Fix firefox styling

Author: vincent-pochet

css/style.css

@@ -490,9 +490,6 @@ html[lang="fr"] [data-lang="en"] {
    ========================================== */
 .thanks {
   padding: 10rem 0 6rem;
-  display: flex;
-  align-items: center;
-  justify-content: center;
   min-height: calc(100vh - 72px - 73px);
 }