Use font-awesome stacked icons (alternative to bootstrap badges). Here are more examples: http://fontawesome.io/examples/
.no-border {_x000D_
border: none;_x000D_
background-color: white;_x000D_
outline: none;_x000D_
cursor: pointer;_x000D_
}_x000D_
.color-no-focus {_x000D_
color: grey;_x000D_
}_x000D_
.hover:hover {_x000D_
color: blue;_x000D_
}_x000D_
.white {_x000D_
color: white;_x000D_
}
_x000D_
<button type="button" (click)="doSomething()" _x000D_
class="hover color-no-focus no-border fa-stack fa-lg">_x000D_
<i class="color-focus fa fa-circle fa-stack-2x"></i>_x000D_
<span class="white fa-stack-1x">1</span>_x000D_
</button>_x000D_
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>
_x000D_