git init

css/header.css

@@ -0,0 +1,40 @@
+@keyframes NavItem {
+    0% {
+        width: 0;
+    }
+
+    100% {
+        width: 80%;
+    }
+}
+
+.navbar-nav .cur a {
+    color: #1362AD;
+}
+
+.navbar-nav .cur a::after {
+    display: block !important;
+}
+
+.navbar-nav .nav-item a {
+    transition: 500ms;
+}
+
+.navbar-nav .nav-item {
+    position: relative;
+}
+
+.navbar-nav .nav-item:hover a::after {
+    display: block;
+}
+
+.navbar-nav .nav-item a::after {
+    content: '';
+    width: 0;
+    height: 2px;
+    background-color: #1362AD;
+    position: absolute;
+    bottom: -31px;
+    display: none;
+    animation: NavItem 500ms forwards;
+}

css/index.css

@@ -0,0 +1,4 @@
+* {
+    margin: 0;
+    padding: 0;
+}