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Helicase

Accessibility

Helicase should work for everyone who wants to learn biology, however they use the web.
Last updated October 8, 2026

Our goal

We aim to meet the Web Content Accessibility Guidelines (WCAG) 2.2 at level AA. This statement describes what we have done, what we have and have not tested, and the limits we know about. It is not a claim of conformance.

What is built in

  • Readable text. Every text color was checked for a contrast ratio of at least 4.5 to 1 against every background, in both the dark and the light theme. Control borders meet the 3 to 1 minimum. The typeface, Atkinson Hyperlegible, was designed by the Braille Institute so that easily confused letters and numbers look different.
  • Reading levels. Explanations come at beginner, intermediate and advanced levels, chosen in Settings.
  • Keyboard use. Controls are standard links, buttons and form fields. Focus is always visible, a skip link jumps to the main content, and dialogs keep focus inside until they close.
  • Words for every picture. Interactive diagrams, such as the cell and the plant, have a list that does the same job. Charts have a table view. The knowledge graph picture has an A to Z index and a page for every concept that describes each link in words.
  • Motion. Helicase follows your device’s reduced motion setting, and Settings has a switch to reduce motion on this site regardless.
  • Zoom and small screens. Pages are designed to work from 320 pixels wide without scrolling sideways, and text can be enlarged with browser zoom.
  • Color is never the only signal. Labels such as “Emerging research” always carry words and an icon as well as a color.

What has been tested

These checks run automatically on every build we test, in Chrome on a desktop and on an emulated phone:

  • The automated checker axe-core, set to the WCAG 2.0, 2.1 and 2.2 level A and AA rules, finds no problems on more than thirty public pages, covering every lab, in both the dark and light themes, on the account pages, on a quiz after grading, and with the search, settings and menu panels open.
  • Keyboard use: the first Tab reaches a skip link, focus is always visible, the search panel opens with Ctrl or Command and K and works from the keyboard, and a whole quiz can be answered and submitted without a mouse.
  • No page scrolls sideways at widths from 320 to 1440 pixels, signed in or not.

Automated checks find only some kinds of problems. A full audit with screen readers (such as NVDA, JAWS and VoiceOver) and with people who use assistive technology has not been done yet. Until it has, we do not claim that Helicase conforms to WCAG; this statement will be updated with the results.

Known limitations

  • The overview picture of the knowledge graph is made for pointing devices. The A to Z index below it, and each concept’s page, carry the same links for keyboard and screen reader users.
  • Some simulations show their results as charts; each chart has a table view with the same numbers.
  • Links to outside sources lead to other websites, such as journals and agency pages, whose accessibility we do not control.

Tell us about a problem

If something on Helicase is hard or impossible to use, please contact us. Say what you were trying to do, which device and assistive technology you use, and what happened. Accessibility problems are treated as bugs.