Style Guide

This is a guide to the styles and patterns used throughout the site.


The main page header of this guide is an h1 element. Any header elements may include links.


The secondary header above is an h2 element, which may be used for any form of important page-level header. Consider using an h2 unless you need a header level of less importance, or as a sub-header to an existing h2 element.

Third-level header 

The header above is an h3 element, which may be used for any form of page-level header which falls below the h2 header in a document hierarchy.

Fourth-level header 

The header above is an h4 element, which may be used for any form of page-level header which falls below the h3 header in a document hierarchy.

Fifth-level header 

The header above is an h5 element, which may be used for any form of page-level header which falls below the h4 header in a document hierarchy.

Sixth-level header 

The header above is an h6 element, which may be used for any form of page-level header which falls below the h5 header in a document hierarchy.

Structural elements 


All paragraphs are wrapped in p tags. Additionally, p elements can be wrapped with a blockquote element if the p element is indeed a quote.


The blockquote element represents a section that is being quoted from another source:

Many forms of Government have been tried, and will be tried in this world of sin and woe. No one pretends that democracy is perfect or all-wise. Indeed, it has been said that democracy is the worst form of government except all those other forms that have been tried from time to time.

— Winston Churchill, in a speech to the House of Commons (11th November 1947)

Horizontal rules 

The hr element represents a paragraph-level thematic break, for example a scene change in a story, or a transition to another topic within a section of a reference book. The following extract from Pandora’s Star by Peter F. Hamilton shows two paragraphs that precede a scene change and the paragraph that follows it:

Dudley was ninety-two, in his second life, and fast approaching time for another rejuvenation. Despite his body having the physical age of a standard fifty-year-old, the prospect of a long degrading campaign within academia was one he regarded with dread. For a supposedly advanced civilization, the Intersolar Commonwealth could be appallingly backward at times, not to mention cruel.

Maybe it won’t be that bad, he told himself. The lie was comforting enough to get him through the rest of the night’s shift.

The Carlton AllLander drove Dudley home just after dawn. Like the astronomer, the vehicle was old and worn, but perfectly capable of doing its job. It had a cheap diesel engine, common enough on a semi-frontier world like Gralmond, although its drive array was a thoroughly modern photoneural processor. With its high suspension and deep-tread tyres it could plough along the dirt track to the observatory in all weather and seasons, including the metre-deep snow of Gralmond’s winters.

List elements 

Ordered lists 

The ol element denotes an ordered list. Each item requires a surrounding li tag, to denote individual items within the list.

Here is an example list showing the monarchs of Great Britain and the United Kingdom:

  1. House of Stuart
    1. Anne
  2. House of Hanover
    1. George I
    2. George II
    3. George III
    4. George IV
    5. William IV
    6. Victoria
  3. House of Saxe-Coburg and Gotha
    1. Edward VII
  4. House of Windsor
    1. George V
    2. Edward VIII
    3. George VI
    4. Elizabeth II

Unordered lists 

The ul element denotes an unordered list (i.e. a list of loose items that don’t require numbering, or a bulleted list). Again, each item requires a surrounding li tag, to denote individual items.

Here is an example list showing the constituent parts of the British Isles:

  • United Kingdom of Great Britain and Northern Ireland:
    • England
    • Scotland
    • Wales
    • Northern Ireland
  • Republic of Ireland
  • Isle of Man
  • Channel Islands:
    • Bailiwick of Guernsey
    • Bailiwick of Jersey

Sometimes you may want each list item to contain block elements, typically a paragraph or two:

  • The British Isles is an archipelago consisting of the two large islands of Great Britain and Ireland, and many smaller surrounding islands.

  • Great Britain is the largest island of the archipelago. Ireland is the second largest island of the archipelago and lies directly to the west of Great Britain.

  • The full list of islands in the British Isles includes over 1,000 islands, of which 51 have an area larger than 20 km2.

Table elements 

Tables should be used when displaying tabular data. The thead, tfoot and tbody elements enable you to group rows within each table.

If you use these elements, you must use every element. They should appear in this order: thead, tfoot and tbody, so that browsers can render the foot before receiving all the data. You must use these tags within the table element.

Example with Team GB’s London 2012 medal table:

Canoe Slalom1102
Canoe Sprint1012
Cycling — Road1113
Cycling — Track7119
Gymnastics - Artistic0134
Modern Pentathlon0101

Media elements 


The img element embeds an image into the document. The src attribute is required, and contains the path to the image you want to embed. The alt attribute holds a text description of the image, which isn’t mandatory but is incredibly useful for accessibility. Example:

Example image

An image can also take up the whole column. Example:

Example image
Concept art for breakup scene in Coffee Run, by Blender Studio.


The video element embeds a media player which supports video playback into the document. Example:

Clip of cafe scene in Coffee Run, by Blender Studio.

Inline frame 

The iframe element represents a nested browsing context, embedding another HTML page into the current one. Examples:

Text formatting elements 

The a element is used to hyperlink text, be that to another page, a named fragment on the current page or any other location on the web. Example:

Go to the home page or return to the top of this page.

Stressed emphasis 

The em element is used to denote text with stressed emphasis. Where italicizing is required for stylistic differentiation, the i element may be preferable. Example:

You simply must try the negitoro maki!

Strong importance 

The strong element is used to denote text with strong importance. Where bolding is used for stylistic differentiation, the b element may be preferable. Example:

Don’t stick nails in the electrical outlet.


The i element is used for text in an alternate voice or mood, or otherwise offset from the normal prose. Examples include taxonomic designations, technical terms, idiomatic phrases from another language, the name of a ship or other spans of text whose typographic presentation is typically italicised. Example:

There is a certain je ne sais quoi in the air.


The b element is used for text stylistically offset from normal prose without conveying extra importance, such as key words in a document abstract, product names in a review, or other spans of text whose typographic presentation is typically emboldened. Example:

You enter a small room. Your sword glows brighter. A rat scurries past the corner wall.

Inline quotes 

The q element is used for quoting text inline. Example showing nested quotations:

John said, I saw Lucy at lunch, she told me Mary wants you to get some ice cream on your way home. I think I will get some at Ben and Jerry’s, on Gloucester Road.


The abbr element is used for any abbreviated text, whether it be acronym, initialism, or otherwise. Generally, it’s less work and useful (enough) to mark up only the first occurrence of any particular abbreviation on a page, and ignore the rest. Any text in the title attribute will appear when the user’s mouse hovers the abbreviation (although, notably, this does not work in Internet Explorer for Windows). Example:

Get the latest news from the BBC in Stoke and Staffs.


The dfn element is used to highlight the first use of a term. The title attribute can be used to describe the term. Example:

Bob’s canine mother and equine father sat him down and carefully explained that he was an allopolyploid organism.


The cite element is used to represent the title of a work (for example a book, essay, poem, song, film, TV show, sculpture, painting, musical, exhibition, etc.). This can be a work that is being quoted or referenced in detail, or it can just be a work that is mentioned in passing. Example:

Universal Declaration of Human Rights, United Nations, December 1948. Adopted by General Assembly resolution 217 A (III).

Marked or highlighted text 

The mark element is used to represent a run of text marked or highlighted for reference purposes. When used in a quotation it indicates a highlight not originally present but added to bring the reader’s attention to that part of the text. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its relevance to the user’s current activity. Example:

I also have some kittens who are visiting me these days. They’re really cute. I think they like my garden! Maybe I should adopt a kitten.


The del element is used to represent deleted or retracted text which still must remain on the page for some reason. Meanwhile its counterpart, the ins element, is used to represent inserted text. Example:

As a result, Kodos Kang was elected president.


The var element is used to denote a variable in a mathematical expression or programming context, but can also be used to indicate a placeholder where the contents should be replaced with your own value. Example:

If there are n pipes leading to the ice cream factory then I expect at least n flavours of ice cream to be available for purchase!

Superscript and subscript text 

The sup element represents a superscript and the sub element represents a sub. These elements must be used only to mark up typographical conventions with specific meanings, not for typographical presentation. As a guide, only use these elements if their absence would change the meaning of the content. Example:

Chemical formulas are written using subscripts (for example C6H12O6), but atomic isotopes are written using superscripts (for example 13C, 131I, and 238U).

Small print 

The small element is used to represent disclaimers, caveats, legal restrictions, or copyrights (commonly referred to as ‘small print’). It can also be used for attributions or satisfying licensing requirements. Example:

Copyright (C) 1912-2012 Acme Corporation. All Rights Reserved.


The time element is used to represent either a time on a 24-hour clock, or a precise date in the proleptic Gregorian calendar, optionally with a time and a time-zone offset. Example:

Queen Elizabeth II was proclaimed sovereign of each of the Commonwealth realms on and , after the death of her father, King George VI.


The details HTML element creates a disclosure widget in which information is visible only when the widget is toggled into an “open” state. A summary or label must be provided using the summary element.

Details Something small enough to escape casual notice.

Keyboard entry 

The kbd element is used to denote user input (typically via a keyboard, although it may also be used to represent other input methods, such as voice commands). Example:

To take a screenshot on your Mac, press ⌘ Cmd + ⇧ Shift + 3.

Sample output 

The samp element is used to represent (sample) output from a program or computing system. Useful for technology-oriented sites, not so useful otherwise. Example:

The computer said Too much cheese in tray two but I didn’t know what that meant.

Pre-formatted text 

The pre element represents a block of pre-formatted text, in which structure is represented by typographic conventions rather than by elements. Here’s an example showing the printable characters of ASCII:

  ! " # $ % & ' ( ) * + , - . /
0 1 2 3 4 5 6 7 8 9 : ; < = > ?
@ A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z [ \ ] ^ _
` a b c d e f g h i j k l m n o
p q r s t u v w x y z { | } ~


The code element is used to represent fragments of computer code. Useful for technology-oriented sites, not so useful otherwise. Example:

The requestAnimationFrame method in the window object tells the browser that you wish to perform an animation and requests that the browser call a specified function to update an animation before the next repaint.

Code blocks 

The code element can also be used in conjunction with the pre element to represent verbatim text like markup or a fragment of computer code. Example:

function microsoftShuffle(arr) {
  return arr.slice().sort(function () {
    return (0.5 - Math.random());

You may choose to display line numbers next to the code. Example:

1function microsoftShuffle(arr) {
2  return arr.slice().sort(function () {
3    return 0.5 - Math.random();
4  });

You may also specify the language of a code block, so that it can be properly highlighted. Below you can find the classic Hello World program implemented in different languages.


echo "Hello, world!"

#include <stdio.h>
int main(int argc, char *argv[]) {
  printf("Hello, world!\n");
  return 0;


#include <iostream>
using namespace std;
int main() {
  cout << "Hello, world!" << endl;
  return 0;


using System;
class Program {
  public static void Main() {
    Console.WriteLine("Hello, world!");


(println "Hello, world!")


body::before {
  content: "Hello, world!";


diff --git a/foo.txt b/foo.txt
index c62237e..af5626b 100644
--- a/foo.txt
+++ b/foo.txt
@@ -1 +1 @@
-Goodbye, world!
+Hello, world!


IO.puts "Hello, world!"


import Text
main = Text.plainText "Hello, world!"


io:format("~s~n", ["Hello, world!"])


printf "Hello, world!\n"


package main
import "fmt"
func main() {
  fmt.Println("Hello, world!")


main = putStrLn "Hello, world!"


    Hello, world!


public class HelloWorld {
  public static void main(String[] args) {
    System.out.println("Hello, world!");


console.log("Hello, world!");


println("Hello, world!")


fun main(args : Array<String>) {
  println("Hello, world!")


(princ "Hello, world!")


print("Hello, world!")


#import <stdio.h>
int main(void) {
  printf("Hello, world!\n");
  return 0;


print "Hello, world!";


<?= 'Hello, world!' ?>


print "Hello, world!"

cat('Hello, world!')


puts "Hello, world!"


fn main() {
  println!("Hello, world!");


object HelloWorld extends App {
  println("Hello, world!")


(display "Hello, world!")


echo 'Hello, world!'


Transcript show: 'Hello, world!'.


println("Hello, world!")


console.log("Hello, world!");


You can use admonitions to call attention to information. Example:


All VPC networks include firewall rules.


After you delete a bucket, you can’t recover archived object versions.


Do not manually edit or delete generated table entries.

Error pages 

There’s a 404 page, but hopefully you’ll never see it.