Adding a few lines of css (setting body width, font-size to 16, line-height to 1.4, Georgia for font and larger font size for headings ) makes for a decent reading experience.
Sans-serifs are generally harder to read. Note, for example, how virtually all books are set in serifs. The primary reason sans-serifs are widely used in computers is the lack of decent display resolution required to display the actual serifs. So if you are using a larger font size to read something off the screen, there is no reason not to use a serifed typeface.
Everything that has to do with the perception might very well be a myth :)
However, in typography and type designer circles it is commonly accepted that Serifs are superior for consuming large quantities of text. Also in layman terms - serifs make the glyphs more distinct and easier to recognize at a glance, in contrast to the sans where there are several glyph pairs that look virtually the same.
Please don't pull a Wikipedia on me here. As an old physicist joke goes -
Experimental physicist comes to a theoretical physicist office,
bring a graph from a recent experiment and asks for a help with
interpreting the results.
- Well, it's all rather obvious. Here's a peak, here's a dip,
because of this, that and third.
- Hold it, hold it... you are looking at it upside down.
- Ah, right, right. *Rotates the graph*. Oh, it's now even more
obvious than before.
In other words, the "actual science" you are referring to frequently ends up to be nothing more than a matter of interpretation and a subject to all sorts of biases. Especially when it concerns something as unquantifiable as "comfort of reading". Just pick up a couple of fiction books, one set in serif and another in sans-serif, go through a pageful of text and see for yourself.
My university teacher who was a fan of LaTex, taught web development and actually had a job outside the uni, told us that Serif fonts look bad and unreadable oncomputerdisplays. He said the reason is resolution. Books don't have DPI limits, and you can have a serif font look good to the tiniest detail.
It's a catch-22 pretty much. If you set it as pixels, it can be either too narrow (600 px on a full hd in full screen, though lines that are too wide/long suck too) or too wide (which leads to scroll bars).
Setting it as a percentage will obviously always make it look the same since it scales. However, a percentage on a huge screen usually makes it too wide to read lines comfortably.
You pretty much have to pick your poison, though IMO about 600 px is the maximum width for a line before it's horrible to read on a full hd screen.
That's partially true. A CSS pixel isn't necessarily the same as a screen pixel. A Mac with a retina display set to "native" resolution, for example, should actually make that 1200 pixels wide (max). In general, though, I think most browsers will treat a css pixel as a screen pixel.
Of course you could also use points or ems if you prefer.
But, having an extension like Stylebot installed and using a tiny custom CSS does offer an advantage - the CSS applies across the domain and takes effect every time the page is loaded.
Yes, though it's slightly more complex than that: if you've got multiple tabs open, you'll probably want to resize the window again to view the other tabs, and (at least in Chrome) if you open a new tab or window it'll also have that increased font-size which you'll have to decrease again.