Fix funny looking errors in conf-tx

ui/app/components/pending-tx.js

@@ -31,7 +31,7 @@ PendingTx.prototype.render = function () {
       `),
 
       txData.simulationFails ?
-        h('span.error', {
+        h('.error', {
           style: {
             marginLeft: 50,
             fontSize: '0.9em',

ui/app/conf-tx.js

@@ -170,6 +170,9 @@ function warningIfExists (warning) {
   if (warning &&
       // Do not display user rejections on this screen:
      warning.indexOf('User denied transaction signature') === -1) {
-    return h('span.error', { style: { margin: 'auto' } }, warning)
+    return h('.error', {
+      style: {
+        margin: 'auto',
+    }}, warning)
   }
 }