_content: fix go.dev/play text color

The text color in go.dev/play was accidentally set to color-text-subtle
in CL 384874 whereas the correct color is color-text.

Fixes golang/go#51584

Change-Id: I0a512d826bb88dc16db032334350935503724f09
Reviewed-on: https://go-review.googlesource.com/c/website/+/391394
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Trust: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Valentin Deleplace <deleplace@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/_content/css/styles.css b/_content/css/styles.css
index b89f259..ec2a49c 100644
--- a/_content/css/styles.css
+++ b/_content/css/styles.css
@@ -4056,7 +4056,7 @@
 .Playground-input,
 .Playground-outputContainer,
 .Playground-output {
-  color: var(--color-text-subtle);
+  color: var(--color-text);
 }
 .Playground-inputContainer,
 .Playground-outputContainer {