.back-to-top {
    display: inline-block;
    cursor: pointer;
    position: fixed;
    right: 2rem;
    bottom: 2rem;
    font-size: 2rem;
    padding: 0.75rem;
    border: solid var(--primary-color-0);
    border-width: 0 var(--bold-thickness) var(--bold-thickness) 0;
    transform: rotate(-135deg);
}

.back-to-top:hover {
    border: solid var(--primary-color-0);
    border-width: 0 var(--bold-thickness) var(--bold-thickness) 0;
}

.spinner {
    display: inline-block;
    width: 1.5rem;
    height: 1.5rem;
    border-radius: 50%;
    border: var(--bold-thickness) solid var(--background-color-2);
    border-top: var(--bold-thickness) solid var(--primary-color-0);
    -webkit-animation: spin var(--fast-animation-duration) linear infinite;
            animation: spin var(--fast-animation-duration) linear infinite;
}

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

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