Sometimes in the Terms of Service for a website, there are instructions that the user cannot "alter or modify the Website", or cannot access content "through any technology or means other than the Website itself". For example, see here section 4.B and 4.C. Now, some browsers offer a "Reading Mode" where they display the main text from a website in a simplified display, removing the website's style as well as any advertising and any copyright notice. Does using the Reading View break the terms of service, since I'm accessing the content via a means other than the website? I think I'm either altering the website or accessing the content via a means other than the website, depending on how "website" is defined.
As I understand it, that site allows you some level of write-access (given login) to the website. In agreeing "not to alter or modify any part of the Website" while they grant you "permission to access and use the Website" and say "you may submit textual, audio, visual, or audiovisual content", they have obscured the restriction a bit: they are basically saying that you can't change the structure of the website, but you can add stuff, for example in a forum. They are not claiming any control over how your computer interprets the data stream coming when you click a link: that doesn't change the website. Using reading mode, expanding character size, and so on does not constitute "modifying the Website", it constitutes "modifying the data stream received by you".
Similarly, stripping out stuff that they send to your computer (using Reading Mode) is not accessing the content via means other than the website, it is, again, accessing the website as allowed, and doing something with the data that they send you. One means of accessing the content would be using FTP, to download content files – that is prohibited.
It would be preferable for such terms to be written in a way that people could understand. However, if they were to give "for examples", or any further information about what they mean, then there is the fear that people would interpret the restriction as against using FTP, but any other file-access method like scp would be okay. If you are too specific in your examples, that can backfire.
Such terms are likely invalid and unenforcable, because HTML does not work that.
If they wanted that level of control, they might try making their entire site a large image or PDF document. HTML is nothing more than a polite suggestion for how something should be displayed, and no Terms of Service could reasonably be expected to alter the fundamental nature of the World Wide Web.