Tweak docs and blog styles (#772) * Adjust theme and style to match Spice brand color * Update header styles in docs and blog * tweak colors --------- Co-authored-by: Luke Kim <80174+lukekim@users.noreply.github.com>

Tweak docs and blog styles (#772) * Adjust theme and style to match Spice brand color * Update header styles in docs and blog * tweak colors --------- Co-authored-by: Luke Kim <80174+lukekim@users.noreply.github.com>