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CSS 3

Getting Started

Introduction {.row-span-3}

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 {.row-span-2}

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
divAll div tags
.classnameAll elements with class
#idnameElement with ID
div,pAll divs and paragraphs
#idname *All elements inside #idname

See also: Type / Class / ID / Universal selectors

Combinators

SelectorDescription
div.classnameDiv with certain classname
div#idnameDiv with certain ID
div pParagraphs inside divs
div > pAll p tags
one level deep in div
div + pP tags immediately after div
div ~ pP 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"] | Starts with 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::afterAdd content after p
p::beforeAdd content before p
p::first-letterFirst letter in p
p::first-lineFirst line in p
::selectionSelected by user
::placeholderPlaceholder attribute
:rootDocuments root element
:targetHighlight active anchor
div:emptyElement with no children
p:lang(en)P with en language attribute
:not(span)Element that’s not a span

Input pseudo classes

input:checkedChecked inputs
input:disabledDisabled inputs
input:enabledEnabled inputs
input:focusInput has focus
input:in-rangeValue in range
input:out-of-rangeInput value out of range
input:validInput with valid value
input:invalidInput with invalid value
input:optionalNo required attribute
input:requiredInput with required attribute
input:read-onlyWith readonly attribute
input:read-writeNo readonly attribute
input:indeterminateWith indeterminate state

Structural pseudo classes

p:first-childFirst child
p:last-childLast child
p:first-of-typeFirst of some type
p:last-of-typeLast 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-typeUnique of its parent
p:only-childOnly child of its parent

CSS Fonts

Properties {.row-span-3}

PropertyDescription
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 / right
center / justify | | text-transform: | capitalize / uppercase / lowercase | {.left-text}

See also: Font

Shorthand {.secondary .col-span-2}

styleweightsize (required)line-heightfamily
font:italic40014px/1.5sans-serif
styleweightsize (required)line-heightfamily (required)

Example

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

Case {.row-span-2}

/* 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 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(30 100% 50% / 60%);
color: hsla(30.2 100% 50% / 60%);

Other

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


color: currentcolor; /* keyword */

CSS Backgrounds

Properties {.row-span-2}

PropertyDescription
background:(Shorthand)

| background-color: | See: Colors | | background-image: | url(…) | | background-position: | left/center/right
top/center/bottom | | background-size: | cover X Y | | background-clip: | border-box
padding-box
content-box | | background-repeat: | no-repeat
repeat-x
repeat-y | | background-attachment: | scroll/fixed/local | {.left-text}

Shorthand {.secondary .col-span-2}

colorimagepositionXpositionYsizerepeatattachment
background:#ff0url(a.jpg)lefttop/100px autono-repeatfixed;
background:#abcurl(b.png)centercenter/coverrepeat-xlocal;
colorimageposXposYsizerepeatattach..

Examples {.col-span-2}

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 {.cols-5}

Shorthand {.col-span-5 .secondary}

namedurationtiming-functiondelaycountdirectionfill-modeplay-state
animation:bounce300mslinear100msinfinitealternate-reversebothreverse
namedurationtiming-functiondelaycountdirectionfill-modeplay-state

Properties {.row-span-2 .col-span-2}

PropertyValue
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 {.col-span-3}

/* @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 {.col-span-3}

.one('webkitAnimationEnd oanimationend msAnimationEnd animationend')

CSS Flexbox {.cols-2}

Simple example

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

Container {.row-span-2}

.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 {.col-span-2}

.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 {.col-span-2}

.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

Modern CSS

container queries(size)

.element-wrap {
  container: element / inline-size;
}
@container element (min-inline-size: 300px) {
  .element {
    display: flex;
    gap: 1rem;
  }
}

container qeries(style)

.container {
  --variant: 1;


  &.variant2 {
    --variant: 2;
  }
}


@container style(--variant: 1) {
  button {
  } /* You can't style .container, but can select inside it */
  .other-things {
  }
}


@container style(--variant: 2) {
  button {
  }
  .whatever {
  }
}

container units

  • The units are cqw (“container query width”),
  • cqh (“container query height”),
  • cqi (“container query inline”),
  • cqb (“container query block”),
  • cqmin (smaller of cqi and cqb),
  • and cqmax (larger of cqi and cqb)
.card {
  padding: 5cqi;
  font-size: 4cqi;
  border: 1cqi solid brown;
  height: 100%;
}


h2 {
  font-size: 10cqi;
  margin-block: 0 3cqi;
}

the :has() pseudo selector

figure:has(figcaption) {
  border: 1px solid black;
  padding: 0.5rem;
}

nesting

.cards {
  .card {
    & .card-description {
      color: blue;
    }
    & .card-title {
      color: red;
    }
  }
}

scoping

@scope {
  :scope {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    padding: 1rem;
    border: 1px solid black;
  }
  .card {
    padding: 1rem;
    border: 1px solid black;
    background: lightgray;
    h2 {
      margin: 0 0 1rem 0;
    }
  }
}

cascade layers

/* Specify the order to apply styles in cascade */
@layer legacyCard, newCard;


/* Imagine you have a lot of styles */
@layer newCard {
  .card {
    background-color: red;
  }
}
@layer legacyCard {
  .card {
    background-color: green;
  }
}

logical properties

button {
  background-color: #4caf50;
  border: none;
  color: white;
  padding: 0.5rem 1.5rem;
  text-decoration: none;
  font: inherit;
  border-radius: 4px;
  .icon {
    position: relative;
    top: 0.125em;
    fill: white;
    width: 1em;
    aspect-ratio: 1;
    margin-inline-end: 0.25rem;
  }
}

p3 colors

<div class="container">
  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-color: color(display-p3 1 0.5 0);
        }
      }
    </style>
  </div>
  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-color: oklch(61.88% 0.286 342.4);
        }
      }
    </style>
  </div>
  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-color: oklab(0.73 0.15 0.16);
        }
      }
    </style>
  </div>


  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-image: linear-gradient(to right in oklch, red, blue);
        }
      }
    </style>
  </div>


  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-image: linear-gradient(to right in oklab, red, blue);
        }
      }
    </style>
  </div>


  <div class="swatch">
    <style contenteditable>
      @scope {
        :scope {
          background-image: linear-gradient(to right in srgb, red, blue);
        }
      }
    </style>
  </div>
</div>

color mixing

.swatch {
  color: white;
  width: 100px;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  text-align: center;


  &:nth-child(1) {
    background-color: var(--bg);
  }
  &:nth-child(2) {
    background-color: color-mix(in oklch, var(--bg), black 30%);
  }
  &:nth-child(3) {
    background-color: color-mix(in oklch, var(--bg), white 30%);
  }
}

margin trim

.container {
  /* prevent "extra" margin at the end of the element */
  margin-trim: block-end;


  /* an element like this might be the culprit, but it could be anything */
  > p {
    margin-block-end: 1rem;
  }
}

text wrapping

.balance {
  text-wrap: balance;
}
.pretty {
  text-wrap: pretty;
}


html {
  font-family: system-ui, sans-serif;
}


main {
  max-inline-size: 60ch;
  margin-inline: auto;
}

subgrid

.grid {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(4, minmax(100px, auto));
}


.item {
  display: grid;
  grid-column: 2 / 7;
  grid-row: 2 / 4;
  grid-template-columns: subgrid;
  grid-template-rows: repeat(3, 80px);
}


.subitem {
  grid-column: 3 / 6;
  grid-row: 1 / 3;
}

Also see {.cols-1}