viewer: Phase 0 redesign — slim headers, navy accent, icon nav

First pass of the viewer redesign (see docs/review/VIEWER_REDESIGN.md), no
structural change:

- TitleLabel: replace the 50px solid #FA7268 section bars with a slim 26px
  navy-bold header + coral accent rule, removing the "venetian blind" stack
  while keeping the salmon identity.
- Palette: switch the accent (QPalette::Highlight) from teal to navy #1F3A5F.
- Image toolbar: replace the unicode arrow glyphs (|<= <= => =>|) with flat
  media icons (first/prev/next/last) + tooltips, and a play icon on Movie.
- Bottom dock: give the per-dataset plot more default height (340 -> 420).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

viewer/JFJochViewerWindow.cpp

@@ -426,8 +426,9 @@ JFJochViewerWindow::JFJochViewerWindow(QWidget *parent, bool dbus, const QString
     if (lastDatasetInfoDock) {
         splitDockWidget(lastDatasetInfoDock, processingDock, Qt::Horizontal);
         resizeDocks({lastDatasetInfoDock, processingDock}, {650, 350}, Qt::Horizontal);
-        // Give the bottom area enough height so the plots and their labels are fully visible.
-        resizeDocks({lastDatasetInfoDock, processingDock}, {340, 340}, Qt::Vertical);
+        // Give the bottom area generous height: the per-dataset plot is a headline feature, so it
+        // gets real room rather than a thin strip.
+        resizeDocks({lastDatasetInfoDock, processingDock}, {420, 420}, Qt::Vertical);
     }
     menuBar->AddDockEntry(processingDock, "Processing");
 

viewer/JFJochViewerWindow.h

@@ -19,7 +19,7 @@ class QDockWidget;
 class JFJochViewerWindow : public QMainWindow {
 Q_OBJECT
     // Theming is done via the application palette in main() (salmon panels, white entry fields,
-    // teal accent) so it applies consistently to every widget, including dialogs.
+    // navy accent) so it applies consistently to every widget, including dialogs.
 public:
     explicit JFJochViewerWindow(QWidget *parent = nullptr, bool dbus = true, const QString &file = "");
     ~JFJochViewerWindow() override;

viewer/jfjoch_viewer.cpp

@@ -18,7 +18,7 @@ int main(int argc, char *argv[]) {
     QApplication app(argc, argv);
 
     // Theme via the palette (robust across widgets): salmon panels, white entry fields that fall back
-    // to salmon when disabled, and a teal accent for selections and progress-bar chunks.
+    // to salmon when disabled, and a navy accent for selections and progress-bar chunks.
     app.setStyle("Fusion");
     QPalette pal = app.palette();
     pal.setColor(QPalette::Window, QColor(255, 235, 230));
@@ -26,7 +26,7 @@ int main(int argc, char *argv[]) {
     pal.setColor(QPalette::AlternateBase, QColor(255, 245, 242));
     pal.setColor(QPalette::Button, QColor(255, 235, 230));
     pal.setColor(QPalette::Disabled, QPalette::Base, QColor(255, 235, 230));
-    pal.setColor(QPalette::Highlight, QColor(0x2a, 0x9d, 0x8f));
+    pal.setColor(QPalette::Highlight, QColor(0x1f, 0x3a, 0x5f));
     pal.setColor(QPalette::HighlightedText, Qt::white);
     app.setPalette(pal);
     // Fusion fills QGroupBox interiors with a flat light colour; make them transparent so they show

viewer/toolbar/JFJochViewerToolbarImage.cpp

@@ -3,6 +3,7 @@
 
 #include "JFJochViewerToolbarImage.h"
 #include <QTimer>
+#include <QStyle>
 
 JFJochViewerToolbarImage::JFJochViewerToolbarImage(QWidget *parent) : QToolBar(parent) {
     image_count_in_dataset = 0;
@@ -10,11 +11,15 @@ JFJochViewerToolbarImage::JFJochViewerToolbarImage(QWidget *parent) : QToolBar(p
     auto title = new QLabel("<b>Image number</b>   ", this);
     addWidget(title);
 
-    leftmost_button = new QPushButton("|⇐", this);
+    leftmost_button = new QPushButton(this);
+    leftmost_button->setIcon(style()->standardIcon(QStyle::SP_MediaSkipBackward));
+    leftmost_button->setToolTip("First image");
     leftmost_button->setFixedWidth(32);
     addWidget(leftmost_button);
 
-    left_button = new QPushButton("⇐", this);
+    left_button = new QPushButton(this);
+    left_button->setIcon(style()->standardIcon(QStyle::SP_MediaSeekBackward));
+    left_button->setToolTip("Previous (by jump)");
     left_button->setFixedWidth(32);
     addWidget(left_button);
 
@@ -30,11 +35,15 @@ JFJochViewerToolbarImage::JFJochViewerToolbarImage(QWidget *parent) : QToolBar(p
     total_number_label = new QLabel("/0", this);
     addWidget(total_number_label);
 
-    right_button = new QPushButton("⇒", this);
+    right_button = new QPushButton(this);
+    right_button->setIcon(style()->standardIcon(QStyle::SP_MediaSeekForward));
+    right_button->setToolTip("Next (by jump)");
     right_button->setFixedWidth(32);
     addWidget(right_button);
 
-    rightmost_button = new QPushButton("⇒|", this);
+    rightmost_button = new QPushButton(this);
+    rightmost_button->setIcon(style()->standardIcon(QStyle::SP_MediaSkipForward));
+    rightmost_button->setToolTip("Last image");
     rightmost_button->setFixedWidth(32);
     addWidget(rightmost_button);
 
@@ -57,6 +66,7 @@ JFJochViewerToolbarImage::JFJochViewerToolbarImage(QWidget *parent) : QToolBar(p
 
 
     movie_button = new QPushButton("&Movie");
+    movie_button->setIcon(style()->standardIcon(QStyle::SP_MediaPlay));
     movie_button->setCheckable(true);
     movie_button->setChecked(false);
     movie_button->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_M));

viewer/widgets/TitleLabel.cpp

@@ -4,8 +4,18 @@
 #include "TitleLabel.h"
 
 TitleLabel::TitleLabel(QString text, QWidget *parent) : QLabel(parent) {
-    setText(QString("<h3>%1</h3>").arg(text));
-    setStyleSheet("background-color: #FA7268; color: #ffffff;");
-    setAlignment(Qt::AlignmentFlag::AlignCenter);
-    setFixedHeight(50);
+    // Slim section header: navy bold text with a coral accent rule, in place of a heavy 50px
+    // full-width salmon bar. Keeps the salmon identity (the rule) while letting panels breathe.
+    setText(text);
+    QFont f = font();
+    f.setBold(true);
+    setFont(f);
+    setStyleSheet("QLabel {"
+                  " color: #1F3A5F;"
+                  " background-color: transparent;"
+                  " border-left: 3px solid #FA7268;"
+                  " border-bottom: 1px solid #FA7268;"
+                  " padding: 3px 6px 3px 8px; }");
+    setAlignment(Qt::AlignLeft | Qt::AlignVCenter);
+    setFixedHeight(26);
 }