.main-content {
    width: calc(100% - 200px); /* 减去左侧导航栏宽度 */
    padding: 20px;
    box-sizing: border-box;
    display: flex;
    flex-wrap: wrap;
    align-content: flex-start;
}

.form-container {
    width: 100%;
    background-color: #0f0;
}

.image-container {
    margin: 10px;
    box-sizing: border-box;
    flex: 1 1 calc(25% - 40px); /* 4列布局 */
    transition: background-color 0.3s; /* 平滑过渡 */
    border-radius: 10px; /* 圆角 */
    overflow: hidden; /* 隐藏超出部分 */
    aspect-ratio: 1/1.3; /* 固定比例 */
    background-color: aquamarine;
    max-width: 300px;
}
.image-container:hover {
    background-color: #ddd; /* 鼠标移上去时变色 */
}
.image-container a {
    text-decoration: none;
    color: #333;
}
.image-container img {
    width: 100%;
    height: calc(100% - 40px);
    object-fit: cover; /* 使图片居中并裁剪 */
    display: block;
}
.image-container .caption {
    margin-top: 10px;
    text-align: center;
}
/* 响应式设计 */
@media (max-width: 1200px) {
    .image-container {
        flex: 1 1 calc(33.33% - 40px); /* 3列布局 */
    }
}
@media (max-width: 900px) {
    .image-container {
        flex: 1 1 calc(50% - 40px); /* 2列布局 */
    }
}
@media (max-width: 768px) {
    .main-content {
        width: 100%;
    }
    .image-container {
        flex: 1 1 calc(50% - 40px); /* 2列布局 */
    }
}
@media (max-width: 480px) {
    .image-container {
        flex: 1 1 100%; /* 1列布局 */
    }
}