update .gitignore

remove ./css  from untracked list
[#73270866]implement syntax highlight

add third party css file

update README.md
Merge 6f0b2aaf6a3d00c66a96e949ba0beec84b34de30 into 2841f83c64e67b5a4228c9444b249090c86b767e
Travis build 26