body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #f5f7fa, #e4ecf7);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Card */
.login-container {
    width: 100%;
    max-width: 420px;
    background: #ffffff;
    padding: 35px 30px;
    border-radius: 22px;
    box-shadow: 0 20px 50px rgba(0,0,0,0.08);
    animation: slideUp 0.8s ease;
}

/* Animación */
@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(25px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Logo */
.logo {
    width: 90px;
    height: 90px;
    background: linear-gradient(135deg, #4facfe, #00f2fe);
    border-radius: 50%;
    margin: 0 auto 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 8px 20px rgba(79,172,254,.4);
}

.logo i {
    font-size: 42px;
    color: white;
}

/* Título */
h3 {
    font-weight: 700;
    color: #2c3e50;
}

/* Labels */
.form-label {
    font-weight: 500;
    color: #555;
}

/* Inputs */
.input-group-text {
    background: #f1f4f9;
    border: none;
    border-radius: 12px 0 0 12px;
    color: #4facfe;
}

.form-control {
    border: none;
    background: #f1f4f9;
    height: 52px;
    border-radius: 0 12px 12px 0;
    font-size: 15px;
}

.form-control:focus {
    box-shadow: 0 0 0 3px rgba(79,172,254,0.25);
}
.btn-back {
    height: 50px;
    border-radius: 14px;
    margin-top: 12px;
    background: #f1f4f9;
    color: #4facfe;
    font-weight: 600;
    border: 2px solid #4facfe;
    transition: 0.3s;
}

.btn-back:hover {
    background: linear-gradient(135deg, #4facfe, #00f2fe);
    color: white;
    box-shadow: 0 6px 15px rgba(79,172,254,0.35);
    transform: translateY(-2px);
}


/* Botón login */
.btn-login {
    height: 52px;
    border-radius: 14px;
    background: linear-gradient(135deg, #4facfe, #00f2fe);
    border: none;
    font-weight: 600;
    font-size: 17px;
    transition: 0.3s;
}

.btn-login:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(79,172,254,0.35);
}

/* Botón regresar */
.btn-back {
    margin-top: 12px;
    border-radius: 14px;
    font-weight: 500;
}

/* Alert */
.alert {
    border-radius: 14px;
    font-size: 14px;
}

/* Responsive */
@media(max-width: 500px){
    .login-container{
        padding: 25px 20px;
    }
}