Text Customisation Deep Dive
Font families, line spacing, letter spacing, word spacing, and paragraph spacing.
Overview
Text Customisation transforms how text appears across all websites. Adjust fonts and spacing to create your optimal reading environment. For colour, use Screen Color Overlay.
Who benefits most: Users with dyslexia, low vision, visual processing difficulties, or anyone who finds default website text uncomfortable to read.
All Settings Explained
Font Family
These fonts change the page text.
| Font | Category | Best For |
|---|---|---|
| System default | System | Leaves the website’s own font in place |
| Lexend | Accessibility | Designed for reading fluency, clean and open. Bundled with the extension |
| OpenDyslexic | Dyslexia | Weighted bottoms prevent letter flipping. Bundled with the extension |
| Comic Sans MS | Casual | Familiar, distinct letters |
| Arial | Sans-serif | Clean, widely readable |
Lexend and OpenDyslexic ship inside the extension, so they work whether or not they are installed on the machine, and no font service is contacted. Comic Sans MS and Arial come from the operating system; if a system does not have them, the browser substitutes its nearest match.
Atkinson Hyperlegible, Verdana, Andika and Comic Neue appear in the list but do not change the page font in 1.0.0.
Font recommendations by need:
| Challenge | Recommended Fonts |
|---|---|
| Dyslexia | OpenDyslexic, Lexend, Comic Sans MS |
| Low vision | Arial, at a larger Chrome zoom level |
| Eye strain | Lexend |
| Long documents | Lexend |
| Beginning readers | Comic Sans MS |
Text Size
AssisT has no font-size setting of its own. Chrome already does this well and does it per site: use Ctrl and + or - to zoom the page, or set a default text size under Chrome Settings, Appearance. AssisT’s spacing controls below then apply on top of whatever size you have chosen.
Line Spacing
| Setting | Range | Default |
|---|---|---|
| Line spacing | 1.0 - 3.0 | 1.5 |
Spacing guide:
| Spacing | Visual Effect | Best For |
|---|---|---|
| 1.0 | Tight (touching) | Not recommended |
| 1.2 | Compact | Dense technical content |
| 1.5 | Normal | General reading |
| 1.8 - 2.0 | Spacious | Dyslexia, tracking difficulty |
| 2.5 - 3.0 | Very open | Severe visual processing issues |
Letter Spacing
| Setting | Range | Default |
|---|---|---|
| Letter spacing | 0 - 0.5em | 0.12em |
Effects:
- 0em: the font’s own spacing
- 0.12em: the default, slightly more open than normal
- 0.2em: noticeably spaced
- 0.5em: maximum spacing
When to increase letter spacing:
- Letters appear to merge together
- Difficulty distinguishing similar letters (m/n, c/e)
- Using narrow fonts
- Reading at smaller sizes
Word Spacing
| Setting | Range | Default |
|---|---|---|
| Word spacing | 0 - 0.5em | 0.16em |
Effects:
- 0em: the font’s own word spacing
- 0.16em: the default, a slightly wider gap between words
- 0.3-0.5em: noticeable word separation
When to increase word spacing:
- Words seem to run together
- Difficulty tracking word boundaries
- Using justified text alignment
- Dense paragraphs
The defaults for letter and word spacing are not zero on purpose: WCAG 2.2 SC 1.4.12 sets 0.12em letter spacing and 0.16em word spacing as the point at which text must stay readable, and that is where AssisT starts you.
Paragraph Spacing
| Setting | Range | Default |
|---|---|---|
| Paragraph spacing | 1.0 - 4.0em | 2.0em |
Space between paragraphs, as a multiple of the font size. Wider gaps make it easier to keep your place when moving from one paragraph to the next, and 2.0em meets the SC 1.4.12 requirement of twice the font size.
Colours
AssisT does not change text or background colours. Use Screen Color Overlay for a tint.
Where Your Settings Apply
Your font and spacing choices are remembered, like every other AssisT setting, and applied on every page where Text Customization is on. There is no separate switch for this any more: earlier versions had an “Apply to all windows” switch, and with it off your choices were lost on the next page. To go back to a website’s own styling, turn Text Customization off.
Step-by-Step Setup
Basic Setup
- Click AssisT icon in toolbar
- Open the Seeing group
- Toggle Text Customization ON
- Adjust settings to preference
Creating a Dyslexia-Optimised Setup
- Font: OpenDyslexic or Lexend
- Size: Chrome zoom at 125%
- Line spacing: 1.8 - 2.0
- Letter spacing: 0.05 - 0.1em
- Word spacing: 0.1em
- Colour: Screen Color Overlay in Cream or a soft yellow, if a white page is hard to read
Creating a Low Vision Setup
- Font: Arial, or the system default if the site already uses a clear sans-serif
- Size: Chrome zoom at 150-200%
- Line spacing: 1.5 - 1.8
- Letter spacing: 0.12em (the default) or more
- Contrast: AssisT does not set text or background colours. Use the site’s own dark mode, or Chrome’s, for contrast
Creating a Reduced Eye Strain Setup
- Font: Lexend
- Line spacing: 1.6
- Word spacing: 0.16em (the default)
- Combine with: Screen Color Overlay, Cream or Warm Sepia, at a low intensity
- Page size: Chrome’s own zoom, if you want the whole page larger
Common Use Cases
Long Reading Sessions
Challenge: Eye fatigue, difficulty maintaining focus over time.
Settings:
- Font: Lexend
- Line spacing: 1.6
- Paragraph spacing: 2.5em, so you keep your place between paragraphs
- Combine with: Screen Color Overlay, Cream, at 20% intensity
Dense Academic Content
Challenge: Lots of information, complex vocabulary, small margins.
Settings:
- Font: Lexend or Arial
- Line spacing: 1.8 (more space helps comprehension)
- Letter spacing: 0.12em (the default) or a little more
Coding/Technical Documentation
Challenge: Need clear distinction between characters (1/l/I, 0/O).
Settings:
- Font: Arial, which keeps similar characters reasonably distinct. AssisT has no font designed specifically for character disambiguation
- Line spacing: 1.4
- Letter spacing: 0
AssisT has no monospace font option, and it does not restyle code blocks a site has marked up as code, so a code sample keeps the site’s own font.
Reading Before Sleep
Challenge: Bright screens and alertness late in the evening.
Settings:
- Font: Lexend
- Line spacing: 1.6
- Add: Screen Color Overlay, Warm Sepia, at a low intensity
AssisT sets no text or background colour of its own, and it has no blue-light filter. Use your operating system’s night mode or a dark theme on the site alongside the overlay.
Troubleshooting
Text Looks Wrong
Solutions:
- Some websites use important CSS that overrides changes
- Some fonts may not be available on all systems
Font Doesn’t Change
Solutions:
- Font may not be installed on your system (this applies to Comic Sans MS and Arial only)
- Website may use
!importantCSS - Try a different font option
- Refresh the page after changing settings
Spacing Looks Inconsistent
Solutions:
- Different page sections may respond differently
- Some dynamically loaded content may reset
- Try applying smaller adjustments
- Some layouts break with large spacing changes
Text Overlaps or Gets Cut Off
Solutions:
- Reduce Chrome’s zoom slightly
- Reduce letter/word spacing
- Some layouts can’t accommodate large changes
- Website wasn’t designed for text flexibility
Combining with Other Features
Text Customisation + Dyslexia Mode
- Dyslexia Mode adds Bionic/Syllable/Grammar formatting
- Text Customisation sets base typography
- Complementary — both can be active
Text Customisation + Reading Mode
- Reading Mode strips page clutter and uses its own fixed layout (cream background, Arial, 18px text)
- Use Text Customisation on normal pages
For Educators & Parents
Choosing Settings for Students
| Student Profile | Key Settings |
|---|---|
| Dyslexia | OpenDyslexic font, 1.8+ line spacing |
| Low vision | Arial, generous letter and word spacing, Chrome zoom at 150–200% |
| Attention difficulties | Lexend, moderate spacing |
| Eye strain complaints | Lexend, wider line spacing, Screen Colour Overlay at low intensity |
Starting Points by Grade
AssisT sets no font size of its own; use Chrome’s zoom for size and AssisT’s spacing controls on top of it.
| Grade Level | Chrome Zoom | Line Spacing |
|---|---|---|
| Elementary | 125–150% | 1.8 |
| Middle School | 110–125% | 1.6 |
| High School | 100% | 1.5 |
| College | 100% | 1.5 |
Important Notes
- Let students choose — Preferences are personal
- Test on actual content — Different subjects may need different settings
- Adjust over time — Needs change as reading skills develop
- Consistent use helps — Brain adapts to familiar settings
Privacy Note
Text Customisation works entirely locally. No reading preferences or font choices are collected or transmitted.
Related Features
- Visual Comfort — Text Customisation overview
- Dyslexia Reading Modes — Combine with Dyslexia Mode
- Reading Help — Reading Mode for clean layouts