Bug: Wrong background color in catppuccin-frappe tmux theme

[LucEast]

I am not requesting help with my configuration and believe something is genuinely broken.

• Something is really actually broken.

Is there an existing issue outlining your problem?

• I have searched the existing issues and troubleshooting guide, and they do not solve my problem.

Describe your problem.

When using the catppuccin-frappe theme in tmux alongside the official iTerm2 Frappe color scheme, the background color used by tmux is noticeably too light. Instead of the expected #303446, it shows as #53586b.

Paste your configuration.

tmux.conf

# .tmux.conf of Lucas "LucEast" Ostmann, based on others (see below)
# last modified: 01 Mai 2025
# Using tmux 3.5a
#
# Remember: prefix-? shows all keybindings
# Priority: prefix key and reloading tmux.conf:
#-------------------------------------------------------#

# === LOOK & FEEL === #
set -g default-terminal "tmux-256color"
set -g @catppuccin_flavor 'frappe' # latte, frappe, macchiato or mocha
set -gq @catppuccin_status_left_separator "█"
set -gq @catppuccin_window_text "#(t=\$(tmux display-message -p ' #T'); [ \${#t} -le 15 ] && echo \"\$t\" || echo \" ...\${t: -15}\")"
set -gq @catppuccin_window_current_text "#(t=\$(tmux display-message -p ' #T'); [ \${#t} -le 15 ] && echo \"\$t\" || echo \" ...\${t: -15}\")"

# Load catppuccin
run ~/.config/tmux/plugins/catppuccin/tmux/catppuccin.tmux

# Make the status line pretty and add some modules
set -g status-right-length 100
set -g status-left-length 100
set -g status-justify "left"
set -g status-left ""
set -g status-right "#{E:@catppuccin_status_application}"
set -ag status-right "#{E:@catppuccin_status_directory}"
set -ag status-right "#{E:@catppuccin_status_user}"
set -ag status-right "#{E:@catppuccin_status_host}"
set -ag status-right "#{E:@catppuccin_status_date_time}"

# === PREFIX KEY SETTINGS === #
unbind C-b 
set -g prefix C-a  
bind C-a send-prefix
bind r source-file ~/.tmux.conf \; display "Reloaded ~/.tmux.conf"

# === R DEVELOPMENT ENVIRONMENT SETUP === #
bind F4 \
    select-window -t :=1 \;\
    rename-window 'R' \;\
    split-window -h -c '#{pane_current_path}' \;\
    new-window -c '#{pane_current_path}' \;\
    rename-window 'scripts' \;\
    new-window -c '#{pane_current_path}' \;\
    rename-window 'git' \;\
    new-window -c '#{pane_current_path}' \;\
    rename-window 'tests' \;\
    select-window -t :=1 \;\
    display "R development environment created"

# === WINDOW NAVIGATION === #
bind -r b previous-window
bind -r n next-window
bind -r p last-window

# === TERMINAL ADMINISTRATION === #
set -g mouse on
set -g default-terminal "xterm-256color"
set -g base-index 1
set -g pane-base-index 1
setw -g mode-keys vi
set -g status-keys vi

# === PANE COLORS (commented out for now) === #
# set -g window-style 'fg=colour247,bg=colour236'
# set -g window-active-style 'fg=colour250,bg=black'
# set -g pane-border-bg colour235
# set -g pane-border-fg colour238
# set -g pane-active-border-bg colour236
# set -g pane-active-border-fg colour51
# set -g pane-border-style fg=colour6

# === PANE NAVIGATION AND MANAGEMENT === #
bind _ split-window -h -c '#{pane_current_path}'
bind - split-window -v -c '#{pane_current_path}'
bind c new-window -c '#{pane_current_path}'

bind -n M-Left select-pane -L
bind -n M-Right select-pane -R
bind -n M-Up select-pane -U
bind -n M-Down select-pane -D

bind -r j resize-pane -D 2
bind -r k resize-pane -U 2
bind -r h resize-pane -L 2
bind -r l resize-pane -R 2

# Pane Movement
bind J switch-client -T joinops
bind -T joinops v command-prompt -p "join vertical from:" "join-pane -v -s '%%' ; switch-client -T root"
bind -T joinops h command-prompt -p "join horizontal from:" "join-pane -h -s '%%' ; switch-client -T root"

bind S switch-client -T sendops
bind -T sendops v command-prompt -p "send vertical to:" "join-pane -v -t '%%' ; switch-client -T root"
bind -T sendops h command-prompt -p "send horizontal to:" "join-pane -h -t '%%' ; switch-client -T root"

# === PANE COPY/PASTING === #
bind C-v paste-buffer

# === ESCAPE TIME === #
set -s escape-time 1

# === STATUS LINE AND MESSAGES === #
set -g status-bg black
setw -g monitor-activity on
set -g visual-activity on

# === macOS SPECIFIC SETTINGS === #
if-shell 'test "$(uname)" = "Darwin"' 'source ~/.tmux-osx.conf'

# === LaTeX ADDITIONS === #
# F6: pdflatex
bind-key -n F6 send-keys Escape :w C-m \; split-window -v -p 20 -c '#{pane_current_path}' \; send-keys clear C-m\; send-keys 'thistexfile=$(ls -1t *.tex | head -1)' C-m \; send-keys 'pdflatex $thistexfile && exit' C-m 

# F5: xelatex
bind-key -n F5 send-keys Escape :w C-m \; split-window -v -p 20 -c '#{pane_current_path}' \; send-keys clear C-m\; send-keys 'thistexfile=$(ls -1t *.tex | head -1)' C-m \; send-keys 'xelatex $thistexfile && exit' C-m 

# F7: masterfile compile
bind-key -n F7 send-keys Escape :w C-m \; split-window -v -p 20  -c '#{pane_current_path}' \; send-keys 'thistexfile=$(ls -1t *.tex | head -1)' C-m \; send-keys 'mastertexfile=$(ls -1t *.latexmaster | head -1)' C-m \; send-keys 'echo $mastertexfile' C-m  \; send-keys clear C-m \; send-keys 'texfiletocompile=`echo $mastertexfile | sed -E ' \; send-keys "'s/(.*).latexmaster(.*)/\\1/'`" C-m  \; send-keys 'if [ -z "$texfiletocompile" ] ; then exit ;  else pdflatex $texfiletocompile && exit; fi' C-m

# F8: bibtex
bind-key -n F8 send-keys Escape :w C-m \; split-window -v -p 20 -c '#{pane_current_path}'   \; send-keys 'thistexfile=$(ls -1t *.tex | head -1)' C-m \; send-keys clear C-m \; send-keys 'thisfilebase=`echo $thistexfile | sed -E ' \; send-keys "'s/(.*).tex(.*)/\\1/'`" C-m  \; send-keys 'echo $thisfilebase' C-m \; send-keys 'auxext=.aux' C-m \; send-keys 'thisauxfile=$thisfilebase$auxext' C-m \; send-keys 'echo $thisauxfile' C-m \; send-keys 'bibtex $thisauxfile && exit || printf "\nError while compiling $thisauxfile ; perhaps no .bib file/references for $thistexfile \n\n"' C-m

# === PLUGINS === #
set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-sensible'

# Initialize TMUX plugin manager (keep this line at the very bottom of tmux.conf)
run '~/.tmux/plugins/tpm/tpm'

### End of tmux.conf

tmux-osx.conf

# === KEYS === #

unbind C-b
set-option -g prefix C-a
bind C-a send-prefix

unbind /
bind / last-window

unbind o
bind o select-pane -t :.-

bind C-q command-prompt -I "htop" -p "Quick window command: " "new-window '%%'"

bind p paste-buffer

bind C-c run "tmux save-buffer - | pbcopy"
bind C-v run "tmux set-buffer \"$(pbpaste)\"; tmux paste-buffer"

bind C-s choose-session

# === OPTIONS === #

set-option -g status-keys vi
set-option -g mode-keys vi

set -sg escape-time 0

set -g base-index 1
setw -g pane-base-index 1

Attach screenshots.

What tmux version are you seeing the issue on?

tmux 3.5a

What shell are you using?

zsh

Any additional comments?

How to reproduce:

1. Set iTerm2 to use the official Catppuccin Frappe theme
2. Configure tmux with the following:

set -g @catppuccin_flavour 'frappe'
run-shell ~/.tmux/plugins/catppuccin-tmux/catppuccin.tmux

3. Open a new tmux session: tmux new -As
4. Observe the background color mismatch

This issue seems to be related to how tmux picks up the background color from the terminal emulator.
When I switch the color scheme in iTerm2, the tmux background changes accordingly — it doesn’t appear to be set explicitly by the tmux theme.
I’ve observed the same behavior with MobaXTerm on Windows: tmux background inherits the terminal’s background rather than applying the expected #303446 from the theme

[kjnsn]

The way a terminal works is that it has a grid of cells. Each cell may have one or more attributes, such as the character it contains, and foreground/background colors.

Tmux does not set a background color for every single cell in a terminal. If it did then memory usage and performance would really suffer.

I'm also curious about the sentence "how tmux picks up the background color from the terminal emulator". Are you referring to tmux potentially using OSC 5?

[LucEast]

Thank you for clarifying how a terminal works.
All I was trying to say is that the background appears to be too bright.
Here is an example Image of what I mean. Both are the frappé theme:

However, the background set by TMUX seems to be dependent on the terminal theme:

[kjnsn]

I'm really unsure what you are asking for here. You are changing the theme of your terminal, and the colors in your terminal change. Tmux does not set a background for panes, so what you are observing is working exactly as intended. If you believe tmux should set a background other than 48, then please raise a bug with tmux.

What is the intended behaviour here?

[LucEast]

Hi Kaley 👋
Thank you for the quick reply and for maintaining this awesome theme 🙏
I just wanted to kindly clarify something you mentioned:

Tmux does not set a background for panes

While tmux may not apply a background color automatically, it does allow setting it explicitly via options like:

set -g window-style "bg=#{@thm_overlay_0},fg=default"
set -g window-active-style "bg=#{@thm_bg},fg=default"

These two lines set the background for all panes (window-style) and the currently active pane (window-active-style) respectively — which works well for matching the theme background with the rest of the terminal UI.

Additionally, for targeted styling, you can also do:

select-pane -P 'bg=red'

This will immediately apply a red background to the active pane.

In my case, using the above configuration allowed me to correctly apply @thm_bg as the pane background color and match the terminal emulator’s expected appearance. So it might make sense for the theme to optionally set these values to ensure visual consistency with the terminal theme (especially in full-screen tmux usage).