diff --git a/build.sh b/build.sh
index 4100244..79b8afb 100755
--- a/build.sh
+++ b/build.sh
@@ -100,8 +100,9 @@ if [ "$OS" = "darwin" ]; then
     mv "$PRODUCED" "$APP"
   fi
 
-  echo "[build] sembrando games.toml en Contents/Resources…"
+  echo "[build] sembrando games.toml y icon.png en Contents/Resources…"
   cp games.toml "$APP/Contents/Resources/games.toml"
+  cp assets/icon.png "$APP/Contents/Resources/icon.png"  # usado por el diálogo «Quant a»
 
   # Bundle ad-hoc (sin Developer ID): quitamos quarantine para abrir sin fricción local.
   xattr -dr com.apple.quarantine "$APP" 2>/dev/null || true
diff --git a/jlauncher/__main__.py b/jlauncher/__main__.py
index b27ffe9..7821a79 100644
--- a/jlauncher/__main__.py
+++ b/jlauncher/__main__.py
@@ -4,10 +4,11 @@ from __future__ import annotations
 
 import sys
 
+from PySide6.QtGui import QIcon
 from PySide6.QtWidgets import QApplication, QMessageBox
 
 from .config import load_config
-from .paths import config_file, data_root
+from .paths import app_icon_path, config_file, data_root
 from .ui.main_window import MainWindow
 from .ui.theme import apply_theme
 
@@ -15,6 +16,9 @@ from .ui.theme import apply_theme
 def main() -> int:
     app = QApplication(sys.argv)
     app.setApplicationName("jlauncher")
+    icon_path = app_icon_path()
+    if icon_path is not None:
+        app.setWindowIcon(QIcon(str(icon_path)))
     # Tema del sistema para el posible diálogo de error previo a la ventana;
     # MainWindow re-aplica el modo guardado (system/light/dark) y vigila los cambios.
     apply_theme(app)
diff --git a/jlauncher/paths.py b/jlauncher/paths.py
index d50f58e..b15dc17 100644
--- a/jlauncher/paths.py
+++ b/jlauncher/paths.py
@@ -55,6 +55,20 @@ def macos_app_bundle() -> Path | None:
     return None
 
 
+def app_icon_path() -> Path | None:
+    """Ruta al PNG del icono para la UI (icono de ventana/Dock y diálogo «Quant a»).
+
+    En .app vive en ``Contents/Resources/icon.png``; desde fuente, en ``assets/icon.png``.
+    Devuelve None si no se encuentra.
+    """
+    bundle = macos_app_bundle()
+    if bundle is not None:
+        candidate = bundle / "Contents" / "Resources" / "icon.png"
+    else:
+        candidate = base_dir() / "assets" / "icon.png"
+    return candidate if candidate.exists() else None
+
+
 def support_dir() -> Path:
     """Carpeta de soporte escribible en macOS (.app); se crea si no existe."""
     root = (
diff --git a/jlauncher/ui/main_window.py b/jlauncher/ui/main_window.py
index c17372d..768f750 100644
--- a/jlauncher/ui/main_window.py
+++ b/jlauncher/ui/main_window.py
@@ -5,10 +5,14 @@ from __future__ import annotations
 from pathlib import Path
 
 from PySide6.QtCore import QEasingCurve, QPropertyAnimation, QThreadPool, Qt, QTimer
-from PySide6.QtGui import QAction, QActionGroup
+from PySide6.QtGui import QAction, QActionGroup, QPixmap
 from PySide6.QtWidgets import (
     QApplication,
+    QDialog,
+    QDialogButtonBox,
+    QHBoxLayout,
     QInputDialog,
+    QLabel,
     QLineEdit,
     QMainWindow,
     QMessageBox,
@@ -21,6 +25,7 @@ from PySide6.QtWidgets import (
 
 from .. import __version__, gitops
 from ..config import Config, Game
+from ..paths import app_icon_path
 from ..settings import load_settings, save_settings
 from ..workers import CheckUpdatesWorker, DownloadWorker, RunWorker
 from . import theme
@@ -257,13 +262,73 @@ class MainWindow(QMainWindow):
         help_menu.addAction(self.action_about)
 
     def _show_about(self) -> None:
-        QMessageBox.about(
-            self,
-            f"Quant a {APP_NAME}",
-            f"<b>{APP_NAME}</b><br>"
-            f"Versió {__version__}<br><br>"
-            "© 2026 JailDesigner",
-        )
+        """Diàleg «Quant a» personalitzat: icona, nom gran i tot centrat."""
+        dlg = QDialog(self)
+        dlg.setWindowTitle(f"Quant a {APP_NAME}")
+        dlg.setModal(True)
+
+        lay = QVBoxLayout(dlg)
+        lay.setContentsMargins(40, 30, 40, 24)
+        lay.setSpacing(0)
+
+        # Logo (si el trobem); s'escala suau des del PNG gran.
+        icon_path = app_icon_path()
+        if icon_path is not None:
+            pix = QPixmap(str(icon_path))
+            if not pix.isNull():
+                logo = QLabel(alignment=Qt.AlignCenter)
+                logo.setPixmap(
+                    pix.scaled(
+                        96, 96, Qt.KeepAspectRatio, Qt.SmoothTransformation
+                    )
+                )
+                lay.addWidget(logo)
+                lay.addSpacing(16)
+
+        # Nom de l'app: gran, en negreta i amb el morat de la marca.
+        name = QLabel(APP_NAME, alignment=Qt.AlignCenter)
+        nf = name.font()
+        nf.setPointSize(nf.pointSize() + 13)
+        nf.setBold(True)
+        name.setFont(nf)
+        name.setStyleSheet("color: #7c4dff;")
+        lay.addWidget(name)
+        lay.addSpacing(4)
+
+        # Versió en cursiva i atenuada.
+        ver = QLabel(f"Versió {__version__}", alignment=Qt.AlignCenter)
+        vf = ver.font()
+        vf.setItalic(True)
+        vf.setPointSize(vf.pointSize() + 1)
+        ver.setFont(vf)
+        ver.setStyleSheet("color: #8a8a8a;")
+        lay.addWidget(ver)
+        lay.addSpacing(18)
+
+        # Lema discret.
+        tag = QLabel("Clona, compila i juga · jailgames", alignment=Qt.AlignCenter)
+        tag.setStyleSheet("color: #8a8a8a;")
+        lay.addWidget(tag)
+        lay.addSpacing(14)
+
+        copy = QLabel("© 2026 JailDesigner", alignment=Qt.AlignCenter)
+        cf = copy.font()
+        cf.setPointSize(cf.pointSize() - 1)
+        copy.setFont(cf)
+        lay.addWidget(copy)
+        lay.addSpacing(24)
+
+        # Botó OK centrat.
+        buttons = QDialogButtonBox(QDialogButtonBox.Ok)
+        buttons.button(QDialogButtonBox.Ok).setText("D'acord")
+        buttons.accepted.connect(dlg.accept)
+        row = QHBoxLayout()
+        row.addStretch(1)
+        row.addWidget(buttons)
+        row.addStretch(1)
+        lay.addLayout(row)
+
+        dlg.exec()
 
     def _build_theme_menu(self, parent_menu) -> None:
         """Submenú Tema amb tres opcions exclusives: Sistema / Clar / Fosc."""