I'm building a responsive website and I'm wondering what unit I should use? I've seen a lot of sites using pixels (px) for measurements and I've seen some using percent (%). Is there a preferred — or right — way of doing responsive design?
I've found percent to be hard to use, since it makes calculations hard and I've ended up with values like 2.754% and so on when setting widths/margins etc. Pixels seems easier, it's just simple addition and subtraction, but I've read that it isn't "future proof" or something like that and wont scale properly if the user zooms in the browser window. Is that still true?
If you have any experience or expertise, please share! I would love to hear what you guys have to say!
Thanks!
For layout type things like the sizes of boxes, you want to use % because you will typically have several columns sized as a percentage of their parent that will stack on top of each other at a certain breakpoint (width:100%). No other unit will allow you to fill 100% of the space like % does.
For padding/margins use em, normally you will want to space your elements out relative to the size of your text. With em (the with of an 'M' character) you can quite easily say I want approximately 1 character spacing here.
For borders you can use px or em, there is a difference though. If you want your border to look like it's one pixel wide on all devices, use 1px. It may not be one pixel on all devices however, high density displays convert 1px into 2px for example. If you want your border to be a size based on your font, use em.
For fonts use em (or %), the use of em carries through parents to children and it just a nicer unit to work with over px.
Of course you must use percentage. But with the min-height, max-height, min-width, max-width CSS keys.
For the next generation
vw and vh. The vw is 1/100th of the window's width and the vh is 1/100th of the window's height.
For responsiveness they are going to be the new units.
Use percentages along with min-width and max-width in pixels. This stops percentages making your divs too small or too large. eg
div {
width:100%; //full width of browser
max-width: 960px; //this means it will be 100% of the browser until 960px then it will stop expanding
}
For layouts vh and vw are good because they are relative to the device's view port. They give you the possibility of designing with the view port of the device in mind. With this said you know what will show on the window and what won't without being too careful.
For text em is best because if it's responsive features.
Related
I am aware of vw units, however, these are based on the size of the viewport, i.e., the entire screen. What if I need a font-size to be large enough to fit a particular width of a div.
Is that possible?
Any solution or workarounds if it's not?
Thanks!
I agree with user1902183 that there is no need to downvote this question as its perfectly legitimate.
I would suggest taking a look at the rem unit.
rem stands for relative em.
As most developers know, an em is fixed according to device. For example, in a browser 1em = 16px. On mobile devices this may be a smaller figure.
With a relative em the font size is dependent on the parent I believe but investigate this. This may be the closest to what you are trying to achieve without resorting to JavaScript.
I'm in the process of trying to wrap my head around using srcset and sizes on img tags.
Whilst I think I have grasped the basics – mainly thanks to this article – I'm struggling in practical application of the sizes attribute.
In all the examples I can find, things are massively simplified and the sizes attribute is declared as if at each breakpoint, the image width will be an exact proportion of the viewport width, allowing the use of vm units. For example:
sizes="(min-width: 36rem) 33.3vw,
100vw"
Of course in real life, images are often within other containers which themselves might be within other containers and so on, each with their own margin, padding or positioning.
Is it fair to say that in all but the simplest cases (when images are of fluid width and are not simply an exact percentage of the viewport), calc must be used, potentially adding hideously complex calculations to the html markup as an images dimensions need to be calculated working from viewport width, down through any containers to the image? For example how would you calculate the correct size for an image located a container with 7px padding that is itself inside a container that is 45% of its container with 15px margin that is inside a sidebar that is 25% of the main page container which has 15px of padding and has a min-width of 1220px?
sizes="(min-width: 36rem) calc(((((1220px - (2 * 15px) * 25%) * 45%) - (2 * 15px) - (2 * 7px)),
100vw"
Trying to calculate this in the sizes attribute seems ludicrous, especially given that all this might change at each breakpoint. having to keep this massively complex calculation in sync with changes to the CSS seems like madness. And then you have the patchy browser support for calc.
I feel like I'm missing something obvious, but what is it?
Note: I'm aware of Alexander Farkas's excellent Lazy Sizes which does the size calculations for you through the use of data attributes, but I'm interested in standard usage.
First of all % units are not allowed in sizes. You must use vw units. (Which can include the scrollbar width). So your 25% becomes 24-25vw for example.
Second there is no real difference between rem and em (in context of sizes attribute). In case you don't use em/rem based media queries / min-width/max-width in your CSS, never use those in your sizes attribute.
Basically sizes don't need to match your real image size 100% exactly. It is a tell for the browser to find the right image candidate approximately.
Your min-width: 1200px rule as also every max-width usage in your CSS, should be clearly part of a new media condition in your sizes attribute.
This leaves us with the following sizes part:
(min-width: 1200px) calc(11vw - 44px)
In case you add have a max-width defined or a media query that stops sidebar from growing, you can be less correct and simply transform 11vw - 44px into 10vw:
For example:
sizes="<...,>(min-width: 1800px) 180px, (min-width: 1200px) 10vw, <....>"
About calc support: picturefill 3.0 beta as also respimage, do include calc support for IE8+, so all browsers which do support sizes have good enough calc support and all respimage polyfilled browsers do support calc in sizes also.
About getting this straight. This is clearly painfull and in most cases your CMS/backend system should help here. In most projects you should agree upon a limited set of allowed image formats and write the sizes for those corresponding to your design. And your backend should manage to attach those sizes at the right place. In case this is not possible. Either use indeed lazySizes or use srcset with sizes at least for the most important images (i.e.: large image formats, because this is where you can save data most).
If you want you can pick a real website and we attach full correct sizes to it. But be aware. It must be only width constrained. The standard currently does not support height constrained images (This is a lazysizes feature only).
If I want my website to look the same on many different screen sizes and want my divs to all be the same height and width regardless of if it's on a 11 inch macbook or a 27 inch monitor.
Do I set my height and width in pixels or in percentages in my CSS?
I'm guessing percentages, but just want to make sure.
It depends on exactly what you mean by "same height". If you want something to always take the full width of the page regardless of resolution, use 100%. If you want something to always take x number of pixels, specify in px. If you want something to use relative sizing so that as fonts get bigger, everything scales, then use ems.
As it is worded, your question and intent isn't clear. You should decide what it is you want to do and then implement it.
Web development is about making content usable in a variety of formats and sizes. Consider why you want a fixed size, and work to achieve your goals within the constraints of CSS. And remember, you can always mix metrics if you need to.
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.
I have designed and developed more than 10 sites, but I still have a doubt about the correct unit I should use. Should it be px, em or %?
EDIT 1: FOR LAYOUTS (Especially for container boxes)
Different units depending on context. If there was one that was best for every situation, then there wouldn't be so many units.
As rules of thumb go:
If you are working on screen media:
Use % for font sizes
Use px for images
Use px, %, or em for box sizes
Use ratios for line height
If you are working in print media:
It might be wise to avoid px (this is not a hard rule by any means) and everything else is fair game. It really depends how much control you want.
There's no real right or wrong, but as a rule of thumb:
For anything you want a certain, fixed size, use PX
For anything you want to scale with font-size, use EM
For anything you want to scale to the available space in the window/container, use %
Each used to have specific advantages or disadvantages in different browsers when it came to users scaling the browser's base font-size/zooming, but more recent versions of the browsers by-and-large get around these issues by scaling everything, not just font-size.
If you're talking about font-size then px and pt are not ideal.
Ems and Percent units are scalable, therefore they are far more accessible - friendly for the visually-impaired. They also scale down well for mobile phone users.
Px and Pt units do not scale upward for visually-impaired users, or downward for mobile phones.
If you're talking about layout or containers then it depends on the type of design you want - fluid or static - and there isn't necessarily a "right" answer.
Without going into an example, it's difficult to advice. Do you have a site in mind we could look at?
Use the unit you need in the specific context.
Unit Description
====================
% percentage
in inch
cm centimeter
mm millimeter
em 1em is equal to the current font size. 2em means 2 times the size of the current font. E.g., if an element is displayed with a font of 12 pt, then '2em' is 24 pt. The 'em' is a very useful unit in CSS, since it can adapt automatically to the font that the reader uses
ex one ex is the x-height of a font (x-height is usually about half the font-size)
pt point (1 pt is the same as 1/72 inch)
pc pica (1 pc is the same as 12 points)
px pixels (a dot on the computer screen)
source: http://www.w3schools.com/css/css_units.asp
For flexibility and accessibility I recommend using % for horizontal measures (relative to the user's screen), and em for vertical measures (relative to the user's font setting).
For fixed width layouts
For as much as pixel perfection I would suggest to use PX for width ,height, margin, and padding
for line-height use unit-less value like {line-height:1.2}
for typographic elemets use {font-size:62.5%) for body then use em for other elements
in HTML for <img> always use unit-less width and height .