What do you foresee will be the major trends in web site design of 2017? In the past few years we've seen a huge growth in fixed headers, parallax, and other "chrome" elements. How do you identify big web trends (particularly these style-focused elements)?
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The “hot new thing” in web design is still often driven by what the technology will support.
So, checking out http://caniuse.com and looking at what features will soon have near-universal support will give you a good clue about what sorts of things may be coming to websites soon. (That is to websites that target general audiences. If a site doesn’t need to support every browser, it may be using these technologies already, see below.)
Blending raster and vendor graphics
Two technologies nearing this point currently are blending of HTML & SVG elements, and the calc() function. Together, these technologies will make it easier to incorporate vector graphics into a web design. (Check out the links for some examples of what these technologies enable.)
Two technologies for embedding video into web pages without plugins are
HTTP Live Streaming and WebRTC. MSIE (up to 11) does not support either, but Chrome, Edge, Safari, and Firefox support one or the other.
Remember when Flash animations were everywhere? (Back when Flash has a very high installed base.) With these HTML video technologies becoming widespread, ubiquitous web video may be coming back.
Check out cutting-edge apps
Some web apps have limited browser support, and focus on delivering cutting-edge experience for a short list of supported browsers. Some (but not all) of the features they utilize are on the “coming soon” list for other browsers. These sites are doing now some of the things that will be coming to general audience websites as those features become more universally available.
One of my favorite “cutting edge” web apps is roll20.net, which officially supports only evergreen Chrome and Firefox. You can check out many (but not all) of the tricks they use for free (while a few require a subscription). You inspect their pages and see that they are using all sorts of HTML5 functionality. Their WebRTC video for peer-to-peer connections is a big improvement over older Flash-based systems, for example.
Not everything roll20, or other sites like them are doing, is going to be the “next big thing,” but if you watch them (and read their change logs) you can watch the innovation happening.