public/styles/components/_orientation.scss

.viewer-orientation {
    display: inline-block;
    padding: 5px;
}

.viewer-orientation__button {
    display: inline-block;

    cursor: pointer;
    padding: 8px 13px;

    background-color: #F0F0F0;

    border-top: 3px solid #F0F0F0;

    &:hover {
        border-top: 3px solid #d0d0d0;
        background-color: #d0d0d0;
    }
}

.viewer-orientation__button.is-selected {
    color: #00a8ed;
    border-top: 3px solid #00a8ed;
}