Add signup completion page

app/styles/_buttons.scss

@@ -23,6 +23,10 @@ button, input[type=submit], .button {
     border-color: $primary-color;
   }
 
+  &[disabled] {
+    color: rgba(255,255,255,0.5);
+  }
+
   &.small {
     font-size: 0.8rem;
     padding: 0.2rem 0.8rem;

app/styles/_forms.scss

@@ -1,12 +1,17 @@
 section#add-contributor,
 section#add-contribution,
-section#add-proposal {
+section#add-proposal,
+section#signup {
 
   form {
 
     p {
       margin-bottom: 1.5rem;
 
+      &.mg-bottom-md {
+        margin-bottom: 2rem;
+      }
+
       &.actions {
         padding-top: 1.5rem;
         text-align: center;

app/styles/_layout.scss

@@ -40,6 +40,10 @@ main {
       }
 
       p {
+        &.mg-bottom-md {
+          margin-bottom: 2rem;
+        }
+
         &.actions {
           text-align: center;
           padding-top: 2rem;