A introduction presentation in the world of CSS preprocessors. Including SASS and LESS examples.

1. CSS Frameworks
Dimitar Belchugov
@belchugov

2. CSS Preprocessor
• Has anybody used CSS preprocessors?
• Did you ever wished for a variable in CSS?
• Do you like to write CSS faster?

3. CSS Preprocessor
• SASS (SCSS)
• LESS
• Stylus

4. The sassy way

5. Variables
$blue: #3bbfce;
$margin: 16px;
.content-navigation {
border-color: $blue;
color:
darken($blue, 9%);
}
.border {
padding: $margin / 2;
margin: $margin / 2;
border-color: $blue;
}
/* CSS */
.content-navigation {
border-color: #3bbfce;
color: #2b9eab;
}
.border {
padding: 8px;
margin: 8px;
border-color: #3bbfce;
}

6. Nesting
table.hl {
margin: 2em 0;
td.ln {
text-align: right;
}
}
li {
font: {
family: serif;
weight: bold;
size: 1.2em;
}
}
/* CSS */
table.hl {
margin: 2em 0;
}
table.hl td.ln {
text-align: right;
}
li {
font-family: serif;
font-weight: bold;
font-size: 1.2em;
}

7. Mixins
@mixin table-base {
th {
text-align: center;
font-weight: bold;
}
td, th {padding: 2px}
}
@mixin left($dist) {
float: left;
margin-left: $dist;
}
#data {
@include left(10px);
@include table-base;
}
/* CSS */
#data {
float: left;
margin-left: 10px;
}
#data th {
text-align: center;
font-weight: bold;
}
#data td, #data th {
padding: 2px;
}

8. Selector Inheritance
.error {
border: 1px #f00;
background: #fdd;
}
.error.intrusion {
font-size: 1.3em;
font-weight: bold;
}
.badError {
@extend .error;
border-width: 3px;
}
/* CSS */
.error, .badError {
border: 1px #f00;
background: #fdd;
}
.error.intrusion,
.badError.intrusion {
font-size: 1.3em;
font-weight: bold;
}
.badError {
border-width: 3px;
}

9. Arguments
/* style.scss */
@mixin rounded($vert, $horz, $radius: 10px) {
border-#{$vert}-#{$horz}-radius: $radius;
-moz-border-radius-#{$vert}#{$horz}: $radius;
-webkit-border-#{$vert}-#{$horz}-radius:
$radius;
}
#navbar li { @include rounded(top, left); }
#footer { @include rounded(top, left, 5px); }
#sidebar { @include rounded(top, left, 8px); }
/* style.css */
#navbar li {
border-top-left-radius: 10px;
-moz-border-radius-topleft: 10px;
-webkit-border-top-left-radius: 10px; }
#footer {
border-top-left-radius: 5px;
-moz-border-radius-topleft: 5px;
-webkit-border-top-left-radius: 5px; }
#sidebar {
border-top-left-radius: 8px;
-moz-border-radius-topleft: 8px;
-webkit-border-top-left-radius: 8px; }

10. @import
* _rounded.scss */
@mixin rounded($vert, $horz, $radius: 10px) {
border-#{$vert}-#{$horz}-radius: $radius;
-moz-border-radius-#{$vert}#{$horz}: $radius;
-webkit-border-#{$vert}-#{$horz}-radius:
$radius;
}
/* style.scss */
@import "rounded";
#navbar li { @include rounded(top, left); }
#footer { @include rounded(top, left, 5px); }
#sidebar { @include rounded(top, left, 8px); }
/* style.css */
#navbar li {
border-top-left-radius: 10px;
-moz-border-radius-topleft: 10px;
-webkit-border-top-left-radius: 10px; }
#footer {
border-top-left-radius: 5px;
-moz-border-radius-topleft: 5px;
-webkit-border-top-left-radius: 5px; }
#sidebar {
border-top-left-radius: 8px;
-moz-border-radius-topleft: 8px;
-webkit-border-top-left-radius: 8px; }

11. LESS

12. Variables
// LESS
@color: #4D926F;
#header {
color: @color;
}
h2 {
color: @color;
}
/* Compiled CSS */
#header {
color: #4D926F;
}
h2 {
color: #4D926F;
}

13. Mixins
// LESS
.rounded-corners (@radius: 5px) {
-webkit-border-radius: @radius;
-moz-border-radius: @radius;
-ms-border-radius: @radius;
-o-border-radius: @radius;
border-radius: @radius;
}
#header {
.rounded-corners;
}
#footer {
.rounded-corners(10px);
}
/* Compiled CSS */
#header {
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
-ms-border-radius: 5px;
-o-border-radius: 5px;
border-radius: 5px;
}
#footer {
-webkit-border-radius: 10px;
-moz-border-radius: 10px;
-ms-border-radius: 10px;
-o-border-radius: 10px;
border-radius: 10px;
}

14. Nested Rules
// LESS
#header {
h1 {
font-size: 26px;
font-weight: bold;
}
p { font-size: 12px;
a { text-decoration: none;
&:hover { border-width: 1px }
}
}
}
/* Compiled CSS */
#header h1 {
font-size: 26px;
font-weight: bold;
}
#header p {
font-size: 12px;
}
#header p a {
text-decoration: none;
}
#header p a:hover {
border-width: 1px;
}

15. Functions & Operations
// LESS
@the-border: 1px;
@base-color: #111;
@red: #842210;
#header {
color: (@base-color * 3);
border-left: @the-border;
border-right: (@the-border * 2);
}
#footer {
color: (@base-color + #003300);
border-color: desaturate(@red, 10%);
}
/* Compiled CSS */
#header {
color: #333;
border-left: 1px;
border-right: 2px;
}
#footer {
color: #114411;
border-color: #7d2717;
}

16. The Apps
• On Mac:
– Livereload
– CodeKit

17. The Apps
• On Windows
– Web workbench
– Scout
– SimpLESS
– Web Essentials 2012

18. Which CSS preprocessor language
should I choose?
http://css-tricks.com/sass-vs-less/
“Winner: Used to be Sass, but LESS is
more active development lately”
Chris Coyier

19. Live demo!

20. Questions

21. Thank you!

22. Referenses
• http://sass-lang.com/
• http://lesscss.org/
• http://learnboost.github.io/stylus/
• http://css-tricks.com/sass-vs-less/
• http://css-tricks.com/musings-on-preprocessing/
• http://livereload.com/
• http://incident57.com/codekit/
• http://mhs.github.io/scout-app/
• http://wearekiss.com/simpless
• http://thesassway.com/