Holo vs Metro
ホロ / メトロ
Holo comes from Google UI and Metro from Microsoft UI. Both are read here as style. They are reached for with some of the same intent, which is where they get confused.
Holo
Google's design language for Android, introduced with 3.0 and pushed so hard that carrying it unmodified became a compatibility requirement for every 4.0 device. It rules a black ground with hairlines and lets a single cyan blue carry selection, focus and progress. It arrived as a guarantee as much as a look, since an app that asked for the theme by name would be drawn the same way even on a phone wearing a manufacturer's skin.
Metro
Windows Phone's flat language, which cast type rather than icons in the lead role. Large typography, flat-color live tiles and layouts that run off the edge of the screen transplanted the clarity of transit signage into UI, opening the flat era ahead of iOS 7.
| Holo | Metro | |
|---|---|---|
| Era | 2011–2014 | 2010–2015 |
| Family | Google UI | Microsoft UI |
| Kind | Style | Style |
| Cues | White text on black, with sections divided by one pixel hairlines instead of filled panels / A single cyan blue at #33B5E5 lighting only selection, the underline of a text field, and progress / A full width action bar pinned to the top, and a strip of Back, Home and Recents keys at the bottom / Tab labels and list section headers set in bold, all uppercase | Type as the hero / Flat-color tiles / Compositions running off-screen / Chrome eliminated |
| Best used for | Recreating an Android app screen from roughly 2011 to 2013 with the period's actual widgets and theme names · Building hierarchy in a dark admin screen from hairlines and one accent color, without adding panels or shadows | Dashboards listing news or weather where borders would only add noise · Indoor wayfinding and signage read from a distance in one word |
| Type | One geometric leaning sans across the whole interface, in two weights only. Tabs and section headers go uppercase with the tracking opened slightly. | Headings five times body size, kept in a light weight |
| Composition | A full width action bar is fixed at the top and a single column list fills the space under it. Sections are separated by hairlines rather than white space, and a strip is reserved at the bottom for the navigation keys. | Headings running off the edge, tiles in two rectangle sizes |
| Material | Ground is black or a pale #F3F3F3, text is white or dark gray, and rules are one pixel of white at reduced opacity. Restrict the accent to #33B5E5 alone and let it glow only on press, selection and progress. | No shadows or borders, black or white ground, saturated flat panels |
| Caution | Redrawing the widgets so they no longer inherit from the theme throws away the one thing this style buys you, which is looking identical across devices, and leaves your app the odd one out on a skinned phone. | Stripping every border and shadow erases the difference between a tappable tile and a plain heading, leaving people guessing where to touch. |