/* 研究方向页面样式 */
.research-themes {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 60px;
    margin-top: 2rem;
}

.section-title h1 {
    font-size: 2.5em;
    margin-bottom: 20px;
    color: #1a1a1a;
}

.section-title p {
    font-size: 1.2em;
    color: #666;
    max-width: 800px;
    margin: 0 auto;
}

.theme-grid {
    display: flex;
    flex-direction: column;
    gap: 5rem;
    margin: 5rem 0;
}

.theme-item {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 5rem;
    align-items: center;
    background: #fff;
    padding: 3rem;
    border-radius: 12px;
    box-shadow: 0 4px 24px rgba(0,0,0,0.06);
    transition: transform 0.3s ease;
}

.theme-item:nth-child(even) {
    direction: rtl;
}

.theme-item:nth-child(even) .theme-content {
    direction: ltr;
}

.theme-item:hover {
    transform: translateY(-5px);
}

.theme-content {
    max-width: 540px;
    margin: 0 auto;
    padding-top: 1rem;
}

.theme-content h2 {
    font-size: 2.2em;
    margin-bottom: 2rem;
    font-weight: 500;
    color: #2c3e50;
    line-height: 1.3;
    margin-top: -1rem;
}

.theme-content p {
    font-size: 1.15em;
    line-height: 1.8;
    color: #505965;
    margin-bottom: 2.2rem;
    letter-spacing: 0.3px;
    text-align: justify;
    text-indent: 2em;
}

.browse-link {
    display: inline-block;
    color: #3498db;
    text-decoration: none;
    font-weight: 500;
    font-size: 1.15em;
    transition: all 0.3s ease;
    position: relative;
    padding-bottom: 2px;
    margin-left: 2em;
}

.browse-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: #3498db;
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.3s ease;
}

.browse-link:hover {
    color: #2980b9;
}

.browse-link:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}

.theme-image {
    width: 100%;
    height: 400px;
    object-fit: cover;
    border-radius: 12px;
    box-shadow: 0 6px 30px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.theme-image:hover {
    transform: scale(1.02);
    box-shadow: 0 8px 40px rgba(0,0,0,0.15);
}

/* CTA 部分样式 */
.cta-section {
    margin: 6rem 0 2rem;
    text-align: center;
    padding: 4rem 0;
    background: #f8f9fa;
    border-radius: 8px;
}

.cta-content {
    max-width: 600px;
    margin: 0 auto;
}

.cta-content h2 {
    font-size: 2em;
    margin-bottom: 1rem;
    color: #333;
}

.cta-content p {
    font-size: 1.2em;
    color: #666;
    margin-bottom: 2rem;
}

.cta-button {
    display: inline-block;
    padding: 1rem 2rem;
    background: #0066cc;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    transition: background 0.3s ease;
}

.cta-button:hover {
    background: #004999;
}

/* 响应式设计 */
@media (max-width: 1200px) {
    .theme-item {
        gap: 4rem;
        padding: 2.5rem;
    }
    
    .theme-content {
        max-width: 100%;
    }
    
    .theme-image {
        height: 350px;
    }
}

@media (max-width: 768px) {
    .theme-grid {
        gap: 3rem;
        margin: 3rem 0;
    }

    .theme-item {
        grid-template-columns: 1fr;
        gap: 2rem;
        padding: 1.5rem;
    }

    .theme-item:nth-child(even) {
        direction: ltr;
    }

    .theme-content h2 {
        font-size: 2em;
        margin-bottom: 1.8rem;
        margin-top: -0.5rem;
    }

    .theme-content p {
        font-size: 1.1em;
        line-height: 1.7;
        text-indent: 2em;
    }

    .theme-image {
        height: 300px;
    }

    .browse-link {
        font-size: 1.1em;
        margin-left: 2em;
    }

    .cta-section {
        margin: 3rem 0 1rem;
        padding: 2rem 1rem;
    }
}