Use the new button mixin

src/styles/_app_base.sass

@@ -212,6 +212,7 @@ input, input.form-control
 	&:hover
 		border: thin solid $color-text-dark-hint
 
+
 #status-bar
 	color: $color-text-dark-secondary
 	margin-left: auto

src/styles/_app_utils.sass

@@ -9,7 +9,7 @@
 		content: ' '
 
 
-@mixin button-rounded($mixin-color, $roundness, $filled: false)
+@mixin button($mixin-color, $roundness, $filled: false)
 	font-family: $font-body
 	text-transform: uppercase
 	opacity: .9

src/styles/_errors.sass

@@ -90,9 +90,9 @@
 				font-size: 1.2em
 				margin: 0 15px
 				&.sign-up
-					@include button-rounded($color-primary, 999em, true)
+					+button($color-primary, 999em, true)
 				&.sign-in
-					@include button-rounded($color-background, 999em)
+					+button($color-background, 999em)
 					border-color: transparent