C preprocessor colors improvement

Fixes go-gitea#18670

Author: braoult

web_src/less/chroma/light.less

@@ -53,8 +53,8 @@
 .chroma .cm { color: #999988; } /* CommentMultiline */
 .chroma .c1 { color: #6a737d; } /* CommentSingle */
 .chroma .cs { color: #999999; } /* CommentSpecial */
-.chroma .cp { color: #999999; } /* CommentPreproc */
-.chroma .cpf { color: #999999; } /* CommentPreprocFile */
+.chroma .cp { color: #109295 } /* CommentPreproc */
+.chroma .cpf { color: #4C4DBC; } /* CommentPreprocFile */
 .chroma .gd { color: #000000; background-color: #ffdddd; } /* GenericDeleted */
 .chroma .ge { color: #000000; } /* GenericEmph */
 .chroma .gr { color: #aa0000; } /* GenericError */