JSFiddle - React, Tailwind, and code Playground

HTML

<div class="author-wrapper">
<button class="sign-social" type="submit">Войти</button>
<button class="author-submit" type="submit">Войти</button>
</div>

CSS

.author-wrapper{
	width: 500px;
    border: 1px solid #000;
	text-align: justify;
	text-justify:newspaper;
    font-size: 0;
    line-height: 0;
}
.author-wrapper:after{
	content: "";
	width: 100%;
}
.sign-social,
.author-submit{
    font-size: normal;
    line-height: normal;
	text-align: left;
}
.author-wrapper:after,
.sign-social{
	display: inline-block;
}