JSFiddle - React, Tailwind, and code Playground

HTML

<div class="outer-container">
    <div class="button"></div>
    <div class="box">content here is variable</div>
</div>

<div style="clear: both; height: 10px;"></div>

<div class="outer-container-2">
    <div class="button"></div>
    <div class="box-2">content here is variable</div>
</div>

CSS

.outer-container {
    float: right;
}

.button {
    float: right;
    height: 35px;
    width: 35px;
    background-color: red;
}

.box {
    float: none;
    overflow: hidden;
    height: 35px;
    background-color: green;
    display: inline-block;
}

.box-2 {
      float: none;
    overflow: hidden;
    height: 35px;
    background-color: green;
}

.outer-container-2 {}