Susy - Compass Plugin
Susy is a semantic CSS framework creator entirely native to
Susy is an expert at fluid grids in an elastic (or fluid, or fixed) shell that
will never activate that bloody side-scroll bar. Susy sets your width on the
outer element (
container), adds a
100% and builds the rest
of your grid in percentages. The philosophy and technique are based on
Natalie Downe's "CSS
Systems" - which introduces
difficult math in the service of beautiful structure. With the power of
Compass/Sass, Susy will do that math for you.
Using simple mixins, columns can be created, suffixed, prefixed, and nested easily - and always in flexible percentages.
sudo gem sources --add http://gemcutter.org/ sudo gem install compass-susy-plugin
Create a Susy-based Compass Project
compass -r susy -f susy <project name>
Then edit your
files accordingly. A reset is added automatically, and includes help for some
Philosophy and Goals
It is important for accessibility and usability that we are:
Responsive to text sizing: In order for our site to be accessible we need to allow different font-sizes to be set by the client. In order to maintain design integrity of proportions and line-lengths, the grid needs to respond to those sizes.
Responsive to window sizing: In order to maintain usability across platforms/monitors, our grid needs to respond to the size of the viewport. This is mainly an issue as the viewport shrinks and we are given a side-scroll bar. No one likes that. On the large end our design integrity and line lengths are more important than taking up all the possible space.
In order to achieve both goals we need to combine the best of the elastic (em-based) and fluid (%-based) models. The solution is simple: First we build a fluid grid, then place it inside an elastic shell, and apply a maximum width to that shell so that it never exceeds the size of the viewport. It's simple in theory, but daunting in practice, as you constantly have to adjust your math based on the context.
But Susy harnesses the power of Compass and Sass to do all the math for you.
Set up your default grid values (total columns, column width, gutter width, side gutter width), your base font size, and important mixins in
Set defaults for all the important HTML tags in
_defaults.sass. It's better than using the browser defaults. And better than using ours.
Create your grid in
screen.sass: apply the
+susymixin at the top level and the
+containermixin to the element that contains the page grid.
+columnsmixin to declare the width in columns of an element, or
+fullfor any element spanning the full width of its context.
+omegato declare elements which include the first or last column within their parent element (
+fullto declare both
+alphais actually only needed in the very top level, and does nothing in nested contexts. Neither is needed on a
+suffixto give the width (in columns) of an elements left or right margin, or
+padto give both
In nested contexts, all of these mixins take an extra final argument, the width in columns of the parent (nesting) element.
That's it for the basics! Here's a sample Susy grid layout:
+susy #page +container #brand +full +pad(1,1) h1 +full(8) +pad(1,2,8) #nav +columns(2) +alpha #content +columns(8) +omega #description +columns(5,8) #credit +columns(3,8) +omega(8)
For more details, read the tutorial.
It's also included with Susy in the docs/ folder.
Extra Utility Mixins
Extra utilities are included in Susy's
utils.sass file, with additional list
options, experimental (CSS3/proprietary) CSS, and more.
+show-grid(!src)- Repeat the specified grid image on an element. Good for testing your baseline and grid.
+inline-block-list([!horizontalpadding])- Make list items inline-block when floating just won't do the trick (if you need them centered or right).
+hide- Hide content from visual browsers while keeping accessability intact.
+skip-link([!top, !right, !bottom, !left])- Hide a link, and then show it again on focus. the TRBL settings allow you to place it absolutely on display. Default will be top left of the positioning context.
And then the fun stuff in
_vertical_rhythm.sass, written by Chris Eppstein
and probably moving to the compass core before too long:
+adjust-font-size-to(!to_size, [!lines, !from_size])- adjust the font size and number of baseline (line) units to occupy.
+leader([!lines, !font_size, !property])and
+trailer([!lines, !font_size, !property])- add leading or trailing whitespace to an element. These are added as top and bottom margins (by default) that keep your vertical rhythm intact. You can also send "padding" as the
+padding-trailer. Be aware that this may conflict with uses of rhythm-borders.
+leading-border([!width, !lines, !font_size, !style])and
+trailing-border([!width, !lines, !font_size, !style])will combine border and padding to create borders that also keep the vertical rhythm going. The defaults are
1px, 1, !base_font_size, 'solid'. Also available:
+horizontal-borders(for both leading and trailing), and
+rhythm-bordersfor applying equal borders and padding to all sides of a box.
Susy is built for flexibility, so that you always write the code you want to write. While everything should 'just work' out of the box, there are plenty of advanced options hidden inside. Here's a few:
!hacksis a boolean constant that you can set in your base.sass file to choose between using targeted hacks for IE (a variation of the star hack in most cases) in your screen.css, or using a conditional-comment targeted ie.css. All the needed mixins are available for either setting.
!hacksis true by default so there is no extra work maintaining multiple files unless you want to.
!hacks = true #nav +inline-block-list
!hacks = false (in screen.sass) #nav +inline-block-list (in ie.sass) #nav li +ie-inline-block
It requires more maintenance on your part, but the result is a hack-free output.
The Susy mixins that use either hacks or targeted mixins are
+ie-omega([!right-floated = false])),
+inline-blockon the list items.
The ie-specific mixins only add the needed ie-specific adjustments, so they need to be used in addition to their counterparts, not on their own.
gutter(!context)is a function that you can call at any time to return the size of a gutter in your given context as a percentage.
#nav padding-right= gutter(5)
columns(!number, !context)returns the span of
!contextas a percentage. This span includes any gutters between the columns spanned.
#nav padding-left= columns(3,5)
side_gutter()is also available and takes no arguments since it is always used at the top nesting level.
!px2emis a variable that represents the height of one pixel as a fraction of your base em-height. Multiply it with your target pixel value to represent that value in ems. Note that this is only accurate at your
#nav border-bottom: style: solid width= !px2em*2px