Learning CSS

Cascading Stylesheets
and how they work with HTML

body {
      background-color: #e6e6e6; 
      color: #031B3F; 
      font-family: arial, helvetica, sans-serif; 
      padding:15px; 
      line-height:1.4em
      }

Sample Code!

CSS syntax

Selector  {declaration;

                   declaration; }

Selector  {property: value;

                   property: value;}

Stacking the code
 

body {
      background-color: #e6e6e6; 
      color: #031B3F; 
      font-family: arial, helvetica, sans-serif; 
      padding:15px; 
      line-height:1.4em
      }

One CSS declaration per line: keep your code tidy and legible!

Commenting on the code
 

body {
      background-color: #e6e6e6; /*#C5D3D3*/ /*#B4D6B4*/
     /*trying different shades of grey-green */
      color: #031B3F; 
      font-family: arial, helvetica, sans-serif; 
      padding:15px; 
      line-height:1.4em
      }
  • "Comment out" values you're experimenting with.
  • Or write comments to explain what you're trying to do.

How to connect CSS to your HTML:
Three ways

  • inline HTML (not recommended, makes "code bloat"):
    <p style="color:blue;">....</p>
     
  • "Separation of concerns":
    • Good for one HTML page only:  a <style> element inside an HTML <head>
    • Good for an entire website: a separately linked .css file:
      <link> element in the HTML <head>

How to connect CSS to your HTML:
<style> element inside the <head>

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title>My Webpage</title>
        <style>
	body {
          background-color: #e6e6e6 /*#C5D3D3*/ /*#B4D6B4*/;
          color: #031B3F; 
          font-family: arial, helvetica, sans-serif; 
          padding:15px; 
          line-height:1.4em
				}
	p { padding: 2em;
               }
        </style>
    </head>
    <body>
       <p>..some text...</p>
    </body>
</html>





How to connect CSS to your HTML:
<link> element inside the <head>

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <title>My Webpage</title>
        <link rel="stylesheet" type="text/css" href="css/syllsched.css" />
    </head>
    <body>
       <p>..some text...</p>
    </body>
</html>





  • Preferred for a whole website: Update once, updates everywhere!
  • Relative file association: This one is saved in a folder named "css" in my web folder 
    • docs/
      • index.html
      • css/
        • syllsched.css

How to link a separate CSS Stylesheet

  • <link/> element: for linking a CSS file
  • <script> element can link a JS file

Inside the <head>.....</head>

<head>
  <title>My Portfolio Site</title>
  <link rel="stylesheet" type="text/css" href="style.css"/>
</head>

CSS Inheritance

  • Put CSS declarations for styling across your entire page on top-level HTML elements like <body>. . . </body>
     
  • Examples: set a background-color, set a font or font-family, set your normal font color
     
  • Inheritance:  the declarations you set for one element are passed down the HTML tree (to the elements nested inside it.)

CSS Box Model

  • To CSS, every element is a box
  • This includes the block and inline HTML elements
  • The box has a structure with several properties you can control with CSS: 
  • To adjust how much space goes around your HTML elements, work with

CSS Box Model: Properties

  • content: literally takes up the space needed for text, image, etc.
  • padding: a little room inside the box, just outside the content. By default, transparent.
  • border: this can be made visible around your content (draw the box!)
  • margin: area outside the border. By default, transparent.
  • Details: w3schools Box Model Demo

CSS: Units of “length”

  • Absolute (cm or mm) vs. Relative lengths
  • Why we prefer relative lengths!

Some length units we use most:

  • em: literally the size of the standard letter “m” in the default font you're using
  • vw: a percentage of the width of the viewport window (much smaller than an em)
  • px: technically an absolute dimension: 1 device pixel or ”dot” in your display. Pixel size depends on the device!

Writing CSS Demands

Looking Stuff Up!

Favorite resources for ALL available CSS properties:

1. w3schools CSS Tutorial

  • Plus: Lets you try as you go
  • Minus: Often has inline CSS examples (learn to adapt)

2. w3schools CSS Reference

  • All properties in alphabetical order for lookup! 

 

 

 

CSS: Color!

How to reference colors:

  • by name:
  • RGB values:
    • Red / Green / Blue values
    • scale from 0 to 255
    • rgb(0,0,255) = most intense blue
    • rgb(0,0,0) = black
    • rgb(255,255,255) = white
    • rgb(20,20,20)  (or make all the values equal): something grey

See w3C colors tutorial for more details.

CSS: Color! Hexadecimal values

 

  • Hex value looks like this: #RRGGBB
  • On base 16 scale: 0 -10, A, B, C, D, E, F
    • lowest value: 00
    • highest value: FF
    • Can refer to them in threes or sixes
      • #FF0000 = red
      • #F00 = same red

See w3C colors tutorial for more details.

Combinations of CSS properties in declarations

body { 
	background-color:SlateBlue;
	color: black;
}

h1 {
  padding: 2px;
  border: 1px solid violet;
}

CSS: Working with Accessible Color Schemes

 

CSS: Resources for Choosing  Color Schemes

HTML @class, @id and CSS

  • @ (short for attribute)
     as in @href in:
    <a href="https://behrend.psu.edu/">Penn State Erie</a>

     
  • Any HTML display element can hold @class and @id
     
  •  @class : creates a shared category for group of elements
    • everything associated with a topic, or to be arranged
      in a certain area of the page
    • Multiple elements can share an @class value.
       
  • @id : marks an element as unique, different from all the others.
    • Each @id attribute has a unique value (cannot be used again anywhere else on the page).
    • You can have lots of elements with @id on your page, but each one has its own unique value.
       
  • These attributes are useful for CSS styling.
    • ​Write CSS rules for all elements of a particular @class
    • Write CSS rules for a specific element with a distinct @id

HTML with @id and @class for a navigation bar

        <nav id="menu">
            <div class="button"><a href="index.html">Home</a></div> 
            <div class="button"><a href="resume.html">Resume</a></div> 
            <div class="button"><a href="gallery.html">Gallery</a></div>
            <div class="button"><a href="essays.html">DIGIT 100 Essays</a></div>
        </nav>

CSS rules to match

nav#menu {padding:2vw; }

/* This means: style the <nav id="menu"> element. */

.button { 
  border:2px; 
  border-style:solid;
  border-color:red; 
  padding:2vw; 
  background-color:#E6E6FA; 
  color:yellow; 
  width:10%; 
  display:inline;
  border-radius: 20px;
 }
/* This means: style ANY element that as an @class set to button, as in */
/* <li class="button"> or <p class="button"> or <div class="button">. */

        <nav id="menu">
            <div class="button"><a href="index.html">Home</a></div> 
            <div class="button"><a href="resume.html">Resume</a></div> 
            <div class="button"><a href="gallery.html">Gallery</a></div>
            <div class="button"><a href="essays.html">DIGIT 100 Essays</a></div>
        </nav>

You could also write it like this:

#menu {padding:2vw; }

/* This means: style the <nav id="menu"> element. */

.button { 
  border:2px; 
  border-style:solid;
  border-color:red; 
  padding:2vw; 
  background-color:#E6E6FA; 
  color:yellow; 
  width:10%; 
  display:inline;
  border-radius: 20px;
 }
/* This means: style ANY element that as an @class set to button, as in */
/* <li class="button"> or <p class="button"> or <div class="button">. */

# means @id, . means @class

        <nav id="menu">
            <div class="button"><a href="index.html">Home</a></div> 
            <div class="button"><a href="resume.html">Resume</a></div> 
            <div class="button"><a href="gallery.html">Gallery</a></div>
            <div class="button"><a href="essays.html">DIGIT 100 Essays</a></div>
        </nav>

or, like this (no spaces between element name and . or #)

#menu {padding:2vw; }

/* This means: style the <nav id="menu"> element. */

div.button { 
  border:2px; 
  border-style:solid;
  border-color:red; 
  padding:2vw; 
  background-color:#E6E6FA; 
  color:yellow; 
  width:10%; 
  display:inline;
  border-radius: 20px;
 }
/* This means: style ANY element that as an @class set to button, as in */
/* <li class="button"> or <p class="button"> or <div class="button">. */

# means @id, . means @class

LearningCSS

By Elisa Beshero-Bondar

LearningCSS

Slides to help with learning CSS

  • 78
Loading comments...

More from Elisa Beshero-Bondar