Highlight Claude Code User Message

I use a transparent iTerm2 profile. In Claude Code, the default gray highlight for user messages blends into the background, which makes old messages hard to spot.

Attempts

I asked Claude Code about it, and it suggested using the Trigger feature in iTerm2.
Profiles → Default → Advanced → Triggers
Use the regex ^❯ for matching, and choose Highlight Text as the Action.
But, it could only match one line, which did not solve the problem.

Solution

Open Claude Code

/theme

• Move the cursor to New custom theme... and create a custom theme
• Enter a custom theme name, for example my-dark

Edit the config

• The config file is ~/.claude/themes/my-dark.json
• Open it yourself, or let your AI help edit the file
• Add an overrides field: "userMessageBackground": "rgb(20, 50, 35)"

Done. Now go enjoy chatting with Claude Code a bit more happily.