All major browsers today use page zoom by default, as opposed to "text size". "text size" options are still there, but they are a bit more hidden [especially in Chrome and Firefox]. Given this fact, is there still a reason why EMs are advantageous over PX or %? Why?
Most browsers indeed are capable of sizing pixels, and Zoom is now the more popular way which works well across browser - there is even a very simple fix the old IE6 behaviour of not being able to 'text size' (declare the original body size as a percentage - 100% will do - then fire away with pixels)
Remember too that if a user so desires, or needs to, they can set their own minimum pixel size so if they're basing their defaults on pixels why go through the nightmare of calculations..
IMHO pixels are perfect for text and borders (who needs to size a border lol..), always have been really.
em and percentage really are the same thing well they work identically, and their inheritance can be an absolute nightmare.. em's are great for widths and heights for a bit of fluidity
So no, I don't think we should still use them for text.. not that I ever did ;)
Even with the page-zoom feature turned off, most major browsers these days are capable of resizing text in px units. I think it was IE6 and under that was not capable of resizing px-based text.
I prefer specifying sizes in px just because I think it's easier than working off "relative" sizes.
Related
One of the specs for Web accessibility level AA that is text can be resized to 200% without loss of content or function.
So if I zoom up to 200%, everything needs to look right.
How can I achieve that regarding the font size?
The issue is not so much a matter of font size or font size units, since most common browsers have a built-in zoom function that will zoom any text, regardless of the font size unit. The issue is that resizing may result in text containers that start to overlap, which then causes some content or functionality to become invisible (because it ends up behind something else). Success criterion 1.4.4 was written when zooming functionality was not yet as widespread as today. (In 2008, there were several browsers that supported zooming, but many people were still using older browsers that didn't support zooming, and text resizing—which is not quite the same as zooming—could cause overlap in web content.)
So, while using units such as em, %, rem etc. is a good idea, you need to make sure that text containers (such as section elements, nav, etc.) that are displayed next to each other don't overlap when you zoom in to 200% or resize text up to 200%. For example, you can describe column width using units such as % or em, or you can make sure that text containers that are next to each other at the default size end up below each other when zoomed in. If you use responsive design to make your web pages adapt to different screen sizes, you should also be able to handle zooming in desktop browsers.
You should try using em instead of px..
For example if you have div inside yourbody - suppose the font-size of the body of the page is set to 16px.
If the font-size you want in div section is 12px, then you should specify 0.75em (because 12/16 = 0.75).
You should try use "rem" (support most of the browsers).
Then you set the font-size of the root ( the html).and all the page reasize for example if you want the "h1" be always 2 times the body ,set it to 2rem;
I've been using px for almost all the measurement related styling, but I wanted to know the best places for the use of pixels (px), percentage (%), points (pt) and em.
I've seen the use of em and (I believe) points in typography, but I don't know the best way to use them.
Where should either be used, and why?
pt or cm, in, mm etc. are most used for print stylesheets, as they're most fit for measurements on the physical properties of paper sheets, and the render of printers.
em and en (and the new rem, and more interesting units such as ch) are glyph relative units, and as such are suitable for text styling, in correspondence with absolute units at the root element (e.g. px units at the body).
another interesting uses: ex units (the height of the 'x' glyph in the font) to set vertical measures in relation to text, ch to indent lines.
px are absolutely rendered so one can design a pixel-perfect (or fixed) layout based on these units, applied for containers, or on various widgets demanding fixed size (buttons and the like). disclaimer: absolutely is an over-statement, as pixels are rarely absolute, and has many factors affecting the rendered outcome - see this article about px as an angular measure.
% are mostly used in conjunction with an absolute unit at the top container, and are applied in various CSS techniques, such as the faux centered container. these units are also very handy for layouts that are fluid by nature. others, like the viewport relative vh, vw and vmin, may be used regardless of the parent's units.
all of the above is based on my personal views, as this subject is open for debate, and CSS techniques will keep evolve and we'll see more uses of the specifications and capabilities we had never thought of. it's mostly the creative use of those tools that scopes or favors the use of one unit over another.
It used to be that these distinctions mattered: for example, back in the IE6 days, you should never set your text using px, because then it couldn't be zoomed. That is, back in the day, browsers actually treated px as a number of pixels.
These days, browsers have conformed to web reality: most people use px everywhere, for almost everything. Thus px is now defined as an angular measurement, which essentially means that px behaves just fine in any zoom setting and on any size or DPI device.
Similarly, as part of conforming to web reality, all other units are defined in terms of px, so there is really no reason to use them unless it happens to be more convenient for your case. The only exception is, of course, percentages, since they allow you to specify values in relation to parents' measurements.
Details from the spec:
in, cm, mm, pt, and pc are all defined relative to px, since in practice all devices follow "For a CSS device, these dimensions are ... anchored ... (ii) by relating the pixel unit to the reference pixel." And as discussed, the "reference pixel" is an angular measurement that varies depending on DPI settings, screen size, zoom level, device type and so on.
1em equals the computed font-size of an element, which is usually defined in px. If that size itself is defined in ems or exs, the browser then looks upward until it finds a px to be relative to, eventually falling back to the default font-size (usually 12px).
1ex equals the height of the letter "x" in the defined font-size if possible, but usually (?) falls back to 0.5em.
Use px for elements that are of a set size.
Use percentage when you need the element to be in proportion to the window size or parent element size.
em is the standard for text, it adjust according to screen size on a mac. Make it a habit, there's plenty of good blogs on why to use em, em is not just for font properties it also comes in handy with other elements like div, inputs etc. There may be consequences when using px for font size, there's also situations where px and % will be more ideal, it' takes trial & error to understand fully.
There are no real rule on what to use it's all according to the desired effect. As you create you will test your site in different resolutions and adjust the browser size to see how it appears from a variety of users points of view.
Consider cross browser compatibility & resolution with em,
Consider resolution with percentages,
Disclosure: I am a sysadmin, not a web designer.
I generally use em for padding around images, so as to keep the padding sized according to the text it keeps away from the image.
I use % to handle liquid/fluid layouts sometimes, though most often a fluid layout will just be 100% of the browser but with fixed width (px) columns.
I use px to handle column widths, headers, etc. The height and width attributes of an <img> tag are of course in pixels by default, and an image will render best if you don't ask the browser to resize it from its native/original resolution. In some cases, you need to use px on fonts, when the font has to work with an image (i.e. a spanner icon next to the word "Tools"). If possible, I always use UTF-8 fonts instead of images.
Check this jsfiddle
Why is there a difference in size of the datepicker when font-size is set to 1.5em?
The amount of em's is not important I have tryd different font-sizes and I still get the same problem. The red box is set to 460px and is there for you to see the difference in size of the datepicker in firefox and chrome/safari.
Edit: I have already try'd using px insted of em
Firefox uses DirectWrite to render text, and Chrome doesn't.
That is the reason for the ever so slightly different size of the rendered text.
There is no way to make the text pixel-perfect the same size between the two browsers.
Read this: http://www.basschouten.com/blog1.php/font-rendering-gdi-versus-directwrite
And this, particularly the "Hinting and spacing differences" section: http://blog.mozilla.com/nattokirai/2011/08/11/directwrite-text-rendering-in-firefox-6/
Because 1.5em isn't a precise size and depends on what the browser decides the relevant font metrics to use are.
If you want a precise size, use either px or points.
As you know, you can specify dimensions with CSS in px or em. As far as I understand it, em means "line height of the current element's fonts". My approach currently is to always use px (also for margin which seems to be a controversial practice).
Question: Can I rely on the ratio of px and em to be the same across browsers? If not, then my manually specified margins between paragraphs will likely look odd because they so not match 1em anymore.
I believe that it is better to use em for margins but I have quite a base of existing code that always uses px margins.
No. ems are relative to the user's chosen font size, px aren't. The default font sizes of desktop browsers are about the same in pixels, but mobile devices in particular will vary even before user adjustment.
You should use em for a margin in text content that should be sized similarly to the surrounding fonts, and px for a margin that has to line up with images used by the page layout.
No, you cannot.
The size of em in pixels is related to the font type & size you're using, the resolution of your screen (depending on OS, browser), and possible further OS and browser settings - eg "Show fonts +10%" may alter the em value.
If I mark all my divs in percent, they fill up all the space nicely. I am facing 2 problems:
a) Image sizes: How do I define image sizes so that they do not become larger or smaller than wanted as the window resizes
b) Font sizes: How do I make the font size increase or decrease based on resolution - should this be done at all? (The problem I face is that the text becomes illegible at very high resolutions)
Please point me to a good reference on how to make liquid layouts.
Regarding point b) it is, IMHO, good practice to use relative font sizes, rather than absolute ones, so that the fonts are sized compared to the browsers base settings (I'm guessing, from your problem, that you are using point or px sizes, yes?). You have the heading tags, of course, but you also have the font-size CSS attribute and the ability to size fonts in % or ems. You have hit one good reason to use relative sizes - on high res monitors this can make absolute-sized fonts unreadable (I have seen, in the old days when 14" 800x600 monitors were standard, a website that rendered to about the size of a matchbox on a high-res 21" monitor). There also the issue of "politeness" and accessibility - the user may have set their browser base-font size larger or smaller because of personal preference and/or accessibility issues, and to override this to an arbitrary size doesn't seem, to me, to be a good idea.
have a read on the font-size section of this page:
http://www.w3schools.com/css/css_font.asp
If you need some actual examples then please post a bit of your code and CSS.
Good article here
http://www.kyleschaeffer.com/best-practices/css-font-size-em-vs-px-vs-pt-vs/
for a) I love using this
img {
width:100%;
max-width:400px;
}
then, if you need to, add one of the many javascript fixes for max width in older browsers.
I found a simple solution for your second question about font size.
b) Font sizes:
Using stylesheet calculator and properties like:
vh - viewport height
vw - viewport width.
Your font size will take same size on your view, but it can be unreadable if you don't handle small sizes layout.
For regular size: font-size: calc(.5vh + .8vw);
For large size: font-size: calc(5vh + 5vw);
Hope this might help you.