We can style buttons to a tremendous level using SpectrumStylr.
If you're using the General code, type:
<button class="btn btn-red | btn-blue | btn-yellow | btn-orange | btn-purple | btn-grey | btn-green | btn-red-outline | btn-blue-outline | btn-yellow-outline | btn-orange-outline | btn-purple-outline | btn-grey-outline | btn-green-outline | btn-red-outline | btn-blue-click | btn-yellow-click | btn-orange-click | btn-purple-click | btn-grey-click | btn-green-click">
...
</button>
Note: You can also type "btn-sm" if you're using the General theme.
If you're using any other Theme except for the Fun Theme, type:
<button class="btn">
...
</button>
If you're using the Fun Theme, type:
<button class="btn btn-red | btn-green | btn-turq | btn-purple">
...
</button>