refactor(mobile): styling for sign actions box

src/components/MarkFormField/style.module.scss

@@ -1,11 +1,19 @@
+@import '../../styles/sizes.scss';
+
 .container {
-  width: 100%;
   display: flex;
   flex-direction: column;
   position: fixed;
+
+  @media only screen and (min-width: 768px) {
     bottom: 0;
     right: 0;
     left: 0;
+  }
+  bottom: $tabs-height + 5px;
+  right: 5px;
+  left: 5px;
+
   align-items: center;
   z-index: 1000;
 
@@ -107,7 +115,7 @@
 .actions {
   background: white;
   width: 100%;
-  border-radius: 4px;
+  border-radius: 5px;
   padding: 10px 20px;
   display: none;
   flex-direction: column;