CSS is used to style web documents and has advantages like saving time and improving page load speeds. A style rule has a selector, property, and value. There are three types of CSS: inline CSS within HTML tags, internal CSS within <style> tags in the HTML head, and external CSS in a separate .css file linked via <link>. CSS selectors target elements by type, class, ID, and other attributes. Properties control colors, backgrounds, fonts, text, and borders.

2.  CSS – Cascading Style Sheet
 CSS is used to control the style of a web
document in a simple and easy way.
Advantages of CSS:
 CSS save times
 Pages load faster
 Easy maintenance

3.  A style rule is made of three parts :
1. Selector
2. Property
3. Value
Syntax:
selector{
property1:value1;
property2:value2;
….
}

4.  Inline CSS: Inline CSS contains the CSS property in the body
section attached with element is known as inline CSS. This kind of
style is specified within an HTML tag using style attribute.
 Internal or Embedded CSS: This can be used when a single
HTML document must be styled uniquely. The CSS rule set
should be within the HTML file in the head section i.e the CSS is
embedded within the HTML file.
 External CSS: External CSS contains separate CSS file which
contains only style property with the help of tag attributes (For
example class, id, heading, … etc). CSS property written in a
separate file with .css extension and should be linked to the HTML
document using link tag. This means that for each element, style
can be set only once and that will be applied across web pages.

5. Type Selectors
h1 { color: #36CFFF; }
Universal Selectors
* { color: #000000; }
Descendant Selectors
ul em { color: #000000; }
Class Selectors
.black { color: #000000; }

6. ID Selectors
#black { color: #000000; }
Child Selectors
body > p { color: #000000; }
Attribute Selectors
input[type = "text"] { color: #000000; }
Grouping Selectors
h1, h2, h3 { color: #000000;}

7. CSS Colors:

8. CSS Background:
 background-color : color_name|color_code
 background-image : url(path)
 background-repeat : repeat|repeat-x|repeat-y|no-
repeat
 background-size : auto|length|cover|contain
 background-attachment : scroll|fixed|local
 background-position : align align|% %|px px

9. Font:
 font-family: family-name
 font-size:medium|xx-small|x-small|small|large|x-
large|xx-large|smaller|larger|length
 font-style: normal|italic|oblique
 font-variant: normal|small-caps
 font-weight: normal|bold|bolder|lighter|number

10. Text:
 text-align: left|right|center|justify
 text-decoration-line: none|underline|overline|line-through
 text-decoration-style: solid|double|dotted|dashed|wavy
 text-transform: none|capitalize|uppercase|lowercase

11. Border:
 border-color: color|transparent
 border-radius: 1-4 length|%
 border-style:
none|hidden|dotted|dashed|solid|double|groove|ridge|inset
|outset
 border-width: medium|thin|thick|length