:root {
            --bg: #0b0b0b;
            --soft: #151515;
            --line: #2d2d2d;
            --text: #f6f6f6;
        }
        * { box-sizing: border-box; }
        body {
            margin: 0;
            font-family: 'Space Grotesk', sans-serif;
            color: var(--text);
            background: radial-gradient(circle at 10% 10%, rgba(255,255,255,.08), transparent 30%), var(--bg);
            min-height: 100vh;
            padding: 24px;
            display: grid;
            place-items: center;
        }
        .login-button-top {
    position: fixed;
    top: 24px;
    right: 24px;
    z-index: 50;
    padding: 10px 24px;
    border-radius: 10px;
    background: #ffffff; /* Fondo blanco que pediste */
    color: #000000; /* Letra negra para contrastar */
    text-decoration: none;
    font-weight: 700;
    font-size: 0.95rem;
    font-family: 'Space Grotesk', sans-serif;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.login-button-top:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 25px rgba(0, 0, 0, 0.6);
    background: #e5e7eb; /* Un gris muy clarito al pasar el ratón */
    color: #000000;
}
        .card {
            width: min(640px, 100%);
            background: var(--soft);
            border: 1px solid var(--line);
            border-radius: 14px;
            padding: 22px;
        }
        .card-head {
            display: flex;
            align-items: flex-start;
            justify-content: space-between;
            gap: 12px;
            margin-bottom: 6px;
        }
        h1 {
            margin: 0 0 6px;
            font-family: 'Syne', sans-serif;
            text-transform: uppercase;
            font-size: 1.6rem;
        }
        .subtitle {
            margin: 0 0 16px;
            color: #9ca3af;
            font-size: 0.9rem;
        }
        .error {
            margin-bottom: 12px;
            border: 1px solid #ef4444;
            border-radius: 8px;
            background: rgba(239, 68, 68, 0.12);
            color: #fecaca;
            padding: 10px 12px;
            font-size: 0.85rem;
        }
        .field {
            display: flex;
            flex-direction: column;
            gap: 8px;
        }
        label {
            font-size: 0.85rem;
            color: #d1d5db;
            font-weight: 600;
        }
        input {
            background: var(--bg);
            border: 1px solid var(--line);
            border-radius: 8px;
            padding: 11px 12px;
            color: var(--text);
            font-size: 0.9rem;
            font-family: 'Space Grotesk', sans-serif;
        }
        .actions {
            display: flex;
            gap: 10px;
            margin-top: 14px;
        }
        .btn {
            flex: 1;
            padding: 11px 12px;
            border-radius: 8px;
            border: 1px solid var(--line);
            background: #fff;
            color: #000;
            text-align: center;
            text-decoration: none;
            font-weight: 700;
            cursor: pointer;
            font-family: 'Space Grotesk', sans-serif;
            font-size: 0.9rem;
        }
        .btn-secondary {
            background: transparent;
            color: var(--text);
            font-weight: 600;
        }
        .login-button {
            flex: 0 0 auto;
            padding: 10px 14px;
            border-radius: 8px;
            border: 1px solid var(--line);
            background: transparent;
            color: var(--text);
            text-decoration: none;
            font-weight: 700;
            font-size: 0.85rem;
            line-height: 1;
        }
        @media (max-width: 520px) {
            .card-head {
                flex-direction: column;
            }
        }