MainNav-border 추가

client/src/components/Navs/MainNav.js

-import Search from "../Search/Search";
+import Search from "../Search";
 
 const MainNav = () => {
     return (
-        <nav class="nav justify-content-evenly bg-dark py-1">
+        <nav class="nav justify-content-evenly bg-dark border border-start-0 border-end-0 border-white border-2 py-1">
             <a class="nav-link text-white" href="#">영화</a>
             <a class="nav-link text-white" href="#">빠른예매</a>
             <a class="nav-link text-white" href="#">극장</a>