How to display Google sign-in button using HTML
If you use Bootstrap v4, you can get a nice-looking button like the one below with something like:
<div class="row">
<div class="col-md-3">
<a class="btn btn-outline-dark" href="/users/googleauth" role="button" style="text-transform:none">
<img width="20px" style="margin-bottom:3px; margin-right:5px" alt="Google sign-in" src="https://upload.wikimedia.org/wikipedia/commons/thumb/5/53/Google_%22G%22_Logo.svg/512px-Google_%22G%22_Logo.svg.png" />
Login with Google
</a>
</div>
</div>
<!-- Minified CSS and JS -->
<link rel="stylesheet"
href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm"
crossorigin="anonymous">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
crossorigin="anonymous">
</script>
This is an elegant solution I came up with using materializecss.
Code
<div class="col s12 m6 offset-m3 center-align">
<a class="oauth-container btn darken-4 white black-text" href="/users/google-oauth/" style="text-transform:none">
<div class="left">
<img width="20px" style="margin-top:7px; margin-right:8px" alt="Google sign-in"
src="https://upload.wikimedia.org/wikipedia/commons/thumb/5/53/Google_%22G%22_Logo.svg/512px-Google_%22G%22_Logo.svg.png" />
</div>
Login with Google
</a>
</div>
<!-- Compiled and minified CSS -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/materialize/1.0.0-beta/css/materialize.min.css">
<!-- Compiled and minified JavaScript -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/materialize/1.0.0-beta/js/materialize.min.js"></script>