@mixin switch-on {
    background: #aaa;
}
@mixin switch-off {
    background: none;
}
.settings-switch {
    display: block;
    padding: .5em;
    margin: .5em;
    border: 1px solid #aaa;
    border-radius: 1em;
}

nav #menu-settings {
    display: none;
}

#settings-annotations {@include switch-on;}
.no-annotations {
    #settings-annotations {@include switch-off;}
    .annotation {display: none;}
}

#settings-themes {@include switch-on;}
.always-hide-themes {
    #settings-themes {@include switch-off;}
}

#settings-line-numbers {@include switch-on;}
.always-hide-line-numbers {
    #settings-line-numbers {@include switch-off;}
}