OK, I finally succeeded in changing the analog clock to red. It wasn’t pretty and I don’t know if there is a better way. But here’s what I did, for the record:

In modules/default/clock/faces, I copied face-010.svg to face-013.svg to create a new face.

I edited face-013.svg to modify the style to have a fill color:
<style>.cls-1{fill:#f00;}</style>

Added the following to my custom.css:

/* for the date display */ .nightclock .date.normal.medium { color: #f00; } /* for the hour hand */ .nightclock .clockHour { background: #f00; } /* for the minute hand */ .nightclock .clockMinute { background: #f00; } Edit the config: section of the clock module in config.js. Added secondsColor: “#f00” to the config: section of the clock module in config.js to change the color of the second hand Change the analogFace config to the newly edited “face-013”.