Day 5 Flex Panels Image Gallery

What’s this flex box thing?
What is this css:
`.panel > * {…`
`.panel > *:first-child`

Author: bweisberg

05 - Flex Panel Gallery/index-START.html

@@ -24,6 +24,7 @@
     .panels {
       min-height:100vh;
       overflow: hidden;
+      display: flex;
     }
 
     .panel {
@@ -41,6 +42,10 @@
       font-size: 20px;
       background-size:cover;
       background-position:center;
+      flex: 1;
+      justify-content:center;
+      display: flex;
+      flex-direction: column;
     }
 
 
@@ -54,8 +59,18 @@
       margin:0;
       width: 100%;
       transition:transform 0.5s;
+      flex: 1 0 auto;
+      display: flex:
+      justify-content: center;
+      align-items: center;
+      
     }
 
+    .panel > *:first-child { transform: translateY(-100%);}
+    .panel.open-active > *:first-child { transform: translateY(0);}
+    .panel > *:last-child { transform: translateY(100%);}
+    .panel.open-active > *:last-child { transform: translateY(0); }
+
     .panel p {
       text-transform: uppercase;
       font-family: 'Amatic SC', cursive;
@@ -67,6 +82,7 @@
     }
 
     .panel.open {
+      flex: 5;
       font-size:40px;
     }
 
@@ -107,6 +123,21 @@
   </div>
 
   <script>
+    const panels = document.querySelectorAll('.panel');
+
+    function toggleOpen() {
+      this.classList.toggle('open');
+    }
+
+    function toggleActive(e) {
+      console.log(e.propertyName);
+      if(e.propertyName.includes('flex')){
+        this.classList.toggle('open-active');
+      }   
+    }
+
+    panels.forEach(panel => panel.addEventListener('click', toggleOpen));
+    panels.forEach(panel => panel.addEventListener('transitionend', toggleActive));
 
   </script>