In the examples for Go and C/C++, the types are highlighted in a dark, subdued color (#a7a7a7, sat:0% lght: 65%), very similar to the background color(#eeeedd, sat:33% lght: 90%) . This makes what I would argue is an important syntactic element stand out kind of poorly. In keeping with perldoc.org's highlighting for scalars and arrays, I would suggest 00688B, which I've attached here as well. I think this stands out well, without the need for bold emphasis.
Default perldoc highlighting for Go
Default perldoc highlighting for C
And here with the perldoc scalar coloring (and bold removed):