I would still recommend using CUA Mode over simply rebinding C-x, C-v and C-z. CUA Mode does a few more things than that, and is smarter about it: <https://www.gnu.org/software/emacs/manual/html_node/emacs/CU...>

Also, you can prefix code blocks by two extra spaces on each line:

  (bind-keys*
   ;; file operations
   ("C-o" . find-file)         ; open file
   ("C-s" . save-buffer)       ; save file
   ("C-S-s" . write-file)      ; save as
   ("M-Q" . kill-this-buffer)  ; close file
   ;; folder tree
   ("C-d" . neotree-toggle)  ; toggle hide/show folder tree
   ;; buffer content operations
   ("C-a" . mark-whole-buffer) ; select all
   ("C-f" . isearch-forward)   ; find in file and highlight
   ("C-S-f" . query-replace)   ; find and replace
   ("C-z" . undo-tree-undo)    ; undo
   ("C-S-z" . undo-tree-redo)  ; redo
   ("C-c" . kill-ring-save)    ; Copy
   ("C-x" . kill-region)       ; Cut
   ("C-v" . yank)              ; Paste
   ;; font size
   ("C-+" . text-scale-increase)
   ("C--" . text-scale-decrease)
   ;; Pane/buffer switching
   ("M-1" . other-window)      ; toggle
   ("M-2" . previous-buffer)   ; previous
   ("M-3" . next-buffer)       ; next 
   ("<M-down>" . split-window-vertically)
   ("<M-right>" . split-window-horizontally)
   ("<s-up>" . shrink-window)
   ("<s-down>" . enlarge-window)
   ("<s-left>" . shrink-window-horizontally)
   ("<s-right>" . enlarge-window-horizontally)
   ("M-q" . delete-window)     ; close window
   ;; launch term
   ("M-0" . term)
   ;; code folding
   ("M-e" . hs-show-block)
   ("M-E" . hs-hide-block)
   ("M-h" . hs-hide-all))