improve modal display on mobile

src/components/Modal/styles.module.scss

@@ -9,18 +9,28 @@
 }
 
 .modalContent {
-    @include horizontal-vertical-center();
-
     position: absolute;
-    bottom: auto;
-    right: auto;
     padding: 15px;
-    max-height: 80vh;
     outline: 0;
     background-color: $color-white;
+
+    @include mobile {
+        top: 0;
+        bottom: 0;
+        left: 0;
+        right: 0;
+        overflow-y: auto;
+    }
+
+    @include desktop {
+        @include horizontal-vertical-center();
+        bottom: auto;
+        right: auto;
+        max-height: 80vh;
         border-radius: 15px;
         border: $border-large;
     }
+}
 
 .closeButton {
     position: absolute;

src/components/VolunteerBoard/TeamWishesForm/styles.module.scss

@@ -2,8 +2,10 @@
 @import "../../../theme/mixins";
 
 .root {
+    @include desktop {
         width: 680px;
     }
+}
 
 .title {
     padding: 4px;
@@ -21,8 +23,11 @@
 }
 
 .formArea {
-    display: flex;
     margin-bottom: 10px;
+
+    @include desktop {
+        display: flex;
+    }
 }
 
 .leftCol {