Add background-go-input

src/site/sass/includes/_main.sass

@@ -501,6 +501,7 @@ body
 					border-right: none
 					max-width: 230px
 					width: 30vw
+					background-color: map-get($theme, "background-go-input")
 
 					@media screen and (max-width: 520px)
 						width: 80vw

src/site/sass/themes/_classic.scss

@@ -18,6 +18,7 @@ $theme: (
 	"background-power-palest": #ffbebe,
 	"background-power-pale": #ff7c7c,
 	"background-power-quote": #191919,
+	"background-go-input": #fff,
 	"background-primary-quote": #ccc,
 	"background-error-page": #191919,
 	"background-alert": #282828,