su
DIY Sass grid engine. We use this engine for Susy, but you can use it to build any grid system you want.
Make up your own, or port existing tools like oocss, singularity, zurb, neat, zen, blueprint, 960gs, etc.
Settings
Su has only two settings:
columns
(a number or list of numbers), and
gutters
(a number).
$symmetrical: (
columns: 12,
gutters: 1/4,
);
$asymmetrical: (
columns: (1 3 4 6 2),
gutters: .5,
);
Both columns
and gutters
are set
as unitless numbers,
but you can think of them as "grid units" โ
as they are all relative to each other.
1/4
gutter is a quarter the size of 1
column.
Susy Count
Find the number of columns in a given layout.
$columns
:<number>
|<list>
This is only necessary for asymetrical grids, since symmetrical are already defined by their count, but the function handles both styles for the sake of flexibility.
<number>
:
Susy grid layouts are defined by columns.
In a symmetrical grid
all the columns are the same relative width,
so they can be defined by the number of columns.
We can have an "8-column" grid, or a "12-column" grid.
// input
$count: susy-count(12);
// output
$count: 12;
<list>
:
Asymmetrical grids are more complex.
Since each column can have a different width
relative to the other columns,
we need to provide more detail about the columns.
We can do that with a list of relative (unitless sizes).
Each number in the list
represents a number of grid units
relative to the other numbers.
// input
$count: susy-count(1 2 4 3 1);
// output
$count: 5;
For asymmetrical grids, the number of columns is egual to the list length. This isn't complex math.
Susy Sum
Find the total sum of column-units in a layout.
$columns
:<number>
|<list>
$gutters
:<ratio>
$spread
:false
/narrow
|wide
|wider
Rather than counting how many columns there are,
the susy-sum
function calculates
the total number of grid units covered.
It's a simple matter of adding together all the columns
as well as the gutters between them.
// input
$susy-sum: susy-sum(7, .5);
// output: 7 + (6 * .5) = 10
$susy-sum: 10;
Most grids have one less gutter than column,
but that's not always true.
The spread
argument allows you to also include
the gutters on either side.
While the default narrow
spread subtracts a gutter,
the wide
spread
(common when using split gutters)
has an equal number of columns and gutters.
// input
$wide-sum: susy-sum(7, .5, wide);
// output: 7 + (7 * .5) = 10.5
$wide-sum: 10.5;
On rare occasions
you may actually want gutters on both sides,
which we call a wider
spread.
// input
$wider-sum: susy-sum(7, .5, wider);
// output: 7 + (8 * .5) = 11
$wider-sum: 11;
This is all possible with asymmetrical grids as well.
// input
$susy-sum: susy-sum(1 2 4 2, 1/3);
// output: (1 + 2 + 4 + 2) + (3 * 1/3) = 10
$susy-sum: 10;
Susy Slice
Return a subset of columns at a given location.
$span
:<number>
$location
:<number>
$columns
:<number>
|<list>
This is only necessary for asymmetrical grids, since a symmetrical subset is always equal to the span, but the function handles both styles for the sake of flexibility.
The location
is given
as a column index, starting with 1,
so that 1
is the first column,
2
is the second, and so on.
// input
$sym-slice: susy-slice(3, 2, 7);
$asym-slice: susy-slice(3, 2, (1 2 3 5 4));
// output: 3 columns, starting with the second
$sym-slice: 3;
$asym-slice: (2 3 5);
Susy
Find the sum of a column-span.
$span
:<number>
$location
:<number>
$columns
:<number>
|<list>
$gutters
:<ratio>
$spread
:false
/narrow
|wide
|wider
This is where it all comes together.
susy
is the base version of
:ref:span <tools-span-function>
โ
the core building-block for any grid system.
It combines susy-span
with susy-sum
to return the (still unitless) width of a given span.
// input
$sym-span: susy(3, 2, 7, .5);
$asym-span: susy(3, 2, (1 2 3 5 4), .5);
// output
$sym-span: 4;
$asym-span: 11;
Is Symmetrical
Returns null
if a grid is asymmetrical.
$columns
:<number>
|<list>
It's not a difficult test, but it's important to know what you're dealing with.
// input
$sym: is-symmetrical(12);
$asym: is-symmetrical(2 4 6 3);
// output
$sym: 12;
$asym: null;
Build Something New
That's really all it takes to build a grid system.
The rest is just syntax.
Start with susy
.
$sum: susy(3, 2, 7);
If you want static grids, you can multiply the results by the width of one column.
// static
$column-width: 4em;
$static: $sum * $column-width;
For a fluid grid, divide the results by the context span sum, to get a percentage.
// fluid
$context: susy(7);
$fluid: percentage($sum / $context);
That's all it takes. Now go build yourself a grid system!