HTML布局技巧：利用CSS Grid实现复杂多列结构

<form class="data-entry-form">
    <div class="form-section">
        <label for="date-inquiry">查询日期:</label>
        <input type="date" id="date-inquiry" name="date_inquiry">
    </div>

    <div class="form-section complex-field-group">
        <label>联系人信息:</label>
        <!-- 这个div是“单列”容器，它内部将包含三列 -->
        <div class="contact-details-grid">
            <div class="contact-item">
                <label for="first-name">姓氏:</label>
                <input type="text" id="first-name" name="firstname">
            </div>
            <div class="contact-item">
                <label for="middle-name">中间名:</label>
                <input type="text" id="middle-name" name="middlename">
            </div>
            <div class="contact-item">
                <label for="last-name">名字:</label>
                <input type="text" id="last-name" name="lastname">
            </div>
        </div>
    </div>

    <div class="form-section">
        <label for="email">电子邮件:</label>
        <input type="email" id="email" name="email">
    </div>

    <div class="form-actions">
        <button type="submit">保存记录</button>
    </div>
</form>

/* 基础表单样式 */
.data-entry-form {
    max-width: 800px;
    margin: 30px auto;
    padding: 25px;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    background-color: #ffffff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.form-section {
    margin-bottom: 20px;
}

.form-section label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: #333;
}

.form-section input[type="date"],
.form-section input[type="text"],
.form-section input[type="email"],
.form-section textarea {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #ccc;
    border-radius: 5px;
    box-sizing: border-box; /* 确保padding和border不增加总宽度 */
    font-size: 1rem;
    color: #555;
}

.form-actions {
    text-align: right;
    margin-top: 30px;
}

.form-actions button {
    padding: 10px 25px;
    background-color: #007bff;
    color: white;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.form-actions button:hover {
    background-color: #0056b3;
}

/* 关键部分：实现“单列下嵌套多列” */
.complex-field-group {
    /* 这个容器本身是一个表单区域，内部的label和子网格垂直排列 */
    display: grid; /* 使其成为一个网格容器 */
    grid-template-columns: 1fr; /* 默认一列 */
    gap: 15px; /* 内部元素间距 */
    padding: 15px;
    border: 1px dashed #a0a0a0;
    background-color: #f8f8f8;
    border-radius: 5px;
}

.complex-field-group > label {
    font-size: 1.1rem;
    color: #007bff;
    margin-bottom: 0; /* 已经被grid的gap控制 */
}

.contact-details-grid {
    display: grid; /* 将此容器设置为网格容器 */
    grid-template-columns: repeat(3, 1fr); /* 定义三等分列 */
    gap: 20px; /* 子列之间的间距 */
}

.contact-item {
    background-color: #e9ecef;
    padding: 15px;
    border: 1px solid #d0d0d0;
    border-radius: 5px;
}

.contact-item label {
    font-weight: normal;
    margin-bottom: 5px;
    font-size: 0.95rem;
    color: #495057;
}

.contact-item input[type="text"] {
    width: 100%;
    padding: 8px 10px;
    font-size: 0.9rem;
}

/* 响应式调整 */
@media (max-width: 768px) {
    .contact-details-grid {
        grid-template-columns: 1fr; /* 在小屏幕上变为单列 */
    }
}