Set max-width on all noVNC panels

All panels should be limited in this way, not just the clipboard panel.
One additional upside of this is that the numbers used to calculate the
max-width are closer by, in the code. This hopefully makes it easier to
avoid mistakes in the future.

app/styles/base.css

@@ -422,6 +422,7 @@ html {
 
   transition: 0.5s ease-in-out;
 
+  max-width: calc(100vw - 2*15px - 75px - 25px); /* minus padding, and left and right margins */
   max-height: 100vh; /* Chrome is buggy with 100% */
   overflow-x: hidden;
   overflow-y: auto;
@@ -568,10 +569,6 @@ html {
 :root:not(.noVNC_connected) #noVNC_clipboard_button {
   display: none;
 }
-#noVNC_clipboard {
-  /* Full screen, minus padding and left and right margins */
-  max-width: calc(100vw - 2*15px - 75px - 25px);
-}
 #noVNC_clipboard_text {
   width: 500px;
   max-width: 100%;