JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="content">
        <div class="col1">
            <select>
                <option selected="" value="1">1</option>
                <option value="2">2</option>
            </select>
        </div>
        <div class="col2">
            <input type="text" value="100.0"/>
        </div>
    </div>
</div>

CSS

.container { vertical-align: bottom; }
.content { white-space: nowrap; width: 20%; }
.col1 { float: right; display: block; }
.col1 select { display: block; width: 60px }
.col2 { display: block; padding-right: 100px; }
.col2 input { width: 100%; text-align: right }