Breaking Out of the Field – A Checklist Aside


    CSS is about styling packing containers. The truth is, the entire net is manufactured from packing containers, from the browser viewport to parts on a web page. However each occasionally a brand new characteristic comes alongside that makes us rethink our design strategy.

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    Spherical shows, for instance, make it enjoyable to play with round clip areas. Cellular display notches and digital keyboards supply challenges to finest set up content material that stays away from them. And twin display or foldable gadgets make us rethink methods to finest use obtainable house in quite a lot of completely different system postures.

    Sketches of a spherical show, a standard rectangular cellular show, and a tool with a foldable show.

    These current evolutions of the online platform made it each tougher and extra attention-grabbing to design merchandise. They’re nice alternatives for us to interrupt out of our rectangular packing containers.

    I’d like to speak a few new characteristic just like the above: the Window Controls Overlay for Progressive Internet Apps (PWAs).

    Progressive Internet Apps are blurring the strains between apps and web sites. They mix the very best of each worlds. On one hand, they’re steady, linkable, searchable, and responsive identical to web sites. Alternatively, they supply extra highly effective capabilities, work offline, and skim recordsdata identical to native apps.

    As a design floor, PWAs are actually attention-grabbing as a result of they problem us to consider what mixing net and device-native person interfaces may be. On desktop gadgets particularly, we have now greater than 40 years of historical past telling us what purposes ought to appear like, and it may be onerous to interrupt out of this psychological mannequin.

    On the finish of the day although, PWAs on desktop are constrained to the window they seem in: a rectangle with a title bar on the high.

    Right here’s what a typical desktop PWA app appears to be like like:

    Sketches of two rectangular person interfaces representing the desktop Progressive Internet App established order on the macOS and Home windows working programs, respectively. 

    Positive, because the writer of a PWA, you get to decide on the colour of the title bar (utilizing the Internet Software Manifest theme_color property), however that’s about it.

    What if we might suppose outdoors this field, and reclaim the true property of the app’s total window? Doing so would give us an opportunity to make our apps extra lovely and really feel extra built-in within the working system.

    That is precisely what the Window Controls Overlay affords. This new PWA performance makes it potential to make the most of the total floor space of the app, together with the place the title bar usually seems.

    Concerning the title bar and window controls#section2

    Let’s begin with a proof of what the title bar and window controls are.

    The title bar is the world displayed on the high of an app window, which normally accommodates the app’s title. Window controls are the affordances, or buttons, that make it potential to attenuate, maximize, or shut the app’s window, and are additionally displayed on the high.

    A sketch of an oblong utility person interface highlighting the title bar space and window management buttons.

    Window Controls Overlay removes the bodily constraint of the title bar and window controls areas. It frees up the total peak of the app window, enabling the title bar and window management buttons to be overlaid on high of the appliance’s net content material. 

    A sketch of an oblong utility person interface utilizing Window Controls Overlay. The title bar and window controls are now not in an space separated from the app’s content material.

    In case you are studying this text on a desktop laptop, take a fast have a look at different apps. Likelihood is they’re already doing one thing just like this. The truth is, the very net browser you might be utilizing to learn this makes use of the highest space to show tabs.

    A screenshot of the highest space of a browser’s person interface displaying a gaggle of tabs that share the identical horizontal house because the app window controls.

    Spotify shows album paintings all the way in which to the highest fringe of the appliance window.

    A screenshot of an album in Spotify’s desktop utility. Album paintings spans the whole width of the principle content material space, all the way in which to the highest and proper edges of the window, and the appropriate fringe of the principle navigation space on the left aspect. The appliance and album navigation controls are overlaid immediately on high of the album paintings.

    Microsoft Phrase makes use of the obtainable title bar house to show the auto-save and search functionalities, and extra.

    A screenshot of Microsoft Phrase’s toolbar interface. Doc file data, search, and different performance seem on the high of the window, sharing the identical horizontal house because the app’s window controls.

    The entire level of this characteristic is to permit you to make use of this house with your individual content material whereas offering a option to account for the window management buttons. And it lets you supply this modified expertise on a variety of platforms whereas not adversely affecting the expertise on browsers or gadgets that don’t help Window Controls Overlay. In any case, PWAs are all about progressive enhancement, so this characteristic is an opportunity to boost your app to make use of this further house when it’s obtainable.

    Let’s use the characteristic#section3

    For the remainder of this text, we’ll be engaged on a demo app to study extra about utilizing the characteristic.

    The demo app known as 1DIV. It’s a easy CSS playground the place customers can create designs utilizing CSS and a single HTML factor.

    The app has two pages. The primary lists the present CSS designs you’ve created:

    A screenshot of the 1DIV app displaying a thumbnail grid of CSS designs a person created.

    The second web page lets you create and edit CSS designs:

    A screenshot of the 1DIV app editor web page. The highest half of the window shows a rendered CSS design, and a textual content editor on the underside half of the window shows the CSS used to create it.

    Since I’ve added a easy net manifest and repair employee, we will set up the app as a PWA on desktop. Here’s what it appears to be like like on macOS:

    Screenshots of the 1DIV app thumbnail view and CSS editor view on macOS. This model of the app’s window has a separate management bar on the high for the app title and window management buttons.

    And on Home windows:

    Screenshots of the 1DIV app thumbnail view and CSS editor view on the Home windows working system. This model of the app’s window additionally has a separate management bar on the high for the app title and window management buttons.

    Our app is wanting good, however the white title bar within the first web page is wasted house. Within the second web page, it could be very nice if the design space went all the way in which to the highest of the app window.

    Let’s use the Window Controls Overlay characteristic to enhance this.

    Enabling Window Controls Overlay#section4

    The characteristic remains to be experimental for the time being. To attempt it, you must allow it in one of many supported browsers.

    As of now, it has been applied in Chromium, as a collaboration between Microsoft and Google. We are able to subsequently use it in Chrome or Edge by going to the interior about://flags web page, and enabling the Desktop PWA Window Controls Overlay flag.

    Utilizing Window Controls Overlay#section5

    To make use of the characteristic, we have to add the next display_override member to our net app’s manifest file:

      "title": "1DIV",
      "description": "1DIV is a mini CSS playground",
      "lang": "en-US",
      "start_url": "/",
      "theme_color": "#ffffff",
      "background_color": "#ffffff",
      "display_override": [
      "icons": [

    On the floor, the characteristic is absolutely easy to make use of. This manifest change is the one factor we have to make the title bar disappear and switch the window controls into an overlay.

    Nonetheless, to offer an important expertise for all customers no matter what system or browser they use, and to take advantage of the title bar space in our design, we’ll want a little bit of CSS and JavaScript code.

    Here’s what the app appears to be like like now:

    Screenshot of the 1DIV app thumbnail view utilizing Window Controls Overlay on macOS. The separate high bar space is gone, however the window controls are actually blocking among the app’s interface

    The title bar is gone, which is what we wished, however our brand, search discipline, and NEW button are partially coated by the window controls as a result of now our structure begins on the high of the window.

    It’s comparable on Home windows, with the distinction that the shut, maximize, and decrease buttons seem on the appropriate aspect, grouped along with the PWA management buttons:

    Screenshot of the 1DIV app thumbnail show utilizing Window Controls Overlay on the Home windows working system. The separate high bar space is gone, however the window controls are actually blocking among the app’s content material.

    Utilizing CSS to maintain away from the window controls#section6

    Together with the characteristic, new CSS surroundings variables have been launched:

    • titlebar-area-x
    • titlebar-area-y
    • titlebar-area-width
    • titlebar-area-height

    You employ these variables with the CSS env() operate to place your content material the place the title bar would have been whereas making certain it gained’t overlap with the window controls. In our case, we’ll use two of the variables to place our header, which accommodates the brand, search bar, and NEW button. 

    header {
      place: absolute;
      left: env(titlebar-area-x, 0);
      width: env(titlebar-area-width, 100%);
      peak: var(--toolbar-height);

    The titlebar-area-x variable offers us the gap from the left of the viewport to the place the title bar would seem, and titlebar-area-width is its width. (Bear in mind, this isn’t equal to the width of the whole viewport, simply the title bar portion, which as famous earlier, doesn’t embody the window controls.)

    By doing this, we be sure that our content material stays absolutely seen. We’re additionally defining fallback values (the second parameter within the env() operate) for when the variables usually are not outlined (akin to on non-supporting browsers, or when the Home windows Management Overlay characteristic is disabled).

    Screenshot of the 1DIV app thumbnail view on macOS with Window Controls Overlay and our CSS up to date. The app content material that the window controls had been blocking has been repositioned.
    Screenshot of the 1DIV app thumbnail view on the Home windows working system with Window Controls Overlay and our up to date CSS. The app content material that the window controls had been blocking has been repositioned.

    Now our header adapts to its environment, and it doesn’t really feel just like the window management buttons have been added as an afterthought. The app appears to be like much more like a local app.

    Altering the window controls background coloration so it blends in#section7

    Now let’s take a better have a look at our second web page: the CSS playground editor.

    Screenshots of the 1DIV app CSS editor view with Window Controls Overlay in macOS and Home windows, respectively. The window controls overlay areas have a stable white background coloration, which contrasts with the recent pink coloration of the instance CSS design displayed within the editor.

    Not nice. Our CSS demo space does go all the way in which to the highest, which is what we wished, however the way in which the window controls seem as white rectangles on high of it’s fairly jarring.

    We are able to repair this by altering the app’s theme coloration. There are a few methods to outline it:

    • PWAs can outline a theme coloration within the net app manifest file utilizing the theme_color manifest member. This coloration is then utilized by the OS in numerous methods. On desktop platforms, it’s used to offer a background coloration to the title bar and window controls.
    • Web sites can use the theme-color meta tag as properly. It’s utilized by browsers to customise the colour of the UI across the net web page. For PWAs, this coloration can override the manifest theme_color.

    In our case, we will set the manifest theme_color to white to offer the appropriate default coloration for our app. The OS will learn this coloration worth when the app is put in and use it to make the window controls background coloration white. This coloration works nice for our fundamental web page with the listing of demos.

    The theme-color meta tag may be modified at runtime, utilizing JavaScript. So we will do this to override the white with the appropriate demo background coloration when one is opened.

    Right here is the operate we’ll use:

    operate themeWindow(bgColor) {
      doc.querySelector("meta[name=theme-color]").setAttribute('content material', bgColor);

    With this in place, we will think about how utilizing coloration and CSS transitions can produce a easy change from the listing web page to the demo web page, and allow the window management buttons to mix in with the remainder of the app’s interface.

    Screenshot of the 1DIV app CSS editor view on the Home windows working system with Window Controls Overlay and up to date CSS demonstrating how the window management buttons mix in with the remainder of the app’s interface.

    Dragging the window#section8

    Now, eliminating the title bar fully does have an essential accessibility consequence: it’s far more troublesome to maneuver the appliance window round.

    The title bar offers a large space for customers to click on and drag, however by utilizing the Window Controls Overlay characteristic, this space turns into restricted to the place the management buttons are, and customers need to very exactly goal between these buttons to maneuver the window.

    Luckily, this may be fastened utilizing CSS with the app-region property. This property is, for now, solely supported in Chromium-based browsers and wishes the -webkit- vendor prefix. 

    To make any factor of the app grow to be a dragging goal for the window, we will use the next: 

    -webkit-app-region: drag;

    It is usually potential to explicitly make a component non-draggable: 

    -webkit-app-region: no-drag; 

    These choices may be helpful for us. We are able to make the whole header a dragging goal, however make the search discipline and NEW button inside it non-draggable to allow them to nonetheless be used as regular.

    Nonetheless, as a result of the editor web page doesn’t show the header, customers wouldn’t be capable of drag the window whereas modifying code. So let’s use a distinct strategy. We’ll create one other factor earlier than our header, additionally completely positioned, and devoted to dragging the window.

    <div class="drag"></div>
    .drag {
      place: absolute;
      high: 0;
      width: 100%;
      peak: env(titlebar-area-height, 0);
      -webkit-app-region: drag;

    With the above code, we’re making the draggable space span the whole viewport width, and utilizing the titlebar-area-height variable to make it as tall as what the title bar would have been. This fashion, our draggable space is aligned with the window management buttons as proven under.

    And, now, to verify our search discipline and button stay usable:

    header .search,
    header .new {
      -webkit-app-region: no-drag;

    With the above code, customers can click on and drag the place the title bar was once. It’s an space that customers count on to have the ability to use to maneuver home windows on desktop, and we’re not breaking this expectation, which is nice.

    An animated view of the 1DIV app being dragged throughout a Home windows desktop with the mouse.

    Adapting to window resize#section9

    It could be helpful for an app to know each whether or not the window controls overlay is seen and when its dimension modifications. In our case, if the person made the window very slim, there wouldn’t be sufficient house for the search discipline, brand, and button to suit, so we’d need to push them down a bit.

    The Window Controls Overlay characteristic comes with a JavaScript API we will use to do that: navigator.windowControlsOverlay.

    The API offers three attention-grabbing issues:

    • navigator.windowControlsOverlay.seen lets us know whether or not the overlay is seen.
    • navigator.windowControlsOverlay.getBoundingClientRect() lets us know the place and dimension of the title bar space.
    • navigator.windowControlsOverlay.ongeometrychange lets us know when the scale or visibility modifications.

    Let’s use this to pay attention to the scale of the title bar space and transfer the header down if it’s too slim.

    if (navigator.windowControlsOverlay) {
      navigator.windowControlsOverlay.addEventListener('geometrychange', () => {
        const { width } = navigator.windowControlsOverlay.getBoundingClientRect();
        doc.physique.classList.toggle('slim', width < 250);

    Within the instance above, we set the slim class on the physique of the app if the title bar space is narrower than 250px. We might do one thing comparable with a media question, however utilizing the windowControlsOverlay API has two benefits for our use case:

    • It’s solely fired when the characteristic is supported and used; we don’t need to adapt the design in any other case.
    • We get the scale of the title bar space throughout working programs, which is nice as a result of the scale of the window controls is completely different on Mac and Home windows. Utilizing a media question wouldn’t make it potential for us to know precisely how a lot house stays.
    .slim header {
      high: env(titlebar-area-height, 0);
      left: 0;
      width: 100%;

    Utilizing the above CSS code, we will transfer our header down to remain away from the window management buttons when the window is simply too slim, and transfer the thumbnails down accordingly.

    A screenshot of the 1DIV app on Home windows displaying the app’s content material adjusted for a a lot narrower viewport.

    Thirty pixels of thrilling design alternatives#section10

    Utilizing the Window Controls Overlay characteristic, we have been in a position to take our easy demo app and switch it into one thing that feels a lot extra built-in on desktop gadgets. One thing that reaches out of the standard window constraints and offers a customized expertise for its customers.

    In actuality, this characteristic solely offers us about 30 pixels of additional room and comes with challenges on methods to cope with the window controls. And but, this further room and people challenges may be become thrilling design alternatives.

    Extra gadgets of all shapes and varieties get invented on a regular basis, and the online retains on evolving to adapt to them. New options get added to the online platform to permit us, net authors, to combine increasingly deeply with these gadgets. From watches or foldable gadgets to desktop computer systems, we have to evolve our design strategy for the online. Constructing for the online now lets us suppose outdoors the oblong field.

    So let’s embrace this. Let’s use the usual applied sciences already at our disposal, and experiment with new concepts to offer tailor-made experiences for all gadgets, all from a single codebase!

    In the event you get an opportunity to attempt the Window Controls Overlay characteristic and have suggestions about it, you may open points on the spec’s repository. It’s nonetheless early within the growth of this characteristic, and you may assist make it even higher. Or, you may check out the characteristic’s current documentation, or this demo app and its supply code


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