Buzzline

A BeeLine reader extension that doesn't suck ass.

Buzzline applies eye-guiding color gradients to text on every webpage so your eye is pulled smoothly from the end of one line to the start of the next.

Install (unpacked)

1. Open chrome://extensions.
2. Enable Developer mode (top right).
3. Click Load unpacked and select this project folder.
4. Pin the Buzzline icon, click it, and flip the switch on.

How it works

The content script:

1. Walks every text node in the page (skipping <script>, <code>, inputs, and page chrome — <nav>, <header>, <footer>, <aside>, ARIA navigation/banner/complementary/search roles, and elements whose class or id contains junk tokens like nav, sidebar, ad, banner, promo, comment, share, byline, pagination, cookie, etc.).
2. Wraps each remaining character in a <span data-bzln> so each glyph is independently colorable.
3. Groups spans into visual lines using getBoundingClientRect() — a new line starts when the top coordinate jumps more than ~60% of a glyph's height or when we cross into a new block-level ancestor.
4. For line index i, interpolates the color of each span along the line between palette color i mod N and color (i+1) mod N. The end color of each line therefore matches the starting color of the next.
5. Reapplies on window resize (the line grouping changes when text reflows) and watches the DOM with a MutationObserver (childList + characterData) to handle dynamic content.

Per-site opt-out: the popup shows the current hostname and a "Disable on this site" toggle. Hostnames you opt out of are stored in chrome.storage.sync under disabledHosts and are skipped even when the global switch is on.

Colors are applied via a CSS custom property (--bzln-c) read by a rule in content.css. That rule carries !important so it overrides site CSS; the extension-declared stylesheet is not subject to page CSP.

Text is split on grapheme clusters via Intl.Segmenter, so emoji, flags, and ZWJ sequences stay intact.

Sprint (RSVP reader)

Every colored block gets a small yellow launcher icon at its start. Click it to open Sprint — an RSVP overlay that flashes one word at a time with the Optimal Recognition Point (ORP) highlighted in red and horizontally aligned on a fixed guide so your eye stays still.

Controls: play/pause (space), prev/next word (← / →), close (Esc), speed slider (150–900 WPM, default 500). Punctuation and long words get proportionally longer holds so you can catch clause boundaries.

Color schemes

Preset palettes cycle through four colors — each line starts in one and ends in the next, so adjacent lines share a handoff color:

• Classic — black / blue / black / red
• Dark mode — light gray / light blue / light gray / peach
• Ocean — navy / teal / navy / seafoam
• Bumblebee — near-black / gold / near-black / brown
• High contrast — black / pure blue / black / pure red

Known limitations

• Per-character spans on very long articles (10k+ characters) use measurable memory and add a small layout cost. Fine on normal pages; heavy pages may flash briefly while processing.
• Does not descend into iframes or shadow DOM in this release.
• Code blocks, inputs, and contenteditable regions are intentionally left alone.
• Vertical writing modes (writing-mode: vertical-rl etc.) are detected and skipped — those blocks stay their original color.
• Pages with very strict CSP (style-src excluding 'unsafe-inline') may block the inline custom-property assignment. The base rule still loads, so spans fall back to inherit and look normal (just uncolored).

Files

manifest.json          Chrome MV3 manifest
src/content.js         Per-char span + gradient engine + Sprint launchers
src/sprint.js          RSVP reader overlay (ORP-aligned word flashing)
src/content.css        Base CSS + launcher + Sprint overlay styles
src/popup.html/css/js  Toolbar popup (toggle, scheme picker, live preview)
icons/                 Extension icons (cropped from assets/logo.png)
scripts/gen_icons.py   Regenerates the icons (Pillow)

Dev notes

• No build step. Edit files, reload the extension in chrome://extensions, reload the page.
• State lives in chrome.storage.sync under the keys enabled, scheme, and disabledHosts (array of hostnames to skip).
• To regenerate icons: python3 scripts/gen_icons.py.

Caveat

BeeLine Reader's gradient technique is covered by US Patent 9,026,907. Personal/educational use is generally fine; consult a lawyer before distributing publicly.