<ul class="steps">
    <li class="steps__item steps__item--current">Моя корзина</li>
    <li class="steps__item">Способы оплаты</li>
    <li class="steps__item">Способ доставки</li>
</ul>

.steps {
    display: flex;
    max-width: 800px;
    margin: 0;
    padding: 0;

    list-style: none;
    border: 1px solid #eee;
    border-radius: 3px;
    overflow: hidden;
}

.steps__item {
    position: relative;

    flex-basis: calc(100% / 3);
    flex-shrink: 0;
    padding: 10px;

    font-family: Arial, Helvetica, sans-serif;
    font-size: 13px;
    text-align: center;
    color: #ccc;
    white-space: nowrap;
}

.steps__item--current {
    color: #000;
    
    background: #eee;
}

.steps__item +.steps__item::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;

    border-left: 12px solid #eee;
    border-top: 17.5px solid transparent;
    border-bottom: 17.5px solid transparent;
}

.steps__item:nth-child(2)::after {
    content: "";
    position: absolute;
    top: 0;
    left: calc(100% - 2px);
    z-index: 1;

    border-left: 12px solid #fff;
    border-top: 17.5px solid transparent;
    border-bottom: 17.5px solid transparent;
}