;
    border-bottom: 1px solid var(--rf-border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.filter-group {
    display: flex;
    gap: 40px;
    justify-content: center; /* PC端居中 */
}

.filter-btn {
    background: transparent;
    border: none;
    color: var(--rf-gray);
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    padding: 10px 0;
    position: relative;
    display: flex;
    align-items: center;
    gap: 8px;
    transition: 0.3s ease;
    font-family: inherit;
}

.filter-btn .dot {
    width: 6px; height: 6px;
    background: var(--rf-red);
    border-radius: 50%;
    opacity: 0;
    transition: 0.3s;
}

.filter-btn:hover { color: var(--rf-dark); }
.filter-btn.active { color: var(--rf-dark); font-weight: 700; }
.filter-btn.active .dot { opacity: 1; }

.filter-btn::after {
    content: '';
    position: absolute;
    bottom: 0; left: 0;
    width: 0; height: 2px;
    background: var(--rf-red);
    transition: 0.3s ease;
}

.filter-btn.active::after { width: 100%; }

/* ==================== 3. 错落式网格区 (Editorial Grid) ==================== */
.cases-showcase-section {
    padding: 100px 0 120px;
    background-color: var(--rf-white);
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr); /* 极简两列，大图更有质感 */
    gap: 80px 60px;
}

/* 核心：制造高级的错落感 */
@media (min-width: 1025px) {
    .cases-grid .case-card:nth-child(even) {
        margin-top: 120px;
    }
}

.case-card {
    transition: all 0.4s ease;
}

/* 图片容器 */
.case-img-wrap {
    display: block;
    position: relative;
    overflow: hidden;
    margin-bottom: 30px;
    aspect-ratio: 4 / 3; /* 固定高级比例 */
}

/* 黑白褪色效果 (高端核心) */
.case-img-wrap img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    filter: grayscale(100%); /* 默认黑白 */
    transition: transform 0.8s ease, filter 0.8s ease;
}

.case-hover-mask {
    position: absolute;
    top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(139, 0, 0, 0.8); /* 瑞峰红半透明 */
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: 0.4s ease;
}

.view-text {
    color: #fff;
    font-size: 16px;
    font-weight: 600;
    letter-spacing: 2px;
    transform: translateY(20px);
    transition: 0.4s ease;
    display: flex;
    align-items: center;
    gap: 10px;
}

.case-card:hover .case-img-wrap img {
    filter: grayscale(0%); /* 悬浮恢复彩色 */
    transform: scale(1.05);
}

.case-card:hover .case-hover-mask {
    opacity: 1;
}

.case-card:hover .view-text {
    transform: translateY(0);
}

/* 文本信息区 */
.case-info {
    padding-right: 20px;
}

.case-meta {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 15px;
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.case-tag {
    color: var(--rf-red);
    font-weight: 700;
}

.case-industry {
    color: #999;
    border-left: 1px solid #ccc;
    padding-left: 15px;
}

.case-title {
    font-size: 28px;
    line-height: 1.4;
    margin-bottom: 20px;
}

.case-title a {
    color: var(--rf-dark);
    text-decoration: none;
    transition: color 0.3s ease;
}

.case-title a:hover {
    color: var(--rf-red);
}

.case-desc {
    color: var(--rf-gray);
    font-size: 15px;
    line-height: 1.8;
}

/* ==================== 4. CTA 区域 ==================== */
.cases-cta {
    background: var(--rf-light);
    padding: 100px 0;
    border-top: 1px solid var(--rf-border);
}

.text-center { text-align: center; }

.cta-title {
    font-size: 40px;
    color: var(--rf-dark);
    margin-bottom: 20px;
}

.cta-desc {
    font-size: 18px;
    color: var(--rf-gray);
    margin-bottom: 40px;
}

.rf-btn-primary {
    display: inline-block;
    background: var(--rf-dark);
    color: var(--rf-white);
    padding: 16px 40px;
    font-size: 16px;
    font-weight: 600;
    text-decoration: none;
    transition: 0.3s ease;
    border: 1px solid var(--rf-dark);
}

.rf-btn-primary:hover {
    background: var(--rf-white);
    color: var(--rf-dark);
}

/* ==================== 动画与交互 ==================== */
.reveal-up {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

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

/* ==================== 响应式 (Mobile Adaptation) ==================== */
@media (max-width: 1024px) {
    .cases-grid {
        gap: 60px 40px;
    }
    .case-title { font-size: 24px; }
}

@media (max-width: 768px) {
    .rf-container { padding: 0 20px; }
    
    .header-banner { height: 360px; }
    .page-title .zh-title { font-size: 40px; }
    .banner-desc { font-size: 15px; }
    
    /* 移动端取消错落，改为单列直排 */
    .cases-grid { 
        grid-template-columns: 1fr; 
        gap: 60px;
    }
    
    /* 移动端关闭默认黑白，直接显示彩色，因为手机端没有hover概念 */
    .case-img-wrap img { filter: grayscale(0%); }
    
    /* 移动端分类支持横向滑动，防止拥挤换行 */
    .filter-group {
        justify-content: flex-start;
        overflow-x: auto;
        white-space: nowrap;
        padding-bottom: 10px;
    }
    
    .cases-showcase-section { padding: 60px 0; }
    .cta-title { font-size: 28px; }
}