body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: rgba(28, 108, 178, 0.9);
    color: white;
    padding: 20px;
    width: 100%;
    position: fixed;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 90%;
    margin: 0 auto;
    position: relative;
}

.header-content .btn-back {
    padding: 10px 20px;
    background-color: #1c6cb2;
    color: white;
    border: none;
    border-radius: 5px;
    text-decoration: none;
}

.header-content .btn-back:hover {
    background-color: #155a8c;
}

.header-content h1 {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
}

.header-content .header-spacer {
    width: 100px; /* 占位符，确保标题居中 */
}

main {
    flex: 1;
    width: 80%;
    margin: 20px auto;
    padding-top: 80px; /* 给主内容增加顶部填充，以避免被固定导航栏遮挡 */
}

.content {
    background-color: rgba(255, 255, 255, 0.9);
    padding: 30px;
    border-radius: 10px;
    text-align: center;
    width: 400px;
    position: relative;
    margin: auto;
}

h2 {
    color: #1c6cb2;
}

form {
    margin-top: 20px;
}

.tab {
    display: flex;
    justify-content: space-around;
    margin-bottom: 20px;
}

.tab button {
    background-color: #f1f1f1;
    border: none;
    outline: none;
    cursor: pointer;
    padding: 10px 20px;
    transition: 0.3s;
    font-size: 17px;
    border-radius: 5px;
}

.tab button:hover {
    background-color: #ddd;
}

.tab button.active {
    background-color: #1c6cb2;
    color: white;
}

.tabcontent {
    display: none;
}

.form-group {
    margin-bottom: 15px;
    text-align: left;
}

.form-group div {
    margin-bottom: 5px;
    font-weight: bold;
}

.form-group input {
    width: 100%;
    padding: 10px;
    box-sizing: border-box;
}

button[type="submit"] {
    padding: 10px 20px;
    background-color: #1c6cb2;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    width: 100%;
    font-size: 16px;
}

button[type="submit"]:hover {
    background-color: #155a8c;
}

footer {
    background-color: rgba(28, 108, 178, 0.9);
    color: white;
    text-align: center;
    padding: 10px 0;
    width: 100%;
    position: relative;
    margin-top: auto; /* 将footer推到页面底部 */
}