Enable CSS Grid Layout

Chrome

Enable the flag called Enable experimental Web Platform features going to:
chrome://flags/#enable-experimental-web-platform-features

Firefox

Enable the flag called layout.css.grid.enabled going to:
about:config

Internet Explorer

Enabled by default since IE10 (old syntax).

Prefixed -ms

Opera

Enable the flag called Enable experimental Web Platform features going to:
opera://flags/#enable-experimental-web-platform-features

WebKit

In Safari Technology Preview and WebKit Nightly Builds you can enable the experimenta feature called CSS Grid using the menu: Develop > Expermiental Features > CSS Grid

Epiphany

Set the environment variable WEBKITGTK_EXPERIMENTAL_FEATURES:

$ export WEBKITGTK_EXPERIMENTAL_FEATURES="CSS_GRID_LAYOUT=1"