Please add syntax support for C/C++
The coloursheme for C/C++ doesn't seem quite right - I attached a screen-shot. The colors.lua file doesn't seem to have the bright green and yellow colours which are causing the issue. So I am guessing we need to add a C++ theme in theme.lua?

Hi thanks for the report. Are you using treesiter?
No, my neovim version doesn't support treesiter. I do use 'sheerun/vim-polyglot' though.
this colour scheme is using tree sitter as its core, also if you are using cpp you definitely need to upgrade to using tree sitter as clangd has dropped the support for its custom document highlighting protocol in favour of the official one. Coc has been updated to support this feature and a merge request is in to align tree sitter highlight groups with lsp document highlighting.
in other word, you need to use tree sitter moving forward.