CSS

html button scale to fit text

display: inline-block;
//add thos
//You can also add
text-align:center;

make button stretch to fit text

/* Will stretch the buttons height if text is too long and has to break*/

min-height: 50px;
font-size: 36px;

text size to fit button

/*I have absolutely no idea how to do this properly*/
/*The closest I can do is - */
/*Make the text just right, trial and error with:*/
text-align: center;
font-size: 20px;