CSS Notes For Web Development

a year ago

Hello fellas, today in this article, I would share with you CSS Notes For Web Development, CSS is responsible for styling of our web page.

Let's Get Started-

The General Rule

selector {

     property: value;

     anotherProperty: value;


For example, make all <h1> tags purple with 56-pixel font:

h1 {

     color: purple;

     font-size: 56px;


Three Basic Selectors

·      Element selectors select all instances of a given element. For example, "div" is a CSS element selector that will modify the properties of all <div> HTML tags.

·      The ID selector selects a single element with an octothorp ("#") ID (only one per page). For example, the following HTML/CSS combination will result in the word "hello" appearing in yellow, while the word "goodbye" will remain as is:


     <p id="special">hello</p>





#special {

     color: yellow;


·      The Class selector selects all elements in a given class by functioning just like an ID selector; however, a class is instead prefaced with a period ("."). For example, the following items marked as "completed" on a "To Do List" will be crossed out with a line:


     <p class="completed">TASK #1</p>



     <p class="completed">TASK #2</p>


.completed {

     text-decoration: line-through;


o  An element can be modified by multiple class or ID tags by simply adding a space between the two tag names, e.g.:

<p class="completed uncompleted">Text</p>

 Five More Advanced Selectors

·      The Star (*) selector applies to every element on the page.

·      The Descendant selector applies to selectors that have been "nested" under another. For example, if you want to modify the color of only those <a> tags that are nested within the <li> tags of a <ul> list, use the following:

ul li a {

     color: red;


o  In addition to HTML tags, CSS selectors such as "ID" or "Class" may be used within a Descendant selector.

o  HOWEVER: If, for example, you have a second-tier <ul> nested within a first-tier <ul> that is nested within <div id="box">, and you only want to select the first-tier <ul> and not the second-tier, then you must use the ">" combinator to select only the DIRECT first-tier "child" <ul> (rather than the second-tier "grandchild" <ul>) of <div id="box">:

#box > ul {

     color: red;


·      The Adjacent (+) selector will select only the element that comes IMMEDIATELY after another element (a "sibling" element, rather than a "nested" element). For example, to modify the font size of all <ul> tags that follow an <h4> tag (which are typed on the same "level" as the <ul> tags, and not nested under them), use the following:

h4 + ul {

     font-size: 24px;


o  If, in the above example, you want to select ALL <ul> tags after any <h4> tag, then use the more generalized sibling combinator of "~" instead of "+".

·      The Attribute selector will allow the selection of any element based off of any attribute. For example, to change the font family of all <a> tags that link to Google, use the following:

a[href="https://www.google.com/"] {

     font-family: cursive;


o  This selector an also be used to select all images of a particular source, or all inputs of a particular type, such as all checkboxes:

input[type="checkbox"] {

     border: 2px solid green;


o  TIP: See the complete list of Attribute Selectors.

·      The Nth-of-Type selector takes a specific number and selects the "-nth" instance of an element. For example, to change the background color of every second <li> tag in every list (literally meaning the second tag, not every other tag), use the following:

li:nth-of-type(2) {

     background-color: rgba(100, 175, 225, 0.5);


o  NOTE: To select every other tag, use the phrases (even) or (odd) instead of a specific number.

 For more advanced selectors, view The 30 CSS Selectors You Must Memorize.

  CSS Location

 CSS should generally be saved to its own file, but can also be included in the HTML head by using the <style> tag:

<style type="text/css">

     li {

           color: red;



The preferred method is to use a <link> tag in the HTML head to refer to the separate file containing CSS:

<link rel="stylesheet" type="text/css" href="directory/filename.css">

o  Specificity is the means by which browsers decide which CSS property values are the most relevant to an element and, therefore, will be applied (e.g., if the body is styled to have red text, but a paragraph within the body is styled to have green text, then the text will be green because the green text style is more relevant to the specific paragraph than the general body).

 The following list of selector types increases by specificity (in magnitudes of 10):

1.    Type selectors (e.g., li) and pseudo-element (e.g., :before)

2.    Class selectors (e.g., .hello), attributes selectors (e.g., [type="text"]) and pseudo-classes (e.g., :hover)

3.    ID selectors (e.g., #hello)

 This Specificity Calculator may be used to test CSS specificity rules.

o  The Box Model

In a document, each element is represented as a rectangular box. In CSS, each of these boxes is described using the standard "box model." Each box has four edges: (1) Content Edge, (2) Padding Edge, (3) Border Edge, and (4) Margin Edge. Padding is the space between the border and the element within the border, and the margin is the space between the border and everything outside of the border.

·      The content edge can be controlled by setting the "width" and "height" properties in "px" or "%" (with percentage in relation to the parent element), which in turn pushes out the border edge as well, as there is direct contact between the content and border (if no padding has yet been set).

o  NOTE: By using the "max-width" property in conjunction with "width", you can tell the browser to make an element's width a certain percentage, but then also cap that width to a maximum number of pixels, e.g.:

#container {

     width: 66.66%;

     max-width: 700px;


·      Space can be added between the content edge and border edge (and between the border edge and the next element's edge) by using the "padding" and "margin" properties respectively (in "px" or "%").

o  By default, padding and borders are set to go around all edges of an element, but can be limited by using more specific properties for top, right, bottom, and left—such as "padding-left" or "margin-top".

o  Alternatively, rather than typing a line of CSS for all four sides, the following shorthand can be used (with the first value setting the top property, and the remainder moving in a clockwise fashion):

p {

     margin: 20px 40px 60px 80px;


·      NOTE: By setting the "margin" property to "auto" on the left and right, an element will automatically be horizontally centered:

p {

     margin: 0 auto 0 auto;


o  The above syntax can also be shorted as (with the first value representing the vertical axis, and the second value representing the horizontal axis):

p {

     margin: 0 auto;



 Colors can be created through the Hexadecimal system by combining the octothorp (#) with a string of 6 hexadecimal "numbers" from 0-F, e.g.:

color: #FF1493;

·      This system follows an RGB scheme in which the first two numbers modify the amount of "red," the second two modify "green," and the last two modify "blue."

 Alternatively, colors can be created through the RGB system: 3 channels consisting of red, green, and blue, with each ranging from 0-255, e.g.:

color: rgb(0, 255, 0);

Colors can be made Transparent through the RGBA system. Just like RGB but with an alpha (transparency) channel ranging from 0.0-1.0, e.g.:

color: rgba(11, 99, 150, .6);


 Follows the same format as colors, e.g., background: #FF6789;

The background property can also set a background image, e.g.:

body {

     background: url(http://www.website.com/image.png);


·      To prevent the background from Repeating an image, add the following property:

background-repeat: no-repeat;

·      To allow the background image to Stretch out across the entire body, use:

background-size: cover;


Borders have three key properties: "width" (typically in pixels), "color" (as noted above), and "style" (generally solid, dotted, or dashed). All three properties must be present in order for a border to take effect, e.g.:

h1 {

     border-width: 5px;

     border-style: solid;

     border-color: purple;


The alternative shorthand syntax may also be used (in the specified order):

border: 5px solid purple;

o  Fonts

Font-Family specifies the font for an element:

p {

     font-family: Arial;


·      While not always necessary, you may sometimes have to put quotation marks around the font name—particularly when the font name begins with a number.

·      CSS Font Stack shows what percentages of operating systems have a given system font (useful for choosing a safe bet on system compatibility).

o  However, rather than using those limited fonts, it is better to use Google Fonts, choose a font, and embed the font's stylesheet link in your HTML <head> prior to the CSS link, e.g.:

<link href="https://fonts.googleapis.com/css?family=Esteban" rel="stylesheet">

 Font-Size specifies how big the font appears (typically in pixels or "px"):

h1 {

     font-size: 25px;


·      Another size unit is "em", which dynamically sets font size in relation to a parent element. For example, if you want to make a section of a paragraph's text in <span> tags be twice the size of the rest of the text in the <p> tags, you would say:

span {

     font-size: 2em;


o  BUT NOTE: What constitutes the "standard" 1em (i.e., the default font size on a page without CSS markup) varies from browser to browser, although the size is typically around 16 PIXELS. To ensure uniformity among browsers, it is useful to set the body's font size at the outset.

o  ALSO: Similar to "em" is "rem", which—rather than setting font size in relation to the parent element—sets the font size in relation to the "root" element on the page (i.e., the default font size discussed above).

Font-Weight specifies how thick or thin the font appears.

·      Typically involves absolute values of "normal" or "bold", or relative (to parent) values of "lighter" and "bolder", but can also be assigned a numeric value in increments of 100 generally from "100" to "800" depending on the font itself.

Line-Height controls the height of a given line (similar to changing line spacing in Word to 1.5 or 2.0, which means that a larger font will result in larger spacing).

Text-Align controls where an element's text is aligned on the page (typically "left", "right", and "center").

Text-Decoration is used to give text effects such as "underline", "overline", or "line-through".

o  Float

 Normally, block level elements (such as <div>) are stacked directly underneath the preceding element on the page. To change this, use the "float" property and specify a value of the direction in which the element should float ("left", "right", "none"). 

 When an element is floated, it is taken out of the normal flow of the document (though still remaining part of it), and it is shifted to the left or right until it touches the edge of its containing box, or another floated element.

 When <img> tags are laid out in a consecutive sequence, HTML automatically places some small amount of white space between the images. If you want to remove the white space, you can use "float" to remove that white space.

So,these were some of the CSS Notes, hope you liked them, if you have any query feel free to mention in comment box below.

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