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Readest

Customization

Reading is personal — the whole point of a good ebook reader is that you decide how a book looks. Readest lets you tune pretty much everything about the reader surface, from themes down to individual line-height values. Changes apply live, so you can tweak while you read.

Find settings under Font & Layout in the reader, or the global Settings (Cmd+, / Ctrl+,) for defaults that apply to new books.

Themes & color mode

Built-in color modes:

  • Light — standard white background
  • Dark — dark background for night reading
  • Auto — follows system preference

Beyond the built-ins, you can edit background, text, and accent colors directly to build your own theme. Add a textured background image with opacity/size controls for a more paper-like feel.

Fonts

Readest separates serif, sans-serif, and monospace selections — the reader uses the right one depending on the book's markup.

  • Bundled fonts — several carefully chosen typefaces are included (varies by platform).
  • System fonts — pick any font installed on your device.
  • Custom fonts — upload your own .ttf, .otf, .ttc, or .woff2. Uploaded fonts appear in the font picker.
  • CJK font override — a separate slot for Chinese / Japanese / Korean text, independent of the main Latin font.

Font weight and size are both adjustable. The size slider is fine-grained, so you can land on exactly the size that works for your screen and eyes.

Typography

Fine typography controls:

  • Line height — 1.2× to 2.5×. Defaults around 1.6×.
  • Paragraph margin — space between paragraphs.
  • Word spacing — fine-grained, positive or negative.
  • Letter spacing — typographic refinement for certain fonts.
  • Text indent — first-line indent on each paragraph.
  • Full-width justification — on or off.
  • Hyphenation — language-aware line-break hyphens.

By default, Readest respects the book's own stylesheet. Toggle Override book fonts / layout / colors independently to let your own settings take precedence. This is especially useful for EPUBs that ship opinionated but poorly-tuned CSS.

Layout & writing mode

  • Columns — 1 or 2 columns in paginated mode, with configurable gap.
  • Margins — top, bottom, left, right. Separate compact margins for the header/footer chrome.
  • Writing mode — horizontal (LTR or RTL) or vertical — supports Chinese, Japanese, and classical Mongolian text flow.
  • Max width / height — caps for very wide screens so lines stay readable.

See Reading › Page layout for the paginated-vs-scrolled choice.

CJK typography

For Chinese, Japanese, and Korean text, Readest adds a few CJK-specific knobs:

  • CJK font — a separate font slot independent from the Latin font.
  • Chinese variant conversion — convert between Simplified and Traditional on the fly. Supported variants: s2t (Simplified → Traditional), t2s, t2tw (Traditional → Taiwan), t2hk (Traditional → Hong Kong), s2twp (Simplified → Taiwan, including phrase conversion), tw2s, hk2s, tw2sp.
  • Vertical writing — full-book vertical layout for classical Chinese and Japanese texts.

Custom CSS

For anything the settings UI doesn't cover, Readest has a Custom CSS editor — two slots, one for book content and one for the reader UI chrome. Paste any CSS, save, and it applies immediately.

Find it under Reader → Font & Layout → Custom → Custom CSS.

The book-content editor targets the rendered book HTML: body, p, blockquote, img, a:any-link, and everything else inside an EPUB. The UI-chrome editor targets the toolbars and progress indicators: .pages-left-number, .pages-left-label, and similar helper classes.

For ideas, worked examples, and the full selector list, see the Custom CSS wiki page.

E-ink mode

Readest detects many e-ink devices (Onyx Boox, Kindle, Kobo, and similar) and automatically enables e-ink optimizations:

  • Reduced or zero animations (no fade, no flashing)
  • High-contrast colors
  • Simpler layout transitions

Three modes are available under Settings → Behavior → Device → E-Ink Mode:

  • On — force e-ink mode on. Useful if auto-detect missed your device.
  • Off — disable even on detected hardware. Useful if you're mirroring an e-ink Android tablet to a color display.

For color e-ink devices (like the Boox Go Color), enable the color e-ink option to allow a limited color palette.