HTML
- Approach
- HTML-only users MUST be treated as first-class citizens (Service standard - Progressive enhancement)
 
 - Style
- All HTML for National Archive applications MUST adhere to the HTML5 standard
 - The 
<html>element SHOULD have alangattribute - The 
langattribute on the<html>element SHOULD been - The 
<title>element SHOULD either follow the pattern[page] - [service] - The National Archivesor[page] - The National Archives - All tags MUST be closed, even where HTML5 might allow them not to be (as is the case for 
<li>and<p>tags) - Full attribute syntax MUST be used and all attributes quoted (see the W3C description of quoted attribute syntax)
 - All tag names and attributes MUST be written in in lower case
 - HTML SHOULD be properly indented to reflect its structure
 - Optional tags MUST be used
 
 - Accessibility
- Services MUST follow the TNA Accessibility standards
 
 
Images
Acceptable file formats for images are:
| Format | Extention | MIME type | Purpose | 
|---|---|---|---|
| JPEG | .jpg | 
image/jpeg | 
General purpose images | 
| WebP | .webp | 
image/webp | 
General purpose images | 
| PNG | .png | 
image/png | 
Images requiring lossless-ness or transparency (prefer SVG) | 
| SVG | .svg | 
image/svg+xml | 
Logos, icons and fonts | 
WebP
- WebP images MUST be served with a JPEG fallback
 
SVGs
- Embedded SVGs MUST be made as accessible as possible (see CSS Tricks - Accessible SVGs for more details)
 
Videos
Acceptable file formats for videos are:
| Format | Extention | MIME type | 
|---|---|---|
| MP4 | .mp4 | 
video/mp4 | 
| WebM | .webm | 
video/webm | 
To use embedded media, refer to YouTube.
Player
Use video.js as a video player for videos hosted by TNA as well as an overlay for YouTube videos.
See ds-frontend for an example implimentation of video.js.