fix modal on mobile (codesandbox#1375)

Author: SaraVieira

packages/app/src/app/pages/Curator/SandboxCard/index.js

@@ -1,7 +1,6 @@
 // @ts-check
 /* eslint-disable react/prefer-stateless-function */
 import React from 'react';
-import history from 'app/utils/history';
 import { sandboxUrl, profileUrl } from 'common/utils/url-generator';
 
 import { observer } from 'mobx-react';
@@ -64,16 +63,9 @@ class SandboxItem extends React.Component<Props> {
     }
   }
 
-  openSandbox = (openNewWindow = false) => {
-    // Git sandboxes aren't shown here anyway
+  openSandbox = () => {
     const url = sandboxUrl({ id: this.props.id });
-    if (openNewWindow === true) {
-      window.open(url, '_blank');
-    } else {
-      history.push(url);
-    }
-
-    return true;
+    window.open(url, '_blank');
   };
 
   openUser = username => {

packages/homepage/src/screens/explore/Modal/index.js

@@ -30,6 +30,7 @@ const Content = styled.div`
   width: 1000px;
   margin-top: 5%;
   z-index: 20;
+  max-width: 90%;
 `;
 
 export default class Modal extends React.PureComponent {

packages/homepage/src/screens/explore/_SandboxModal.elements.js

@@ -32,12 +32,20 @@ export const StyledRightArrow = styled(RightArrow)`
   position: absolute;
   right: -54px;
   ${ArrowStyles};
+
+  @media screen and (max-width: 800px) {
+    right: -40px;
+  }
 `;
 
 export const StyledLeftArrow = styled(LeftArrow)`
   position: absolute;
   left: -54px;
   ${ArrowStyles};
+
+  @media screen and (max-width: 800px) {
+    left: -40px;
+  }
 `;
 
 export const SandboxInfoContianer = styled.div`