UI: Json React Form - textarea height fix

@@ -56,8 +56,14 @@ class ThingsboardText extends React.Component<JsonFormFieldProps, ThingsboardTex
     }
 
     const multiline = this.props.form.type === 'textarea';
-    const rows = multiline ? this.props.form.rows : 1;
-    const rowsMax = multiline ? this.props.form.rowsMax : 1;
+    let rows = 1;
+    let rowsMax = 1;
+    let minHeight = 48;
+    if (multiline) {
+      rows = this.props.form.rows || 2;
+      rowsMax = this.props.form.rowsMax;
+      minHeight = 19 * rows + 48;
+    }
 
     return (
       <div>
@@ -77,7 +83,7 @@ class ThingsboardText extends React.Component<JsonFormFieldProps, ThingsboardTex
           rowsMax={rowsMax}
           onFocus={this.onFocus}
           onBlur={this.onBlur}
-          style={this.props.form.style || {width: '100%'}}/>
+          style={this.props.form.style || {width: '100%', minHeight: minHeight + 'px'}}/>
       </div>
     );
   }

@@ -58,6 +58,15 @@ $previewSize: 100px !default;
 
   .tb-field {
     padding-bottom: 18px;
+
+    .MuiInputBase-multiline {
+      flex: 1;
+      flex-direction: column;
+      .MuiInputBase-inputMultiline {
+        flex: 1;
+      }
+    }
+
     &.tb-required {
       label::after {
         font-size: 13px;