* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    width: 100%;
}

body {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 16px;
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    background: #111 url("background.jpg") center / cover no-repeat fixed;
}

.card {
    width: 100%;
    max-width: 360px;
    padding: 32px 28px;
    border-radius: 14px;
    background: rgba(20, 20, 20, 0.6);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.15);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
    color: #fff;
}

.card img {
    display: block;
    width: 56px;
    height: 56px;
    margin: 0 auto 12px;
}

h1 {
    margin: 0 0 24px;
    font-size: 1.4rem;
    font-weight: 600;
    text-align: center;
}

.hint {
    margin: -12px 0 20px;
    font-size: 0.9rem;
    text-align: center;
    opacity: 0.8;
}

label {
    display: block;
    margin-bottom: 6px;
    font-size: 0.9rem;
    opacity: 0.85;
}

input[type="text"], input[type="password"] {
    width: 100%;
    margin-bottom: 18px;
    padding: 11px 12px;
    font-size: 1rem;
    color: #fff;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.25);
    border-radius: 8px;
    outline: none;
}

input.code {
    font-size: 1.4rem;
    letter-spacing: 0.3em;
    text-align: center;
}

input:focus {
    border-color: #fff;
    background: rgba(255, 255, 255, 0.15);
}

button {
    width: 100%;
    padding: 12px;
    font-size: 1rem;
    font-weight: 600;
    color: #111;
    background: #fff;
    border: 0;
    border-radius: 8px;
    cursor: pointer;
}

button:hover {
    background: #e6e6e6;
}

.error {
    margin: 0 0 18px;
    padding: 10px 12px;
    font-size: 0.9rem;
    border-radius: 8px;
    background: rgba(220, 50, 50, 0.25);
    border: 1px solid rgba(255, 90, 90, 0.5);
}

.back {
    display: block;
    margin-top: 16px;
    font-size: 0.85rem;
    text-align: center;
    color: #fff;
    opacity: 0.75;
}