container aware prompt

etc/vim/vimrc.rookie

@@ -82,17 +82,19 @@ nnoremap <C-u> g-
 nnoremap <A-u> g+
 nnoremap <C-A-u> :earlier 1f<CR>
 
-" Terminal <Ctrl+Backspace>
-tnoremap <C-BS> <C-h>
 
 " <Super+Alt+Backspace> means <Alt+Backspace>
 imap <M-D-BS> <A-BS>
 nmap <M-D-BS> <A-BS>
-tnoremap <M-D-BS> <A-BS>
 
 " Ghostty <Super+Alt+Backspace> <=> ÿ means <ALT+Backspace>
 nmap ÿ <A-BS>
 imap ÿ <A-BS>
-tnoremap ÿ <A-BS>
 
+" Terminal keybindings for vim 8.1+
+if exists(':tmap')
+  tnoremap <C-BS> <C-h>
+  tnoremap <M-D-BS> <A-BS>
+  tnoremap ÿ <A-BS>
+endif