SOURCE

<div class="line-box">
        <div class="child-box1">
        </div>
        <div class="child-box2">
        </div>
        <span>xxx</span>

.line-box {
        padding-left: 100px;
        border: 1px solid black;
    }
    .line-box::after {
        content: 'x';
        vertical-align: top;
    }
    .child-box1, .child-box2 {
        display: inline-block;
        width: 100px;
        height: 100px;
        border: 1px solid red;
    }
    .child-box1 {
        margin-top: 20px;
        vertical-align: top;
    }