:root {
    --bs-dark-rgb: 26, 26, 26;
    --bs-body-color: #f8f9fa;
    --bs-body-bg: #121212;
    --bs-border-color-translucent: rgba(255, 255, 255, 0.15);
    --brand-color-1: #4F46E5;
    --brand-color-2: #D63384;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    background-color: #121212;
    background-image: radial-gradient(circle at center, #1f1f1f 0%, #121212 35%);
    background-repeat: no-repeat;
    overflow-x: hidden; /* 保留这个 - 它能防止水平滚动条 */
}

/* 渐变高亮文字 */
.text-primary-gradient {
    background: linear-gradient(90deg, var(--brand-color-1), var(--brand-color-2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    -text-fill-color: transparent;
}

/* 渐变高亮按钮 */
.btn-primary {
    background-image: linear-gradient(90deg, var(--brand-color-1) 0%, var(--brand-color-2) 100%);
    border: none;
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(214, 51, 132, 0.2);
}


/* 统一导航栏中所有按钮的 padding 和高度 */
.navbar .d-flex .btn {
    padding: 0.75rem 1.5rem;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(214, 51, 132, 0.3);
}

.section {
    padding: 6rem 0;
}

.section-light {
    background-color: #1a1a1a;
}

/* Hero 区域 */
.hero-section {
    position: relative;
}

/* Hero 动态光晕效果 (纯 CSS) */
.hero-visual-container {
    position: relative;
    min-height: 400px;
    border-radius: 1rem;
    background-color: #1e1e1e; /* 深色底板 */
    border: 1px solid #333;
    overflow: hidden; /* 关键：隐藏光晕的边缘 */
    z-index: 1;
}

/* 动态光球 1 */
.hero-visual-container::before {
    content: '';
    position: absolute;
    width: 400px;
    height: 400px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(79, 70, 229, 0.4) 0%, transparent 70%);
    top: -100px;
    left: -100px;
    animation: move-glow-1 15s infinite alternate ease-in-out;
    z-index: 0;
}

/* 动态光球 2 */
.hero-visual-container::after {
    content: '';
    position: absolute;
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(214, 51, 132, 0.4) 0%, transparent 70%);
    bottom: -50px;
    right: -50px;
    animation: move-glow-2 18s infinite alternate ease-in-out;
    z-index: 0;
}

/* 光球动画 */
@keyframes move-glow-1 {
    from { transform: translate(0, 0) scale(1); opacity: 0.7; }
    to   { transform: translate(50px, 100px) scale(1.2); opacity: 0.9; }
}
@keyframes move-glow-2 {
    from { transform: translate(0, 0) scale(1); opacity: 0.6; }
    to   { transform: translate(-80px, -50px) scale(1.1); opacity: 0.8; }
}

.hero-content {
    position: relative;
    z-index: 2;
}
@media (max-width: 991.98px) {
    .hero-section {
        padding-top: 6rem;
        padding-bottom: 6rem;
        text-align: center;
    }
    .hero-visual-container {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        z-index: 0;
        opacity: 0.3;
    }
    .hero-content {
        padding-top: 2rem;
    }
}


/* “探索Sora-2”卡片：玻璃拟态 */
.feature-card {
    background-color: rgba(30, 30, 30, 0.7);
    backdrop-filter: blur(5px);
    border: 1px solid #333;
    border-radius: 0.75rem;
    transition: all 0.3s ease;
    z-index: 1; /* 确保在背景之上 */
}
.feature-card:hover {
    transform: translateY(-5px);
    border-color: var(--brand-color-1);
    box-shadow: 0 0 20px rgba(79, 70, 229, 0.4), 0 0 20px rgba(214, 51, 132, 0.4);
}

/* 轮播图中的占位符 */
.carousel-visual-placeholder {
    background-color: #2a2a2a;
    border: 1px solid #333;
    min-height: 400px;
    border-radius: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #666;
    font-size: 1.2rem;
    font-style: italic;
}

/* 轮播指示器 (标签) */
.use-cases-indicators {
    position: relative;
    bottom: auto;
    margin-bottom: 2rem;
    justify-content: center;
}
.use-cases-indicators [data-bs-target] {
    background-color: #333;
    color: #fff;
    padding: 0.5rem 1rem;
    border: 0;
    border-radius: 0.5rem;
    margin: 0 0.5rem;
    text-indent: 0;
    width: auto;
    height: auto;
    opacity: 0.7;
    transition: opacity 0.3s ease, background-color 0.3s ease, background-image 0.3s ease;
}
.use-cases-indicators .active {
    opacity: 1;
    background-color: var(--brand-color-1); /* Fallback */
    background-image: linear-gradient(90deg, var(--brand-color-1) 0%, var(--brand-color-2) 100%);
}

/* 隐藏轮播的左右箭头 */
#useCasesCarousel .carousel-control-prev,
#useCasesCarousel .carousel-control-next {
    display: none;
}

/* 如何开始 步骤 */
.step-number {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1;
}

/* 价格对比表 */
.comparison-table {
    border: 1px solid #333;
}
.comparison-table thead th {
    background-color: #2a2a1a;
    font-size: 1.2rem;
}
.comparison-table td, .comparison-table th {
    padding: 1.25rem;
    vertical-align: middle;
}
.comparison-table .text-advantage {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--brand-color-1);
}
.comparison-table .text-disadvantage {
    font-size: 1.5rem; /* 调整为与右侧一致 */
    font-weight: 700; /* 调整为与右侧一致 */
    color: #dc3545; /* Bootstrap 默认的危险红色 */
    text-decoration: none; /* 移除删除线 */
}
.comparison-table .fa-check-circle {
    color: #198754;
}
.comparison-table .fa-times-circle {
    color: #dc3545;
}

/* 定价卡片 */
.pricing-card {
    background-color: #1e1e1e;
    border: 1px solid #333;
    border-radius: 0.75rem;
}
.pricing-card .card-header {
    background-color: #2a2a2a;
    border-bottom: 1px solid #333;
    font-size: 1.2rem;
    font-weight: 600;
}
.pricing-card .list-unstyled li {
    padding: 0.5rem 0;
}
.pricing-card-highlight {
    border: 2px solid var(--brand-color-1);
}

/* 页脚 */
.footer {
    background-color: #1a1a1a;
    color: #adb5bd;
}
.footer a {
    color: #f8f9fa;
    text-decoration: none;
    transition: color 0.2s;
}
.footer a:hover {
    color: var(--brand-color-1);
}
.footer .social-icons a {
    font-size: 1.5rem;
    margin: 0 0.75rem;
}

/* 【新】导航栏链接基础样式 (为动画做准备) */
.navbar-nav .nav-link {
    position: relative;
    padding-bottom: 0.5rem; /* 为下划线留出空间 */
    color: rgba(255, 255, 255, 0.7); /* 非激活状态的颜色 */
    transition: color 0.3s ease;
}

/* 鼠标悬停时变亮 */
.navbar-nav .nav-link:hover {
    color: #fff;
}

/* 【新】激活状态下的下划线动画 */
.navbar-nav .nav-link::after {
    content: '';
    position: absolute;
    bottom: 0.25rem;
    left: 50%; /* 从中心开始 */
    transform: translateX(-50%); /* 确保居中 */
    width: 0; /* 默认宽度为 0 */
    height: 3px; /* 下划线粗细 */
    background-image: linear-gradient(90deg, var(--brand-color-1), var(--brand-color-2));
    border-radius: 2px;
    transition: width 0.3s ease-in-out; /* 宽度变化的过渡动画 */
}

/* 【新】激活状态的样式 (触发下划线动画) */
.navbar-nav .nav-link.active {
    color: #fff; /* 激活时文本变白 */
    font-weight: 600;
}

.navbar-nav .nav-link.active::after {
    width: 90%; /* 展开下划线 (90%比100%更好看) */
}

/* ... (您现有的所有 CSS 样式) ... */

/* 【新】回到顶部按钮样式 */
.back-to-top {
    position: fixed; /* 固定在屏幕上 */
    bottom: 25px;
    right: 25px;
    width: 50px;
    height: 50px;
    /* 使用您的品牌渐变色 */
    background-image: linear-gradient(90deg, var(--brand-color-1) 0%, var(--brand-color-2) 100%);
    color: #fff;
    border-radius: 50%; /* 圆形按钮 */
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    text-decoration: none;
    
    opacity: 0; /* 默认隐藏 */
    visibility: hidden;
    transform: translateY(20px); /* 默认下移，配合动画 */
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
    z-index: 1000; /* 确保在最上层 */
}

/* 【新】用于显示按钮的 'show' 类 */
.back-to-top.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0); /* 激活时上移到原位 */
}

/* 【新】鼠标悬停效果 */
.back-to-top:hover {
    color: #fff;
    box-shadow: 0 4px 15px rgba(214, 51, 132, 0.4);
    transform: translateY(-3px); /* 悬停时轻微上浮 */
}

/* 响应式修复：轮播指示器（标签）在手机上的样式 */
@media (max-width: 767.98px) {
    .use-cases-indicators {
        /* 允许按钮在手机上自由换行 */
        flex-wrap: wrap; 
    }
    
    .use-cases-indicators [data-bs-target] {
        /* 缩小字体和内边距，使其在手机上能并排显示更多 */
        font-size: 0.85rem;
        padding: 0.5rem 0.75rem;
        
        /* 缩小左右边距，增加上下边距，以便换行时不会紧贴 */
        /* 原先是 margin: 0 0.5rem; (上下0, 左右0.5rem)
           现在是 margin: 0.25rem; (上下左右都是 0.25rem)
        */
        margin: 0.25rem; 
    }
}


/* 响应式修复：移动端导航栏 CTA 按钮 */
/* (仅在 < 992px 时生效, 即 'lg' 断点以下) */
@media (max-width: 991.98px) {
    .navbar-cta-mobile .btn {
        /* 大幅缩小内边距 */
        padding: 0.35rem 0.6rem;
        /* 缩小字体 */
        font-size: 0.8rem;
    }
    
    /* 登录按钮的图标，缩小右边距 */
    .navbar-cta-mobile .btn .fa-sign-in-alt {
        margin-right: 0.25rem !important; /* 覆盖 me-1 */
    }
}


/* 移动端菜单样式 */
@media (max-width: 991.98px) {
    
    /* (删除了 .navbar.sticky-top, .navbar-hidden, 和 .navbar-collapse 规则) */

    /* (保留这个) 当菜单展开时，给它一个深色背景 */
    .navbar-collapse.show {
        background-color: var(--bs-body-bg);
        border-bottom: 1px solid var(--bs-border-color-translucent);
        padding: 0 1rem 1rem 1rem;
    }
}