diff --git a/README.md b/README.md
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+++ b/README.md
@@ -155,7 +155,7 @@ A template is also available in Settings > Theme > Create from Template.
-
+ 
## Settings
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+# booru-viewer Theme Reference
+
+Copy any `.qss` file from this folder to your data directory as `custom.qss`:
+
+- **Linux**: `~/.local/share/booru-viewer/custom.qss`
+- **Windows**: `%APPDATA%\booru-viewer\custom.qss`
+
+Restart the app after changing themes.
+
+## Widget Targets
+
+### Global
+
+```css
+QWidget {
+ background-color: #282828;
+ color: #ebdbb2;
+ font-size: 13px;
+ font-family: monospace;
+ selection-background-color: #fe8019; /* also sets grid selection highlight */
+ selection-color: #282828;
+}
+```
+
+### Buttons
+
+```css
+QPushButton {
+ background-color: #333;
+ color: #fff;
+ border: 1px solid #555;
+ border-radius: 4px;
+ padding: 5px 14px;
+}
+QPushButton:hover { background-color: #444; }
+QPushButton:pressed { background-color: #555; }
+QPushButton:checked { background-color: #0078d7; } /* Browse/Favorites active tab */
+```
+
+### Text Inputs
+
+```css
+QLineEdit, QTextEdit {
+ background-color: #1a1a1a;
+ color: #fff;
+ border: 1px solid #555;
+ border-radius: 4px;
+ padding: 4px 8px;
+}
+QLineEdit:focus, QTextEdit:focus {
+ border-color: #0078d7;
+}
+```
+
+### Dropdowns
+
+```css
+QComboBox {
+ background-color: #333;
+ color: #fff;
+ border: 1px solid #555;
+ border-radius: 4px;
+ padding: 3px 6px;
+}
+QComboBox::drop-down {
+ border: none;
+ width: 20px;
+}
+QComboBox QAbstractItemView {
+ background-color: #333;
+ color: #fff;
+ border: 1px solid #555;
+ selection-background-color: #444;
+}
+```
+
+### Spin Box (Score Filter)
+
+```css
+QSpinBox {
+ background-color: #333;
+ color: #fff;
+ border: 1px solid #555;
+ border-radius: 2px;
+}
+```
+
+### Scrollbars
+
+```css
+QScrollBar:vertical {
+ background: #1a1a1a;
+ width: 10px;
+ border: none;
+}
+QScrollBar::handle:vertical {
+ background: #555;
+ border-radius: 4px;
+ min-height: 20px;
+}
+QScrollBar::handle:vertical:hover { background: #0078d7; }
+QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical { height: 0; }
+
+QScrollBar:horizontal {
+ background: #1a1a1a;
+ height: 10px;
+}
+QScrollBar::handle:horizontal {
+ background: #555;
+ border-radius: 4px;
+}
+QScrollBar::add-line:horizontal, QScrollBar::sub-line:horizontal { width: 0; }
+```
+
+### Menu Bar & Context Menus
+
+```css
+QMenuBar {
+ background-color: #1a1a1a;
+ color: #fff;
+}
+QMenuBar::item:selected { background-color: #333; }
+
+QMenu {
+ background-color: #1a1a1a;
+ color: #fff;
+ border: 1px solid #333;
+}
+QMenu::item:selected { background-color: #333; }
+```
+
+### Status Bar
+
+```css
+QStatusBar {
+ background-color: #1a1a1a;
+ color: #888;
+}
+```
+
+### Splitter Handle
+
+```css
+QSplitter::handle {
+ background: #555;
+ width: 2px;
+}
+```
+
+### Tab Bar (Settings Dialog)
+
+```css
+QTabBar::tab {
+ background: #333;
+ color: #fff;
+ border: 1px solid #555;
+ padding: 6px 16px;
+}
+QTabBar::tab:selected {
+ background: #444;
+ color: #0078d7;
+}
+```
+
+### Video Player Controls
+
+```css
+QSlider::groove:horizontal {
+ background: #333;
+ height: 4px;
+ border-radius: 2px;
+}
+QSlider::handle:horizontal {
+ background: #0078d7;
+ width: 12px;
+ margin: -4px 0;
+ border-radius: 6px;
+}
+```
+
+### Progress Bar (Download)
+
+```css
+QProgressBar {
+ background-color: #333;
+ border: none;
+}
+QProgressBar::chunk {
+ background-color: #0078d7;
+}
+```
+
+### Tooltips
+
+```css
+QToolTip {
+ background-color: #333;
+ color: #fff;
+ border: 1px solid #555;
+ padding: 4px;
+}
+```
+
+### Labels
+
+```css
+QLabel {
+ background: transparent; /* important: prevents opaque label backgrounds */
+}
+```
+
+## States
+
+| State | Description |
+|-------|-------------|
+| `:hover` | Mouse over |
+| `:pressed` | Mouse down |
+| `:focus` | Keyboard focus |
+| `:checked` | Toggle buttons (Browse/Favorites) |
+| `:selected` | Selected menu item or tab |
+| `:disabled` | Grayed out |
+
+## Notes
+
+- `selection-background-color` on `QWidget` controls the **grid thumbnail selection highlight**
+- Setting a custom QSS automatically switches to the Fusion Qt style for consistent rendering
+- Tag category colors (Artist, Character, etc.) in the info panel are set in code, not via QSS
+- The favorite/saved dot indicators on thumbnails are painted in code
+- Use `QLabel { background: transparent; }` to prevent labels from getting opaque backgrounds
diff --git a/themes/everforest.qss b/themes/everforest.qss
new file mode 100644
index 0000000..aa0aba7
--- /dev/null
+++ b/themes/everforest.qss
@@ -0,0 +1,116 @@
+/* booru-viewer — Everforest Dark */
+
+QWidget {
+ background-color: #2d353b;
+ color: #d3c6aa;
+ font-size: 13px;
+}
+
+QPushButton {
+ background-color: #343f44;
+ color: #d3c6aa;
+ border: 1px solid #4f585e;
+ border-radius: 4px;
+ padding: 5px 14px;
+}
+QPushButton:hover {
+ background-color: #4f585e;
+ border-color: #a7c080;
+}
+QPushButton:pressed {
+ background-color: #a7c080;
+ color: #2d353b;
+}
+QPushButton:checked {
+ background-color: #a7c080;
+ color: #2d353b;
+ border-color: #a7c080;
+}
+
+QLineEdit, QSpinBox, QComboBox, QTextEdit {
+ background-color: #272e33;
+ color: #d3c6aa;
+ border: 1px solid #4f585e;
+ border-radius: 4px;
+ padding: 4px 8px;
+ selection-background-color: #a7c080;
+ selection-color: #2d353b;
+}
+QLineEdit:focus, QSpinBox:focus, QTextEdit:focus {
+ border-color: #a7c080;
+}
+
+QComboBox::drop-down { border: none; width: 20px; }
+QComboBox QAbstractItemView {
+ background-color: #272e33;
+ color: #d3c6aa;
+ border: 1px solid #4f585e;
+ selection-background-color: #343f44;
+}
+
+QScrollBar:vertical {
+ background: #2d353b;
+ width: 10px;
+ border: none;
+}
+QScrollBar::handle:vertical {
+ background: #4f585e;
+ border-radius: 4px;
+ min-height: 20px;
+}
+QScrollBar::handle:vertical:hover { background: #a7c080; }
+QScrollBar::add-line:vertical, QScrollBar::sub-line:vertical { height: 0; }
+
+QScrollBar:horizontal {
+ background: #2d353b;
+ height: 10px;
+}
+QScrollBar::handle:horizontal {
+ background: #4f585e;
+ border-radius: 4px;
+}
+QScrollBar::add-line:horizontal, QScrollBar::sub-line:horizontal { width: 0; }
+
+QMenuBar, QMenu {
+ background-color: #2d353b;
+ color: #d3c6aa;
+ border: 1px solid #343f44;
+}
+QMenu::item:selected {
+ background-color: #343f44;
+}
+
+QStatusBar {
+ background-color: #272e33;
+ color: #859289;
+}
+
+QSplitter::handle {
+ background: #4f585e;
+ width: 2px;
+}
+
+QLabel { background: transparent; }
+
+QSlider::groove:horizontal {
+ background: #343f44;
+ height: 4px;
+ border-radius: 2px;
+}
+QSlider::handle:horizontal {
+ background: #a7c080;
+ width: 12px;
+ margin: -4px 0;
+ border-radius: 6px;
+}
+
+QTabBar::tab {
+ background: #343f44;
+ color: #d3c6aa;
+ border: 1px solid #4f585e;
+ padding: 6px 16px;
+}
+QTabBar::tab:selected {
+ background: #4f585e;
+ color: #a7c080;
+}