added an icon for the window and basic red black and white style sheet

#story[1003]

visualiser/src/main/resources/css/sail.css

@@ -44,7 +44,7 @@
 
 .scroll-bar > .increment-button:hover > .increment-arrow,
 .scroll-bar > .decrement-button:hover > .decrement-arrow {
-    -fx-background-color: -fx-mark-highlight-color, rgb(240, 240, 240);
+    -fx-background-color: -fx-mark-highlight-color, rgb(255, 255, 255);
 }
 
 .scroll-bar > .increment-button:pressed > .increment-arrow,

visualiser/src/main/resources/css/test.css

@@ -1,57 +0,0 @@
-/*
- * This is an adjustment of the original modena.css for a consistent dark theme.
- * Original modena.css here: https://gist.github.com/maxd/63691840fc372f22f470.
- * This one from: https://github.com/joffrey-bion/javafx-themes/blob/master/css/modena_dark.css
- */
-
-/* Redefine base colors */
-.root {
-    -fx-base: rgb(50, 50, 50);
-    -fx-background: rgb(50, 50, 50);
-
-    /* make controls (buttons, thumb, etc.) slightly lighter */
-    -fx-color: derive(-fx-base, 10%);
-
-    /* text fields and table rows background */
-    -fx-control-inner-background: rgb(20, 20, 20);
-    /* version of -fx-control-inner-background for alternative rows */
-    -fx-control-inner-background-alt: derive(-fx-control-inner-background, 2.5%);
-
-    /* text colors depending on background's brightness */
-    -fx-light-text-color: rgb(220, 220, 220);
-    -fx-mid-text-color: rgb(100, 100, 100);
-    -fx-dark-text-color: rgb(20, 20, 20);
-
-    /* A bright blue for highlighting/accenting objects.  For example: selected
-     * text; selected items in menus, lists, trees, and tables; progress bars */
-    -fx-accent: rgb(0, 80, 100);
-
-    /* color of non-focused yet selected elements */
-    -fx-selection-bar-non-focused: rgb(50, 50, 50);
-}
-
-/* Fix derived prompt color for text fields */
-.text-input {
-    -fx-prompt-text-fill: derive(-fx-control-inner-background, +50%);
-}
-
-/* Keep prompt invisible when focused (above color fix overrides it) */
-.text-input:focused {
-    -fx-prompt-text-fill: transparent;
-}
-
-/* Fix scroll bar buttons arrows colors */
-.scroll-bar > .increment-button > .increment-arrow,
-.scroll-bar > .decrement-button > .decrement-arrow {
-    -fx-background-color: -fx-mark-highlight-color, rgb(220, 220, 220);
-}
-
-.scroll-bar > .increment-button:hover > .increment-arrow,
-.scroll-bar > .decrement-button:hover > .decrement-arrow {
-    -fx-background-color: -fx-mark-highlight-color, rgb(240, 240, 240);
-}
-
-.scroll-bar > .increment-button:pressed > .increment-arrow,
-.scroll-bar > .decrement-button:pressed > .decrement-arrow {
-    -fx-background-color: -fx-mark-highlight-color, rgb(255, 255, 255);
-}