/* 全局设置：字体清晰，背景柔和 */
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    background-color: #f4f4f9;
    color: #333;
}

/* 布局容器：居中显示，最大宽度限制 */
.container {
    max-width: 800px;
    margin: 40px auto;
    padding: 20px;
    background: #ffffff;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

/* 导航栏 */
nav {
    background: #2c3e50;
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
nav a { color: white; text-decoration: none; margin-left: 15px; font-weight: bold; }
nav a:focus { outline: 3px solid #f1c40f; } /* 键盘焦点高亮 */

/* 表单样式 */
label { display: block; margin-bottom: 5px; font-weight: bold; }
input, textarea {
    width: 100%;
    padding: 10px;
    margin-bottom: 20px;
    border: 2px solid #ddd;
    border-radius: 4px;
    box-sizing: border-box; /* 防止边框撑大宽度 */
}
input:focus, textarea:focus {
    border-color: #3498db;
    outline: none;
    box-shadow: 0 0 5px rgba(52,152,219,0.5);
}

/* 按钮样式 */
.btn {
    display: inline-block;
    background: #3498db;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    font-size: 1rem;
}
.btn:hover { background: #2980b9; }
.btn-secondary { background: #95a5a6; }

/* 列表样式 */
.survey-list { list-style: none; padding: 0; }
.survey-item {
    border-bottom: 1px solid #eee;
    padding: 15px 0;
}
.survey-item h3 { margin: 0 0 5px 0; color: #2c3e50; }