Added navbar menu button styles

assets/sass/partials/_navigation.sass

@@ -1,39 +1,49 @@
 #nav
-	margin-bottom: 20px
+  margin-bottom: 20px
 
-	.navbar-nav
-		display: inline-block
-		float: none
+  .navbar-nav
+    display: inline-block
+    float: none
 
-	.navbar-collapse
-		text-align: center
+  .navbar-collapse
+    text-align: center
 
-	ul
-		list-style: none
-		text-align: center
+  ul
+    list-style: none
+    text-align: center
 
-		.nav_item
-			display: inline-block
-			background: none
-			border: none
-			border-bottom: 3px solid rgba($main-color, 0)
-			border-radius: none
-			+transition(border-color, 200ms)
+    .nav_item
+      display: inline-block
+      background: none
+      border: none
+      border-bottom: 3px solid rgba($main-color, 0)
+      border-radius: none
+      +transition(border-color, 200ms)
 
-			a
-				display: block
-				+size(100% 100%)
-				padding: 5px 14px
-				text-decoration: none
-				color: #fff
-				font-size: 32px
-				font-weight: 600
-				+transition(color, 200ms)
+      a
+        display: block
+        +size(100% 100%)
+        padding: 5px 14px
+        text-decoration: none
+        color: #fff
+        font-size: 32px
+        font-weight: 600
+        +transition(color, 200ms)
 
-			&:hover
-				background-color: transparent
-				border-color: rgba($main-color, 1)
+      &:hover
+        background-color: transparent
+        border-color: rgba($main-color, 1)
 
-				a
-					background-color: transparent
-					color: $main-color
+        a
+          background-color: transparent
+          color: $main-color
+
+  #navbar-collapse-button
+    color: #fff
+    font-size: 32px
+    +transition(color, 200ms)
+
+    &:hover,
+    &:active
+      background-color: transparent
+      color: $main-color