Settings Tabs are Weird???

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https://i.redd.it/tng7hrrwwc231.png

So basically I was going around in my mouse settings, and I noticed that the tabs in the settings (circled in red) don't have any outlines. They are still clickable, but it feels weird not having them, so I was wondering if anybody knew a way to bring them back to normal. Note: This isn't just in my mouse settings, but for any settings page with tabs that are supposed to be like this.