/* Organization */

.back {
    /* Space */
    padding: 0.25rem;
    margin:  0.50rem;

    position: fixed;
    top:      0;
    left:     0;

    /* Layout */
    display:         inline-flex;
    align-items:     center;
    justify-content: center;
}

/* Theme */

.back {
    /* Color */
    opacity: 0.75;

    /* Border */
    border: none;
    border-radius: 50%;

    /* Animation */
    transition: background 0.25s;
}

.back:hover {
    background: #FFF4;
    opacity:    1;
    transition: background 0.25s, opacity 0.25s;
}

.back:active {
    background: #FFF4;
    opacity:    1;
    filter:     brightness(90%);
}