.exercise-replace {
    [wlxml-class="answer"] {
        //color: @red;
        text-decoration: line-through;
    }

    .tip {
        position: absolute;
        top: -8px;
        left: 0;
        font-size: 9px;
        line-height: 12px;
        color: lighten(@red, 10%);
        white-space: nowrap;
    }

}