That “ugliness” is beautiful because imo McMaster’s interface facilitates turning unknown unknowns into known knowns.

Having all the options and important specs laid out on one giant page lets you discover blind spots in your thinking. Need an tube adapter for a fluid systems? Open up that page and as your scrolling through, discover that you forgot to think about the pitch of threading when you find the size and psi rating adapter you were looking for comes in several thread pitch options. Not sure which? Open up the handy explainer at the top of the page that explains to you the different options available and what they mean.

McMaster is primarily a B2B tool whose goal is to facilitate their users finding what they need, buying it, and building in a manner that is fast, convenient, and informative.

McMaster is a masterclass in UX and understanding what is really important to their business model, and resisting the urge to switch to trendy, sleek designs simply because it looks prettier.

“content is beautiful” - old japanese proverb

The UI is very obviously responsive, usable and fast.

i think they mean responsive as in it doesnt rearrange everything to fit on a screen 500px wide

I know what responsive means. I went from maximized window to narrower than many websites can handle and it adapts flawlessly. No idea how anyone could call this not responsive.

...the site is not responsive at all to fit to a mobile device?

There's two definitions of responsive, both of which are used in this thread.

1. It responds to your actions. Click stuff and it does that and does it quickly.

2. It gives you a different response based on which device you are using. You log on with a mobile device, it gives you a screen suited to mobile.

It doesn't do the latter. I'm on a phone. It might resize screens on a desktop, but doesn't do it for a phone.