The way that you code this test will be reflective of your skills and creativity. Sometimes there is no wrong answer if you at least code things in the proper structure (classes, external CSS, etc.).
Here is one of the most common challenges that they will give you.. The Dice.
The Challenge is, create this dice using HTML/CSS. So of course you can use minimal HTML and implement things like border-radius, box-shadow, and background colors. Seems simple enough, but it’s not about just getting it done. Think speed, efficient code and accuracy. For example, if your dice does not have the exact background color, then how is that useful to making sure you have a fully branded website?
Remember, your ability to code this dice is secondary to the way you code it. If you have the proper techniques down, then it should be a breeze!