feat: add signature encoding, auto-detect base on decode, and show notification

style.css

@@ -42,6 +42,7 @@ body {
 }
 
 #overbar {
+    position: relative;
     padding: 1.5%;
     font-size: 10px;
     font-weight: bold;
@@ -50,6 +51,22 @@ body {
     border-bottom: 1px solid rgb(0, 126, 199, .5);
 }
 
+#sigDetect {
+    position: absolute;
+    left: 50%;
+    top: 50%;
+    transform: translate(-50%, -50%);
+    font-weight: normal;
+    color: rgb(229, 244, 255, 0.85);
+    opacity: 0;
+    transition: opacity 1s;
+}
+
+#sigDetect.show {
+    opacity: 1;
+    transition: opacity .2s;
+}
+
 #homepage {
     position: fixed;
     text-decoration: none;