CSS3 Media Queries: Mobile Elixir or CSS Snake Oil

MEDIA QUERIES
Mobile Elixir or CSS Snake Oil?
james williamson | lynda.com

Howdy y’all
james williamson

| senior author

man-about-town

@jameswillweb on the Twitter

Let’s Take Your Temperature...

Global mobile internet usage | 2003

Global mobile internet usage | 2011

Why do designers fear the mobile web?

Because we’ve only just now
gotten this to work

...and now we have to deal with this

(images not to scale)

Past options for developing for the mobile web

Build a separate mobile site.

Hire a developer to build an app for you.

Pray.

Surely there must be another option

CSS
MEDIA
QUERIES
R
Reflows content automatically, with no
cramping or bloating. Works overnight, a
soothing balm for your mobile ills

Good for what ails you?

So, what’s a media query?

CSS Media Queries give us a way to
control the application of styles
based on the presence or absence
of speciﬁc media features

The concept isn’t exactly new...

link
rel="stylesheet"
href="desktop.css"
media="screen"

look familiar?

However, we can now apply a little logic...

link
rel="stylesheet"
href="desktop.css"

media="screen
and
(min-‐width:500px)"

that narrows it down a bit.

Media Query syntax
Media Queries are logical expressions, they are either
“true” or “false” depending upon how they are evaluated. If
true, the styles are applied, if false, they are ignored.

link
rel="stylesheet"
href="desktop.css"

media="screen
and

In this example, the styles would only be applied if the UA supported the
screen media type, and the display was at least 500px

Media Query syntax

link
rel="stylesheet"
href="desktop.css"

media="[not
|
only
]
screen
[and]
(expression)"

The keywords “not”, “only”, and “and” can be
used to ﬁlter results, while expressions can be
used to check for speciﬁc media features

Media Query syntax
Logical operator “and” constrains a query based on the
expression that follows it. There is no “or” operator, normal
comma-separated lists serve as “or.”

link
rel="stylesheet"
href="desktop.css"

media="screen
and

Styles are applied for screen devices that have a width of 500px or greater

link
rel="stylesheet"
href="desktop.css"

media="screen
and
(min-‐width:500px),
projection
and
(color)"

Styles are applied for screen devices that have a width of
500px or greater, or color projection devices

Media Query syntax
Logical operator “not” negates the results of the media query
and applies the styles if the conditions are NOT met. It negates
the entire expression, not just media type. Use carefully.

link
rel="stylesheet"
href="desktop.css"

media="not
screen
and

Styles are applied if the device is not a screen device with a width
above 499px. This also means that styles WOULD be applied for
screen devices with widths below 500px and other media types.

Media Query syntax
Logical operator “only” serves to hide style sheets from
older or non-conforming user agents. Conforming user
agents are instructed to ignore “only.”

link
rel="stylesheet"
href="desktop.css"

media="only
screen
and

Would be ignored by non-conforming agents. Other user agents would
apply the styles to screen devices with widths 500px and above.

Media Query syntax

Media Features
width color
height color-‐index
device-‐width monochrome
device-‐height resolution
orientation scan
aspect-‐ratio grid
device-‐aspect-‐ratio

Media Query syntax

Media Feature values

length width:500px

keyword orientation:
landscape
|
portrait

ratio aspect-‐ratio:
16/9

integer color:8

Media Query syntax

Media Feature preﬁxes

In many cases, you can use the “min-” and “max-”
preﬁxes to set less-than or greater-than ranges
for your values

width
min-‐width
max-‐width

Media Query syntax

Be careful!

width
!=
device-‐width

(Honestly, even device-width != device width, or as
PPK said, “a pixel is not a pixel*”)

*http://www.quirksmode.org/blog/archives/2010/04/a_pixel_is_not.html

Enough syntax!
Let’s see it in action!

Visit mediaqueri.es for a gallery of sites using media queries

Oh snap! That changes everything!

Except that it doesn’t.

We still need to talk about how media queries
work in the real world.

“Media queries are fools gold...”
- Jason Grigsby*

So what’s his beef?

Support for media queries isn’t that good

*http://www.cloudfour.com/css-media-query-for-mobile-is-fools-gold/

- Jason Grigsby*


Having browsers scale images is a bad idea


- Jason Grigsby*


Unnecessary resource downloading


- Jason Grigsby*


Hiding elements doesn’t lower overhead


- Jason Grigsby*


Media queries ignore the mobile context


Browser Support
Browser Layout Engine MQ support
Firefox Gecko 3.6+
Google
Chrome WebKit 10+
Safari WebKit 3.2+
Opera Presto 11+
Internet
Explorer Trident 9+
iOS
Safari WebKit 3.2
Opera
Mini Presto 5.0
Opera
Mobile Presto 10.0
Android
Browser
Android
WebKit
2.1
Nokia multiple s40
Blackberry
Browser Mango/WebKit 4.7.1
Samsung Android
WebKit ???
OpenWave ???
UC
Web proprietary
NetFront NetFront
Palm WebKit WebOS
1.4

Another big problem...it doesn’t just...work
For mobile, media queries are typically used to check for screen
size. They do not perform browser or device sniﬃng. The
multitude of diﬀerent screen sizes, resolutions, pixel densities,
and default scaling preferences can cause serious problems
with how media query-driven sites display.

Oh...so....I guess we can go now right?
dang.

Not so fast. Media queries CAN work, and can be an important
part of your mobile development strategy... you just have to use
them correctly, and combine them with other techniques

Let’s talk strategy

Mobile First*
Popularized by Luke Wroblewski, it emphasizes
starting the design process with mobile in mind.

*http://www.lukew.com/presos/preso.asp?26

Mobile first media queries
In terms of media queries, mobile ﬁrst means starting
with your mobile styles, and then enhancing designs
for other screen sizes including desktop.

Now, about media query support...
Respond.js from the Filament Group
https://github.com/scottjehl/Respond
(gzipped version is 1kb)

css3-mediaqueries-js by Wouter van der Graaf
http://code.google.com/p/css3-mediaqueries-js/
(15kb uncompressed)

A mobile-ﬁrst strategy makes using these libraries critical.

Now, let’s tame the viewport!

CSS
MEDIA
QUERIES
+ VIEWPORT
R
Controls scaling and resolution with no
bloating, dizzyness, or unpleasant
aftertaste. A true joy for the home.

= feel better by morning!

Meta Viewport tags

Meta viewport tags can be combined with media
queries to help ensure consistent experiences.

<meta
name="viewport"
content="width=device-‐width,

initial-‐scale=1.0">

what’s this all about then?

So what can meta viewport tags do?

Meta Viewport properties

width
=
[pixel
|
device-‐width
]
height
=
[pixel
|
device-‐height
]

You can set width and height to explicit pixel values, or set
them to device width and height, which instruct the device
to set the viewport width to the device screen width



initial-‐scale
=
0*
-‐
10
minimum-‐scale
=
0*
-‐
10
maximum-‐scale
=
0*
-‐
10

These values allow you to control the initial scaling of the
page (to control whether your page is initially zoomed out
or not), and the minimum and maximum scaling allowed.

* Android minimum is 0.01



user-‐scalable
=
[
yes
|
no
]

Controls whether or not the user can change the scale of
the page. If the value is set to no, any previously set
minimum and maximum scaling values are ignored.



target-‐densitydpi
=
[
dpi_value
|
device-‐dpi

|
high-‐dpi
|
medium-‐dpi
|
low-‐dpi
]
]

Android Only: Allows you to target screen resolution. You can target a dpi
value (70 - 400), the device dpi (prevents default scaling), or you can target
one of three Android screen density categories. Content will then scale up
or down if the resolution doesn’t match the target density. Essentially, it
allows you to control how CSS pixels are scaled to device pixels.

*For WebKit, you can use (-webkit-min-device-pixel-ratio: 2) to target higher density displays

Let’s look at that again...

<meta
name="viewport"
content="width=device-‐width,

initial-‐scale=1.0">

This syntax tells the device to set the viewport width to the
actual device width to ensure the proper media query styles
are used, and set the initial page scale to 100%.

Never use media queries without a meta viewport tag.
Ever.

What about resource loading?

OMG. I cannot believe
I just ate all that!

The truth about media query loading...
<link
rel="stylesheet"
href="desktop.css"
media="screen,

projection">

<link
rel="stylesheet"
href="tablet.css"
media="all
and

(min-‐width:
481px)
and
(max-‐width:
768px)">

<link
rel="stylesheet"
href="mobile.css"
media="all
and

(min-‐width:
0px)
and
(max-‐width:
480px)">

This is very inefficient. All three CSS files will load,
regardless of which media styles are loaded. This creates
additional HTTP requests with no added savings.
Combine these files using inline @media syntax.

#actionCall
{

display:
none;
}

This doesn’t help you either. If a widget or image is
present in the element, it is still downloaded, regardless
of the display property.

@media
//mobile
{
#actionCall
{

background:
none;

}
}
@media
//desktop
{
#actionCall
{

background:
url(big_ole_image.jpg);

}
}

This is better. If the mobile property is set to no
background image, iOS does not download the desktop
version. Sadly it seems that Android currently does.

How can we control resource loading?

Modernizr 2 features both media query tests AND the
YepNope.js library. This allows you to combine feature detection,
media query success, and conditional resource loading.

<BOOM>
http://www.modernizr.com/

How can we control resource loading?
Of course, if you prefer, you can roll your own. PPK reports in his
own testing, document.documentElement.clientWidth and
screen.width give the same results as the width and device-
width media queries*. This means you could do this:

if
(screen.width
>=
600)
{

//
load
resources
}

or
if
(document.documentElement.clientWidth
>=

600)
{

//
load
resources
}

*http://www.quirksmode.org/blog/archives/2010/08/combining_media.html

Media Query best practices
Design with mobile in mind first

Make the mobile styles your default styles and progress up

Use fluid layouts to deal with minor screen size differences

Combine CSS & JS files to reduce HTTP requests

Minimize and gzip compress your code

Use Data URL and CSS Sprites when you can

Don’t use external libraries unless you really need to

Consider using touch frameworks for interactivity

Looks like gold to me!

CSS
MEDIA
QUERIES
R

(That? Oh, that’s just the halo of truth...)

So...where does that leave us?
Just like every other technique in your toolbox, media
queries simply add to your capabilities.

Are they right for every project? Of course not. Mobile
design is far more than simply designing for a smaller
screen.

However, given the right circumstances, media queries
allow you to optimize designs for the mobile environment
in a way that we weren’t able to do before.

Deciding when, and if, to use them is, after all, your job.

THANK YOU
james williamson | lynda.com
jwilliamson@lynda.com
@jameswillweb on the Twitter
www.simpleprimate.com

CSS3 Media Queries: Mobile Elixir or CSS Snake Oil

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