Css basics

CSS Basics
Style and format your web site using CSS

What is CSS?
• CSS (Cascading Style Sheets) allows us to apply
formatting and styling to the HTML that builds our
web pages.
• CSS can control many elements of our web pages:
colors, fonts, alignment, borders, backgrounds,
spacing, margins, and much more.

How does CSS work?
• CSS works in conjunction with HTML.
• An HTML file (or multiple files) links to a CSS file (or
multiple CSS files) and when the web browser displays the
page, it references the CSS file(s) to determine how to
display the content.
• HTML elements are marked with “IDs” and “classes,”
which are defined in the CSS file – this is how the browser
knows which styles belong where. Each element type
(<h1>, <img>, <p>, <li>, etc.) can also be styled with CSS.
• IDs and classes are defined by the person writing the code –
there are no default IDs and classes.

What is the difference between ID and
class?
• IDs and classes function the same way – they can
both provide the same styling functionality to an
HTML element, however…
• IDs are unique; each element can only have one ID, and
that ID can only be on the page once.
• Classes are not unique; an element can have multiple
classes, and multiple elements can have the same class.
• What does that mean?
• IDs can be used to style elements that are different from
anything else on the page.
• Classes can be used to style multiple elements on a single
page that have things in common, like font size, color, or
style.

What does a CSS file look like?
• The styles for each element, ID, or class used on an
HTML page are defined in a CSS document.
 Elements are declared with the element (HTML) tag; styles for the
element are wrapped with curly brackets:
h1 { }
 IDs are declared with a pound sign and the ID name; styles for the ID are
wrapped with curly brackets:
#title { }
 Classes are declared with a period and the class name; styles for the class
are wrapped with curly brackets:
.bodytext { }

What does a CSS file look like?
• Within each CSS element, styles are added that apply
to that particular element/ID/class:
h1 {
color: green;
}
 This style would apply to anything within HTML <h1></h1>
tags; the text inside the tags would be green.

Adding CSS to HTML
• CSS must be used in conjunction with HTML to be
effective. CSS files can be linked to HTML documents
with a bit of code in the <head></head> tags of an
HTML file:
<link rel="stylesheet" type="text/css" href=“myfile.css" />
 CSS can also be written “in line,” within HTML code, but
it’s preferable to include an external style sheet:
<p style=“font-size: 14px;”>Lorem ipsum…</p>

Let’s write some CSS!
• We’ll work in a web-based editing tool, but CSS can
easily be written in text editing software like Notepad.
•Go to http://dabblet.com/gist/9103656
• *This tool references our CSS automatically, so in this case, we don’t
need to link our CSS file like we normally would.

Adding IDs and Classes to HTML
• First, we need to add our IDs and classes to the HTML:
<h1>Wolverine</h1>
<img
src=http://www.uvu.edu/web/images/wolverine.jpg
class=“bordered” />
This class won’t do
anything yet. We’ll
define its associated
styles in our CSS file.

Adding IDs and Classes to HTML
<p id="introduction" class="emphasis">The
wolverine, also referred to as glutton, carcajou,
skunk bear, or quickhatch…
<p class="emphasis">The adult wolverine is
about the size of a medium dog, with a length
usually ranging from…
We only want the styles
from one class to apply
to this paragraph.
We’re adding a class and an ID
to this paragraph; we want the
styles from both to be applied
to it.

Defining Elements in CSS
• We’ve added IDs and classes to our HTML file, but we
need to define what those IDs and classes will do.
• How will each class or ID change the appearance of that
HTML element?
• This is where CSS comes in!
• By defining the styles that go with each attribute/class/ID,
we have complete control over the look of our content.

Writing CSS
• Let’s create a new CSS document in Notepad.
• We’ll begin by defining the “bordered” class that is
applied to one of the images.
• CSS uses . to identify classes, and # to identify IDs. Because
our HTML indicates class=“bordered” we need to use the
matching identifier in our CSS document.
.bordered { }
All the styles inside these brackets will be applied to any
elements in our HTML file that include class=“bordered”.

Writing CSS
• First, let’s add a simple style to .bordered:
.bordered {
width: 300px;
}
Each style ends with a
semicolon.
 Now, any HTML element that includes class=“border” will be
300 pixels wide.

Writing CSS
• Let’s add a border to that image that has class=“bordered”.
• The “border” style requires some additional attributes.
.bordered {
width: 300px;
border: 3px solid #000000;
}
Tells the browser “I
want a border around
this element.”
The border
should be 3
pixels wide.
The border
should be solid.
(Other possible
values include
dotted and dashed.)
The border should
be black (defined
by hexadecimal
color code).

Writing CSS
• We want the image to be on the right side of the
page, so we need to add a “float” to the class styles:
.bordered {
width: 300px;
border: 1px solid #000;
float: right;
}
We could also align the element
to the left side of the page using
“float: left;”.

Writing CSS
• Next, let’s write some styles to apply to our
paragraphs. First, we’ll create styles for the ID called
“introduction.”
• We want this paragraph to stand out from the rest, so
we’ll make the font size bigger and change the color.
#introduction {
font-size: 20px;
color: #4d7123;
}

Writing CSS
• We want a few paragraphs to have some additional
emphasis, so let’s write an additional class for those
styles:
.emphasis {
font-style: italic;
font-weight:
bold;
}
Other font-style options
include “underline,” and
“normal.”
Other font-weight options
include “normal,” “lighter,” or
numerical values.

Writing CSS
• We can also apply CSS styles to HTML elements
without using classes and IDs. These will apply to any
HTML element of that type, unless they are
overwritten by classes or IDs.
h1 {
font-family: “Arial”, sans-serif;
}
Any <h1> tag on the page will
be in Arial unless the <h1>
has a class that overwrites it.

Writing CSS
• We may want the same styles to apply to more than
one element in our site. Combining our styles can
help us do this so that we don’t have to duplicate our
CSS code:
h1, h2 {
font-family: “Arial”, sans-serif;
}
Adding additional, comma-
separated elements, classes, or
IDs allows the same styles to be
used in more than one place.

We also provide classroom and online training classes
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Css basics

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