Shouldn't we use "Pixel" for anything in CSS if we are making a site for mobile devices?
px for layout and font. Should we only use em or % for everything on mobile sites?
and if i'm using <img> then should i defined height and width for <img> in HTML code? or it's good to not to define. or i should define size in css for <img> also in % or em
Edit:
Note: Question is not again about px vs em debate My question is specifically for separate mobile site. when we are making separate mobile site with different domain or sub-domain.
Everything depends on the context. Like with CSS for desktop browsers, there are situations where using pixels is not a good idea (for example mostly for font sizes), and there are situations where pixels are still very useful (for example fixed layout).
In general, avoid using pixels every-time you don't need to. For example, there is no reason to do it for fonts: it's not you, but the user who chooses if the font must be big on a high-res screen or not. Using percentages also helps you somehow to remember that a piece of text can never have an exact width and height, and force you to adapt your design.
Now, sometimes, for cost or other reasons, you have to do fixed layouts, or at least some parts of a page, associating images and text, have to be fixed in size. In this case, there is nothing wrong to use pixels. If I have a <div/> with some text inside and a pretty 200×100px background, the most obvious thing is to set the width and the height of this <div/> to 200 and 100 pixels.
if i'm using <img> then should i defined height and width for <img> in HTML code?
IMHO, you never should do that. The size of an image is purely a layout/design thing, so it has nothing to do with HTML, but with CSS.
Do you have to specify the size of an image in CSS? If you want your image to be displayed 100%, than no, you don't have to: this is by default in every browser. If you want to scale it down and, for some reasons, you can't scale the image itself than save the scaled image on server, than yes, you may want to specify the size of the image.
Remember than sending a big image and scale is down on client side is always a bad idea. The visual quality might be affected, and the client will have to wait more to see the image appear.
Actually, I recommend using different CSS files (and sometimes different templates) for browsers vs. mobile. Mobile isn't just a smaller browser, it is a fundamentally different user experience.
As for the pixel issue, I tend to use pixels in my base CSS rules and then use % or em's everywhere else so that things scale up and down together. It doesn't always work the way I would like, but it normally allows a lot of tweaking during development.
Related
I'm redesigning my site because looks awful on different resolutions (apart devices), most guides and tutorials rely on % and em than fixed values. I'm still learning this so I'm reading everything around.
Thought this would solve the question with different display sizes but again: we have to craft some more CSS for fix some specific issues.
If I need to add media-queries for extra display sizes, why use % then? Do use % really reduce coding? Is ok need to add some extra css for some sizes or am I doing something wrong?
Thanks for any advice!
The purpose of using em sizes is to allow the base your design off of the user's choice of font size. I may use a larger font size because I have a huge monitor and poor eye sight, while someone else might prefer a smaller font. By using em units, your design will accommodate both of our font preferences and resize accordingly instead of forcing the font size to a given standard (eg. "12 point font").
In a similar manner, percent (%) units allow your design to respond to different browser sizes. Used in conjunction with em units, this will allow text-based elements to respond to arbitrary font size choices, and layout elements to respond to arbitrary browser sizes.
It is perfectly acceptable to design a single responsive design for all media types. Media queries are intended when you want different display styles on different devices, not to "support" different display sizes. An example would be to use serif fonts on print media and sans-serif fonts on display media, since usabilities studies have shown that these font faces are preferred for these sorts of media.
Furthermore, it allows you to do custom styling for some situations like mobile devices, where you may want to consider that the user has a limited amount of bandwidth and maybe cut down on extra images. Or if you want to display your content in a completely different layout for the microscopic screen afforded by certain phones.
% allows your site to be responsive to the user's method of viewing. Let's say you have a div that's at 100%. It'll fill the entire section, regardless if it's on a phone or desktop.
It should be okay to add extra CSS for sizes as well. As far as I know, you can have some elements display in % and some with a fixed px value, although they might conflict depending on how the page is setup or what it is being viewed with.
For example.
Your website header have the width of 950px; But in a mobile device, it may fit at 450px;
So, you use media-query to reposition some elements and handle some size issues and set the header width to 450px;
But, if you use % values, you can set your header div to have 100% of width base in its parent. So you can only change the body or some container div width, the all childs going to adapt.
Diana,
I am glad I came across this question. I literally just uploaded my first responsive design which is 90% based off of percentages when it comes to font-size and widths.
Check out the below:
http://www.noxinnovations.com/portfolio/responsive/
Obviously, it doesn't look amazing, and the image looks way out of place... But do me a favor and resize your browser window, by slowly making it smaller and smaller. I did that by setting a percentage width!
Trust me, I tried doing this responsive design test with pixels, and it didn't turn out too well. The percentage width ensures that regardless of the resolution and or pixel dimensions (per se) the design will always cater to the size of the screen. Also, I did not have to use one CSS3 Media Query, but I would highly suggest using CSS3 Media Queries only when you need them.
In my opinion, I should probably have a Media Query for a larger screen.
I hope this helps you as much as it has helped me!
Thank you,
Aaron
Im mobile optimising my site with media queries and making it into a 1 column layout. I want the header text at the top to be the full width available while staying on one line.
I guess I could make multiple media queries for different screen widths, each making the text a different size. However is there a smarter and quicker way of doing this?
Thanks
Hmm, this should be tricky. I understand you are referring to text. Depending on the font used in your layouts and the font used by the user-agent, the width of your text may vary from browser to browser.
This also means whenever you change the content of your header, you will have to change the scaling of your font.
Maybe it would be better to use a graphic instead and scale it via width=100%
Otherwise your solution will probably involve some javascript… pretty nasty for a mobile site. :)
The w3c specification says that the width and height are implied and not required. I have always been told that you're supposed to put it in anyway. If I remember correctly his reason was that the browser may not correctly detect the image size. Is this true?
It harkens back to the dark days of Netscape in the v4 and older versions. The rendering engines were primitive and wouldn't "reflow" content as they built pages and figured out sizes. If you didn't specify an image size, the whole page's rendering would get paused (or a full-page refresh would get pulled) once the image was downloaded and parsed for height/width. This looked bad from a user perspective, so the rule was to ALWAYS specify a size.
Nowadays, engines are better, and can handle an unspecified image size gracefully. Reflowing content is still a somewhat expensive operation, but does look cool from a user perspective as things glide/flow around as images pop in and text shifts to accomodate them.
The reason is that if you do not put them in, the browser will put a default size in, download the image, find the actual size then have to re-flow everything around the new size.
Re-flows are expensive operations - the rendering on screen has to be updated for each such image.
If you provide the size, the browser puts in a placeholder with the correct size and doesn't have to re-flow once the image downloads.
In my experience, not supplying width and height tags will cause the browser to render the image at its original size.
I've found this behaviour to be consistent in modern browsers.
As an aside, I always try to supply images at the size I want them rendered at in order to reduce the amount of bandwidth used and to ensure image quality.
I'm not sure about browsers not detecting it correctly, I've never seen that happen.
But to answer your question, I think the answer depends more on what you are trying to do, and possibly likely to do, which makes the difference.
For example, if the image you are adding is a banner ad which needs to conform to predetermined height/width, then by all means, hard code the height and width.
But if the image is something that might change over time, I would suggest NOT coding the height and width, as more than likely this means that the new image, if not the same exact height/width as the old one, will now be distorted. This is especially true on a dynamic website where images change all the time.
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.
If we make fluid layout we can use em or % for font and div width and height to make fluid but how to make images resizable?
I want to make one layout for all sizes and devices
Joel Spolsky managed to find a very easy solution (a small proprietary CSS definition for IE). He found the solution here.
There's no simple solution for this. You can use flexible units for the images just like you can your other page elements. But this will result in inefficiencies and aesthetic issues including excess file size for a tiny image (if you're sizing it down), pixellation of sized-up images, etc. So what you likely want is to start with a large image and scale down to the appropriate size versions, and use Javascript to write out a tag referring to the correct size image depending on context.
Well you can size images relative to the viewport width (eg. img.thing { width: 50%; }, but you don't generally want to. Scaled images will at best (when the browser does bicubic resizing) look a bit blurry, and at worst totally blocky/jaggy (nearest neighbour resizing). You can include some CSS (SVG's image-rendering will be supported for HTML in Firefox 3.6; -ms-interpolation-mode in IE) to try to coax the browsers to use the better scaling mode, but it's far from reliable and still the best rendering isn't that great.
In addition, CSS background-images cannot be resized at all (yet; it is proposed for CSS3 but you'll have a long wait).
Liquid layout generally aims to adjust the distances between fixed-size images to respond to changes in viewport width, rather than scale the whole page including images. The user can, at least in modern browsers, zoom the whole page including images themselves, taking the image quality hit if they need to.
I reckon you will have to make use of the canvas element from HTML5. Or you could have some JavaScript that sets the size of the image tag but you would have to do some math to figure out the correct proportions.