CSS counter

counter.html

<span class="counter">1</span>
<span class="counter">2</span>
<span class="counter">3</span>
<span class="counter">4</span>
<span class="counter">5</span>

style.scss

span.counter {
    position: relative;
    display: inline-block;
    font-family: monospace;
    font-size: 31px;
    color: #000;
    padding: 2px 5px;
    margin-right: -4px;
    background-color: transparent;
    z-index: 1;

    &:before, &:after {
        display: block;
        position: absolute;
        content: ' ';
        left: 0;
        height: 18px;
        width: 100%;
        background: #fff;
        border-radius: 3px;
        z-index: -1;
    }

    &:before {
        top: 0;
    }

    &:after {
        top: 19px;
    }
}