In a reflowable book you do not control the page. The reader does. They pick the typeface, the size, the margins, the line spacing, the background colour and whether they are holding a phone or a six-inch e-ink screen. Your job, and ours, is to build an interior that still looks deliberate in every one of those combinations, including the ones you would never choose.
Reflowable means the text is poured, not placed. There is no page in the file, only a stream of content that a reading system arranges to fit whatever screen it finds itself on. Change the type size and the words rearrange. Rotate the device and they rearrange again. What you deliver is not a layout. It is a set of relationships that have to survive being rearranged.
This is why a beautifully designed print interior cannot simply be copied across. A drop cap that sits perfectly three lines deep at your settings will collide with the paragraph at somebody else's. An ornament centred on a page will orphan at the top of a screen. A photograph sized in pixels will fill a phone entirely and push your prose out of sight.
Reflowable EPUB formatting is the craft of designing something that holds its shape while its shape is being changed by a stranger. Everything is proportional. Everything has a fallback. And the only way to know that it works is to sit down with the book on real hardware and turn every dial the reader can turn.
Every reading system gives readers control over type size, typeface, line spacing, margins, screen brightness and background theme. Many of them also offer a switch, usually buried, that discards the publisher stylesheet entirely and renders the book in the reader's own defaults. A surprising number of people leave it on without knowing what it does.
A book formatted for one set of those settings is not really a book. It is a screenshot that happens to scroll. We build for the whole space of settings, and we check the corners of it, because that is where readers actually live and where one-star reviews are written.
The same interior has to work at 8 points on a phone and at 28 points on an e-ink reader with poor eyesight behind it. Anything measured absolutely fails at one end or the other.
A black ornament on a transparent background disappears entirely in night mode. So does a scanned diagram with a white surround, which now sits in the text as a glowing rectangle.
The reader discards your stylesheet. What is left is the structure alone. If your chapter openers were only styling, the book collapses into an undifferentiated wall of text.
Everything below is aimed at one thing: the book still behaving when somebody changes something.
Type scale, leading, indents, spacing above and below headings, and the depth of every chapter opener are all expressed relative to the body text. When a reader doubles the type size, the whole interior grows together in proportion instead of a chapter title staying stubbornly small while the prose swells around it.
Drop capitals are the most inconsistently supported thing in eBook typography. Ours are built so that a reading system which cannot float the letter renders a large, deliberate initial instead of a broken overlap. You get the effect where it works and something intentional everywhere else.
A scene break made of blank lines vanishes when it falls at the foot of a screen, and the reader loses the shift in time or point of view completely. Ours are real styled elements, with spacing that holds and a rule preventing them from being stranded alone at a screen edge.
Every picture is sized as a percentage of the viewport with a height cap, so a diagram takes a sensible portion of a phone and a sensible portion of a tablet without two separate files. Line art gets a background so it survives dark mode instead of dissolving into it.
You cannot control where lines fall in a reflowable book, but you can stop a heading being left alone at the bottom of a screen with its first paragraph on the next. The rules that do this are honoured unevenly, so we set them and then verify what each reading system actually did.
Justified text on a narrow e-ink screen with hyphenation switched off produces rivers of white space wide enough to drive through. We set the language attribute, allow hyphenation properly, and choose the alignment that suits your book rather than defaulting to whatever the tool did.
Six recent books, each one read at six reader settings before it was allowed out.
This is the real trade in a reflowable book, and it is better faced at the start than discovered at the proof. Every piece of control you keep is one the reader loses, and readers notice when they lose it.
Embedded fonts, a strong type scale, elaborate chapter openers, ornamental rules. Everything can be built, and on a good tablet it looks exactly as intended.
The cost is that any reader who prefers their own typeface, or who reads at 26 points, or who has publisher styling switched off, sees a book you never designed. The tighter the design, the further it is from what some of your audience will actually see.
A restrained, proportional interior that is defined by structure rather than by ornament. Chapter openers, breaks and hierarchy remain clear at any size, in any theme, with any typeface, and with the stylesheet discarded entirely.
It gives up a little grandeur at the top end and gains a book that is never embarrassing. For prose fiction and most nonfiction this is the right answer, and we will argue for it.
Six failures that are invisible at the settings a book was designed at, and unmistakable at everybody else's.
Eight decisions, made the same way on every book, each one aimed at surviving a setting we do not control.
| Element | How we build it | Why it matters |
|---|---|---|
| Body text sizing | Set at 1em with a line height between 1.4 and 1.6 and no absolute unit anywhere in the cascade. | Any fixed size overrides the reader's preference. That is not a stylistic disagreement, it is an accessibility failure, and it is the fastest route to a review about eye strain. |
| Chapter opener depth | Space above a chapter title is set in em units, so it grows with the type rather than staying a fixed gap around enormous letters. | A fixed opener gap looks generous at 12 points and looks like a mistake at 26, where the title fills the screen and the space above it has not moved. |
| Drop capitals | Built with a float and a line-height ratio tied to the body text, with a large-initial fallback declared for systems that ignore the float. | Drop-cap support is the most inconsistent thing in eBook CSS. Without a fallback, the letter overlaps the second line and the paragraph is unreadable. |
| Scene breaks | A styled block element carrying an ornament or spaced asterisks, with margins in em units and rules against being orphaned at a screen edge. | Empty lines are collapsed by reading systems and disappear at screen boundaries. The reader then misses a change of scene, and the book stops making sense. |
| Images | Width set as a percentage of the viewport with a maximum height in viewport units, exported at twice the target density, alt text attached. | A percentage-sized image behaves correctly on a phone and a tablet from a single file. A pixel-sized one is right on exactly one device and wrong on the rest. |
| Dark mode behaviour | Colour declared rather than assumed, transparent line art given a background panel, and every image checked against a black theme. | Reading systems invert the background, not your artwork. Anything that relied on the page being white will vanish or glow, and no validator will mention it. |
| Justification and hyphenation | Language declared in the package and in the markup, hyphenation enabled, and alignment chosen per book rather than left at the default. | Justified text without hyphenation on a narrow e-ink column produces rivers of whitespace. The language attribute is what lets the device hyphenate at all. |
| Widow and orphan control | Break rules applied to headings, subheadings and captions so they stay attached to what follows them. | Support varies by reading system, so the rules are set and then the behaviour is checked on hardware rather than assumed. Set and unverified is the same as not set. |
Six configurations, all of them real, all of them chosen by real readers. Your book is opened in every one before it reaches you.
Everything that was going to break breaks here. Chapter openers overflow, drop caps collide, tables burst their columns and images crowd out the prose. If a book survives its largest setting, most of the rest of the range is already safe.
The opposite extreme, and it fails differently. Ornaments become specks, indents disappear into the margin, and the type scale between a heading and body text compresses until the hierarchy stops being visible at all.
The background is inverted by the reading system and your images are not. Black line art disappears, scanned signatures glow, and any colour you chose against a white page is now being asked to work against a black one.
A setting many readers use without knowing it exists. Your stylesheet is discarded and only the structure remains. A book built on real semantics still reads correctly. A book built on visual styling collapses into one long undifferentiated column.
Justification, hyphenation and image dithering all fail first on e-ink. It is also where a heavy interior makes page turns sluggish, which readers describe as the book feeling broken even when they cannot say why.
Reflowable is the only format where assistive technology works properly, and that only holds if the structure is real. Reading order, heading levels, alt text and language tags are stepped through with a screen reader rather than assumed.
The book, the source it was built from, and a written account of how it behaves where you cannot see it.
A validated, hand-coded reflowable file that uploads to every store taking EPUB. Proportional throughout, with no absolute sizing anywhere, and built so that the reader can do whatever they like to it without the book falling apart.
A short, deliberate stylesheet you could open and understand. Every rule is there for a reason and the reason is written beside it. This is what makes changing an ornament in three years cost an hour rather than a rebuild.
A written record of how your book renders at each of the six settings we test, including anything a specific reading system does differently and what we did about it. No surprises arriving later from a reviewer.
Amazon reinterprets a good deal of reflowable CSS during ingestion, particularly around margins and fonts. We build the derived file and look at it, so you approve Amazon's version of your typography before your readers meet it.
Every interior image re-exported at high density, sized proportionally, given alt text and checked against a dark background. Line art comes back with a panel behind it so it survives night mode.
One page explaining which decisions were made for reflow and why, which effects were deliberately kept restrained, and what would change if you ever moved the book to a fixed layout.
Five stages. The last one is the one nobody else does properly, and it is the reason the others matter.
We go through the book looking for everything that has to survive reflow: chapter openers, scene breaks, epigraphs, letters, dream sequences, verse, block quotes. Each one becomes a named element rather than a visual effect, because only named things can be rebuilt at another size.
The type scale, the leading, the indents and the spacing are all defined relative to the body text. Nothing is chosen in pixels, and nothing is chosen because it looked right on the monitor it was designed on.
The markup is written, the stylesheet is written, the ornaments are drawn or chosen, the drop caps are built with their fallbacks, and the images go through the pipeline and come out proportional and dark-mode safe.
The book is opened on real hardware and read at the largest and smallest type sizes, in night mode, in sepia, with the reader's own font forced, with publisher styling off, and in landscape. Everything that misbehaves is fixed in the stylesheet.
You read the proof on your own device, at your own settings. Two rounds of notes are worked through, EPUBCheck runs to zero errors, and the master, the source, the images and the settings report are delivered.
Pricing follows word count, because the length of the book determines how much of it has to be read back at each reader setting. The typographic ambition of the interior adjusts it from there.
Required steps are marked with *. Optional extras can be removed from the summary with the cross icon.
What kind of reading experience we are building. This sets how many distinct elements have to survive reflow.
The word count of the finished manuscript, front and back matter included.
How much typographic ambition the interior carries, and which files you want alongside the reflowable master.
How many different kinds of element are in the book. Every distinct one needs its own class and its own pass at six reader settings.
How many pictures sit inside. Each one has to scale proportionally and survive a dark background.
Standard is the pace at which the whole settings matrix can be run. Faster tiers buy queue position, never fewer checks.
Two rounds are included. On a reflowable book they are usually about taste, because the behaviour was settled during testing.
This covers the reflowable interior and how it behaves. Editing, proofreading, cover artwork, ISBN registration and uploading to your retailer accounts sit outside it. We do not change a word of your text, only the structure that carries it.
Both files look correct on the machine they were made on. Only one of them is still correct in a stranger's hands.
| What you are comparing | Formatted for the Designer's Screen | Book Formatting Experts |
|---|---|---|
| Type sizing | ✕ Fixed pixel values, so the reader's own size preference is overridden and low-vision readers are locked out entirely. | ✓ Everything relative to the body text, so the interior scales in proportion whenever the reader changes anything. |
| Drop caps | ✕ A float with a fixed offset. Correct at exactly one type size, colliding with the second line at every other. | ✓ Built proportionally with a declared fallback, so it either works or degrades into a deliberate large initial. |
| Scene breaks | ✕ Blank lines, which reading systems collapse and screen edges swallow. The reader misses the break entirely. | ✓ Real styled elements with proportional spacing and rules preventing them from being orphaned at a screen boundary. |
| Dark mode | ✕ Never opened in it. Black line art vanishes and white-backed scans glow in the middle of the prose. | ✓ Checked against a black theme, with every transparent image given a treatment that keeps it visible. |
| Publisher styling off | ✕ Never tested. The book collapses into a single undifferentiated column, because the hierarchy was only ever visual. | ✓ Read in that state deliberately. The structure is real, so the hierarchy survives with the stylesheet gone. |
| What testing means | ✕ Opened once in a desktop previewer at the default settings and pronounced finished. | ✓ Read on real hardware at both type extremes, in two themes, with the reader's font forced, and in landscape. |
Every genre stresses a different part of the reading experience.
Hours of continuous reading, which means the small things compound. An indent that is fractionally wrong, a scene break that occasionally vanishes, a chapter opener that swells oddly at large type. Individually invisible, and together they are what readers mean when they say a book felt cheap.
Callouts, frameworks, numbered steps and boxed exercises. Reflow removes the concept of beside, so every sidebar becomes an interruption in the flow, and it has to remain visibly different from the body text even when the reader has discarded your stylesheet.
The hardest thing to reflow. The line is the unit of meaning, and reflow wants to reflow it. Verse needs real line-level markup and a hanging indent for runover lines, so that at 26 points a long line wraps under itself rather than passing itself off as a new one.
Letters, journal entries, quoted documents and photographs, each of which has to read as different from the narrative at any type size. The photographs are usually the problem, because they arrive as scans that vanish or glow the moment somebody switches to night mode.
Footnotes that must link both ways through a book with no pages, tables that have to fold gracefully onto a phone, and figure captions that must stay attached to their figures through every reflow the reader triggers.
Larger type by default, frequent illustration and short chapters. The trap is that the reader may enlarge the type further still, at which point a picture sized for a comfortable ratio suddenly dwarfs the two sentences it was illustrating.
A reflowable book cannot be checked by looking at it once. It has no single appearance to check. It has a range of appearances, and the only honest way to know it works is to go to the edges of that range and read what is there.
So we do. Largest type, smallest type, night mode, sepia, reader font forced, publisher styling off. It is slow and it is the whole point, because your reader will pick one of those settings on their first evening with the book and never think about it again.
One fixed pixel value in the stylesheet is enough to override a reader's own choice. It is the single most common fault in eBook CSS and the one with the worst consequences for the people it affects.
Drop caps, ornaments, embedded fonts and break rules are all supported unevenly. Build them so that failure is a plain, deliberate outcome rather than a visible mess.
Turn your CSS off and read what is left. If the chapter openers, the breaks and the hierarchy are still legible, the book is built properly. If it collapses, the design was decoration on top of nothing.
Twelve checks, run at the extremes of the reader settings rather than at the defaults.
Six situations where the reading experience, rather than the file, is what has gone wrong.
The story is fine and the reviews are still complaining. Almost always this is a reader setting you never tried: a size, a theme or a font override at which your interior stops behaving. It is fixable, and the fix is usually cheaper than the damage already done.
Someone has written to say they cannot enlarge the type, or that it enlarges and the layout falls apart. There is a fixed pixel value in your stylesheet, and until it comes out, a substantial part of your potential audience simply cannot read you.
The prose has been worked on for years and you are not prepared for it to arrive on a screen looking like a printout. Reflowable typography is a real craft, and the difference between careless and considered is felt over hours rather than seen in a screenshot.
Drop caps, ornaments, real scene breaks and a proper type scale, but built so that they still hold when the reader takes over. This is possible. It just cannot be done by copying the print interior across.
They will check whether your book is genuinely readable with assistive technology, and a reflowable file with real structure is the only kind that passes. Fixed layout and visual-only hierarchy both fail, and they fail before anyone reads a word.
Kindle, Apple Books, Kobo, Nook, Google Play, library platforms, and every one of them with a different renderer and a different set of reader controls. A book built for one of them is a book that disappoints on the other five.
Three promises, each of which you can test yourself in about ten minutes.
Open the stylesheet we deliver and search it. You will not find an absolute font size. Every reader keeps full control of the type, which is the one thing a reflowable book must never take away.
Set your device to its largest type size and then its smallest, and read a chapter at each. If anything in a book we built collides, vanishes or falls apart, tell us and we will fix it, whenever you find it.
Switch publisher styling off and read. The hierarchy is still there, because it was built into the structure rather than painted on top of it. That is the test that separates a formatted book from a decorated one.
Three principles that settle nearly every argument during a build.
They read at 22 points in night mode on a five-year-old e-reader with your typeface stripped out. They are not a fringe case, they are thousands of people, and the book has to be good for them too.
Nothing in a reflowable book can be placed. Everything has to be related to something else, so that when the reader changes one thing, everything else moves with it rather than against it.
The interiors that still look right in five years are the restrained ones. Elaborate effects depend on support that changes, and every one of them is a thing that can break in a stranger's hands.
Three tests, applied to every element before it is allowed into the book.
Take the type from smallest to largest and watch what this element does. If it grows in proportion with everything around it, it stays. If it holds still while the text swells past it, it is rebuilt in relative units.
Turn off the support it depends on. A drop cap that cannot float, an embedded font that is stripped, a break rule that is ignored. What is left has to look like a decision, not like an accident.
Discard the CSS entirely and read what remains. If a scene break, a chapter opener or a pull quote disappears at that point, it was never structure. It was decoration, and it gets rebuilt as structure.
Rated 4.9 out of 5 across 174 reviewed projects.
I had already paid someone else to format this book once. The chapter headings shifted every time a reader changed the font size and I only found out from a review. This team rebuilt the interior from the structure up and sent me photographs from four real devices before I uploaded anything. First launch day I have not spent refreshing the reviews in a panic.
What sold me was the audit. They came back and told me two chapters had been pasted in from another document and were carrying invisible styles, and that fixing that first would save me money later. Nobody had mentioned it in three years of self-publishing. The proof needed no corrections at all.
My book has footnotes, tables and two appendices, and every quote I got either ignored that or doubled the price because of it. Here the pricing was laid out step by step and I could see what each element cost before I committed. It arrived early and the notes link both ways, which nobody else had even offered.
The proof came back from the printer with the margins exactly where they should be, the running heads correct, and not one chapter opening on a left-hand page. This is my fourth book and the first time I have not had to pay for a second proof copy.
English is my second language and I was nervous about the back and forth. Everything was explained plainly, and when I asked the same question twice they answered as if it were the first time. The revisions were turned round inside two days and I was never made to feel like a nuisance.
I write cookbooks, so the interior is the product. Ingredients have to sit beside the method or the recipe stops working, and the last person I hired reflowed the whole thing into nonsense. These people understood the problem before I had finished describing it and the finished layout is genuinely beautiful.
Straightforward from beginning to end. A fixed price, a delivery window they actually hit, and files that went up to KDP and IngramSpark without a single rejection. I have since sent them two more titles and recommended them to my writing group without hesitation.
My memoir has photographs and I had resigned myself to them looking muddy. They optimised every image, told me honestly which two were too low-resolution to save, and suggested crops instead of shrugging. That candour is worth more to me than the discount I was chasing elsewhere.
I sent them a 480-page reference book with a nightmare of cross-references and a table on nearly every spread. They quoted it accurately, they did not come back later asking for more money, and the index still works. Any author will tell you what that is worth.
The questions authors actually ask us, answered without sales language.
Reflowable EPUB formatting builds a book as a stream of structured content rather than as a set of pages. The reading system arranges the text to fit whatever screen it lands on, and the reader controls the typeface, the size, the margins, the spacing and the background. Fixed layout does the opposite: every element is placed on a canvas of a known size and nothing moves. Reflowable is right for nearly all prose. Fixed layout is right when the relationship between image and word on a page is the point of the book.
Because they own the reading experience and the specification is built around that. This is not a flaw to be worked around, it is the reason eBooks are readable by people who cannot read print. A reader with low vision sets the type to 26 points. A commuter reads at 11 on a phone. Someone with dyslexia switches to their preferred typeface. Your interior has to be good in all three situations, and any design that only works at your settings has quietly excluded a lot of people.
The things that were measured rather than related. A chapter opener with a fixed gap above it keeps that gap while the title swells to fill the screen. A drop cap with a fixed offset collides with the second line. An image sized in pixels stays the same while the text around it doubles, so it shrinks into insignificance or, on a phone, dominates everything. A table bursts its columns. Everything we build is expressed relative to the body text precisely so that none of this happens.
By building them proportionally and giving them somewhere to fall. A drop cap is a floated letter whose height is tied to the line height of the body text, so it stays three lines deep whatever size the reader chooses. Support for that float is genuinely inconsistent, so we declare a fallback: on a system that will not float it, the reader gets a large, deliberate initial capital instead of a letter overlapping the sentence. You get the effect where it works, and something intentional everywhere else.
They will if they are real elements rather than empty lines, which is the mistake almost every do-it-yourself interior makes. Blank lines get collapsed by reading systems and swallowed at screen boundaries, so the reader turns a page, finds a new scene underway and never registers that anything shifted. We build breaks as styled blocks with proportional spacing, and we set rules that prevent them being stranded alone at the foot of a screen, then we check what each reading system actually did with those rules.
It works, but your images may not, and no validator will ever tell you. The reading system inverts the background and leaves your artwork alone. Black line art on a transparent background disappears completely against a black page. A scanned signature or diagram with a white surround becomes a glowing white rectangle sitting in the middle of your prose. We check every image against a dark theme and give the ones that need it a background treatment, so the book is legible whichever way round your reader has it.
A relative unit expresses a measurement as a ratio of something else, usually the body text size, rather than as a fixed number of pixels. Set an indent at 1.2em and it grows when the reader grows the type. Set it at 20 pixels and it does not, so at a large size it becomes an invisible nudge and at a small size an enormous gutter. The same logic applies to every space, every heading and every ornament. A reflowable book with fixed measurements in it is not really reflowable, it is a layout that happens to rearrange.
Partly, and honesty is required here. You cannot control where lines fall, because you do not control the screen or the type size, so a widow at the bottom of one reader's screen is mid-paragraph on another's. What you can control is whether a heading is allowed to be left alone at the foot of a screen with its first paragraph on the next, and whether a caption can be separated from its figure. Those rules exist, they are honoured unevenly, and we set them and then verify on hardware what each system actually did.
They do not flow around anything, and it is better to accept that early. Text wrap in a reflowable book is unreliable and looks wrong the moment the reader changes anything. Instead, images sit in the flow as blocks, sized as a percentage of the viewport with a cap on their height, so they occupy a sensible proportion of a phone and a sensible proportion of a tablet from a single file. Where a picture genuinely needs to stand alone, it gets its own break, so it never lands halfway through a sentence.
Most reading systems have a setting, usually not prominent, that discards the book's stylesheet and renders it in the reader's own defaults. Plenty of people leave it on without ever knowing what it does. When it is on, everything you paid for in the visual design is gone, and only the structure remains. A book built on real semantics still reads correctly, because a heading is still a heading. A book built on visual styling collapses into one long undifferentiated column of text. We read every book in that state before delivery.
It depends on whether the picture explains the words or is the point of the page. A cookbook where each photograph illustrates a recipe usually works reflowably, and it should, because readers hold cookbooks on phones in kitchens and need to enlarge the ingredients. A cookbook where the food photography bleeds across a spread with type placed on it will not survive reflow, and forcing it to is a slow way to ruin the design. We will look at your book and argue for one, with reasons.
Carefully, because e-ink is where this fails hardest. A narrow column, justified, with hyphenation disabled, produces rivers of white space wide enough to distract from the sentence. The device can only hyphenate if the language is declared, and a surprising number of eBooks never declare it. We set the language attribute in the package and in the markup, enable hyphenation properly, and then choose between justified and ragged-right per book after looking at it on an actual e-ink screen rather than guessing.
Where the licence permits embedding, yes, and with two caveats worth knowing before you get attached to the idea. Some reading systems strip embedded fonts in some contexts, so a fallback stack has to sit behind every family or your reader gets whatever the device felt like. And many readers override your typeface with their own preference regardless, which they are entitled to do. Your interior therefore has to look intentional in your typeface and in theirs, which means the hierarchy cannot depend on the font.
Because Amazon converts your EPUB into its own internal format during ingestion, and that conversion reinterprets a good deal of reflowable CSS, particularly around margins, indents and fonts. It is not a fault in your file, it is the platform. The answer is to write the interior so it degrades sensibly rather than depending on any single rule being honoured, and then to look at the converted file in Kindle Previewer before publishing so you know exactly which of your decisions Amazon has overruled.
First by asking whether it needs to be a table, because a great many are lists wearing a grid and behave far better as lists. Where the data is genuinely tabular, it is built as a real table with header cells and then read at the largest type size on the narrowest screen we own, which is the moment of truth. If it bursts, we restructure it into a stacked, labelled form where each row becomes a small block. A reader who gets the data beats a reader who gets a horizontal scroll bar.
It is the only format that works properly. A screen reader needs real structure to follow, and a reader with low vision needs to be able to enlarge the text without the layout collapsing. Both of those are exactly what a well-built reflowable book provides and exactly what a fixed layout cannot, since fixed layout is a picture of a page. This is also why libraries, universities and several jurisdictions now require reflowable, structurally sound files before they will buy a title at all.
Left to itself, it is destroyed, and this is the case we care most about getting right. Reflow wants to treat a line as a fragment of a paragraph, but in verse the line is the unit of meaning. We set poetry as real line-level markup, so each line is a line, and we give runover lines a hanging indent, so that when a reader enlarges the type a long line wraps beneath itself as an obvious continuation rather than masquerading as the next line of the poem.
It can look considered, coherent and clearly designed, and at a good tablet at sensible settings it can look genuinely beautiful. What it cannot do is look identical for everyone, because everyone is holding a different page. The right ambition is not to reproduce the print interior but to carry its character into a form the reader controls. Books that try to reproduce a printed page inside a reflowable file end up worse than either, and that is the mistake we spend most of our time talking authors out of.
It tells you what your readers are actually seeing, which you otherwise have no way of knowing. It records how the book renders at each setting we test, on each device we test on: largest and smallest type, night mode, sepia, reader font forced, publisher styling off, landscape. Where a particular reading system does something unusual, that is noted along with what we did about it. It is the difference between hoping your book behaves and being able to point at evidence that it does.
Yes. Rescuing a reflow that has gone wrong is a steady part of our week. Send us the file and tell us what you or your readers have noticed. Most of these repairs come down to a small number of causes: absolute sizing in the stylesheet, drop caps or ornaments with no fallback, images sized in pixels, blank lines standing in for scene breaks, and a stylesheet so bloated by a converter that nothing in it can be reasoned about. All of them are fixable, and usually for considerably less than a rebuild.
We will read it, tell you which effects will hold at every reader setting and which ones will let you down, and give you a fixed price and a real date. If your book wants restraint rather than ornament, we will say so.