Colors & Typography

Colours and fonts are the two most visible aspects of any design. This chapter covers every way CSS lets you define colours and control how text looks.

Colour values

CSS offers several formats for specifying colours. They all produce the same result - pick the one that fits your workflow.

Named colours

CSS defines 148 named colours. Some common ones:

Name	Colour	Name	Colour
`red`	Red	`blue`	Blue
`green`	Green	`orange`	Orange
`white`	White	`black`	Black
`tomato`	Tomato	`coral`	Coral
`navy`	Navy	`teal`	Teal

h1 {
    color: navy;
    background-color: lightyellow;
}

Named colours are convenient for quick prototyping but limited for precise design work.

Two related keywords are worth knowing even though they are not named colours:

transparent - fully transparent black (rgba(0, 0, 0, 0))
currentColor - reuses the element's current color value

Hexadecimal (hex)

Hex codes are the most common colour format on the web. They start with # followed by six characters (0-9, a-f):

h1 {
    color: #1a1a2e;
    background-color: #f5f5dc;
}

The six characters represent three pairs: red, green, blue (RR GG BB). Each pair ranges from 00 (none) to ff (full intensity).

Hex	Meaning
`#000000`	Black (no colour)
`#ffffff`	White (all colours full)
`#ff0000`	Pure red
`#00ff00`	Pure green
`#0000ff`	Pure blue
`#808080`	Medium grey

Shorthand: When each pair has identical characters, you can shorten to three characters:

#ff0000 → #f00
#336699 → #369
#ffffff → #fff

rgb() and rgba()

The rgb() function takes red, green, and blue values from 0 to 255:

h1 {
    color: rgb(26, 26, 46);
    background-color: rgb(245, 245, 220);
}

To add transparency, use a fourth value (the alpha channel) between 0 (fully transparent) and 1 (fully opaque):

.overlay {
    background-color: rgb(0, 0, 0, 0.5);
}

Note: The older rgba() syntax still works, but modern CSS allows the alpha value directly inside rgb().

hsl() and hsla()

HSL stands for Hue, Saturation, Lightness. Many designers prefer it because it maps to how humans think about colour:

Hue - a degree on the colour wheel (0-360). 0 = red, 120 = green, 240 = blue
Saturation - how vivid the colour is (0% = grey, 100% = full colour)
Lightness - how light or dark (0% = black, 50% = pure colour, 100% = white)

h1 {
    color: hsl(234, 28%, 14%);
}

.muted {
    color: hsl(234, 10%, 50%);
}

HSL makes it easy to create colour variations by adjusting a single value:

.primary {
    background-color: hsl(210, 80%, 50%);
}

.primary-light {
    background-color: hsl(210, 80%, 70%);
}

.primary-dark {
    background-color: hsl(210, 80%, 30%);
}

All three share the same hue and saturation - only lightness changes.

Alpha transparency works the same way:

.overlay {
    background-color: hsl(0, 0%, 0%, 0.5);
}

Which format to use?

Format	Best for
Named	Quick prototyping, reading code
Hex	Copy-pasting from design tools, most common
`rgb()`	When you need alpha transparency
`hsl()`	Creating colour systems, adjusting shades

Tip: Most design tools (Figma, Sketch, Adobe XD) export hex values by default. Use hex for one-off colours and HSL when building a colour system with consistent hues.

The opacity property

The opacity property makes an entire element transparent, including all its children:

.faded {
    opacity: 0.5;
}

Values range from 0 (invisible) to 1 (fully visible).

The key difference from alpha colours: opacity affects everything inside the element (text, images, child elements), while rgb(0, 0, 0, 0.5) only makes the background transparent.

Color properties

CSS has two main colour properties:

Property	What it colours
`color`	Text colour
`background-color`	Element background

.alert {
    color: #721c24;
    background-color: #f8d7da;
}

Other properties that accept colour values include border-color, outline-color, box-shadow, text-shadow, and text-decoration-color.

currentColor

The special keyword currentColor refers to the element's color value. It is useful for keeping borders, shadows, and other elements in sync with the text:

.link {
    color: #4a90d9;
    border-bottom: 2px solid currentColor;
}

If you change the text colour, the border colour changes automatically.

Font family

The font-family property sets the typeface:

body {
    font-family: Georgia, "Times New Roman", serif;
}

The value is a font stack - an ordered list of fonts. The browser uses the first available font and falls back to the next one if it is not installed.

Always end with a generic family as the final fallback:

Generic family	Style	Examples
`serif`	Letters have decorative ends	Georgia, Times New Roman
`sans-serif`	Clean, no decorative ends	Arial, Helvetica, Verdana
`monospace`	Fixed-width characters	Courier New, Consolas
`cursive`	Handwriting style	Comic Sans MS
`system-ui`	OS default UI font	Varies by platform

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

code {
    font-family: "Fira Code", "Cascadia Code", Consolas, monospace;
}

Note: Font names with spaces must be quoted: "Times New Roman", "Fira Code".

Web-safe fonts

These fonts are installed on almost every computer and are safe to use without loading external files:

Serif: Georgia, Times New Roman
Sans-serif: Arial, Verdana, Trebuchet MS, Tahoma
Monospace: Courier New, Lucida Console

Loading Google Fonts

For a wider selection, load fonts from Google Fonts. Add a <link> tag in your HTML <head>:

<link rel="preconnect" href="https://fonts.googleapis.com" />
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
<link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap"
      rel="stylesheet" />

Then use the font in CSS:

body {
    font-family: "Inter", sans-serif;
}

Tip: Only load the weights you actually use. Each additional weight increases page load time. If performance or privacy matters, self-host WOFF2 files instead of calling Google Fonts at runtime. See Web Performance for the trade-offs.

Font weight

The font-weight property controls how bold text is:

h1 {
    font-weight: 700;
}

p {
    font-weight: 400;
}

.light {
    font-weight: 300;
}

Value	Name
`100`	Thin
`300`	Light
`400`	Normal
`600`	Semi-bold
`700`	Bold
`900`	Black

You can also use keywords: normal (= 400) and bold (= 700).

Note: The font file must include the weight you request. If you set font-weight: 300 but the font only has 400 and 700, the browser will substitute the nearest available weight.

Font style

The font-style property handles italic text:

em {
    font-style: italic;
}

.no-italic {
    font-style: normal;
}

Values: normal, italic, oblique.

Line height

The line-height property controls the vertical spacing between lines of text. It is one of the most important properties for readability:

body {
    line-height: 1.6;
}

h1 {
    line-height: 1.2;
}

A unitless number like 1.6 means "1.6 times the font size". For 18px text, the line height would be 18 × 1.6 = 28.8px.

Value	Best for
`1.2`	Headings (tight spacing)
`1.5`	Body text (comfortable reading)
`1.6`	Long-form content (generous spacing)

Tip: Always use unitless values for line-height. Values with units (28px, 1.5em) do not scale properly when child elements have different font sizes.

Text alignment

The text-align property controls horizontal text alignment:

h1 {
    text-align: center;
}

.right-align {
    text-align: right;
}

p {
    text-align: left;
}

.justified {
    text-align: justify;
}

Text decoration

The text-decoration property adds (or removes) underlines, overlines, and strikethroughs:

a {
    text-decoration: none;
}

.deleted {
    text-decoration: line-through;
}

.fancy-underline {
    text-decoration: underline wavy #4a90d9;
}

The shorthand accepts up to three values: line (underline, overline, line-through, none), style (solid, dashed, dotted, wavy), and colour.

Text transform

The text-transform property changes the capitalisation of text:

.uppercase {
    text-transform: uppercase;
}

.lowercase {
    text-transform: lowercase;
}

.capitalize {
    text-transform: capitalize;
}

Letter and word spacing

Fine-tune spacing between characters and words:

.spaced {
    letter-spacing: 2px;
}

.wide-words {
    word-spacing: 8px;
}

Small amounts of letter-spacing (0.5-2px) are common on headings and uppercase text to improve readability.

Putting it together

Here is a complete typography system for a simple page:

*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    font-family: "Inter", -apple-system, sans-serif;
    font-size: 18px;
    line-height: 1.6;
    color: #333;
    background-color: #fafafa;
    margin: 0;
    padding: 40px;
}

h1, h2, h3 {
    font-family: Georgia, serif;
    color: #1a1a2e;
    line-height: 1.2;
}

h1 {
    font-size: 36px;
    margin-bottom: 12px;
}

h2 {
    font-size: 28px;
    margin-top: 40px;
    margin-bottom: 8px;
}

h3 {
    font-size: 22px;
    margin-top: 32px;
    margin-bottom: 8px;
}

p {
    margin-top: 0;
    margin-bottom: 16px;
}

a {
    color: #4a90d9;
    text-decoration: underline;
}

a:hover {
    color: #2d6cb4;
    text-decoration: none;
}

small {
    font-size: 14px;
    color: #777;
}

This gives you a clean, readable typographic foundation to build on.

What you learned

CSS supports named, hex, rgb(), and hsl() colour formats
Use alpha values for transparent colours; use opacity to fade entire elements
font-family sets the typeface with a font stack and generic fallback
font-size, font-weight, and line-height control text size, boldness, and spacing
text-align, text-decoration, and text-transform handle alignment, underlines, and capitalisation
Load custom fonts from Google Fonts with a <link> tag
A good typography system uses consistent sizes, weights, and line heights

Next step

Now that you can control colours and fonts, the next chapter covers units and sizing - when to use px vs em vs rem vs % and how each one behaves.

Colour values​

Named colours​

Hexadecimal (hex)​

rgb() and rgba()​

hsl() and hsla()​

Which format to use?​

The opacity property​

Color properties​

currentColor​

Font family​

Web-safe fonts​

Loading Google Fonts​

Font size​

Font weight​

Font style​

Line height​

Text alignment​

Text decoration​

Text transform​

Letter and word spacing​

Putting it together​

What you learned​

Next step​