/* 整体布局 */
*{margin:0;padding:0;box-sizing:border-box;font-family:'PingFang SC','Helvetica Neue',Arial,sans-serif;}

body{
    height:100vh;
    display:flex;
    align-items:center;
    justify-content:center;
    background:#d5d1e8;            /* 柔和紫色背景 */
}

.container{
    width:90%;max-width:420px;
}

.login-form{
    background:#fff;
    padding:36px 28px;
    border-radius:14px;
    box-shadow:0 4px 12px rgba(0,0,0,.08);
}

.login-form h2{
    font-size:24px;
    font-weight:600;
    text-align:center;
    margin-bottom:32px;
}

/* 输入框组 */
.input-group{
    position:relative;
    margin-bottom:26px;
}

.input-group input{
    width:100%;
    padding:14px 16px;
    font-size:16px;
    border:2px solid #aaa3;
    border-radius:10px;
    outline:none;
    transition:border .25s;
}

.input-group input:focus{
    border-color:#1296ff;
}

.input-group label{
    position:absolute;
    left:18px;
    top:50%;
    transform:translateY(-50%);
    color:#999;
    pointer-events:none;
    transition:all .25s;
}

/* 上浮效果 */
.input-group input:focus + label,
.input-group input:not(:placeholder-shown) + label{
    top:0;
    transform:translateY(-50%) scale(.86);
    background:#fff;
    padding:0 4px;
    color:#1296ff;
}

/* 登录按钮 */
button[type="submit"]{
    width:100%;
    padding:14px 0;
    font-size:18px;
    font-weight:600;
    color:#fff;
    background:#1296ff;
    border:none;
    border-radius:10px;
    cursor:pointer;
    transition:opacity .25s;
}
button[type="submit"]:hover{opacity:.9;}

.error-message{
    margin-top:18px;
    font-size:14px;
    color:#e02424;
    text-align:center;
    display:none;
}