Links in code blocks go white and lose underline

Site URL: https://usabilitymapping.com/test-page

Hey all,

I'm trying to insert a link in a code block - but the text goes white and I lose the underline. I would like links in code blocks to show up just like they do regular text blocks.

I've attached a screen shot and set up a simple example at https://usabilitymapping.com/test-page - Part A shows what a regular text block displays as, Part B is a simple code block (for demonstration purposes) to show what happens to links in code blocks. I've repeated Part B with "display source" turned on for the second instance of Part B.

I suspect this is because of styles for code blocks, but for the life of me can't track down the relevant CSS.

Any help appreciated!
- Neville

.code-block a {
    background-repeat: repeat-x;
    background-image: linear-gradient(to right,currentColor 100%,currentColor 0);
    background-size: 1px 1px;
    background-position: 0 100%;
    white-space: initial;
    color: #87172c;
}