feat: implement password authentication

app/assets/stylesheets/application.css

@@ -1,6 +1,6 @@
 body {
     font-family: sans-serif;
-    margin: 40px;
+    margin: 10px 40px;
 }
 
 header {
@@ -103,12 +103,15 @@ button.action:hover {
     cursor: pointer;
 }
 
-.action {
+.needs_pwd {
     display: none;
 }
 
-.action.shown {
+.needs_pwd.shown {
     display: block;
+}
+
+.action.shown {
     height: 100%;
 }
 
@@ -134,3 +137,16 @@ section .meta {
     top: 0;
     left: 0;
 }
+
+span#password {
+    font-family: monospace;
+    background-color: black;
+    color: white;
+    font-weight: bold;
+    font-size: 16px;
+    padding: 1px 4px;
+}
+
+.hidden {
+    display: none;
+}