li#bigger_text_button,
li#smaller_text_button{
    user-select:none;
    transition! .25s;
}

li#bigger_text_button:hover,
li#smaller_text_button:hover{
    opacity: .75;
}

li#bigger_text_button.disabled,
li#smaller_text_button.disabled {
    opacity: .25;
    cursor: default;
}