CSS
    CSS stands for Cascading Style Sheets
    CSS describes how HTML elements are to be displayed on screen, paper, or in other media

Example - same HTML - different CSS
    http://www.w3schools.com/css/css_intro.asp
    http://www.csszengarden.com

Syntax
    Basic syntax
        p {
            color: red;
            text-align: center;
        }
    CSS
        /* comment */
    Selectors
        Element - article
        id - #idName
        class - .className
    Selectors grouping
        h1, h2, p { color: red; }
    Combinator selectors
        Descendant selector
            article h2 - all h2 inside of article
    Pseudo selectors
        First paragraph
            p:first-child { color: red; }
        Mouse hover
            p:hover { color: red; }

Add CSS
    Style tag
        <style>
            p {
                color: red;
            }
        </style>
    Inline style
        <p style="color: red;">text</p>
    Link to external document
        <link rel="stylesheet" type="text/css" href="./link.css">

CSS cascade and selector specificity
    http://kod.djpw.cz/xuoc
    https://css-tricks.com/specifics-on-css-specificity/

Examples
    color: red
    text-align: center
    colors
        red
        #000
        #00000
        rgb(0, 0, 0)
        rgba(0, 0, 0, .5)
    units
        px
        em
        %
    spacing, dimensions
        margin
        padding
        border
        width
        height
    box-model
        box-sizing: content-box
        box-sizing: border-box
    Margin collapsing

Hide element
    display: none;
    visibility: hidden;

Pseudo classes
    http://www.w3schools.com/css/css_pseudo_classes.asp
    a:visited
    a:hover
    a:active
    a:focus
    p:first-child
    p:last-child
    p:nth-child
    input:checked
    input:disabled
    input:invalid