Bugzilla

**Found in**
* 125.0b6

**Affected versions**
* 126.0a1
* 125.0b6
* 124.0.1
* 115.9.1

**Tested platforms**
* Affected platforms: Windows 11, Ubuntu 22.04, macOS 12.6.6

**Preconditions**
* Have Firefox browser installed and open;

**Steps to reproduce**
1. Go to the following webpage https://speckyboy.com/css-javascript-text-animation-snippets/ 
2. Scroll down until you reach the “1. Title Animation” section
3. Press the “Run Pen” button from the animation area (from “Title Animation)
4. Press any of the “HTML”/”SCC”/”JS” buttons from the code editor menu
5. Observe the animated text

**Expected result**
* The animated text is correctly displayed, without overlapping; 

**Actual result**
* The animated text is overlapping after pressing one of the button from the code editor menu; 

**Regression range**
* I attempted to determine a regression range, but I am uncertain about the results as the issue seems to be intermittent on older versions, such as Firefox Nightly 73.0a1
* I have reached the following approximate dates for the last good build: 2020-01-01 and 2020-01-02 for the first bad build
* Pushlog: https://hg.mozilla.org/mozilla-central/pushloghtml?startdate=2020-01-01&enddate=2020-01-03

**Additional notes**
* See the attached video
* Not reproducing with Chrome, Safari or Edge
* The issue is fixed after pressing the “Rerun” button from the bottom right corner of the animation
* Not sure if this is the correct component for this issue, please change it if it belongs somewhere else