So I know that my question is pretty technical, but basically I would like to know specifically how the following CSS affects the display of text in <p> tags.
p {
letter-spacing:2px;
font-family:"Georgia";
}
I know that Georgia is a proportional font, that the designer has spent time crafting the spaces between letters to make the font more readable and visually pleasing.
But my question is how does the letter-spacing property affect this proportionality? Does this code add two pixels onto the spacing already defined by the type designer, or does it reset that spacing to two pixels?
This property is additive to what the font would normally use. So, 1px will increase it by a pixel. Sitepoint calls it "extra" space (with negative values allowed).
The W3C docs say the same thing:
"This value indicates inter-character space in addition to the default space between characters. Values may be negative..."
It is in addition to any default spacing.
See: https://developer.mozilla.org/en-US/docs/CSS/letter-spacing
From my experiment on Firefox on OSX, using a kerned font (Arial) as opposed to Georgia which does not appear to have kerning on my machine, I can testify that the spacing is in addition to existing spacing, and kerning, and can be either additive, or subtractive.
It is also worth mentioning that different browsers and operating systems replace fonts, and handle them slightly differently to each other, making it impossible to predict 100% how any font will be rendered.
Related
I would like to make each font take equal amount of space, similar to fonts displayed in a Linux terminal
For example:
Notice that each character take same amount of space
Use a font designed so that every character in it is of the same width.
These are called monospaced fonts.
The CSS generic font family monospace will select the system's default font of that style.
Various values of the white-space property such as pre will cause multiple spaces to be treated as significant, although the <pre> element should be used if the semantics of the text mean that the spacing is significant rather than just presentational.
It's not super clear to me what you're asking for, but I'll try to help.
-Terminal fonts generally used monospacing, here is a list of monospaced fonts: https://www.typewolf.com/top-10-monospaced-fonts
-If you're looking to evenly increase the amount of spacing between letters I suggest checking out letter spacing for css: https://www.w3schools.com/cssref/pr_text_letter-spacing.asp
The vertical position of text rendered in Helvetica and the size of its content area differ between Firefox and Chrome for Mac. For example, in Chrome, the descenders are clipped if the line-height is identical to font-size.
(I’ve adjusted the position of the block elements in this picture—keeping the baseline consistent—to illustrate the difference in size and text positioning). If you have a Mac, you can see what I’m talking about in this JS Bin.
Now, I'm not directly interested in how to fix this specific discrepancy. I realize there are hand-tuned reset stylesheets that attempt to eliminate or paper-over the differences, but I'm specifically interested in the factors that caused these browsers to render differently in the first place.
I'm making some assumptions here:
Standards exist for both the rendering of fonts and the sizing and positioning of glyphs within the standard box model, but may be unspecified in terms of how they interact.
Bugs exist in browser-makers interpretations of the aforementioned standards, which may influence how text is sized, positioned and rendered.
For these specific browsers, much of the design discussion and actual implementation is public in some form. Therefore, it is possible to learn the source of such discrepancies, if one knows where to look.
Both browsers start in the same place - the markup, styles and font definitions are consistent between them. At some point, they diverge in how they use these to produce the final output.
Therefore, my specific question is: where in the process does this divergence occur, and what causes it to occur?
I feel that, armed with this knowledge, I can better understand how to correct for such discrepancies. Both in this case specifically, and in similar situations that I may encounter in the future.
Unfortunately, re: rendering of the content area based on the font, CSS2.1 does not say much at all:
The height of the content area should be based on the font, but this specification does not specify how. A UA may, e.g., use the em-box or the maximum ascender and descender of the font. (The latter would ensure that glyphs with parts above or below the em-box still fall within the content area, but leads to differently sized boxes for different fonts; the former would ensure authors can control background styling relative to the 'line-height', but leads to glyphs painting outside their content area.)
In other words, typesetting, and how exactly to draw and position the content area of a line box, is left up to the browser's own implementation, at least in CSS2.1. This may however be better defined in a future specification (likely the Fonts module, if not a separate module1).
Section 10.8.1 contains some details on how the line-height property affects the rendering of the content area around text that flows inline, but again it depends on the height of the content area itself, which as stated above is undefined in CSS2.1.
Note that auto is not a valid value for line-height; you probably meant to use normal, which incidentally is also its initial value (but not necessarily the browser default). Also, this is what the spec says about the value normal:
normal
Tells user agents to set the used value to a "reasonable" value based on the font of the element. The value has the same meaning as . We recommend a used value for 'normal' between 1.0 to 1.2. The computed value is 'normal'.
As you can see, there's not much to go on, even with regards to comparing line-height: normal and line-height: 1 (or 1em or 100%), because what constitutes a "normal" line height is up to the browser to decide as well. However, it looks like Chrome and Firefox do a good job of keeping glyphs within reasonable boundaries when asked to use a normal line height.
By the way, Chrome does not clip the descenders. It does render them outside of the content box, but it should never clip them to the bounds of the box unless you set overflow: hidden.
1 A CSS3 definition of the line-height property currently resides in this module, but it's immediately obvious that it's been long abandoned, or at least pending a rewrite. The module in its current state is extremely detailed, but suffice it to say that it's been largely ignored by both browser vendors and the working group.
'Line height is auto' => the browser gets to choose.
'Line height = font size' => user error: the text will be illegible, and again it is reasonable, indeed essential, for the browser to make some adjustment.
You must use some leading. Books for example may be set 10pt on 12pt line spacing.
I read somewhere on a site :
In principle, using a px measurement for font-size is not a good idea. A handful of browsers will prevent the font from being resized by the user if you do this.
Is this right??
Is this right??
Well, yes, certainly there are a few (generally older) browsers that won't let you resize the text when it's sized in px, pt, in, mm and so on.
But even in browsers with a working zoom, it's polite to work relative to the user's stated preference for font size, so they don't have to resize the text or zoom the page manually to make it comfortable. (Fixed fonts plus fixed width page can be particularly bad for this in page-zooming browsers as zooming up is likely to make the columns of text too wide to fit the screen.)
In principle, using a px measurement for font-size is not a good idea.
I wouldn't go so far as to say it's always a bad idea.
There are often elements on the page where you want the text to be sized to match an image (say, a header with text below it that should fit more-or-less without wrapping, or text above a background image made to fit it). In that case you should use px to make fonts and images line up nicely.
For the page's main body text, yes, it's nicer to use em/% and let the user decide the size. But for text that plays a part in the page's graphical layout, px fonts are typically the best bet.
The issue is mainly with aspect ratio. Let's say my resolution is 1024x768 for an aspect ratio of 1.33. For 1920x1080, the aspect ratio becomes 1.77, meaning that any image displayed at a specific pixel width and height will be a different size in inches due to the scaling effect of the aspect ratio. The same basic issue exists if you zoom as you are effectively using the aspect ratio in the zoom window.
Most websites get around this by using em which, to be honest, suffers from some of the same downfalls as any other rendering mode. Even "device independent pixels" are based on the DPI of a monitor. So, use em knowing that it just has less faults than px, not because it's perfect.
Read the following article if you want a more in depth study.
http://www.w3.org/WAI/GL/css2em.htm
Yes, at least IE6 & IE7 do that. Take a look at How to Size Text in CSS.
Quoting CSS: The Definitive Guide by Eric Meyer
There is one more value that is
potentially the same as 36pt, and
that's 36px, which would be the same
physical distance if the display
medium is 72 pixels-per-inch (ppi).
However, there are very few monitors
with that setting anymore. Most are
much higher, in the range of 96ppi to
120ppi. Many very old Macintosh web
browsers treat points and pixels as
though they are equivalent, so the
values 14pt and 14px may look the same
on them. This is not, however, the
case for Windows and other platforms,
including Mac OS X, which is one of
the primary reasons why points can be
a very difficult measurement to use in
document design.
Because of these variations between
operating systems, many authors choose
to use pixel values for font sizes.
This approach is especially attractive
when mixing text and images on a web
page, since text can (in theory) be
set to the same height as graphic
elements on the page by declaring
font-size: 11px; or something similar,
as illustrated by Figure 5-15.
Using pixel measurements for font-size
is certainly one way to get
"consistent" results with font-size
(and, indeed, with any length at all),
but there is a major drawback.
Internet Explorer for Windows up
through Version 6.0 does not allow
users to easily resize text that has
been set with pixels. Other browsers,
including Mozilla, Netscape 6+,
IE5+/Mac, Opera, and even IE7, allow
the user to resize text no matter how
it's been set. Thus, using pixels to
size text is no more of a guarantee
that it will stay the same size than
is any other method. The other
approaches discussed in this chapter,
such as keywords and percentages, are
a much more robust (and user-friendly)
way to go, as they can be used to
scale text from the user's default
font size.
That said, the issue here is what unit to use for your body element. In most cases, you should use the em unit for other elements like headings and paragraphs.
what are cons to use relative values em and % for fonts, What is rounding problem? and how to avoid/solve rounding problem. Is there any calculator?
How to use relative values as easy as we use px
There are not a lot of cons using em or %.
Sometimes i had trouble to make fonts look exactly the same size in IE and the normal browsers. But most of the time i have to do a IE CSS anyway so its not really a problem.
When you define fonts in PX, the fonts are not antialiased on some computers running windows. If you use EM or % they are and you have a very precise control of the font size. (1.249em for example).
Unlike #scunliffe i would always use EM as font-size. Even when you have fixed design withs. Sometimes its not possible to do a pixelperfect design with PX fonts, because fonts rendered by Photoshop looks different then in the browser.
I have made a test tool to show the differences:
http://bluesys.ch/csstest/
and here you can find a tool to convert your PX values in to EM:
http://pxtoem.com/
I may be preaching to the choir here, but I find the Firefox "Web Developer" addon is a real help when I'm dealing with font sizing.
https://addons.mozilla.org/en-US/firefox/addon/60/
Use 'Information' > 'Display element information' to view the exact pixel size for your (relatively sized) element. Tweaking the CSS (to within 1 decimal point) until the amount returned is a round number minimises the chances of your text being different sizes in different browsers / operating systems.
Oh, and from my current project:
Standard (appearing as 12px) font set on site wrapper is 75% (body is 100%) , then use:
14px: 116.7%
16px: 133.3%
18px: 150%
18px: 166.7%
There are loads of reasons to not use fixed text sizes (accessibility being the big one), and once you've spent a while getting your CSS sorted you'll never look back.
Here's a nice little trick for you.
In the your CSS, set the font-size on the BODY of the document to 62.5%.
Now, whenever you want to set a font-size, you use EM values. 1.1em would be equivelant to 11px and 1.2em to 12px and so on.
That's how I work anyhow.
Good luck.
Michael.
I don't believe there are (m)any cons. Using px limits your ability to scale text in IE6 but otherwise using % or em should allow you to scale nicely.
The only con I can think of is that if you want your text to be exactly 12pt, or 13px then using % or em isn't what you want. However If you are trying to create a fixed width design where everything is measured out to the pixel I would advise against it. The Web is a free-flowing canvas... each user has a different sized window, personal font/zoom size choice and Operating System differences. Your content should look good on any screen by adapting to the real-estate you are provided with.
em vs px is like a holy war. Everyone has their own ideas on what's best. Using px is perfectly fine, the only real problem is that text will not resize in IE6.
One other issue is how much you will change your mind about the general font size. If you do everything in absolute values (px, pt), then decide the font size across the site is too small, then you might have to change a lot of values to make everything bigger. Conversely, if you do everything in relative values (em, %) then you want to change the size of one thing only, it will affect all its child elements.
In the end, the best choice is to simply be consistent.
This question already has answers here:
What is the difference between px, em and ex?
(4 answers)
Closed 1 year ago.
When setting the size of fonts in CSS, should I be using a percent value (%) or em? Can you explain the advantage?
There's a really good article on web typography on A List Apart.
Their conclusion:
Sizing text and line-height in ems,
with a percentage specified on the
body (and an optional caveat for
Safari 2), was shown to provide
accurate, resizable text across all
browsers in common use today. This is
a technique you can put in your kit
bag and use as a best practice for
sizing text in CSS that satisfies both
designers and readers.
Both adjust the font-size relative to what it was. 1.5em is the same as 150%. The only advantage seems to be readability, choose whichever you are most comfortable with.
From http://archivist.incutio.com/viewlist/css-discuss/1408
%: Some browsers doesn't handle
percent for font-size but interprets
150% as 150px. (Some NN4 versions,
for instance.) IE also has problems
with percent on nested elements. It
seems IE uses percent relative to
viewport instead of relative to
parent element. Yet another problem
(though correct according to the W3C
specs), in Moz/Ns6, you can't use
percent relative to elements with no
specified height/width.
em: Sometimes browsers use the wrong
reference size, but of the relative
units it's the one with least
problems. You might find it
interpreted as px sometimes though.
pt: Differs greatly between
resolutions, and should not be used
for display. It's quite safe for
print use though.
px: The only reliable absolute unit on
screen. It might be wrongly
interpreted in print though, as one
point usually consist of several
pixels, and thus everything becomes
ridiculously small.
The real difference comes apparent when you use it not for font-sizes. Setting a padding of 1em is not the same as 100%. em is always relative to the font-size. But % might be relative to font-size, width, height and probably some other things I don't know about.
Given that (nearly?) all browsers now resize the page as a whole, rather than just the text, previous issues with px vs. % vs. ems in terms of accessible font resizing are rather moot.
So, the answer is that it probably doesn't matter. Use whatever works for you.
% is nice because it allows for relative resizing.
px is nice because it's fairly easy to manage expectations when using it.
em can be useful when also used for layout elements as it can allow for proportional sizing related to the text size.
As Galwegian mentions, px is the most reliable for web typography, as everything else you do on the page is mostly laid out in reference to a computer monitor. The problem with absolute sizes is that some browsers (IE) won't scale pixel-value elements on a web-page, so when you try to zoom in/out, everything adjusts except for those elements.
I do not know whether IE8 handles this properly, but all other browser vendors handle pixels just fine and it is still a minority case where a user needs to enlarge/diminish text (this text box on SO perhaps being the exception). If you want to get really dirty, you could always add a javascript function for making your text size larger and offer a "small"/"larger" button to the user.
Regarding the difference between the css units % and em.
As far as I understand (at least theoretically/conceptually, but possibly not how these two units might be implemented in browsers) these two units are equivalent, i.e. if you multiply your em value with 100 and then replace em with % it should be the same thing ?
If there actually is some real difference between em and % then can someone explain it (or provide a link to an explanation) ?
(I wanted to add this comment of mine where it would belong, i.e. indented just below the answer by "Liam, answered Sep 25 '08 at 11:21" since I also want to know why his answer was downvoted, but I could not figure out how to put my comment there and therefore had to write this "thread global" reply)
Yahoo User Interface library (http://developer.yahoo.com/yui/) has a nice set of base css classes used to "reset" the browser specific settings so that the basis for displaying the site is same for all (supported) browsers.
With YUI one is supposed to use percentages.