Improve CSS styling implementation of the UI

[laim2003]

Task summary

In a lot of areas of the UI, we still use hard-coded CSS styling. Instead of hard-coding our CSS styles, we should create proper CSS files with classes, that are then used by our UI components.

Additional context

These are the current areas in which raw CSS styling is still found (as of 15.09.2026):

File	Line	Code
console.fxml	12	style="-fx-background-color: #FFFFFF; -fx-border-color: #cccccc; -fx-border-width: 1;"
console.fxml	18	style="-fx-border-color: #cccccc; -fx-border-width: 1 0 0 0;"
console.fxml	25	style="-fx-padding: 5;"
console.fxml	26	style="-fx-font-weight: bold; -fx-font-size: 12;"
console.fxml	27	style="-fx-padding: 0;"
console.fxml	29	style="-fx-font-size: 11;" (clear button)
console.fxml	33	style="-fx-font-size: 11;" (auto-scroll checkbox)
console.fxml	39	style="-fx-font-family: 'Consolas', monospace; -fx-font-size: 11; -fx-control-inner-background: #f5f5f5;" (list view)
console.fxml	41	style="-fx-padding: 3; -fx-border-color: #e0e0e0; -fx-border-width: 1 0 0 0;"
console.fxml	42	style="-fx-font-size: 10; -fx-text-fill: #666666;" (status label)
console.fxml	44	style="-fx-font-size: 10; -fx-text-fill: #666666;" (line-count label)
MainWindowView.java	187-189	this.statusLabel.setStyle("-fx-text-fill: blue;" + "-fx-cursor: hand")
MainWindowView.java	192	this.statusLabel.setStyle("")
ConsoleController.java	220	private static final String BASE_STYLE = "-fx-font-family: 'Consolas', monospace; -fx-font-size: 11;";
ConsoleController.java	221	private static final String ERROR_STYLE = BASE_STYLE + " -fx-text-fill: #cc0000;";
ConsoleController.java	222	private static final String WARNING_STYLE = BASE_STYLE + " -fx-text-fill: #cc8800;";
ConsoleController.java	223	private static final String INFO_STYLE = BASE_STYLE + " -fx-text-fill: #000000;";
ConsoleController.java	224	private static final String DEBUG_STYLE = BASE_STYLE + " -fx-text-fill: #666666;";
ConsoleController.java	225	private static final String TRACE_STYLE = BASE_STYLE + " -fx-text-fill: #888888;";
ConsoleController.java	226	private static final String PLAIN_STYLE = BASE_STYLE + " -fx-text-fill: #333333;";
ConsoleController.java	227	private static final String ERROR_BG = "-fx-background-color: #fff0f0;";
ConsoleController.java	228	private static final String WARNING_BG = "-fx-background-color: #fff8e0;";
ConsoleController.java	236	setStyle(BASE_STYLE);
ConsoleController.java	239	setStyle(getStyleForEntry(entry));