style code disappearing

Hello,

I am adding the following snippet of code to edit a table in one of my questions, the code runs and it shows what I want, and then it disappears. Does anybody have any idea of what I could do to either make the code stay or write it differently so that it doesn’t disappear? (I have seen some related questions about disappearing code but couldn’t find an answer that helped me).

The code is:

<style>

.no_borders {border-top: hidden;border-bottom: hidden;border-left: hidden;border-right: hidden;}

.all_b { border-top: 1px solid black;

border-bottom: 1px solid black;

border-left: 1px solid black;

border-right: 1px solid black; }

</style>

And then, I’m using it on a table like this…

<td class=”all_b”> …

<td class=”no_borders”>...

Thanks a lot!