.btn-loading-spinner {
    display: inline-block;
    width: 1rem;
    height: 1rem;
    border: 2px solid rgba(255, 255, 255, .3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: btn-spin .6s linear infinite;
    vertical-align: middle;
    margin-right: .25rem;
}

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

.login-content {
    min-height: 100vh;
    background: linear-gradient(135deg, #e8f5e9, #dcedc8, #e0f2f1, #f1f8e9, #e8f5e9);
    background-size: 400% 400%;
    animation: bgShift 12s ease infinite;
}

@keyframes bgShift {
    0% { background-position: 0% 50%; }
    25% { background-position: 50% 0%; }
    50% { background-position: 100% 50%; }
    75% { background-position: 50% 100%; }
    100% { background-position: 0% 50%; }
}