Writing fraction in html is quite tricky. My site fraction calculator always display fractions in html format. The trick is to use table to display fraction. I will share here my html code. Here is my code to display 1/2 in html format.
<table><tbody><tr><td style="border-top:0px;border-left:0px;border-right:0px;border-bottom:1px solid #333;padding:0px;font-size:0.7em;text-align:center;vertical-align: bottom;padding:0px;">1</td></tr><tr><td style="font-size:0.7em;text-align:center;border:0px;vertical-align:top;padding:0px;">2</td></tr></tbody></table>