How to setup a rounded button in SASS?

I'd to like to setup a rounded button with an ionic icon in the center.

I have something like that:

button {
    color: white;

&.button-rounded {
    display: block;
    width: 30px;
    height: 30px;
    line-height: 30px;
    border: 2px solid white;
    border-radius: 50%;
    color: white;
    text-align: center;
    text-decoration: none;
    font-size: 10px;
    font-weight: bold;
}
}

And the html:

<button class="button button-clear icon ion-home button-rounded"></button>

But the icon is not centered.

Any help, please?