  We demonstrate for the first time the two-color cooling and trapping of
alkaline-earth atoms in a grating magneto-optical trap (gMOT). The trap is
formed by a single incident laser beam together with four secondary beams that
are generated via diffraction from a nanostructured wafer. A grating structure
for a gMOT operating with strontium atoms is optimized and fabricated. We trap
$10^6$ $^{88}$Sr atoms on the $^1$S$_0$ $\rightarrow$ $^1$P$_1$ transition at
$461\;\mathrm{nm}$ and transfer $25\;\%$ of these atoms to the second cooling
stage on the narrower $^1$S$_0$ $\rightarrow$ $^3$P$_1$ intercombination
transition at $689\;\mathrm{nm}$, preparing a sample of $2.5\times 10^5$ atoms
at $5\;\mu$K. These results demonstrate for the first time the applicability of
the gMOT technology in conjunction with two widely differing wavelengths and
enable the continued miniaturization of alkaline-earth based quantum
technologies like optical atomic clocks.
