Alignment issue in Releases subnav #2325

<img width="1026" alt="" src="https://user-images.githubusercontent.com/1402241/62921154-0ec3b700-bdd2-11e9-8be3-c09e24faeb8f.png">

Test url: https://github.com/sindresorhus/refined-github/releases

DOM as it appears:

<div class="subnav">
    <div class="d-flex flex-md-row flex-justify-between flex-md-items-center">
        <div class="subnav-links float-left" role="navigation">
            <a class="js-selected-navigation-item selected subnav-item" aria-current="page"
                data-selected-links="repo_releases /sindresorhus/refined-github/releases"
                href="/sindresorhus/refined-github/releases">Releases</a>
            <a class="js-selected-navigation-item subnav-item"
                data-selected-links="repo_tags /sindresorhus/refined-github/tags"
                href="/sindresorhus/refined-github/tags">Tags</a>

            <a class="js-selected-navigation-item subnav-item"
                data-selected-links="repo_packages /sindresorhus/refined-github/packages"
                href="/sindresorhus/refined-github/packages">Packages</a>
        </div>

        <div class="pt-2 pt-md-0">
            <span class="text-gray-light f6">
                <a href="/features/package-registry/signup">Sign up for the GitHub Package Registry</a><span
                    class="lh-condensed ml-1 px-1 rounded-1 border border-green f6">Beta</span>
            </span>
        </div>
    </div>


    <div class="float-right hide-sm">
        <a href="/sindresorhus/refined-github/releases/new" class="btn">Draft a new release</a>
    </div>
    <div class="rgh-tags-dropdown float-right d-flex flex-shrink-0 flex-items-center">
        <details class="details-reset details-overlay select-menu branch-select-menu position-relative">
            <summary class="btn select-menu-button css-truncate" data-hotkey="w" title="Find tags" aria-haspopup="menu">Select
                tag&nbsp;</summary>
            <!-- tags list-->
        </details>
    </div>
</div>