:root {
    --tracks-blue: #1f3871;
}

/* ===== Base ===== */
body {
    margin: 0;
    min-height: 100vh;
    background: radial-gradient(circle at top, #2b4fa3, #0f1f3d);
    font-family: 'Segoe UI', system-ui, sans-serif;
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* ===== Loader ===== */
.loader {
    position: fixed;
    inset: 0;
    background: #0f1f3d;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
}

.loader.hidden {
    display: none;
}

.ring {
    width: 70px;
    height: 70px;
    border: 6px solid rgba(255,255,255,.2);
    border-top: 6px solid var(--tracks-blue);
    border-radius: 50%;
    animation: spin 1.1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Login Card ===== */
.login-card {
    background: rgba(255,255,255,.08);
    backdrop-filter: blur(14px);
    border-radius: 22px;
    padding: 45px 40px;
    width: 100%;
    max-width: 420px;
    box-shadow: 0 25px 60px rgba(0,0,0,.45);
    text-align: center;

    opacity: 0;
    transform: translateY(20px);
    animation: show .9s ease forwards;
}

@keyframes show {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.logo {
    width: 140px;
    margin-bottom: 22px;
}

h2 {
    font-weight: 600;
    font-size: 1.5rem;
    margin-bottom: 6px;
}

.subtitle {
    font-size: .9rem;
    color: #dbe3ff;
    margin-bottom: 35px;
}

/* ===== Form ===== */
.form-group {
    margin-bottom: 20px;
    text-align: left;
}

label {
    font-size: .85rem;
    margin-bottom: 6px;
    display: block;
    color: #e0e6ff;
}

input {
    width: 100%;
    padding: 12px 14px;
    border-radius: 12px;
    border: none;
    outline: none;
    background: rgba(255,255,255,.15);
    color: #fff;
    font-size: .95rem;
    transition: .2s ease;
}

input::placeholder {
    color: rgba(255,255,255,.6);
}

input:focus {
    outline: 2px solid var(--tracks-blue);
    background: rgba(255,255,255,.2);
}

/* ===== Button ===== */
.btn-login {
    width: 100%;
    background: linear-gradient(135deg, #2b5cff, var(--tracks-blue));
    border: none;
    padding: 14px;
    border-radius: 30px;
    color: #fff;
    font-size: .95rem;
    margin-top: 18px;
    cursor: pointer;
    transition: all .3s ease;
    box-shadow: 0 10px 30px rgba(0,0,0,.4);
}

.btn-login:hover {
    transform: translateY(-2px);
    box-shadow: 0 15px 40px rgba(0,0,0,.55);
}

.btn-login:active {
    transform: translateY(0);
}

/* ===== Error Message ===== */
.error {
    background: rgba(255, 0, 0, .15);
    border: 1px solid rgba(255, 0, 0, .4);
    padding: 10px 14px;
    border-radius: 12px;
    font-size: .8rem;
    margin-bottom: 15px;
    animation: shake .35s;
}

@keyframes shake {
    0% { transform: translateX(0); }
    25% { transform: translateX(-4px); }
    50% { transform: translateX(4px); }
    75% { transform: translateX(-4px); }
    100% { transform: translateX(0); }
}

/* ===== Footer ===== */
.footer {
    margin-top: 30px;
    font-size: .75rem;
    color: rgba(255,255,255,.6);
}

@media (max-width: 768px) {
    body {
        padding: 14px;
        align-items: center;
    }

    .login-card {
        max-width: 100%;
        padding: 28px 20px;
        border-radius: 18px;
    }

    .logo {
        width: 118px;
        margin-bottom: 16px;
    }

    h2 {
        font-size: 1.28rem;
    }

    .subtitle {
        font-size: .84rem;
        margin-bottom: 22px;
    }

    .btn-login {
        padding: 12px;
    }
}

@media (max-width: 420px) {
    .login-card {
        padding: 22px 14px;
    }

    input {
        padding: 11px 12px;
        font-size: .9rem;
    }
}