* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f0f2f5;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 500px;
    width: 100%;
    background: #fff;
    padding: 30px 40px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

h2 {
    text-align: center;
    margin-bottom: 24px;
    color: #333;
}

form div {
    margin-bottom: 16px;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 4px;
    color: #555;
}

input[type="email"],
input[type="password"] {
    width: 100%;
    padding: 10px 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 16px;
    transition: border 0.2s;
}

input[type="email"]:focus,
input[type="password"]:focus {
    border-color: #007bff;
    outline: none;
    box-shadow: 0 0 0 3px rgba(0,123,255,0.2);
}

small {
    display: block;
    color: #888;
    font-size: 13px;
    margin-top: 4px;
}

button[type="submit"] {
    width: 100%;
    padding: 12px;
    background: #007bff;
    border: none;
    border-radius: 6px;
    color: #fff;
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

button[type="submit"]:hover {
    background: #0056b3;
}

.alert {
    padding: 12px 16px;
    border-radius: 6px;
    margin-bottom: 20px;
    font-size: 15px;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-danger {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-info {
    background: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

.alert ul {
    margin: 0;
    padding-left: 20px;
}

p {
    text-align: center;
    margin-top: 16px;
}

p a {
    color: #007bff;
    text-decoration: none;
}

p a:hover {
    text-decoration: underline;
}

.checkbox-group {
    display: flex;
    align-items: center;
    gap: 8px;
}

.checkbox-group input[type="checkbox"] {
    width: auto;
    margin: 0;
}

.checkbox-group label {
    margin: 0;
    font-weight: normal;
}
/* 原有样式保持不变，以下为新增 */

.captcha-group {
    margin-bottom: 16px;
}

.captcha-group label {
    display: block;
    font-weight: 600;
    margin-bottom: 4px;
    color: #555;
}

.captcha-group img {
    border-radius: 4px;
    background: #f8f8f8;
}

.captcha-group input[type="text"] {
    padding: 10px 12px;
    border: 1px solid #ccc;
    border-radius: 6px;
    font-size: 16px;
    transition: border 0.2s;
}

.captcha-group input[type="text"]:focus {
    border-color: #007bff;
    outline: none;
    box-shadow: 0 0 0 3px rgba(0,123,255,0.2);
}

.captcha-group small {
    display: block;
    color: #888;
    font-size: 13px;
    margin-top: 4px;
}