There seems to be an issue with setting the max-width and height for flex children. The div is getting squished down to fit its children exactly, possibly due to the styling associated with div .content. It's not clear why this is happening.
The division should ideally have a max-width and height of 1600px x 500px so that it can flex correctly and move closer together as the page width decreases.
//CSS code here
<html>
<body>
<div class="content">
<div class="waveContainer">
//SVG element here
</div>
<div class="flexParent">
//Flex parent content here
</div>
</div>
</body>
</html>