Fix page scrolling when modifying text

I have got a main page, and then other elements below that. This main page (a div) has a set height of 80vh. Below that, there is one hr element, and one div element. This div elements contains some information.

On my main page, there is a title that gets modified by javascript code. At a low screen width, this causes the text to go from one to two lines. The height of the element the title is inside of remains the same due to the set 80vh, but the page still scrolls up when the text goes from two to one lines. I can see that change by printing out the document.documentElement.scrollTop. It changes by exactly the height of one line.

How can I prevent that scrolling?

I can "fix" it by getting the scrollTop before changing the text and then setting the scrollTop to the previous value after changing it, but I would prefer a cleaner, less hacky fix.

I checked all the heights of the elements using dev tools and javascript code, they remain the same.

The general layout of my html looks like this:

<div id="top-bar">stuff</div>
<div id="home-page">the title that changes size</div>
<hr>
<div id="projects-showcase">The elements that contain information</div>

Here is the part of the CSS that I think is most important:

html {
    background-color: #F76E2A;
}

body {
    margin: 0;
    min-height: 100%;
}

#top-bar {
    position: sticky;
    top: 0;
    height: 2.5rem;
    background-color: #222327;
    display: flex;
    z-index: 100;
    box-shadow: 0 0 7px 7px #F76E2A;
}

#home-page {
    height: 80vh;
}

hr {
    height: 5px;
    width: 80%;
    max-width: 700px;
    color: #222327;
    background-color: #222327;
    border-radius: 2px;
    margin: 3rem auto
}

#projects-showcase {
    margin-bottom: 6rem;
}

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