JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form-group tabled-contents">
    <div style="display: table-row;">
        <input id="BodyContentPlaceholder_TxtCustomerId" type="text">
        <input id="BodyContentPlaceholder_BtnShowByCustomerId" type="submit" value="Show">
    </div>
</div>

CSS

.tabled-contents {
	display: table;
	width: 100%;
}

.form-group input[type=text], .form-group input[type=submit] {
	display: table-cell;
	width: 200px;
}

.form-group input[type=text] _:-ms-input-placeholder {
  display: inline-block;
}