1. Check if italic font is supported
echo -e "\e[3mitalic\e[23m"
2. Create screen-256color.terminfo
vim ~/screen-256color.terminfo
screen-256color|screen with 256 colors and italic,
sitm=\E[3m, ritm=\E[23m,
use=screen-256color,
3. Execute the command
tic ~/screen-256color.terminfo
4. Add the following lines to .vimrc:
set t_ZH=^[[3m
set t_ZR=^[[23m
5. Add the following line to .tmux.conf:
set -g default-terminal "screen-256color"
6. Add to ~/.zshrc
env TERM=screen-256color