[Glitch] Add sign-up button to logged-out web UI

Port e623c302d5 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/components/index.scss

@@ -118,6 +118,26 @@
     }
   }
 
+  &.button-tertiary {
+    background: transparent;
+    padding: 6px 17px;
+    color: $highlight-text-color;
+    border: 1px solid $highlight-text-color;
+
+    &:active,
+    &:focus,
+    &:hover {
+      background: $ui-highlight-color;
+      color: $primary-text-color;
+      border: 0;
+      padding: 7px 18px;
+    }
+
+    &:disabled {
+      opacity: 0.5;
+    }
+  }
+
   &.button--block {
     display: block;
     width: 100%;

app/javascript/flavours/glitch/styles/components/signed_out.scss

@@ -5,4 +5,8 @@
     color: $darker-text-color;
     margin-bottom: 20px;
   }
+
+  .button {
+    margin-bottom: 10px;
+  }
 }