fix matrix background don't show bug

quote_generator/matrix.js

@@ -1,8 +1,8 @@
 const canvas = document.getElementById("Matrix")
 const context = canvas.getContext("2d")
 
-canvas.height = window.innerHeight
-canvas.width = window.innerWidth
+canvas.height = window.innerHeight + 100;
+canvas.width = window.innerWidth + 5;
 
 const chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789./*-+#$%^@!~?><:;[]{}\」=_αβΓγΔδεζηΘθικΛλμΞξΠπρΣσςτυΦφχΨψΩω×≦≧≠∞≒≡～∩∠∪∟⊿∫∮∵∴＄￥〒￠￡℃€℉╩◢ⅩⅨⅧⅦⅥⅤⅣⅢⅡⅠあいうえおがぎぐげござじずぜぞだぢつでづどにぬのばひぴぶへぺぼみゃょァゐゎè";
 
@@ -15,11 +15,18 @@ for(let i = 0; i < columns; ++i) {
 }
 
 let frame = 0;
+let str;
 
-function Update(str) {
+context.fillStyle = "rgba(0, 0, 0, 1)";
+context.fillRect(0, 0, canvas.width, canvas.height);
+
+function Update() {
   context.fillStyle = "rgba(0, 0, 0, 0.05)";
   context.fillRect(0, 0, canvas.width, canvas.height);
-
+  if(frame == 0){
+    let a = parseInt(Math.random() * 255);
+    str = `rgba(${a}, ${Math.abs(a - 127)}, ${Math.abs(a - 255)}, 0.9)`;
+  }
   context.fillStyle = str;
   context.font = fontSize + "px monospace";
   
@@ -32,11 +39,9 @@ function Update(str) {
     charArr[i]++;
   }
   frame++;
-  if(frame <= 40 * (Math.floor(Math.random() * 10) + 3)) requestAnimationFrame(Update(str)); // 40 frames a cycle
+  if(frame <= 40 * (Math.floor(Math.random() * 10) + 3)) requestAnimationFrame(Update); // 40 frames a cycle
   else{
     frame = 0;
     Appear();
   }
 }
-
-//Update();