Changing color of the text on the button

So I have got a button:

<button ion-button (click)="login(user)" full color="secondary">Login</button>

and I want to change the color of the text on it.
How can I do this?

Also how can I change color of only half of this text. (So “Log” would be for example red and “in” yellow or something).

<button ion-button (click)="login(user)" full color="secondary">
  <span style="color: red">Log</span><span style="color: yellow">in</span>

Thank you man :):blush: