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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: #ffffff;
    color: #333333;
    line-height: 1.6;
}

/* 头部导航 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    padding: 1rem 2rem;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid #e5e5e5;
    z-index: 1000;
    transition: all 0.3s ease;
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: #2563eb;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    color: #666666;
    text-decoration: none;
    transition: color 0.3s ease;
    font-weight: 500;
}

.nav-link:hover {
    color: #2563eb;
}

.login-btn {
    background: #2563eb;
    color: white;
    padding: 0.6rem 1.2rem;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.login-btn:hover {
    background: #1d4ed8;
    transform: translateY(-1px);
}

.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 8rem 2rem 4rem;
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 100%);
}

.hero-content {
    max-width: 900px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: #1e293b;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: #64748b;
    margin-bottom: 3rem;
    line-height: 1.8;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 4rem;
    flex-wrap: wrap;
}

.cta-btn {
    padding: 0.8rem 2rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.cta-primary {
    background: #2563eb;
    color: white;
}

.cta-secondary {
    background: transparent;
    color: #2563eb;
    border: 2px solid #2563eb;
}

.cta-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.15);
}

.cta-secondary:hover {
    background: #f8fafc;
}

/* 版本选择卡片 */
.versions {
    display: flex;
    gap: 2rem;
    margin-top: 3rem;
    justify-content: center;
    flex-wrap: wrap;
}

.version-card {
    background: white;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 2rem;
    transition: all 0.3s ease;
    position: relative;
    flex: 1;
    min-width: 320px;
    max-width: 400px;
}

.version-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    border-color: #2563eb;
}

.version-badge {
    position: absolute;
    top: -10px;
    right: 20px;
    background: #2563eb;
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.version-title {
    font-size: 1.4rem;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 1rem;
}

.version-desc {
    color: #64748b;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.version-btn {
    width: 100%;
    padding: 0.8rem;
    background: #f8fafc;
    border: 2px solid #e5e7eb;
    border-radius: 8px;
    color: #374151;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
}

.version-btn:hover {
    background: #2563eb;
    color: white;
    border-color: #2563eb;
}

/* 特性展示 */
.features {
    padding: 6rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    background: white;
}

.features-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: #1e293b;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-item {
    text-align: center;
    padding: 2rem;
    background: #f8fafc;
    border-radius: 12px;
    border: 1px solid #e5e7eb;
    transition: all 0.3s ease;
}

.feature-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.feature-icon {
    width: 60px;
    height: 60px;
    background: #2563eb;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    font-size: 1.5rem;
    color: white;
}

.feature-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: #1e293b;
}

.feature-desc {
    color: #64748b;
    line-height: 1.6;
}

/* 应用场景 */
.use-cases {
    padding: 6rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    background: #f1f5f9;
    border-radius: 12px;
    margin-bottom: 4rem;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.05);
}

.use-cases-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: #1e293b;
}

.use-case-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.use-case-item {
    background: white;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 2rem;
    transition: all 0.3s ease;
    text-align: left;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.use-case-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
    border-color: #2563eb;
}

.use-case-icon {
    font-size: 2rem;
    color: #2563eb;
    margin-bottom: 1rem;
}

.use-case-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: #1e293b;
    margin-bottom: 0.8rem;
}

.use-case-desc {
    color: #64748b;
    line-height: 1.6;
    margin-bottom: 1.5rem;
}

.use-case-link {
    color: #2563eb;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
}

.use-case-link:hover {
    text-decoration: underline;
}

/* 常见问题示例 */
.qa-examples {
    padding: 6rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
    background: #ffffff;
    border-radius: 12px;
    margin-bottom: 4rem;
}

.qa-examples-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: #1e293b;
}

.qa-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    justify-content: center;
}

.qa-button {
    padding: 1.2rem 1.5rem;
    background: #e0e7ff;
    border: none;
    border-radius: 10px;
    color: #2563eb;
    font-size: 1.1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: left;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
    line-height: 1.4;
}

.qa-button:hover {
    background: #2563eb;
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 6px 15px rgba(37, 99, 235, 0.2);
}


.overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    opacity: 0;
    visibility: hidden;
    transition: background 1s ease-in-out, opacity 1s ease-in-out;
    z-index: 9999;
}

.overlay.active {
    opacity: 1;
    visibility: visible;
    background: rgba(0, 0, 0, 0.9);
}

.overlay-text {
    color: white;
    font-size: 3rem;
    font-weight: 700;
    text-shadow: 0 0 15px rgba(255, 255, 255, 0.5);
    opacity: 0;
    animation: fadeInOut 2s ease-in-out forwards;
    animation-delay: 0.5s;
}

@keyframes fadeInOut {
    0% { opacity: 0; transform: translateY(20px); }
    50% { opacity: 1; transform: translateY(0); }
    100% { opacity: 1; }
}


.blurrable {
    transition: filter 1s ease-out;
}

.blurrable.blurred {
    filter: blur(10px);
}


/* 页脚 */
.footer {
    background: #f8fafc;
    padding: 3rem 2rem 2rem;
    text-align: center;
    border-top: 1px solid #e5e7eb;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    color: #64748b;
}

.footer-content p {
    margin-bottom: 0.5rem;
}


@media (max-width: 768px) {
    .hero {
        padding: 6rem 1rem 3rem;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .nav-links {
        gap: 1rem;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }

    .versions {
        flex-direction: column;
        align-items: center;
    }

    .version-card {
        max-width: 100%;
    }

    .navbar {
        padding: 1rem;
    }

    .nav-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav-links {
        order: 2;
    }

    .use-cases, .qa-examples {
        padding: 4rem 1rem;
    }

    .use-cases-title, .qa-examples-title {
        font-size: 2rem;
    }

    .qa-button {
        font-size: 1rem;
        padding: 1rem;
    }

    .overlay-text {
        font-size: 2rem;
    }
}

/* 入场动画 */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}