In a tweak to the usual format, this week's show is a frontend-focused rapid-fire question bonanza. Ed's been doing some CSS work this week, and has a lot of questions for Tom (a self-styled CSS expert, whatever that means).

What's wrong with `innerHTML`? And for that matter, why is `eval()` so evil? Should you use `px`, `pt`, `em`, or `rem` (or something else) when setting sixes in CSS? What's the deal with browser prefixes (`-moz-`, `-webkit-` etc.)? Are you a bad programmer if you use a z-index of `99999`? (Spoilers: probably). Is it *ever* appropriate to use `!important` in your CSS? Should you use IDs or classes? And to finish with a famously easy question; how do you name things? Find out all this and more in this week's rapid-fire instalment of A Question of Code.

Mentioned in this episode:

• Never use eval()
• Check if you need a prefix at caniuse.com
• MindBEMding – getting your head ’round BEM syntax