Change colour of forum categories

[Black Snow]

That is because you have 2 pieces of CSS that are conflicting and overlapping each other.

Find .tcat in your CSS, and delete: background-color: #21262b;

Then change the code that HM666 suggested and replace it with this:

.tcatLeft {
    background-color: #21262b;
    border-top-left-radius: 10px;
    border-top-right-radius: 10px;
    height: 47px;
}