body {
    font-family: sans-serif;
    background: linear-gradient(rgba(10,10,30,0.3), rgba(10,10,30,0.5)), url("bg-yinyang.jpg") center/cover no-repeat fixed;
    color: #e0e0e0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    margin: 0;
}
.card {
    background: #16213e;
    padding: 30px;
    border-radius: 12px;
    width: 380px;
    box-shadow: 0 8px 40px rgba(0,0,0,0.6);
}
h1 { margin: 0 0 5px; color: #2ecc71; font-size: 32px; }
.sub { color: #aaa; font-size: 18px; margin-bottom: 20px; }
label { display: block; margin: 12px 0 4px; font-size: 13px; color: #aaa; }
input {
    width: 100%; padding: 10px;
    border: 1px solid #2a2a4a; border-radius: 6px;
    background: #0f0f23; color: #fff; font-size: 14px; box-sizing: border-box;
}
input:focus { border-color: #2ecc71; outline: none; }
.btn {
    width: 100%; padding: 12px; background: #2ecc71;
    border: none; border-radius: 6px; color: #000;
    font-size: 15px; font-weight: bold; cursor: pointer; margin-top: 16px;
}
.btn:hover { background: #27ae60; }
.msg { margin-top: 16px; padding: 10px; border-radius: 6px; font-size: 13px; text-align: center; }
a { color: #2ecc71; }