Replace loss dialog with KABOOM! overlay; bevel the New Game button

- Losing no longer pops a dialog: the board draws a tilted KABOOM! banner
  (theme-independent, auto-scaling, dark translucent panel) over the revealed
  mines; restart via the New Game button or R/Ctrl+N
- Win dialog unchanged (time + new-record note, delayed for the confetti)
- New Game button gets an explicit theme-aware bevel (gradient, border,
  hover/active) so it reads as a button even with themes that flatten widgets

src/board_widget.cpp

@@ -355,6 +355,58 @@ void BoardWidget::on_draw(const Cairo::RefPtr<Cairo::Context>& cr, int width, in
     if (!particles_.empty()) {
         draw_particles(cr);
     }
+
+    if (field_ && field_->state() == GameState::Lost) {
+        draw_game_over_overlay(cr, width, height);
+    }
+}
+
+void BoardWidget::draw_game_over_overlay(const Cairo::RefPtr<Cairo::Context>& cr, int width, int height) {
+    const char* msg = "KABOOM!";
+
+    cr->save();
+
+    // Scale the font to fit both dimensions
+    double font_size = std::clamp(std::min(width, height) * 0.3, 24.0, 120.0);
+    cr->select_font_face("Sans", Cairo::ToyFontFace::Slant::NORMAL, Cairo::ToyFontFace::Weight::BOLD);
+    cr->set_font_size(font_size);
+    Cairo::TextExtents ext;
+    cr->get_text_extents(msg, ext);
+    if (ext.width > width * 0.8) {
+        font_size *= (width * 0.8) / ext.width;
+        cr->set_font_size(font_size);
+        cr->get_text_extents(msg, ext);
+    }
+
+    double cx = (width - ext.width) / 2.0 - ext.x_bearing;
+    double cy = (height - ext.height) / 2.0 - ext.y_bearing;
+
+    // Slight tilt for drama
+    cr->translate(width / 2.0, height / 2.0);
+    cr->rotate(-0.06);
+    cr->translate(-width / 2.0, -height / 2.0);
+
+    // Translucent panel for readability over the revealed board
+    double pad = font_size * 0.35;
+    double px = cx - pad;
+    double py = cy - pad;
+    double pw = ext.width + 2 * pad;
+    double ph = ext.height + 2 * pad;
+    double radius = font_size * 0.12;
+    cr->set_source_rgba(0.0, 0.0, 0.0, 0.5);
+    cr->move_to(px + radius, py);
+    cr->arc(px + pw - radius, py + radius, radius, -M_PI / 2, 0);
+    cr->arc(px + pw - radius, py + ph - radius, radius, 0, M_PI / 2);
+    cr->arc(px + radius, py + ph - radius, radius, M_PI / 2, M_PI);
+    cr->arc(px + radius, py + radius, radius, M_PI, 3 * M_PI / 2);
+    cr->close_path();
+    cr->fill();
+
+    cr->set_source_rgb(1.0, 0.42, 0.08); // Explosive orange
+    cr->move_to(cx, cy);
+    cr->show_text(msg);
+
+    cr->restore();
 }
 
 void BoardWidget::draw_cell(const Cairo::RefPtr<Cairo::Context>& cr, int x, int y, double size, const Cell& cell, const Palette& pal) {

src/board_widget.hpp

@@ -69,6 +69,7 @@ private:
     void draw_flag(const Cairo::RefPtr<Cairo::Context>& cr, double x, double y, double size, const Palette& pal);
     void draw_bomb(const Cairo::RefPtr<Cairo::Context>& cr, double x, double y, double size, bool exploded, const Palette& pal);
     void draw_particles(const Cairo::RefPtr<Cairo::Context>& cr);
+    void draw_game_over_overlay(const Cairo::RefPtr<Cairo::Context>& cr, int width, int height);
 
     std::shared_ptr<Minefield> field_;
     

src/window.cpp

@@ -39,6 +39,20 @@ popover.background > contents { background-color: @theme_bg_color; }
     font-family: monospace;
     font-weight: bold;
 }
+.status-bar button {
+    background-image: linear-gradient(to top, alpha(@theme_fg_color, 0.16), alpha(@theme_fg_color, 0.05));
+    border: 1px solid alpha(@theme_fg_color, 0.3);
+    border-radius: 8px;
+    padding: 4px 18px;
+    color: @theme_fg_color;
+}
+.status-bar button:hover {
+    background-image: linear-gradient(to top, alpha(@theme_fg_color, 0.24), alpha(@theme_fg_color, 0.12));
+}
+.status-bar button:active {
+    background-image: none;
+    background-color: alpha(@theme_fg_color, 0.2);
+}
 )CSS");
     Gtk::StyleContext::add_provider_for_display(
         get_display(), app_css, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
@@ -239,8 +253,10 @@ void MainWindow::on_game_state_changed() {
         if (state == GameState::Won) {
             secs = std::chrono::duration_cast<std::chrono::seconds>(minefield_->get_elapsed_time()).count();
             new_best = leaderboard_.record(current_difficulty_.name, secs);
+            show_game_over_dialog(new_best, secs);
         }
-        show_game_over_dialog(state == GameState::Won, new_best, secs);
+        // Lost: no dialog — the board draws a KABOOM! overlay and the
+        // player restarts via the New Game button.
     }
     
     // Update timer immediately to reflect end time if stopped
@@ -258,15 +274,15 @@ bool MainWindow::on_timer_tick() {
     return true; // Keep calling
 }
 
-void MainWindow::show_game_over_dialog(bool won, bool new_best, int seconds) {
+void MainWindow::show_game_over_dialog(bool new_best, int seconds) {
     // Delay so the win animation/board state is visible before the modal
     // dialog covers it.
     if (dialog_timeout_conn_.connected()) return;
-    dialog_timeout_conn_ = Glib::signal_timeout().connect([this, won, new_best, seconds]() {
+    dialog_timeout_conn_ = Glib::signal_timeout().connect([this, new_best, seconds]() {
         dialog_timeout_conn_.disconnect();
 
         // A new game may have started while the dialog was pending
-        if (!minefield_ || minefield_->state() == GameState::Ready) return false;
+        if (!minefield_ || minefield_->state() != GameState::Won) return false;
 
         // Reuse a single dialog instance: creating a new make_managed dialog
         // per game over leaks (it's never added to a container, so it's never
@@ -286,12 +302,10 @@ void MainWindow::show_game_over_dialog(bool won, bool new_best, int seconds) {
             });
         }
 
-        game_over_dialog_->set_title(won ? "Congratulations!" : "Game Over");
-        game_over_dialog_->set_message(won ? "Congratulations!" : "Game Over");
-        std::string secondary = won
-            ? "You cleared the minefield in " + format_time(seconds) +
-              (new_best ? " — new best time!" : ".")
-            : "Better luck next time.";
+        game_over_dialog_->set_title("Congratulations!");
+        game_over_dialog_->set_message("Congratulations!");
+        std::string secondary = "You cleared the minefield in " + format_time(seconds) +
+                                (new_best ? " — new best time!" : ".");
         game_over_dialog_->set_secondary_text(secondary);
         game_over_dialog_->show();
         return false; // One-shot

src/window.hpp

@@ -23,7 +23,7 @@ private:
     void start_new_game(const GameDifficulty& difficulty);
     void on_game_state_changed();
     bool on_timer_tick();
-    void show_game_over_dialog(bool won, bool new_best, int seconds);
+    void show_game_over_dialog(bool new_best, int seconds);
 
     // Widgets
     Gtk::HeaderBar header_bar_;