Visual Presentation
Mechanism allows users to select foreground/background colors, line width ≤ 80 characters, no full justification, line spacing ≥ 1.5×, paragraph spacing ≥ 1.5× line height, and text resizable to 200% without horizontal scrolling.
What it requires
WCAG 2.0 SC 1.4.8 (AAA) is the most sweeping visual-presentation criterion. It bundles five sub-requirements about line length, justification, line height, paragraph spacing, and color customization.
Few mainstream sites meet all five. The most-violated sub-requirements are line width (most prose blocks exceed 80 characters at desktop widths) and full-justified text (occasionally used in editorial templates).
Common Shopify failure
Editorial-style theme with full-justified prose blocks and line widths over 100 characters at desktop widths.
How to fix it
Cap prose-content max-width at 75ch in CSS; replace `text-align: justify` with `text-align: left` (English) or `text-align: start` (RTL-aware).
Primary source: W3C — WCAG 2.0 Understanding 1.4.8