Hi there,
you have multiple elements in your content that are overflowing their containers, which is causing the issue.
You can add this CSS to your site, which is what some other themes do, to stop all unintended overflow:
html, body {
overflow-x: hidden;
}
Or you can identify each element that is overflowing and fix those issues, it generally haappens when elements have odd margins and padding applied to them. This article explains a good method for identifying the problem elements:
https://css-tricks.com/findingfixing-unintended-body-overflow/