.loader {
    border: 3px solid #f3f3f3;
    border-top: 3px solid #3b82f6;
    border-radius: 50%;
    width: 16px;
    height: 16px;
    animation: spin 1s linear infinite;
    display: inline-block;
}

@keyframes spin { 
    0% { transform: rotate(0deg); } 
    100% { transform: rotate(360deg); } 
}

.toggle-checkbox:checked { right: 0; border-color: #3b82f6; }
.toggle-checkbox:checked + .toggle-label { background-color: #3b82f6; }

body, div, input, button, span, h1, h2, h3, h4, p, i {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}