/* 页面整体 */
body {
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
    background: linear-gradient(135deg, #1e3c72, #2a5298);
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    color: #333;
}

/* 居中卡片 */
.login-container {
    background: #ffffff;
    width: 360px;
    padding: 32px 32px 24px;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
    box-sizing: border-box;
}

.login-title {
    margin: 0 0 8px;
    font-size: 22px;
    text-align: center;
    color: #1e3c72;
}

.login-subtitle {
    margin: 0 0 24px;
    font-size: 13px;
    text-align: center;
    color: #6b7280;
}

/* 表单元素 */
.form-group {
    margin-bottom: 18px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    color: #374151;
}

.form-group input {
    width: 100%;
    padding: 8px 10px;
    border-radius: 6px;
    border: 1px solid #d1d5db;
    font-size: 14px;
    box-sizing: border-box;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: #2563eb;
    box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.15);
}

/* 登录按钮 */
.btn-submit {
    width: 100%;
    padding: 9px 0;
    border: none;
    border-radius: 6px;
    background: #2563eb;
    color: #ffffff;
    font-size: 15px;
    cursor: pointer;
    transition: background 0.2s, box-shadow 0.2s, transform 0.05s;
}

.btn-submit:hover {
    background: #1d4ed8;
    box-shadow: 0 6px 14px rgba(37, 99, 235, 0.35);
}

.btn-submit:active {
    transform: translateY(1px);
    box-shadow: 0 3px 8px rgba(37, 99, 235, 0.35);
}

/* 提示文字 */
.tip {
    margin-top: 16px;
    font-size: 12px;
    color: #6b7280;
    text-align: center;
}

/* 消息提示 */
.messages {
    list-style: none;
    padding: 0;
    margin: 0 0 16px;
    font-size: 13px;
}

.messages li {
    padding: 8px 10px;
    border-radius: 6px;
    background: #fee2e2;
    border: 1px solid #fecaca;
    color: #b91c1c;
    margin-bottom: 6px;
}