Add weight variable, Remove inline-flex, Fix link button

sass/elements/button.sass

@@ -79,6 +79,7 @@
           border-color: darken($color, 10%)
           color: darken($color, 10%)
   &.is-link
+    background: transparent
     border-color: transparent
     color: $text
     text-decoration: underline

sass/elements/controls.sass

@@ -1,12 +1,11 @@
 =control
   -moz-appearance: none
   -webkit-appearance: none
-  align-items: center
   background: $control-background
   border: 1px solid $control-border
   border-radius: $radius
   color: $control
-  display: inline-flex
+  display: inline-block
   font-size: $size-normal
   height: 32px
   line-height: 24px

sass/elements/elements.sass

@@ -146,11 +146,10 @@
   vertical-align: top
 
 .tag
-  align-items: center
   background: $background
   border-radius: 290486px
   color: $text
-  display: inline-flex
+  display: inline-block
   font-size: 12px
   height: 24px
   justify-content: center