好的，我已经分析了您提供的代码。响应式问题的根源在于 `content-wrapper` 的 `display: block;` 覆盖了 `grid` 布局，以及 `news-item` 在小屏幕上布局转换不够灵活。

为了解决这些问题，我已经修改了您的CSS代码。主要改动如下：

1.  **优化 `content-wrapper` 布局**：在小于980px的屏幕上，我将 `content-wrapper` 的布局从 `grid` 改为 `flex`，并允许其内容换行，确保主内容和侧边栏能正确堆叠。
2.  **调整 `news-item` 内部结构**：在小屏幕上，将新闻条目的布局改为垂直堆叠 (`flex-direction: column`)，并调整了图片和文字的间距，防止内容重叠。
3.  **确保图片自适应**：设置新闻图片的宽度为100%，高度自动调整，这样图片就不会超出其容器。
4.  **提升标题可读性**：为新闻标题设置了更合适的行高，避免文字在换行时挤在一起。

这是修改后的完整CSS代码，您可以直接替换掉原来的CSS文件内容：

```css
.main-content {
    padding: 2rem 0;
}

.content-wrapper {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
    padding: 40px 0;
}


.main-section {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.page-header {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid #3465df;
}

.page-header h1 {
    font-size: 2rem;
    color: #1a365d;
    margin-bottom: 0.5rem;
}

.page-header p {
    color: #4a5568;
    font-size: 1.1rem;
}

/* 新闻分类 */
.news-categories {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.category-btn {
    padding: 0.5rem 1.5rem;
    border: 2px solid #e2e8f0;
    background: white;
    color: #4a5568;
    border-radius: 25px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.category-btn:hover,
.category-btn.active {
    background: #3465df;
    border-color: #3465df;
    color: white;
}


.news-list {
    margin-bottom: 2rem;
}

.news-item {
    display: flex;
    gap: 1.5rem;
    padding: 1.5rem;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    transition: all 0.3s ease;
    background: white;
    align-items: center;
}

.news-item:hover {
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
    transform: translateY(-2px);
}

.news-image {
    position: relative;
    flex-shrink: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 120px;
}

.news-image img {
    width: 200px;
    height: 120px;
    object-fit: cover;

    display: block;
    margin: 0 auto;
}

.news-tag {
    position: absolute;
    top: 0.5rem;
    left: 0.5rem;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
    color: white;
}

.news-tag.security {
    background: #e53e3e;
}

.news-tag.product {
    background: #3182ce;
}

.news-tag.industry {
    background: #38a169;
}

.news-tag.tech {
    background: #3465df;
}

.news-content {
    flex: 1;
}

.news-content h3 {
    margin-bottom: 0.75rem;
}

.news-content h3 a {
    color: #000000;
    text-decoration: none;
    font-size: 1.2rem;
    font-weight: 600;
    transition: color 0.3s ease;
}

.news-content h3 a:hover {
    color: #3465df;
}

.news-summary {
    color: #4a5568;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.news-meta {
    display: flex;
    gap: 1.5rem;
    color: #a0aec0;
    font-size: 0.9rem;
}

.news-meta span {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* 分页导航 */
.pagination {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.page-numbers {
    display: flex;
    gap: 0.5rem;
}

.page-btn {
    padding: 0.5rem 1rem;
    border: 1px solid #e2e8f0;
    background: white;
    color: #4a5568;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.page-btn:hover:not(:disabled) {
    background: #3465df;
    border-color: #3465df;
    color: white;
}

.page-btn.active {
    background: #1a365d;
    border-color: #1a365d;
    color: white;
}

.page-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-dots {
    padding: 0.5rem;
    color: #a0aec0;
}

/* 侧边栏 */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.sidebar-widget {
    background: white;
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
}

.widget-title-news {
    color: #1a365d;
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid #3465df;
}

/* 热门新闻 */
.hot-news {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.hot-item {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

.hot-rank {
    background: #3465df;
    color: white;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8rem;
    font-weight: bold;
    flex-shrink: 0;
}

.hot-item a {
    color: #4a5568;
    text-decoration: none;
    font-size: 1rem;
    line-height: 1.4;
    transition: color 0.3s ease;
}

.hot-item a:hover {
    color: #3465df;
}

/* 公告 */
.announcements {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.announcement-item {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    background: #f7fafc;
    border-radius: 6px;
    border-left: 3px solid #3465df;
}

.announcement-date {
    background: #1a365d;
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
    font-weight: 500;
    text-align: center;
    min-width: 40px;
}

.announcement-content h4 {
    color: #1a365d;
    font-size: 0.9rem;
    margin-bottom: 0.25rem;
}

.announcement-content p {
    color: #4a5568;
    font-size: 0.8rem;
}

/* 威胁预警 */
.alert-widget {
    border: 2px solid #e53e3e;
    background: linear-gradient(135deg, #fed7d7 0%, #feb2b2 100%);
}

.alert-widget .widget-title {
    color: #e53e3e;
    border-bottom-color: #e53e3e;
}

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

.threat-indicator {
    display: inline-block;
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.threat-indicator.high {
    background: #e53e3e;
    color: white;
}

.level-text {
    display: block;
    font-size: 1.2rem;
    font-weight: bold;
}

.level-desc {
    display: block;
    font-size: 0.8rem;
    opacity: 0.9;
}

.threat-level p {
    color: #742a2a;
    font-size: 0.9rem;
}

/* 邮件订阅 */
.newsletter p {
    color: #4a5568;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}

.newsletter-form {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.newsletter-form input {
    padding: 0.75rem;
    border: 1px solid #e2e8f0;
    border-radius: 4px;
    font-size: 0.9rem;
}

.newsletter-form button {
    background: #3465df;
    color: white;
    border: none;
    padding: 0.75rem;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 500;
    transition: background 0.3s ease;
}

.newsletter-form button:hover {
    background: #dd7324;
}


/* 响应式设计 */
@media (max-width: 980px) {

    .content-wrapper {
        grid-template-columns: 1fr;
        gap: 1.5rem;
        display: flex;
        flex-direction: column;
    }

    .news-item {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
    
    .news-content h3 {
        line-height: 1.5;
    }

    .news-image {
        width: 100%;
        height: auto;
    }

    .news-image img {
        width: 100%;
        height: auto;
        margin-top: 0;
    }

    .news-categories {
        justify-content: center;
    }

    .news-meta {
        flex-wrap: wrap;
        gap: 1rem;
    }

    .pagination {
        flex-wrap: wrap;
    }

}

@media (max-width: 480px) {

    .main-section,
    .sidebar-widget {
        padding: 1rem;
    }

    .news-content h3 a {
        font-size: 1.1rem;
    }

}