This statement describes how volume-profile-lab.org is built and which accessibility properties were designed in deliberately, rather than claimed after the fact.
01 Structural foundation
Every page is a single HTML document with one first-level heading, sections introduced by second-level headings, and a table of contents distributed across the site rather than hidden inside a menu. Semantic elements are used for what they mean: navigation for navigational grouping, table markup with captions and header cells for tabular data, definition lists for glossary entries, and an address element for postal contact details.
- One heading level one per page, no levels skipped.
- Tables carry captions and column headers; header cells are marked as such.
- Images carry descriptive alternative text that explains their role in the page.
- Language is declared on the document element.
02 Contrast
Text and interface colours were chosen against measured contrast ratios rather than by appearance. The values below were computed from the relative luminance of each pair, and all of them exceed the 4.5:1 threshold applied to normal text under the widely used accessibility guidelines.
| Foreground on background | Ratio |
|---|---|
| Body text #1E1B18 on #F7F3EC | 15.5 : 1 |
| Accent #B3123A on #F7F3EC | 6.2 : 1 |
| Secondary violet #5A4E7C on #F7F3EC | 6.7 : 1 |
| Rail text #F2ECE3 on #221E1B | 14.1 : 1 |
| Rail secondary #A79B8C on #221E1B | 6.1 : 1 |
03 Keyboard access
No part of the site depends on a mouse. Channel panels open when they receive keyboard focus as well as on hover, so every page in every channel can be reached with the tab key alone, and the focused element is visible at all times. Links are real links rather than scripted elements, which means the browser's own navigation features — back, forward, open in a new tab, copy link address — work without any page-level support.
The channel rail precedes the article in the document, so a reader tabbing through a page passes the channel buttons before reaching the content. The current channel is marked as the current page in the markup, which assistive technology announces.
04 Text scaling, motion and scripts
- Scaling. Layout is expressed in relative units and reflows to a single column on narrow screens; text may be enlarged substantially without loss of content or function.
- Motion. The only animation is a slow opacity change on the current channel marker. It is suppressed automatically when the operating system requests reduced motion.
- Scripts. No page contains any script, so no feature can fail because scripting is disabled or blocked.
- Content. No essential information is presented only through colour; every colour-mapped element also carries a number or a label.
05 Feedback and known gaps
Diagrams on this site are inline vector graphics. Where a diagram carries information not already present in the surrounding text, it is given a descriptive label; where it duplicates the text, the label is short by design. Complex tables become horizontally scrollable on narrow screens rather than being reformatted, which is a known trade-off: the alternative would break the row-to-column relationships that make the data readable.
Accessibility problems, including any page that behaves badly with a particular assistive technology, can be reported through the contact page. Reports are treated as corrections and the page is revised; see the terms of use for how revisions are published.