fix: make the reader's typography, width and arrow keys work

Typography was in the stylesheet foliate prepends, which the book overrides;
moved to the appended one. The window keydown handler was never bound.

Also: wider reading area, page on a card, arrows moved onto it, spread gutter,
and the sidebar stays open on chapter clicks.

frontend/src/lib/components/reader/epub-reader.svelte

@@ -95,8 +95,9 @@
 	}
 
 	function navigateToChapter(href: string) {
+		// Deliberately leaves the sidebar open: picking a chapter is usually part of
+		// browsing several, and closing it each time made that tedious.
 		void viewer?.goTo(href);
-		isSidebarOpen = false;
 	}
 
 	onMount(() => {
@@ -191,18 +192,10 @@
 				</div>
 			{/if}
 
-			<div class="flex min-h-0 flex-1 items-stretch {isReady ? '' : 'hidden'}">
+			<div class="min-h-0 flex-1 p-4 {isReady ? '' : 'hidden'}">
-				<Button
+				<!-- The page itself: same colour the book is themed to, so the two
-					variant="ghost"
+				     meet seamlessly and the border reads as the edge of the sheet. -->
-					size="icon"
+				<div class="relative h-full overflow-hidden rounded-lg border bg-card shadow-sm">
-					class="my-auto size-10 shrink-0"
-					onclick={() => viewer?.goBack()}
-					aria-label="Previous page"
-				>
-					<ChevronLeft class="size-5" />
-				</Button>
-
-				<div class="min-w-0 flex-1">
 					{#if file}
 						<FoliateView
 							bind:this={viewer}
@@ -219,18 +212,30 @@
 							}}
 						/>
 					{/if}
-				</div>
+
+					<!-- Overlaid rather than placed beside the page, so they stay within
+					     reach of the text. They sit in foliate's own page margin. -->
+					<Button
+						variant="ghost"
+						size="icon"
+						class="absolute top-1/2 left-1 size-10 -translate-y-1/2 opacity-40 transition-opacity hover:opacity-100"
+						onclick={() => viewer?.goBack()}
+						aria-label="Previous page"
+					>
+						<ChevronLeft class="size-5" />
+					</Button>
 
 					<Button
 						variant="ghost"
 						size="icon"
-					class="my-auto size-10 shrink-0"
+						class="absolute top-1/2 right-1 size-10 -translate-y-1/2 opacity-40 transition-opacity hover:opacity-100"
 						onclick={() => viewer?.goForward()}
 						aria-label="Next page"
 					>
 						<ChevronRight class="size-5" />
 					</Button>
 				</div>
+			</div>
 		{/if}
 	</main>
 </Sidebar.Provider>

frontend/src/lib/components/reader/foliate-view.svelte

@@ -48,6 +48,20 @@
 	// Reactive so the effects below re-run once the book is open — otherwise a
 	// theme flip while it was still loading would never reach the book.
 	let ready = $state(false);
+	let hostWidth = $state(0);
+
+	/**
+	 * How many columns the paginator will actually lay out.
+	 *
+	 * It decides this internally and exposes it only as a custom property inside
+	 * its shadow root, so the formula is mirrored here to place the spread
+	 * divider. Kept in step with paginator.js's `divisor`.
+	 */
+	const columns = $derived(
+		settings.flow === 'scrolled' || hostWidth === 0
+			? 1
+			: Math.min(settings.maxColumnCount, Math.ceil(hostWidth / settings.maxInlineSize))
+	);
 
 	/**
 	 * Where to resume from.
@@ -130,6 +144,11 @@
 	onMount(() => {
 		let disposed = false;
 
+		const resizeObserver = new ResizeObserver(([entry]) => {
+			hostWidth = entry.contentRect.width;
+		});
+		if (container) resizeObserver.observe(container);
+
 		(async () => {
 			try {
 				await loadFoliate();
@@ -180,6 +199,7 @@
 
 		return () => {
 			disposed = true;
+			resizeObserver.disconnect();
 			for (const { doc } of view?.renderer?.getContents?.() ?? []) {
 				doc.removeEventListener('keydown', onKeydown);
 			}
@@ -211,9 +231,25 @@
 	});
 </script>
 
-<svelte:window {onkeydown} />
+<!--
+	Not {onkeydown}: that shorthand resolves to the global window.onkeydown
+	property, which TypeScript accepts and which is null at runtime, so the
+	handler silently never ran and arrows only worked once the book had focus.
+-->
+<svelte:window onkeydown={onKeydown} />
 
-<div bind:this={container} class="foliate-host"></div>
+<div class="relative h-full w-full">
+	<div bind:this={container} class="foliate-host"></div>
+
+	{#if ready && columns === 2}
+		<!-- The gutter between the two pages of a spread. Sits in the column gap,
+		     so it never crosses text. -->
+		<div
+			aria-hidden="true"
+			class="pointer-events-none absolute inset-y-[6%] left-1/2 w-px -translate-x-1/2 bg-border"
+		></div>
+	{/if}
+</div>
 
 <style>
 	/* foliate-view extends bare HTMLElement, so it has no default display. */

frontend/src/lib/reader/settings.ts

@@ -12,7 +12,10 @@ export const DEFAULT_READER_SETTINGS: ReaderSettings = {
 	letterSpacing: 0,
 	margin: 48,
 	gap: 6,
-	maxInlineSize: 720,
+	// foliate caps the reading area at this times the column count, so 1000 gives
+	// a 2000px spread — enough to fill a large display rather than leaving the
+	// book as a narrow strip. Its own default of 720 is noticeably tight.
+	maxInlineSize: 1000,
 	maxColumnCount: 2,
 	flow: 'paginated',
 	justify: true,
@@ -30,7 +33,7 @@ export const READER_BOUNDS = {
 	letterSpacing: { min: -0.05, max: 0.2, step: 0.01 },
 	margin: { min: 0, max: 120, step: 4 },
 	gap: { min: 0, max: 15, step: 1 },
-	maxInlineSize: { min: 480, max: 1400, step: 20 }
+	maxInlineSize: { min: 400, max: 2400, step: 20 }
 } as const;
 
 /**

frontend/src/lib/reader/stylesheet.ts

@@ -35,43 +35,37 @@ export function readReaderPalette(dark: boolean): ReaderPalette {
 	};
 }
 
+/** Body-text containers. Headings are excluded so their scale survives. */
+const TEXT = 'p, li, dd, dt, blockquote, td, th, div';
+
+const HEADINGS = 'h1, h2, h3, h4, h5, h6';
+
 /**
  * Builds the two stylesheets foliate injects into each section document.
  *
  * The paginator creates two <style> elements per document: the first is
  * head.prepend()ed, so the book's own CSS overrides it; the second is
- * head.append()ed, so it wins on equal specificity. setStyles accepts the pair
+ * head.append()ed, so it wins. setStyles takes the pair as a tuple and
- * as a tuple and re-applies it on every section load.
+ * re-applies it on every section load.
  *
- * The split is the point. Typography goes in `before` so a book that styles its
+ * Nearly everything goes in `after`, with !important. These are the reader's
- * own headings still gets to; colour goes in `after` because most EPUBs set a
+ * settings, and EPUBs routinely set their own font-family, font-size and
- * body background and would otherwise leave the page white against a dark UI.
+ * line-height on body and on paragraphs — put the settings in `before` and the
+ * book simply overrides them, which is what made the typography controls look
+ * like they did nothing.
+ *
+ * `before` is left for the few defaults a book should be free to override.
  */
 export function buildReaderStyles(
 	s: ReaderSettings,
 	p: ReaderPalette
 ): [before: string, after: string] {
+	const hyphens = s.hyphenate ? 'auto' : 'manual';
+
 	const before = `
 		@namespace epub "http://www.idpf.org/2007/ops";
 
-		/* On html, not body, and without !important: the book's rem/em headings
+		${TEXT} {
-		   then scale with the setting instead of being flattened to one size. */
-		html {
-			font-size: ${s.fontSize}px;
-		}
-
-		body {
-			font-family: ${s.fontFamily};
-			font-weight: ${s.fontWeight};
-			line-height: ${s.lineHeight};
-			letter-spacing: ${s.letterSpacing}em;
-		}
-
-		p, li, blockquote, dd, div {
-			line-height: ${s.lineHeight};
-			text-align: ${s.justify ? 'justify' : 'start'};
-			-webkit-hyphens: ${s.hyphenate ? 'auto' : 'manual'};
-			hyphens: ${s.hyphenate ? 'auto' : 'manual'};
 			-webkit-hyphenate-limit-before: 3;
 			-webkit-hyphenate-limit-after: 2;
 			-webkit-hyphenate-limit-lines: 2;
@@ -80,18 +74,50 @@ export function buildReaderStyles(
 			orphans: 2;
 		}
 
-		/* Justification must not silently override an explicit align attribute. */
-		[align="left"] { text-align: left; }
-		[align="right"] { text-align: right; }
-		[align="center"] { text-align: center; }
-		[align="justify"] { text-align: justify; }
-
 		pre {
 			white-space: pre-wrap;
 		}
 	`;
 
 	const after = `
+		/* The rem base. Headings sized in em/rem keep their scale relative to it. */
+		html {
+			font-size: ${s.fontSize}px !important;
+		}
+
+		body {
+			font-size: 1rem !important;
+			font-weight: ${s.fontWeight} !important;
+		}
+
+		/* inherit rather than a fixed size: books that set an absolute size in pt
+		   or px on their paragraphs would otherwise ignore the size setting
+		   entirely, while headings keep whatever relative scale they declare. */
+		${TEXT} {
+			font-size: inherit !important;
+		}
+
+		body, ${TEXT}, ${HEADINGS}, figcaption, caption {
+			font-family: ${s.fontFamily} !important;
+		}
+
+		body, ${TEXT} {
+			line-height: ${s.lineHeight} !important;
+			letter-spacing: ${s.letterSpacing}em !important;
+		}
+
+		p, li, dd, blockquote {
+			text-align: ${s.justify ? 'justify' : 'start'} !important;
+			-webkit-hyphens: ${hyphens} !important;
+			hyphens: ${hyphens} !important;
+		}
+
+		/* Justification must not silently override an explicit align attribute. */
+		[align="left"] { text-align: left !important; }
+		[align="right"] { text-align: right !important; }
+		[align="center"] { text-align: center !important; }
+		[align="justify"] { text-align: justify !important; }
+
 		/* Tells the book's own prefers-color-scheme rules which way we are going.
 		   Without it the paginator's media query follows the OS, so a book with
 		   dark styles can invert against the app. */
@@ -99,15 +125,14 @@ export function buildReaderStyles(
 			color-scheme: ${p.dark ? 'dark' : 'light'};
 		}
 
-		/* !important only here. Most EPUBs set their own body background and
+		/* Most EPUBs set their own body background and colour, so an
-		   colour, and an unprioritised override loses to them. */
+		   unprioritised override loses to them and the page stays white. */
 		html, body {
 			background: ${p.bg} !important;
 			color: ${p.fg} !important;
 		}
 
-		p, div, span, li, td, th, dl, dd, dt,
+		${TEXT}, ${HEADINGS}, span, dl, figcaption, caption {
-		h1, h2, h3, h4, h5, h6, blockquote, figcaption {
 			color: ${p.fg} !important;
 		}
 

frontend/src/lib/schema/reader.ts

@@ -22,8 +22,12 @@ export const readerSettingsSchema = z.object({
 	margin: z.number().int().min(0).max(120),
 	/** % of the viewport, the space between columns. */
 	gap: z.number().int().min(0).max(15),
-	/** px, the maximum width of a single column. */
+	/**
-	maxInlineSize: z.number().int().min(480).max(1400),
+	 * px, the maximum width of a single column. foliate caps the whole reading
+	 * area at this times the column count, so on a wide screen it is what decides
+	 * how much of the window the book actually uses.
+	 */
+	maxInlineSize: z.number().int().min(400).max(2400),
 	/** 1 for a single page, 2 for a spread. Reflowable books only. */
 	maxColumnCount: z.number().int().min(1).max(2),
 	flow: readerFlowSchema,