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:

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

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

3. 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;
}

4. 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”.