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Web Compatibility issues change over time. Bugs that were common in 2005 are not often seen in the present. This list represents the most common issues currently being discovered by the webcompat community and will be updated as these change in the future.


Current Popular Issues

(This needs to be adjusted).

Bugzilla WebCompat Core Bug

Full Query
ID Summary Priority Status
47710 Overflowed content does not take into account inner padding and content margins -- REOPENED
91370 Implement setting cssText on various CSSRule implementations P3 NEW
102695 [EVENTTARG]Treat some transparent elements as "transparent to events" P3 NEW
129432 'onkeypress', 'onkeydown', onkeyup' not working on FORM,LEGEND,OPTGROUP,OPTION -- NEW
137687 Computed CSSDeclarations need to implement GetCssText P3 NEW
162369 scrolling to named anchor doesn't consider areas covered by fixed positioned elements -- NEW
307866 min-width/min-height/max-width/max-height does not work for table elements -- NEW
406488 Copy highlighted text to clipboard ignores non-inlined CSS styling when pasting as rich text (to HTML editors, MS Word, Excel, Outlook etc.) -- NEW
477157 Borders scale differently than other sizes (e.g. margins, content-sizes, backgrounds), under full-page-zoom or HiDPI -- NEW
562499 positioned children inside <button> do not propagate events to it -- NEW
568313 Impossible to make <button>s draggable -- NEW
612118 SVGLocatable.getBBox() fails unless the SVG element it is applied to is attached and rendered -- NEW
616436 [meta] Implement column-span (from CSS3 multicolumn) P2 NEW
688556 Background of cell paints over border when borders are collapsed and tbody, row, or cell is relatively positioned P3 NEW
695868 Unable to set document.body.innerHTML of IFrame P3 NEW
697151 Synchronous XMLHttpRequest (XHR) does not block readyState events for async XHR P5 NEW
836897 Implement the WebMIDI API P3 NEW
876985 flex items with flex-basis:auto and width:auto should get sized as max-content -- ASSIGNED
1005603 When possible, <input type=number> should preserve the formatting of the 'value' attribute or any string assigned to input.value P3 ASSIGNED
1034018 outline: auto is not applied in the same way as it is on blink P3 NEW
1043118 Do not select trailing spaces on double clicking. P3 NEW
1099204 Textarea text scrolls under padding instead of over -- REOPENED
1118710 SVG mask animation is not working P2 NEW
1136312 update to match flexbox spec language on "min-width:auto" & items with intrinsic aspect ratios -- NEW
1183449 SVG element with CSS transform and stroke renders at wrong position, probably because of rounding -- NEW
1199665 Consider making <input type=number> always fall back to parsing numbers as English formatted numbers if parsing them as numbers formatted using the user's locale fails P2 ASSIGNED
1200585 when RecomputePosition optimization moves an element, we don't move fixed positioned elements whose hypothetical box comes from that element P3 NEW
1205133 Ship inputmode=numeric P3 NEW
1221416 Add support for styling the disclosure triangle of the <details> element using summary::marker -- NEW
1231147 SVG elements don't support CSS rem units for height/width attributes P3 UNCONFIRMED
1246727 "-moz-appearance: button" doesn't hide a <select>'s downarrow button, on Android -- NEW
1248570 Firefox can't play wav in video or audio element P3 NEW
1256980 "z-index" has an effect on transformed content in Firefox, but not in Edge/Safari/Chrome -- NEW
1273010 Blocky and slow rendering on Firefox Android Nightly - filter: drop-shadow() P3 ASSIGNED
1273836 Copy-Paste of simple HTML adds extra new lines that are not present in original content -- UNCONFIRMED
1274354 [meta] Date.parse, amirite P3 NEW
1289682 Relatively-positioned table-row behaves as absolute containing block in Firefox (unlike other engines) -- NEW
1291467 Implement contenteditable="plaintext-only" P3 NEW
1296042 Implement "word-break: break-word" P3 NEW
1304733 insertRule on cross domain style sheet throws an exception in FF but not Chrome, Edge, IE P3 NEW
1306590 percent "text-indent" values resolve against the wrong container box, for overflow:hidden elements (causing stray character to be visible at reddit) P3 NEW
1307024 [Perf] [google docs] Firefox will get 3~9% faster when running gdoc test cases with chrome user agent -- NEW
1307118 Firefox 49 Does not Show Events in Scoutbook Calendar (background color of text field not rendering) P3 NEW
1307678 Title of latest recommendation of is cut P3 NEW
1316534 [css-flexbox] A non-default "flex-basis" incorrectly prevents min-size:auto from being clamped by specified size -- NEW
1319215 The "Contre Jour" game does not start P3 NEW
1322694 WebGL video textures fail to render in Firefox Nightly for MP4 format with 2048x1024 pixels dimensions P3 UNCONFIRMED
1324307 Ensure that -moz-device-pixel-ratio behavior matches -webkit-device-pixel-ratio P3 NEW
1328474 background: 0 and -moz-appearance: none suppresses the checkmark on input checkbox -- NEW
1328475 Give "-moz-user-select:auto" special spec-defined inheritance-like computation behavior P3 NEW
1331793 Consider not throwing on querySelector("::-webkit-scrollbar") P3 NEW
1332959 RTL web pages are aligned on the left side when the viewport is too small for the content P3 NEW
1335627 In quirks mode, toplevel "height:calc(%)" is treated as "auto", unlike raw percent heights (which are honored) P3 NEW
1336245 Geolocation should return available low-res location when high-res location is not yet available P2 NEW
1337114 Diacritics rendered incorrectly with decomposed unicode and Proxima Nova P3 NEW
1338656 ES_texture_float extension seems to not be found on Android devices where Chrome finds it. P3 NEW
1340064 [viewport] user-scalable, min-scale and max-scale will be ignored starting with iOS10 P3 NEW
1342445 Bad panning and zooming performance and huge memory usage (>10GB) on P3 NEW
1342569 mouseenter/mouseleave fire differently on <select>s in e10s mode. P3 NEW
1343096 Inner/submenus on are broken P3 NEW
1353248 [e10s] select - options styling doesn't work properly if CSS selector :-moz-focusring is present P3 NEW
1362898 content with ::before gets painted at the wrong place -- NEW
1362907 option text in select element with min-height is top aligned instead of centered -- NEW
1365806 empty element has an offsetheight if given overflow-y:scroll, unlike other browsers P3 NEW
1371386 Firefox does not prefer Apple Color Emoji to Times New Roman on OSX, but Chrome/Safari do. P3 NEW
1372325 Allow the same SpeechSynthesisUtterance to be played multiple times in speechSynthesis.speak() P3 NEW
1373826 Wifi purchase form onboard IcelandAir broken (credit card textfields in flex container are too wide) P3 REOPENED
1375720 svg icons on GitHub are blurry (and unevenly so) P3 NEW
1376369 -moz-user-select:none triggers dragging also when @draggable="false" P3 NEW
1378447 Arrow buttons misaligned on mobile view of P3 NEW
1380217 Implement non-standard WheelEvent.wheelDelta properties P3 NEW
1381911 Bug 1359527 broke the radient gradient fade on P3 NEW
1382471 Firefox wraps word-broken text under a previous float-left, rather than starting it on the same line. P3 NEW
1385382 bullet with text-align:center is positioned further to the right in Firefox, as compared to other browsers (breaking fake radio button at P3 NEW
1385419 Parent element stretches to submit input's line-height, rather than its also-specified height. P3 NEW
1387483 [Meta-Bug] Support ReadableStream as Request.body in fetch API P2 NEW
1388931 Consider removing SVGPathSeg APIs P2 NEW
1390749 Flex item is extra-wide in Firefox, with "flex-basis: 100%; width: 100%" P3 NEW
1391109 tables inconsistently back-compute their intrinsic sizes from percent-sized cells (only when they're being *directly* intrinsically sized, but not inside intrinsically-sized container) P3 NEW
1391365 Roboto Android system font gets unexpectedly taller scrollHeight than clientHeight in some cases. P3 NEW
1392460 deltaMode default should be DOM_DELTA_PIXEL P2 NEW
1392669 Left menu text does not always appear on page load for the Canvas-based game at P3 NEW
1395964 Image flash when current source changes P2 NEW
1399019 Cannot play Facebook 360 video using Firefox P2 NEW
1400958 Text stomps on float with negative margin (with margin negative enough to zero out margin-box size) P3 NEW
1403410 Checkbox has 3 states – empty / outlined / with check-mark. P2 ASSIGNED
1404157 option element is being resized when applied a CSS height P3 NEW
1405682 Implement the decode() method on images P3 NEW
1406116 Negative right margin on element inside inline-block element forces text-wrapping on Firefox, not on other browsers. P3 NEW
1407496 Flash Player not loaded or notification to activate P3 NEW
1409490 meta-viewport makes elements with inner :active content unclickable. P2 NEW
1409529 SVG images with width or height only set in CSS rules are not visible (in intrinsically-sized block, e.g. flex item or float) P3 NEW
1411862 Disable 3rd party cookie video does not play in Firefox Dev Edition (v57 with uBlockO). P3 NEW
1414402 Support playback of mp4v video P5 NEW
1415789 -moz-appearance button-bevel should behave like -webkit-appearance: button-bevel P3 ASSIGNED
1417753 Implement -moz-appearance: searchfield-cancel-button which behave like -webkit-appearance: searchfield-cancel-button P3 NEW
1418472 Wrong position of github issue name on hover P3 NEW
1419610 Radio buttons are not visible in Firefox Android while visible in Chrome. P3 NEW
1421157 -moz-appearance: inner-spin-button should render arrow down + arrow up button P3 NEW
1421318 Google Translate: Unable to insert cursor into block of text P2 NEW
1421597 Provide an option to ignore scroll events outside of the control when a |select| drop-down is open P3 NEW
1422891 [Rethink] Support mkv|matroska|video/x-matroska in Firefox P3 UNCONFIRMED
1425291 Implement support for the autocapitalize atttribute P3 NEW
1427020 The site stops loading up to this graphical level P3 NEW
1427678 Scrollbars are covering part of a box when scrolling with a trackpad on a touch screen enabled laptop P3 NEW
1428236 In some occasions, navigating back and forth at the site causes the website to be zoomed in yet not resizeable P3 NEW
1428252 Scripts don't load P3 NEW
1428263 Incorrect layout (position) for position:fixed child of transformed scrollable flex container P3 NEW
1430989 “Weiteres Land hinzüfugen” (“ + Add another country”) button has design issues P3 NEW
1434236 Caption width set to 100% in a table has the width of the document and not the table width P3 NEW
1436225 blocking script and cpu high with SetTimeout P3 NEW
1436227 Unnecessary empty option displayed in the “發票” drop-down menu P3 NEW
1436801 Vertical padding influences baseline alignment of text around span with "vertical-align:middle" (only in Firefox) P3 NEW
1437413 Characters descenders cut out in an html input P3 NEW
1437761 position:sticky inside partially-offscreen position:fixed container has a different behavior in Chrome/Edge vs Firefox P3 NEW
1438105 javascript: doesn't work when a:active {position:relative} is set on a href on Firefox Android P3 NEW
1438398 After opening then closing the Account panel (top-right blue-ish icon), the page doesn't reflow correctly. P3 NEW
1439492 pseudo selector :after/:before + content has no effect on input type=checkbox P3 NEW
1441089 br with height: 0 still creates a line break in Chrome, Safari and Edge but not in Firefox. P3 NEW
1443284 percentage height in auto-height table cell in fixed-height table is treated as auto P3 NEW
1447230 big grey block hide the text when scrolling on Firefox Android P3 NEW
1448776 Allow line-break after - (U+002D / hyphen-minus) between digits. P4 NEW
1449079 PNG background-image icon not positioned at the right place after first rendering P3 NEW
1449753 Turn off layout.css.moz-document.url-prefix-hack.enabled by default. P3 NEW
1450173 input with date/time type doesn't center its contents, with "text-align:center" P3 NEW
1450595 Click to flash not working on macos P3 NEW
1450815 HTTP POST receives a response with a onload event in JS posting to itself and generating an infinite loop P3 NEW
1450842 Videos could not be decoded P3 NEW
1451747 [webvtt] Subtitles can be placed outside the video P3 NEW
1451981 The "Book" dropdown menu appears behind other content in the page. P3 NEW
1451998 the thumbnails all play automatically at the same time, and the website gets so slow it's impossible to use. P3 NEW
1452017 The animation of transition when pressinng the next button is jittery. P3 NEW
1452646 while clicking and navigating back, an outline is drawn P3 NEW
1453797 Carousel images have jagged edges when scrolling through P3 NEW
1454043 Carousel images have jagged edges when scrolling through P3 NEW
1454289 WebGL doesn't load, black screen P3 NEW
1454290 Automatic Caption does not work P3 NEW
1455545 Noto Sans Symbols is not rendered on some Android devices P3 NEW
1456052 Small allocated space for “Comments” hint text field P3 NEW
1457805 Images flickering and slight jankiness because of CSS animations P3 NEW
1459535 Performance is incredibly degraded when idle on P3 NEW
1460186 input type=file is sensitive to height (while chrome and safari don't) P2 NEW
1461246 When editing the Note field in, browser scrolls up. I'm thus typing blindly P3 NEW
1461264 RGB Color space/profile seem different (pictures appear darker in Firefox than in Edge) P3 NEW
1461266 comments framerate is smoother on Chrome than Firefox P3 NEW
1463335 anchor and input superposed makes the JavaScript non active. P3 NEW
1464925 Visual glitch: graphic layers around menu displaced, linked to scroll position. P3 NEW
1466441 Skin color changes don't stick at (race condition?) P3 NEW
1467114 BBC - highlighter for navigation spans extends to body edge P3 NEW
1468906 Mouse wheel Image zoom does not work on Google Photos -- NEW
1469731 Menu is blurred after transition P3 NEW
1470315 The layout becomes blurry when the page is scrolled down/up P3 NEW
1471110 slideshow doesn't work P3 NEW
1471123 Can't play video error message on Firefox Android P3 NEW
1471232 iframe content overflow spontaneously after a couple of seconds P2 REOPENED
1472582 td containing nowrap='' and a fixed width will grow (while Chrome with enforce the width) P3 NEW
1472941 Slow loads and performance at, compared to Chrome P3 NEW
1473495 Flash of Unstyled Content (not happening in Chrome) P3 NEW
1473501 Improve the way Gecko selects images based on srcset values (don't just round up, when rounding up is a huge jump) P3 NEW
1473789 {inc} intrinsically-sized inline-block with orthogonal writing-mode content has size of 0 on the first reflow and correct sizes later P3 NEW
1475316 Consider adding support for -webkit-autofill (and a default stylesheet using it) for interop with Chrome mobile. P3 NEW
1475396 Select will not dropdown on-click when unfocused, given the CSS :focus { position:relative } P3 NEW
1475681 Page CSP can break seeking to unbuffered position (in mp3 playback) P2 REOPENED
1475723 Geckoview and Fennec open select dropdown on tap of parent label; other browsers do not. P3 NEW
1476051 Interop issues with select element styling with appearance:none. P3 NEW
1476812 left:auto on a position:absolute display:inline-block element shouldn't consider floats after the inline-block that would have moved it P3 NEW
1476925 Negative margin doesn't cancel the padding on parent causing undesired line breaking when width is auto P3 NEW
1477110 Select elements seem to get double the text-indent when a percentage is specified. P3 NEW
1479321 Hovering "A propos" sub-menu with the mouse displays the menu for a split second and disappears P3 NEW
1481112 User Agent Stylesheet Default for select, button P3 NEW
1481124 Menu takes longer to open in Firefox than in chrome P3 NEW
1481132 [Android] flashes 3 times when you reload or navigate away P3 NEW
1481581 [meta] More closely align the behavior of '-moz-appearance' with Chrome's '-webkit-appearance' P3 NEW
1481596 Make `-moz-appearance: none` on <textarea> behave more like Chrome P3 NEW
1481717 WebGL doesn't work. drawArrays, Framebuffer not complete P3 NEW
1486362 CPU usage is extremely high at P3 NEW
1486365 The City selection page slightly bounces after opening P3 NEW
1488334 White dots are visible along the Rubik's Cube edges P3 NEW
1490126 Firefox scrolls to a contenteditable item when addRange selects it, even if it is immediately removed from the document. Chrome does not. P3 NEW
1490401 MediaQueryList::Matches shouldn't need a pres context, but a document instead | matchMedia should work in display:none iframes P3 NEW
1490873 Toggling SVG graph elements on and off leaves artifacts and erases parts. P3 NEW
1491743 invalid CSS property value on ::selection kills the default selection settings P3 NEW
1492361 Tracking issues with SSL_ERROR_NO_CYPHER_OVERLAP P1 NEW
1492818 After resizing the browser, the page is not reloaded and the resulted empty space becomes unusable. -- NEW
1493271 Clicking on "share icons" does not open new window P2 NEW
1493434 Inconsistent table column sizing between Firefox and Chrome (with percent sizes on colgroup and col) P3 NEW
1493561 non-specified border-width on input element is wide on Ubuntu P3 NEW
1494157 background-size: cover differs from Chrome/Safari (with background-attachment: fixed, on mobile viewports) P5 NEW
1497375 Page repeatedly jumping toward the end of the page when scrolling P3 NEW
1497742 CSP with invalid U+00A0 character P3 NEW
1497959 clip-path: inset(0 0) cuts off content if it is too long when not using WebRender -- NEW
1499986 Handling return value for a script P3 NEW
1501202 implementation of window.confirm on GeckoView P3 NEW
1501480 mask-image and SVG on input element fails in Firefox, Safari, and Edge, works in Chrome P3 NEW
1502150 getComputedStyle difference between Fennec and Desktop (at least for WebkitAppearance values) -- NEW
1502769 Scrolling is janky when partial menu is sticked to the top of the viewport. P3 NEW
1503173 Render bug, part of page blank at Homey Developer Documentation ( P2 NEW
1503427 Firefox 63 pushing Bootstrap 3 date input text down P3 ASSIGNED
1503899 Sharp printer UI incorrectly rendered, due to table-layout behavior difference (& with CSS enabled by webkit-min-device-pixel-ratio query) P3 NEW
1504121 - Site is nearly unresponsive P3 NEW
1506487 - video not playing, OS needs to be restarted. P3 NEW
1506508 Event is not fire at the first click when position:relative is set on :active P3 ASSIGNED
1507744 word-break: break-all on an inline doesn't cause breaks P3 NEW
1508177 Consider shrinking content even if no content area gets visible P4 NEW
1509231 2 history entries created in Firefox (but not other browsers) P3 NEW
1509425 Can not see the comments on P2 ASSIGNED
1510138 Incorrect shadows on asset buttons P3 NEW
1511150 GitHub emoticon glyphs sometimes appear "cut off" P3 NEW
1512745 Incorrect SVG Rendering P2 NEW
1513435 Incompatible column layout with 'height:0' and definite 'column-width' P3 UNCONFIRMED
1514269 [CSS Multicol] Firefox only web platform tests P2 NEW
1514362 [CSS Selectors] Firefox only web platform test failures P3 NEW
1514367 [CSSOM View] Firefox only web platform test failures P2 NEW
1514371 [CSSOM] Firefox only web platform test failures P2 NEW
1514538 SVGMatrix and DOMMatrix are not interchangeable in Path2D.addPath P3 NEW
1514630 - WebGL errors once we fake UA to be chrome and bypass UA sniffing P3 NEW
1514655 Plaintext documents in subframes (or <object>) don't get word-wrapping P3 NEW
1514974 ul align="left/right" is not enforced with li-less content when the nesting context has text-align P3 NEW
1517388 Can't click on links on (animation and preserve-3d related) P2 REOPENED
1517666 quick zoom in and out will white out Firefox and all tabs P3 NEW
1518040 SVG feBlend should take account of flood-opacity on feFlood input nodes P3 NEW
1519463 shows "this page may be slowing down your browser" and crashes tab eventually -- NEW
1519578 [contenteditable] Elements made block via CSS use <br> for newlines rather than <divs> P3 NEW
1520018 Gecko and Webkit/Blink default to different box-sizing values for table tags. -- NEW

224 Total; 224 Open (100%); 0 Resolved (0%); 0 Verified (0%);


This is the Yeah! Let's party list.

WebKit Flexbox Total Armaggedon in China and Japan

This is not specific to Desktop and Mobile, but more to the specific markets of China and Japan and indeed more often on mobile.

Suggested Fix Use Web standards flexbox properties in addition to the WebKit ones if old devices compatibility is required.

Related Bugs


Many sites have code that detects touch support and assumes mouse input can be ignored. These sites behave oddly on all computers that have a touch screen AND a mouse - usually not responding as expected to mouse input.

Suggested Fix Write JavaScript that will handle both click and touch input, not either-or.

Related Bugs


(Fixed in Gecko) Basically an image with a max-width: 100% was bigger than the viewport It was an issue, created by a different behavior in Gecko and Blink. But the market share of Blink imposed the unspecc’ed behavior of Blink.

Suggested Fix The fix was often a combination of display: table with table-layout: fixed. This is now fixed in Gecko and the spec, but this is a good illustration point in terms of Web Compatbility issues.

Related Bugs

Video streaming using Apple’s proprietary HTTP Live Streaming

Firefox doesn’t support this on Desktop or Mobile.

Suggested Fix Not a trivial thing to fix. Ensure that there is a fallback mechanism for browsers that don’t support HLS (currently on Desktop, only Edge and Safari do).

Related Bugs

Meta viewport fixed size

Very similar to the max-width bug. This is a different of behavior in between blink and Gecko. Basically with a fix width, Gecko on Mobile doesn’t necessary resize the page to fit in the screen.

Suggested Fix Use width=device-width instead of fixed size.

Related Bugs

Faulty UA detection

Sites sniff the user agent string, often to figure out if you’re using a “supported browser”. This goes wrong all the time, because of an unknown UA string, or parsing bugs, or not understanding versions greater than 9, etc. Mobile browsers will frequently end up on “Desktop” sites, rather than mobile ones as a result of this kind of bug.

Suggested Fix Update your UA detection library or framework, or use feature detection rather than relying on User Agent string parsing. User Agent detection is about detecting the past. So it will obviously fail. Feature detection is about inspecting the now.

Related Bugs

Relying on global event object

WebKit (possibly copied from old iE?) has a non-standard global event object. When sites don’t pass in the event object to an event handler, we end up with exceptions like “ReferenceError: event is not defined”

Suggested Fix Use web standards and pass in an explicit event object into your event handlers. For example: a.addEventListener(‘click’, function(e){ blah(e)});

Related Bugs

HTTP Ping Pong

The company has two different sites: desktop and mobile with different domain names. They do user-agent sniffing be with HTTP user-agent header, through JavaScript.

Suggested Fix The issue starts to fix itself by people switching to responsive Web sites. The fix is actually simple. Which ever technique you are using should have a consistent policy in terms of user agent sniffing. Some websites make mistakes when the detection mechanism is not the same on both domains: for example one with HTTP, and one with JS. In HTTP only, the browser is able to identify the infinite loop and will stop after 10 iterations, but when switching from HTTP to JS and then to HTTP, etc the browser is really caught forever.

Related Bugs

Webkit Scrollbar

Websites would like to replace default scrollbars with custom ones. There are known issue of Firefox not hiding the default scrollbar and potential scrollbar lagging introduced with async scrolling (e10s-only).

Related Bugs