For anyone who uses the Custom Totara theme, a small change appears to have been made in 2.5.8 which affects the way you override the colour of block titles.

Previous I would have used the following to change the colour of the block heading:

.block .header{background-color:#2D9AC3;}

This would set the colour of the whole heading, where as after 2.5.8 there is an area behind the title itself the same colour as the main heading background. To resolve this, you would now use:

.block .header, .block .header h2{background-color:#2D9AC3;}

It is of course possible that I was doing this incorrectly to start off with, and I am now doing it right (or possibly neither is actually how it should be done), but if anyone else was also doing it in the same way and had the problem this might help.

Dan