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Your question highlights the grey area between "desktop" GUIs and "web" or "web app" GUIs. There is no real standard for showing web-app-like controls in a 3D space. Browser chrome controls, like radio buttons and pulldowns, have desktop-like properties, but links and tags and whatnot typically don't.

The old Apple Human Interface Guidelines (the basics of which everyone else copied) said that the light source on a desktop GUI came from the top left. There's not much shadow shown in this System 7.0 Control Panel example, but the darker edge is on the bottom right, for sure.

System 7.0 Control Panel

With Mac OS X and later iOS, Apple changed the conceptual light source position to directly above, so the shadow gradients are straight up and down.

Mac OS X Control Panel

iOS Icon

The old Apple Human Interface Guidelines (the basics of which everyone else copied) said that the light source on a GUI came from the top left. There's not much shadow shown in this System 7.0 Control Panel example, but the darker edge is on the bottom right, for sure.

System 7.0 Control Panel

With Mac OS X and later iOS, Apple changed the conceptual light source position to directly above, so the shadow gradients are straight up and down.

Mac OS X Control Panel

iOS Icon

Your question highlights the grey area between "desktop" GUIs and "web" or "web app" GUIs. There is no real standard for showing web-app-like controls in a 3D space. Browser chrome controls, like radio buttons and pulldowns, have desktop-like properties, but links and tags and whatnot typically don't.

The old Apple Human Interface Guidelines (the basics of which everyone else copied) said that the light source on a desktop GUI came from the top left. There's not much shadow shown in this System 7.0 Control Panel example, but the darker edge is on the bottom right, for sure.

System 7.0 Control Panel

With Mac OS X and later iOS, Apple changed the conceptual light source position to directly above, so the shadow gradients are straight up and down.

Mac OS X Control Panel

iOS Icon

1
source | link

The old Apple Human Interface Guidelines (the basics of which everyone else copied) said that the light source on a GUI came from the top left. There's not much shadow shown in this System 7.0 Control Panel example, but the darker edge is on the bottom right, for sure.

System 7.0 Control Panel

With Mac OS X and later iOS, Apple changed the conceptual light source position to directly above, so the shadow gradients are straight up and down.

Mac OS X Control Panel

iOS Icon