Adding sections on Sass functions, import, partials, and math operations. Adding some comments regarding best practices. Adding section on compatibility.

1 files changed, 215 insertions, 0 deletions

diff --git a/sass.html.markdown b/sass.html.markdown
index 509aee9b..02bec47f 100644
--- a/sass.html.markdown
+++ b/sass.html.markdown
@@ -3,6 +3,7 @@ language: sass
 filename: learnsass.scss
 contributors:
   - ["Laura Kyle", "https://github.com/LauraNK"]
+  - ["Sean Corrales", "https://github.com/droidenator"]
 ---
 
 Sass is a CSS extension language that adds features such as variables, nesting, mixins and more. 
@@ -11,6 +12,7 @@ Sass (and other preprocessors, such as [Less](http://lesscss.org/)) help develop
 Sass has two different syntax options to choose from. SCSS, which has the same syntax as CSS but with the added features of Sass. Or Sass (the original syntax), which uses indentation rather than curly braces and semicolons. 
 This tutorial is written using SCSS.
 
+If you're already familiar with CSS3, you'll be able to pick up Sass relatively quickly. It does not provide any new styling options but rather the tools to write your CSS more efficiently and make maintenance much easier.
 
 ```scss
 
@@ -121,6 +123,69 @@ div {
 
 
 
+/*Functions
+==============================*/   
+   
+   
+   
+/* Sass provides functions that can be used to accomplish a variety of 
+   tasks. Consider the following */
+
+/* Functions can be invoked by using their name and passing in the 
+   required arguments */
+body {
+  width: round(10.25px);    
+}
+
+.footer {
+  background-color: fade_out(#000000, 0.25)
+}
+
+/* Compiles to: */
+
+body {
+  width: 10px;
+}
+
+.footer {
+  background-color: rgba(0, 0, 0, 0.75);
+}   
+   
+/* You may also define your own functions. Functions are very similar to 
+   mixins. When trying to choose between a function or a mixin, remember
+   that mixins are best for generating CSS while functions are better for 
+   logic that might be used throughout your Sass code. The examples in 
+   the Math Operators' section are ideal candidates for becoming a reusable 
+   function. */
+
+/* This function will take a target size and the parent size and calculate 
+   and return the percentage */
+   
+@function calculate-percentage($target-size, $parent-size) {
+  @return $target-size / $parent-size * 100%;
+}
+
+$main-content: calculate-percentage(600px, 960px);
+
+.main-content {
+  width: $main-content;
+}
+
+.sidebar {
+  width: calculate-percentage(300px, 960px);
+}
+
+/* Compiles to: */
+
+.main-content {
+  width: 62.5%;
+}
+
+.sidebar {
+  width: 31.25%;
+}
+
+
 
 /*Extend (Inheritance)
 ==============================*/
@@ -150,6 +215,12 @@ div {
   border-color: #22df56; 
 }
 
+/* Extending a CSS statement is preferable to creating a mixin 
+   because of the way it groups together the classes that all share
+   the same base styling. If this was done with a mixin, the width, 
+   height, and border would be duplicated for each statement that 
+   called the mixin. While it won't affect your workflow, it will
+   add unnecessary bloat to the files created by the Sass compiler. */
 
 	
 
@@ -172,6 +243,7 @@ ul {
 /* '&' will be replaced by the parent selector. */
 /* You can also nest pseudo-classes. */
 /* Keep in mind that over-nesting will make your code less maintainable.
+Best practices recommend going no more than 3 levels deep when nesting.
 For example: */
 
 ul {
@@ -212,6 +284,140 @@ ul li a {
 
 
 
+/*Partials and Imports
+==============================*/   
+   
+   
+   
+/* Sass allows you to create partial files. This can help keep your Sass
+   code modularized. Partial files should begin with an '_', e.g. _reset.css.
+   Partials are not generated into CSS. */
+   
+/* Consider the following CSS which we'll put in a file called _reset.css */
+   
+html,
+body,
+ul,
+ol {
+  margin: 0;
+  padding: 0;
+}
+   
+/* Sass offers @import which can be used to import partials into a file.
+   This differs from the traditional CSS @import statement which makes 
+   another HTTP request to fetch the imported file. Sass takes the 
+   imported file and combines it with the compiled code. */
+   
+@import 'reset';
+   
+body {
+  font-size: 16px;
+  font-family: Helvetica, Arial, Sans-serif;
+}
+
+/* Compiles to: */
+
+html, body, ul, ol {
+  margin: 0;
+  padding: 0;
+}   
+
+body {
+  font-size: 16px;
+  font-family: Helvetica, Arial, Sans-serif;
+}
+  
+
+   
+/*Placeholder Selectors
+==============================*/  
+    
+    
+   
+/* Placeholders are useful when creating a CSS statement to extend. If you
+   wanted to create a CSS statement that was exclusively used with @extend,
+   you can do so using a placeholder. Placeholders begin with a '%' instead
+   of '.' or '#'. Placeholders will not appear in the compiled CSS. */
+   
+%content-window {
+  font-size: 14px;
+  padding: 10px;
+  color: #000;
+  border-radius: 4px;
+}
+
+.message-window {
+  @extend %content-window;
+  background-color: #0000ff;
+}
+
+/* Compiles to: */
+
+.message-window {
+  font-size: 14px;
+  padding: 10px;
+  color: #000;
+  border-radius: 4px;
+}
+
+.message-window {
+  background-color: #0000ff;
+}
+
+      
+  
+/*Math Operations
+==============================*/   
+    
+      
+   
+/* Sass provides the following operators: +, -, *, /, and %. These can
+   be useful for calculating values directly in your Sass files instead
+   of using values that you've already calculated by hand. Below is an example
+   of a setting up a simple two column design. */
+   
+$content-area: 960px;
+$main-content: 600px;
+$sidebar-content: 300px;
+
+$main-size: $main-content / $content-area * 100%;
+$sidebar-size: $sidebar-content / $content-area * 100%;
+$gutter: 100% - ($main-size + $sidebar-size);
+
+body {
+  width: 100%;
+}
+
+.main-content {
+  width: $main-size;
+}
+
+.sidebar {
+  width: $sidebar-size;
+}
+
+.gutter {
+  width: $gutter;
+}
+
+/* Compiles to: */
+
+body {
+  width: 100%;
+}
+
+.main-content {
+  width: 62.5%;
+}
+
+.sidebar {
+  width: 31.25%;
+}
+
+.gutter {
+  width: 6.25%;
+}
+
 	
 ```	
 
@@ -226,6 +432,15 @@ Because people were constantly writing it as "SASS", the creator of the language
 If you want to play with Sass in your browser, check out [SassMeister](http://sassmeister.com/).
 You can use either syntax, just go into the settings and select either Sass or SCSS.
 
+
+## Compatibility
+
+Sass can be used in any project as long as you have a program to compile it
+into CSS. You'll want to verify that the CSS you're using is compatible
+with your target browsers. 
+
+[QuirksMode CSS](http://www.quirksmode.org/css/) and [CanIUse](http://caniuse.com) are great resources for checking compatibility. 
+
 	
 ## Further reading
 * [Official Documentation](http://sass-lang.com/documentation/file.SASS_REFERENCE.html)