CSS

What is CSS?

Cascading Style Sheets, fondly referred to as CSS, is a simple design language intended to simplify the process of making web pages presentable. CSS handles the look and feel part of a web page. Using CSS, you can control the color of the text, the style of fonts, the spacing between paragraphs, how columns are sized and laid out, what background images or colors are used, as well as a variety of other effects. CSS is easy to learn and understand but it provides a powerful control over the presentation of an HTML document. Most commonly, CSS is combined with the markup languages HTML or XHTML.

Advantages of CSS 

CSS saves time - You can write CSS once and then reuse the same sheet in multiple HTML pages. You can define a style for each HTML element and apply it to as many web pages as you want.  Pages load faster - If you are using CSS, you do not need to write HTML tag attributes every time. Just write one CSS rule of a tag and apply it to all the occurrences of that tag. So, less code means faster download times.  Easy maintenance - To make a global change, simply change the style, and all the elements in all the web pages will be updated automatically.  Superior styles to HTML - CSS has a much wider array of attributes than HTML, so you can give a far better look to your HTML page in comparison to HTML attributes.  Multiple Device Compatibility - Style sheets allow content to be optimized for more than one type of device. By using the same HTML document, different versions of a website can be presented for handheld devices such as PDAs and cellphones or for printing.  Global web standards – Now HTML attributes are being deprecated and it is being recommended to use CSS. So it’s a good idea to start using CSS in all the HTML pages to make them compatible with future browsers.

Syntax:-

A CSS rule set consists of a selector and a declaration block:

Selectors (h1)                              

Declaration (property :-> color:  or value :-> red;)

The selector points to the HTML element you want to style.

The declaration block contains one or more declarations separated by semicolons.

Each declaration includes a property name and a value, separated by a colon.

CSS Selectors-

CSS selectors allow you to select and manipulate HTML element(s).

CSS selectors are used to "find" (or select) HTML elements based on their id, classes, types, attributes, values of attributes and much more.

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The element Selector

The element selector selects elements based on the element name.

You can select all <p> elements on a page like this: (all <p> elements will be center-aligned, with a red text color)

Example

p {
    text-align: center;
    color: red;
}

The id Selector

The id selector uses the id attribute of an HTML tag to find the specific element.

An id should be unique within a page, so you should use the id selector when you want to find a single, unique element.

To find an element with a specific id, write a hash character, followed by the id of the element.

The style rule below will be applied to the HTML element with id="para1":

Example

#para1 {
    text-align: center;
    color: red;
}

The class Selector

The class selector finds elements with the specific class.

The class selector uses the HTML class attribute.

To find elements with a specific class, write a period character, followed by the name of the class:

In the example below, all HTML elements with class="center" will be center-aligned:

Example

.center {
    text-align: center;
    color: red;
}

You can also specify that only specific HTML elements should be affected by a class.

In the example below, all p elements with class="center" will be center-aligned:

Example

p.center {
    text-align: center;
    color: red;
}

Grouping Selectors

In style sheets there are often elements with the same style:

h1 {
    text-align: center;
    color: red;
}

h2 {
    text-align: center;
    color: red;
}

p {
    text-align: center;
    color: red;
}

To minimize the code, you can group selectors.

To group selectors, separate each selector with a comma.

In the example below we have grouped the selectors from the code above:

Example

h1, h2, p {
    text-align: center;
    color: red;
}