/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    background: #0a0a0a;
    color: #ffffff;
    min-height: 100vh;
    overflow: hidden;
    position: relative;
}

/* 背景星空 */
#starfield-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

/* 主容器 */
.main-container {
    position: relative;
    z-index: 10;
    width: 100%;
    height: 100vh;
}

/* 页面切换 */
section {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.8s ease, visibility 0.8s ease;
}

section.active {
    opacity: 1;
    visibility: visible;
}

/* 欢迎页面 */
.intro-section {
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.main-title {
    font-size: 120px;
    font-weight: 900;
    line-height: 1;
    margin-bottom: 20px;
    letter-spacing: -2px;
}

.title-line {
    display: block;
    color: #ffffff;
}

.title-line.highlight {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: 8px;
}

.subtitle {
    font-size: 16px;
    color: rgba(255, 255, 255, 0.5);
    letter-spacing: 4px;
    text-transform: uppercase;
    margin-bottom: 80px;
}

/* 导航控制 */
.navigation-controls {
    display: flex;
    justify-content: center;
    gap: 30px;
    align-items: center;
}

.nav-control-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    padding: 15px 30px;
    color: rgba(255, 255, 255, 0.6);
    font-size: 12px;
    letter-spacing: 3px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.nav-control-btn i {
    font-size: 20px;
}

.nav-control-btn:hover {
    border-color: rgba(255, 255, 255, 0.5);
    color: rgba(255, 255, 255, 0.9);
    background: rgba(255, 255, 255, 0.05);
}

.nav-control-btn.skip-btn {
    border: none;
    padding: 15px 25px;
}

/* AI类别选择页面 */
.categories-section {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 40px 80px;
    overflow-y: auto;
}

.categories-content {
    width: 100%;
    max-width: 1400px;
    text-align: center;
}

.section-title {
    font-size: 42px;
    font-weight: 700;
    color: #ffffff;
    margin-bottom: 15px;
    letter-spacing: -1px;
}

.section-subtitle {
    font-size: 16px;
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: 60px;
    letter-spacing: 1px;
}

/* AI分类网格 */
.ai-categories-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
    margin-bottom: 60px;
}

.ai-category-card {
    position: relative;
    background: rgba(26, 26, 26, 0.3);
    backdrop-filter: blur(30px) saturate(180%);
    -webkit-backdrop-filter: blur(30px) saturate(180%);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 40px 30px;
    transition: all 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
    cursor: pointer;
    overflow: hidden;
}

.ai-category-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, transparent 100%);
    opacity: 0;
    transition: opacity 0.4s ease;
}

.ai-category-card:hover {
    transform: translateY(-10px);
    border-color: rgba(255, 255, 255, 0.3);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
}

.ai-category-card:hover::before {
    opacity: 1;
}

/* 图标容器 */
.category-icon-wrapper {
    position: relative;
    width: 100px;
    height: 100px;
    margin: 0 auto 25px;
}

.category-icon {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 20px;
    font-size: 42px;
    transition: all 0.4s ease;
    position: relative;
    z-index: 2;
}

.video-icon {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.2) 0%, rgba(118, 75, 162, 0.2) 100%);
    color: #667eea;
}

.game-icon {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.2) 0%, rgba(5, 150, 105, 0.2) 100%);
    color: #10b981;
}

.music-icon {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.2) 0%, rgba(217, 119, 6, 0.2) 100%);
    color: #f59e0b;
}

.art-icon {
    background: linear-gradient(135deg, rgba(236, 72, 153, 0.2) 0%, rgba(219, 39, 119, 0.2) 100%);
    color: #ec4899;
}

.ai-category-card:hover .category-icon {
    transform: scale(1.1) rotateY(360deg);
}

/* 发光效果 */
.category-glow {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 120px;
    height: 120px;
    border-radius: 50%;
    opacity: 0;
    transition: opacity 0.4s ease;
    z-index: 1;
}

.ai-category-card:hover .category-glow {
    opacity: 0.6;
}

.video-icon + .category-glow {
    background: radial-gradient(circle, rgba(102, 126, 234, 0.4) 0%, transparent 70%);
}

.game-icon + .category-glow {
    background: radial-gradient(circle, rgba(16, 185, 129, 0.4) 0%, transparent 70%);
}

.music-icon + .category-glow {
    background: radial-gradient(circle, rgba(245, 158, 11, 0.4) 0%, transparent 70%);
}

.art-icon + .category-glow {
    background: radial-gradient(circle, rgba(236, 72, 153, 0.4) 0%, transparent 70%);
}

.category-name {
    font-size: 22px;
    font-weight: 700;
    color: #ffffff;
    margin-bottom: 10px;
    letter-spacing: 0.5px;
}

.category-desc {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: 20px;
}

/* 功能标签 */
.category-features {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 25px;
    min-height: 80px;
}

.feature-tag {
    font-size: 12px;
    color: rgba(255, 255, 255, 0.4);
    padding: 6px 12px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.08);
    display: inline-block;
}

/* 开始按钮 */
.category-btn {
    width: 100%;
    padding: 14px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 12px;
    color: #ffffff;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
}

.category-btn i {
    transition: transform 0.3s ease;
}

.ai-category-card:hover .category-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-color: transparent;
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.4);
}

.ai-category-card:hover .category-btn i {
    transform: translateX(5px);
}

/* 返回按钮 */
.back-to-intro {
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    padding: 12px 30px;
    color: rgba(255, 255, 255, 0.6);
    font-size: 14px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

.back-to-intro:hover {
    border-color: rgba(255, 255, 255, 0.5);
    color: rgba(255, 255, 255, 0.9);
    background: rgba(255, 255, 255, 0.05);
}

/* 响应式设计 */
@media (max-width: 1200px) {
    .ai-categories-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 25px;
    }
}

@media (max-width: 768px) {
    .main-title {
        font-size: 70px;
    }

    .subtitle {
        font-size: 14px;
        letter-spacing: 3px;
    }

    .section-title {
        font-size: 32px;
    }

    .section-subtitle {
        font-size: 14px;
    }

    .ai-categories-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .categories-section {
        padding: 100px 20px 60px;
    }
}

@media (max-width: 480px) {
    .main-title {
        font-size: 50px;
    }

    .title-line.highlight {
        letter-spacing: 4px;
    }

    .subtitle {
        font-size: 12px;
        letter-spacing: 2px;
        margin-bottom: 60px;
    }

    .navigation-controls {
        flex-direction: column;
        gap: 15px;
    }

    .nav-control-btn {
        width: 200px;
    }

    .section-title {
        font-size: 26px;
    }

    .ai-category-card {
        padding: 30px 25px;
    }

    .category-icon-wrapper {
        width: 80px;
        height: 80px;
    }

    .category-icon {
        font-size: 36px;
    }
}

/* 弹窗样式 */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.glass-modal {
    background: rgba(26, 26, 26, 0.25);
    backdrop-filter: blur(30px) saturate(180%);
    -webkit-backdrop-filter: blur(30px) saturate(180%);
    border: 1px solid rgba(255, 255, 255, 0.18);
    border-radius: 16px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.6),
                0 0 0 1px rgba(255, 255, 255, 0.1) inset;
    width: 90%;
    max-width: 500px;
    overflow: hidden;
    transform: scale(0.9) translateY(20px);
    transition: all 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.modal-overlay.active .glass-modal {
    transform: scale(1) translateY(0);
}

.modal-header {
    padding: 25px 30px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.12);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: linear-gradient(
        135deg,
        rgba(102, 126, 234, 0.15) 0%,
        rgba(118, 75, 162, 0.15) 100%
    );
}

.modal-title {
    font-size: 20px;
    font-weight: 600;
    color: #ffffff;
    letter-spacing: 0.5px;
    margin: 0;
}

.modal-close {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 8px;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #808080;
    cursor: pointer;
    transition: all 0.3s ease;
}

.modal-close:hover {
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(255, 255, 255, 0.3);
    color: #ffffff;
    transform: rotate(90deg);
}

.modal-body {
    padding: 30px;
}

.subscribe-btn {
    padding: 14px 28px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border: none;
    border-radius: 10px;
    color: #ffffff;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.subscribe-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}