CSS 3

Getting Started

Introduction

CSS is rich in capabilities and is more than simply laying out pages.

External stylesheet

<link href="./path/to/stylesheet/style.css" rel="stylesheet" type="text/css">

Internal stylesheet

<style>
body {
    background-color: linen;
}
</style>

Inline styles

<h2 style="text-align: center;">Centered text</h2>

<p style="color: blue; font-size: 18px;">Blue, 18-point text</p>

Add class

<div class="classname"></div>
<div class="class1 ... classn"></div>

Support multiple classes on one element.

!important

.post-title {
    color: blue !important;
}

Overrides all previous styling rules.

Selector

h1 { } 
#job-title { }
div.hero { }
div > p { }

See: Selectors

Text color

color: #2a2aff;
color: green;
color: rgb(34, 12, 64, 0.6);
color: hsla(30 100% 50% / 0.6);

See: Colors

Background

background-color: blue;
background-image: url("nyan-cat.gif");
background-image: url("../image.png");

See: Backgrounds

Font

.page-title {
    font-weight: bold;
    font-size: 30px;
    font-family: "Courier New";
}

See: Fonts

Position

.box {
    position: relative;
    top: 20px;
    left: 20px;
}

See also: Position

Animation


animation: 300ms linear 0s infinite;

animation: bounce 300ms linear infinite;

See: Animation

Comment


/* This is a single line comment */

/* This is a 
   multi-line comment */

Flex layout

div {
    display: flex;
    justify-content: center;
}
div {
    display: flex;
    justify-content: flex-start;
}

See: Flexbox | Flex Tricks

Grid layout

#container {
  display: grid;
  grid: repeat(2, 60px) / auto-flow 80px;
}

#container > div {
  background-color: #8ca0ff;
  width: 50px;
  height: 50px;
}

See: Grid Layout

Variable & Counter

counter-set: subsection;
counter-increment: subsection;
counter-reset: subsection 0;

:root {
  --bg-color: brown;
}
element {
  background-color: var(--bg-color);
}

See: Dynamic content

CSS Selectors

Examples

Groups Selector

h1, h2 {
    color: red;
}

Chaining Selector

h3.section-heading {
    color: blue;
}

Attribute Selector

div[attribute="SomeValue"] {
    background-color: red;
}

First Child Selector

p:first-child {
    font-weight: bold;
}

No Children Selector

.box:empty {
  background: lime;
  height: 80px;
  width: 80px;
}

Basic
* All elements
div All div tags
.classname All elements with class
#idname Element with ID
div,p All divs and paragraphs
#idname * All elements inside #idname
See also: Type / Class / ID / Universal selectors

Combinators

Selector Description
div.classname Div with certain classname
div#idname Div with certain ID
div p Paragraphs inside divs
div > p All p tagsone level deep in div
div + p P tags immediately after div
div ~ p P tags preceded by div
See also: Adjacent / Sibling / Child selectors

Attribute selectors
a[target] With a target attribute
a[target="_blank"] Open in new tab
a[href^="/index"] Starts with /index
`[class =“chair”]`
[class*="chair"] containing chair
[title~="chair"] Contains the word chair
a[href$=".doc"] Ends with .doc
[type="button"] Specified type

See also: Attribute selectors

User action pseudo classes
a:link Link in normal state
a:active Link in clicked state
a:hover Link with mouse over it
a:visited Visited link

Pseudo classes
p::after Add content after p
p::before Add content before p
p::first-letter First letter in p
p::first-line First line in p
::selection Selected by user
::placeholder Placeholder attribute
:root Documents root element
:target Highlight active anchor
div:empty Element with no children
p:lang(en) P with en language attribute
:not(span) Element that’s not a span

Input pseudo classes
input:checked Checked inputs
input:disabled Disabled inputs
input:enabled Enabled inputs
input:focus Input has focus
input:in-range Value in range
input:out-of-range Input value out of range
input:valid Input with valid value
input:invalid Input with invalid value
input:optional No required attribute
input:required Input with required attribute
input:read-only With readonly attribute
input:read-write No readonly attribute
input:indeterminate With indeterminate state

Structural pseudo classes
p:first-child First child
p:last-child Last child
p:first-of-type First of some type
p:last-of-type Last of some type
p:nth-child(2) Second child of its parent
p:nth-child(3n42) Nth-child (an + b) formula
p:nth-last-child(2) Second child from behind
p:nth-of-type(2) Second p of its parent
p:nth-last-of-type(2) …from behind
p:only-of-type Unique of its parent
p:only-child Only child of its parent

CSS Fonts

Properties

Property Description
font-family: <font>
font-size: <size>
letter-spacing: <size>
line-height: <number>

| font-weight: | <number> / bold / normal | | font-style: | italic / normal | | text-decoration: | underline / none |

| text-align: | left / rightcenter / justify | | text-transform: | capitalize / uppercase / lowercase | {.left-text}

See also: Font

Shorthand

style weight size (required) line-height family
font: italic 400 14px / 1.5 sans-serif
style weight size (required) line-height family (required)

Example

font-family: Arial, sans-serif;
font-size: 12pt;
letter-spacing: 0.02em;

Case


/* Hello */
text-transform: capitalize;

/* HELLO */
text-transform: uppercase;

/* hello */
text-transform: lowercase;

@font-face

@font-face {
    font-family: 'Glegoo';
    src: url('../Glegoo.woff');
}

CSS Colors

Named color

color: red;
color: orange;
color: tan;
color: rebeccapurple;

Hexadecimal color

color: #090;
color: #009900;
color: #090a;
color: #009900aa;

rgb() Colors

color: rgb(34, 12, 64, 0.6);
color: rgba(34, 12, 64, 0.6);
color: rgb(34 12 64 / 0.6);
color: rgba(34 12 64 / 0.3);
color: rgb(34.0 12 64 / 60%);
color: rgba(34.6 12 64 / 30%);

HSL Colors

color: hsl(30, 100%, 50%, 0.6);
color: hsla(30, 100%, 50%, 0.6);
color: hsl(30 100% 50% / 0.6);
color: hsla(30 100% 50% / 0.6);
color: hsl(30.0 100% 50% / 60%);
color: hsla(30.2 100% 50% / 60%);

Other

color: inherit;
color: initial;
color: unset;
color: transparent;

color: currentcolor; /* keyword */

CSS Backgrounds

Properties

Property Description
background: (Shorthand)

| background-color: | See: Colors | | background-image: | url(…) | | background-position: | left/center/righttop/center/bottom | | background-size: | cover X Y | | background-clip: | border-boxpadding-boxcontent-box | | background-repeat: | no-repeatrepeat-xrepeat-y | | background-attachment: | scroll/fixed/local | {.left-text}

Shorthand

color image positionX positionY size repeat attachment
background: #ff0 url(a.jpg) left top / 100px auto no-repeat fixed;
background: #abc url(b.png) center center / cover repeat-x local;
color image posX posY size repeat attach..

Examples

background: url(img_man.jpg) no-repeat center;

background: url(img_flwr.gif) right bottom no-repeat, url(paper.gif) left top repeat;

background: rgb(2,0,36);
background: linear-gradient(90deg, rgba(2,0,36,1) 0%, rgba(13,232,230,1) 35%, rgba(0,212,255,1) 100%);

CSS The Box Model

Maximums/Minimums

.column {
    max-width: 200px;
    width: 500px;
}

See also: max-width / min-width / max-height / min-height

Margin / Padding

.block-one {
    margin: 20px;
    padding: 10px;
}

See also: Margin / Padding

Box-sizing

.container {
    box-sizing: border-box;
}

See also: Box-sizing

Visibility

.invisible-elements {
    visibility: hidden;
}

See also: Visibility

Auto keyword

div {
    margin: auto;
}

See also: Margin

Overflow

.small-block {
    overflow: scroll;
}

See also: Overflow

CSS Animation

Shorthand

name duration timing-function delay count direction fill-mode play-state
animation: bounce 300ms linear 100ms infinite alternate-reverse both reverse
name duration timing-function delay count direction fill-mode play-state

Properties

Property Value
animation: (shorthand)
animation-name: <name>
animation-duration: <time>ms
animation-timing-function: ease / linear / ease-in / ease-out / ease-in-out
animation-delay: <time>ms
animation-iteration-count: infinite / <number>
animation-direction: normal / reverse / alternate / alternate-reverse
animation-fill-mode: none / forwards / backwards / both / initial / inherit
animation-play-state: normal / reverse / alternate / alternate-reverse
{.left-text}

See also: Animation

Example

/* @keyframes duration | timing-function | delay |
   iteration-count | direction | fill-mode | play-state | name */
animation: 3s ease-in 1s 2 reverse both paused slidein;

/* @keyframes duration | timing-function | delay | name */
animation: 3s linear 1s slidein;

/* @keyframes duration | name */
animation: 3s slidein;

animation: 4s linear 0s infinite alternate move_eye;
animation: bounce 300ms linear 0s infinite normal;
animation: bounce 300ms linear infinite;
animation: bounce 300ms linear infinite alternate-reverse;
animation: bounce 300ms linear 2s infinite alternate-reverse forwards normal;

Javascript Event

.one('webkitAnimationEnd oanimationend msAnimationEnd animationend')

CSS Flexbox

Simple example

.container {
  display: flex;
}

.container > div {
  flex: 1 1 auto;
}

Container

.container {

  display: flex;
  display: inline-flex;

  flex-direction: row;            /* ltr - default */
  flex-direction: row-reverse;    /* rtl */
  flex-direction: column;         /* top-bottom */
  flex-direction: column-reverse; /* bottom-top */

  flex-wrap: nowrap; /* one-line */
  flex-wrap: wrap;   /* multi-line */

  align-items: flex-start; /* vertical-align to top */
  align-items: flex-end;   /* vertical-align to bottom */
  align-items: center;     /* vertical-align to center */
  align-items: stretch;    /* same height on all (default) */

  justify-content: flex-start;    /* [xxx        ] */
  justify-content: center;        /* [    xxx    ] */
  justify-content: flex-end;      /* [        xxx] */
  justify-content: space-between; /* [x    x    x] */
  justify-content: space-around;  /* [ x   x   x ] */
  justify-content: space-evenly;  /* [  x  x  x  ] */

}

Child

.container > div {

  /* This: */
  flex: 1 0 auto;

  /* Is equivalent to this: */
  flex-grow: 1;
  flex-shrink: 0;
  flex-basis: auto;

  order: 1;

  align-self: flex-start;  /* left */
  margin-left: auto;       /* right */

}

CSS Flexbox Tricks

Vertical center

.container {
  display: flex;
}

.container > div {
  width: 100px;
  height: 100px;
  margin: auto;
}

Vertical center (2)

.container {
  display: flex;

  /* vertical */
  align-items: center; 

  /* horizontal */
  justify-content: center;
}

Reordering

.container > .top {
 order: 1;
}

.container > .bottom {
 order: 2;
}

Mobile layout

.container {
  display: flex;
  flex-direction: column;
}

.container > .top {
  flex: 0 0 100px;
}

.container > .content {
  flex: 1 0 auto;
}

A fixed-height top bar and a dynamic-height content area.

Table-like


.container {
  display: flex;
}


/* the 'px' values here are just suggested percentages */
.container > .checkbox { flex: 1 0 20px; }
.container > .subject  { flex: 1 0 400px; }
.container > .date     { flex: 1 0 120px; }

This creates columns that have different widths, but size accordingly according to the circumstances.

Vertical

.container {
  align-items: center;
}

Vertically-center all items.

Left and right

.menu > .left  { align-self: flex-start; }
.menu > .right { align-self: flex-end; }

CSS Grid Layout

Grid Template Columns

#grid-container {
    display: grid;
    width: 100px;
    grid-template-columns: 20px 20% 60%;
}

fr Relative Unit

.grid {
    display: grid;
    width: 100px;
    grid-template-columns: 1fr 60px 1fr;
}

Grid Gap

/*The distance between rows is 20px*/
/*The distance between columns is 10px*/
#grid-container {
    display: grid;
    grid-gap: 20px 10px;
}

CSS Block Level Grid

#grid-container {
    display: block;
}

CSS grid-row

CSS syntax:

  • grid-row: grid-row-start / grid-row-end;

Example

.item {
    grid-row: 1 / span 2;
}

CSS Inline Level Grid

#grid-container {
    display: inline-grid;
}

minmax() Function

.grid {
    display: grid;
    grid-template-columns: 100px minmax(100px, 500px) 100px; 
}

grid-row-start & grid-row-end

CSS syntax:

  • grid-row-start: auto|row-line;
  • grid-row-end: auto|row-line|span n;

Example

grid-row-start: 2;
grid-row-end: span 2;

CSS grid-row-gap

grid-row-gap: length;

Any legal length value, like px or %. 0 is the default value

CSS grid-area

.item1 {
    grid-area: 2 / 1 / span 2 / span 3;
}

Justify Items

#container {
    display: grid;
    justify-items: center;
    grid-template-columns: 1fr;
    grid-template-rows: 1fr 1fr 1fr;
    grid-gap: 10px;
}

CSS grid-template-areas

.item {
    grid-area: nav;
}
.grid-container {
    display: grid;
    grid-template-areas:
    'nav nav . .'
    'nav nav . .';
}

Justify Self

#grid-container {
    display: grid;
    justify-items: start;
}

.grid-items {
    justify-self: end;
}

The grid items are positioned to the right (end) of the row.

Align Items

#container {
    display: grid;
    align-items: start;
    grid-template-columns: 1fr;
    grid-template-rows: 1fr 1fr 1fr;
    grid-gap: 10px;
}

CSS Dynamic Content

Variable

Define CSS Variable

:root {
  --first-color: #16f;
  --second-color: #ff7;
}

Variable Usage

#firstParagraph {
  background-color: var(--first-color);
  color: var(--second-color);
}

See also: CSS Variable

Counter

/* Set "my-counter" to 0 */
counter-set: my-counter;

/* Increment "my-counter" by 1 */
counter-increment: my-counter;

/* Decrement "my-counter" by 1 */
counter-increment: my-counter -1;

/* Reset "my-counter" to 0 */
counter-reset: my-counter;

See also: Counter set

Using counters

body { counter-reset: section; }

h3::before {
  counter-increment: section; 
  content: "Section." counter(section);
}

ol {
  counter-reset: section;   
  list-marker-type: none;
}

li::before {
  counter-increment: section;
  content: counters(section, ".") " "; 
}

Css 3 tricks

Scrollbar smooth

html {
    scroll-behavior: smooth;
}

Click me, the page will scroll smoothly to Getting started

Also see

web  css  style