diff --git a/server/src/wled_controller/api/routes/color_strip_sources.py b/server/src/wled_controller/api/routes/color_strip_sources.py
index ab63593..6140696 100644
--- a/server/src/wled_controller/api/routes/color_strip_sources.py
+++ b/server/src/wled_controller/api/routes/color_strip_sources.py
@@ -51,6 +51,7 @@ def _css_to_response(source) -> ColorStripSourceResponse:
         gamma=getattr(source, "gamma", None),
         smoothing=getattr(source, "smoothing", None),
         interpolation_mode=getattr(source, "interpolation_mode", None),
+        led_count=getattr(source, "led_count", 0),
         calibration=calibration,
         description=source.description,
         created_at=source.created_at,
@@ -93,6 +94,7 @@ async def create_color_strip_source(
             gamma=data.gamma,
             smoothing=data.smoothing,
             interpolation_mode=data.interpolation_mode,
+            led_count=data.led_count,
             calibration=calibration,
             description=data.description,
         )
@@ -143,6 +145,7 @@ async def update_color_strip_source(
             gamma=data.gamma,
             smoothing=data.smoothing,
             interpolation_mode=data.interpolation_mode,
+            led_count=data.led_count,
             calibration=calibration,
             description=data.description,
         )
diff --git a/server/src/wled_controller/api/schemas/color_strip_sources.py b/server/src/wled_controller/api/schemas/color_strip_sources.py
index 2bf141f..7afb5ce 100644
--- a/server/src/wled_controller/api/schemas/color_strip_sources.py
+++ b/server/src/wled_controller/api/schemas/color_strip_sources.py
@@ -20,6 +20,7 @@ class ColorStripSourceCreate(BaseModel):
     gamma: float = Field(default=1.0, description="Gamma correction (1.0=none, <1=brighter, >1=darker mids)", ge=0.1, le=3.0)
     smoothing: float = Field(default=0.3, description="Temporal smoothing (0.0=none, 1.0=full)", ge=0.0, le=1.0)
     interpolation_mode: str = Field(default="average", description="LED color interpolation mode (average, median, dominant)")
+    led_count: int = Field(default=0, description="Total LED count (0 = auto from calibration)", ge=0)
     calibration: Optional[Calibration] = Field(None, description="LED calibration (position and count per edge)")
     description: Optional[str] = Field(None, description="Optional description", max_length=500)
 
@@ -35,6 +36,7 @@ class ColorStripSourceUpdate(BaseModel):
     gamma: Optional[float] = Field(None, description="Gamma correction (0.1-3.0)", ge=0.1, le=3.0)
     smoothing: Optional[float] = Field(None, description="Temporal smoothing (0.0-1.0)", ge=0.0, le=1.0)
     interpolation_mode: Optional[str] = Field(None, description="Interpolation mode (average, median, dominant)")
+    led_count: Optional[int] = Field(None, description="Total LED count (0 = auto from calibration)", ge=0)
     calibration: Optional[Calibration] = Field(None, description="LED calibration")
     description: Optional[str] = Field(None, description="Optional description", max_length=500)
 
@@ -52,6 +54,7 @@ class ColorStripSourceResponse(BaseModel):
     gamma: Optional[float] = Field(None, description="Gamma correction")
     smoothing: Optional[float] = Field(None, description="Temporal smoothing")
     interpolation_mode: Optional[str] = Field(None, description="Interpolation mode")
+    led_count: int = Field(0, description="Total LED count (0 = auto from calibration)")
     calibration: Optional[Calibration] = Field(None, description="LED calibration")
     description: Optional[str] = Field(None, description="Description")
     created_at: datetime = Field(description="Creation timestamp")
diff --git a/server/src/wled_controller/core/processing/color_strip_stream.py b/server/src/wled_controller/core/processing/color_strip_stream.py
index 90fec69..4814ea7 100644
--- a/server/src/wled_controller/core/processing/color_strip_stream.py
+++ b/server/src/wled_controller/core/processing/color_strip_stream.py
@@ -142,7 +142,8 @@ class PictureColorStripStream(ColorStripStream):
         self._pixel_mapper = PixelMapper(
             self._calibration, interpolation_mode=self._interpolation_mode
         )
-        self._led_count: int = self._calibration.get_total_leds()
+        cal_leds = self._calibration.get_total_leds()
+        self._led_count: int = source.led_count if source.led_count > 0 else cal_leds
         self._gamma_lut: np.ndarray = _build_gamma_lut(self._gamma)
 
         # Thread-safe color cache
@@ -224,10 +225,12 @@ class PictureColorStripStream(ColorStripStream):
         if (
             source.interpolation_mode != self._interpolation_mode
             or source.calibration != self._calibration
+            or source.led_count != self._led_count
         ):
             self._interpolation_mode = source.interpolation_mode
             self._calibration = source.calibration
-            self._led_count = source.calibration.get_total_leds()
+            cal_leds = source.calibration.get_total_leds()
+            self._led_count = source.led_count if source.led_count > 0 else cal_leds
             self._pixel_mapper = PixelMapper(
                 source.calibration, interpolation_mode=source.interpolation_mode
             )
@@ -263,6 +266,15 @@ class PictureColorStripStream(ColorStripStream):
                 led_colors = self._pixel_mapper.map_border_to_leds(border_pixels)
                 t2 = time.perf_counter()
 
+                # Pad or truncate to match the declared led_count
+                target_count = self._led_count
+                if target_count > 0 and len(led_colors) != target_count:
+                    if len(led_colors) < target_count:
+                        pad = np.zeros((target_count - len(led_colors), 3), dtype=np.uint8)
+                        led_colors = np.concatenate([led_colors, pad])
+                    else:
+                        led_colors = led_colors[:target_count]
+
                 # Temporal smoothing
                 smoothing = self._smoothing
                 if (
diff --git a/server/src/wled_controller/static/css/calibration.css b/server/src/wled_controller/static/css/calibration.css
index ba68c05..6a55be1 100644
--- a/server/src/wled_controller/static/css/calibration.css
+++ b/server/src/wled_controller/static/css/calibration.css
@@ -83,6 +83,7 @@
     color: #FFC107;
 }
 
+
 .inputs-dimmed .edge-led-input {
     opacity: 0.2;
     pointer-events: none;
diff --git a/server/src/wled_controller/static/css/modal.css b/server/src/wled_controller/static/css/modal.css
index 85a06b4..ab03a92 100644
--- a/server/src/wled_controller/static/css/modal.css
+++ b/server/src/wled_controller/static/css/modal.css
@@ -221,6 +221,47 @@
     color: var(--text-primary);
 }
 
+.form-collapse {
+    margin-bottom: 12px;
+    border-top: 1px solid var(--border-color);
+    padding-top: 8px;
+}
+
+.form-collapse > summary {
+    cursor: pointer;
+    list-style: none;
+    display: flex;
+    align-items: center;
+    gap: 6px;
+    font-size: 0.9rem;
+    font-weight: 500;
+    color: var(--text-secondary, #888);
+    padding: 4px 0;
+    user-select: none;
+}
+
+.form-collapse > summary::-webkit-details-marker { display: none; }
+
+.form-collapse > summary::before {
+    content: '▶';
+    font-size: 0.6rem;
+    opacity: 0.6;
+    transition: transform 0.15s;
+    flex-shrink: 0;
+}
+
+.form-collapse[open] > summary::before {
+    transform: rotate(90deg);
+}
+
+.form-collapse > summary:hover {
+    color: var(--text-color);
+}
+
+.form-collapse-body {
+    padding-top: 8px;
+}
+
 .error-message {
     background: rgba(244, 67, 54, 0.1);
     border: 1px solid var(--danger-color);
diff --git a/server/src/wled_controller/static/js/features/calibration.js b/server/src/wled_controller/static/js/features/calibration.js
index 8653142..199be5c 100644
--- a/server/src/wled_controller/static/js/features/calibration.js
+++ b/server/src/wled_controller/static/js/features/calibration.js
@@ -30,6 +30,7 @@ class CalibrationModal extends Modal {
             skip_start:     this.$('cal-skip-start').value,
             skip_end:       this.$('cal-skip-end').value,
             border_width:   this.$('cal-border-width').value,
+            led_count:      this.$('cal-css-led-count').value,
         };
     }
 
@@ -112,6 +113,7 @@ export async function showCalibration(deviceId) {
 
         document.getElementById('calibration-device-id').value = device.id;
         document.getElementById('cal-device-led-count-inline').textContent = device.led_count;
+        document.getElementById('cal-css-led-count-group').style.display = 'none';
 
         document.getElementById('cal-start-position').value = calibration.start_position;
         document.getElementById('cal-layout').value = calibration.layout;
@@ -216,6 +218,11 @@ export async function showCSSCalibration(cssId) {
         const preview = document.querySelector('.calibration-preview');
         preview.style.aspectRatio = '';
         document.getElementById('cal-device-led-count-inline').textContent = '—';
+        const ledCountGroup = document.getElementById('cal-css-led-count-group');
+        ledCountGroup.style.display = '';
+        const calLeds = (calibration.leds_top || 0) + (calibration.leds_right || 0) +
+                        (calibration.leds_bottom || 0) + (calibration.leds_left || 0);
+        document.getElementById('cal-css-led-count').value = source.led_count || calLeds || 0;
 
         document.getElementById('cal-start-position').value = calibration.start_position || 'bottom_left';
         document.getElementById('cal-layout').value = calibration.layout || 'clockwise';
@@ -286,8 +293,17 @@ export function updateCalibrationPreview() {
                   parseInt(document.getElementById('cal-left-leds').value || 0);
     const totalEl = document.querySelector('.preview-screen-total');
     const inCSS = _isCSS();
-    const deviceCount = inCSS ? null : parseInt(document.getElementById('cal-device-led-count-inline').textContent || 0);
-    const mismatch = !inCSS && total !== deviceCount;
+    const declaredCount = inCSS
+        ? parseInt(document.getElementById('cal-css-led-count').value || 0)
+        : parseInt(document.getElementById('cal-device-led-count-inline').textContent || 0);
+    if (inCSS) {
+        document.getElementById('cal-device-led-count-inline').textContent = declaredCount || '—';
+    }
+    // In device mode: calibration total must exactly equal device LED count
+    // In CSS mode: warn only if calibrated LEDs exceed the declared total (padding handles the rest)
+    const mismatch = inCSS
+        ? (declaredCount > 0 && total > declaredCount)
+        : (total !== declaredCount);
     document.getElementById('cal-total-leds-inline').textContent = (mismatch ? '\u26A0 ' : '') + total;
     if (totalEl) totalEl.classList.toggle('mismatch', mismatch);
 
@@ -831,10 +847,18 @@ export async function saveCalibration() {
     const leftLeds = parseInt(document.getElementById('cal-left-leds').value || 0);
     const total = topLeds + rightLeds + bottomLeds + leftLeds;
 
+    const declaredLedCount = cssMode
+        ? parseInt(document.getElementById('cal-css-led-count').value) || 0
+        : parseInt(document.getElementById('cal-device-led-count-inline').textContent) || 0;
     if (!cssMode) {
-        const deviceLedCount = parseInt(document.getElementById('cal-device-led-count-inline').textContent);
-        if (total !== deviceLedCount) {
-            error.textContent = `Total LEDs (${total}) must equal device LED count (${deviceLedCount})`;
+        if (total !== declaredLedCount) {
+            error.textContent = `Total LEDs (${total}) must equal device LED count (${declaredLedCount})`;
+            error.style.display = 'block';
+            return;
+        }
+    } else {
+        if (declaredLedCount > 0 && total > declaredLedCount) {
+            error.textContent = `Calibrated LEDs (${total}) exceed total LED count (${declaredLedCount})`;
             error.style.display = 'block';
             return;
         }
@@ -862,7 +886,7 @@ export async function saveCalibration() {
         if (cssMode) {
             response = await fetchWithAuth(`/color-strip-sources/${cssId}`, {
                 method: 'PUT',
-                body: JSON.stringify({ calibration }),
+                body: JSON.stringify({ calibration, led_count: declaredLedCount }),
             });
         } else {
             response = await fetchWithAuth(`/devices/${deviceId}/calibration`, {
diff --git a/server/src/wled_controller/static/js/features/color-strips.js b/server/src/wled_controller/static/js/features/color-strips.js
index ab8c637..949f5bd 100644
--- a/server/src/wled_controller/static/js/features/color-strips.js
+++ b/server/src/wled_controller/static/js/features/color-strips.js
@@ -22,6 +22,7 @@ class CSSEditorModal extends Modal {
             brightness: document.getElementById('css-editor-brightness').value,
             saturation: document.getElementById('css-editor-saturation').value,
             gamma: document.getElementById('css-editor-gamma').value,
+            led_count: document.getElementById('css-editor-led-count').value,
         };
     }
 }
@@ -35,7 +36,8 @@ export function createColorStripCard(source, pictureSourceMap) {
         ? pictureSourceMap[source.picture_source_id].name
         : source.picture_source_id || '—';
     const cal = source.calibration || {};
-    const ledCount = (cal.leds_top || 0) + (cal.leds_right || 0) + (cal.leds_bottom || 0) + (cal.leds_left || 0);
+    const calLeds = (cal.leds_top || 0) + (cal.leds_right || 0) + (cal.leds_bottom || 0) + (cal.leds_left || 0);
+    const ledCount = (source.led_count > 0) ? source.led_count : calLeds;
 
     return `
         <div class="card" data-css-id="${source.id}">
@@ -107,6 +109,8 @@ export async function showCSSEditor(cssId = null) {
             document.getElementById('css-editor-gamma').value = gamma;
             document.getElementById('css-editor-gamma-value').textContent = parseFloat(gamma).toFixed(2);
 
+            document.getElementById('css-editor-led-count').value = css.led_count ?? 0;
+
             document.getElementById('css-editor-title').textContent = t('color_strip.edit');
         } else {
             document.getElementById('css-editor-id').value = '';
@@ -122,6 +126,7 @@ export async function showCSSEditor(cssId = null) {
             document.getElementById('css-editor-saturation-value').textContent = '1.00';
             document.getElementById('css-editor-gamma').value = 1.0;
             document.getElementById('css-editor-gamma-value').textContent = '1.00';
+            document.getElementById('css-editor-led-count').value = 0;
             document.getElementById('css-editor-title').textContent = t('color_strip.add');
         }
 
@@ -160,6 +165,7 @@ export async function saveCSSEditor() {
         brightness: parseFloat(document.getElementById('css-editor-brightness').value),
         saturation: parseFloat(document.getElementById('css-editor-saturation').value),
         gamma: parseFloat(document.getElementById('css-editor-gamma').value),
+        led_count: parseInt(document.getElementById('css-editor-led-count').value) || 0,
     };
 
     try {
diff --git a/server/src/wled_controller/static/js/features/devices.js b/server/src/wled_controller/static/js/features/devices.js
index e906620..5b44aa6 100644
--- a/server/src/wled_controller/static/js/features/devices.js
+++ b/server/src/wled_controller/static/js/features/devices.js
@@ -100,9 +100,7 @@ export function createDeviceCard(device) {
                 <button class="btn btn-icon btn-secondary" onclick="showSettings('${device.id}')" title="${t('device.button.settings')}">
                     ⚙️
                 </button>
-                <button class="btn btn-icon btn-secondary" onclick="showCalibration('${device.id}')" title="${t('device.button.calibrate')}">
-                    📐
-                </button>
+
             </div>
         </div>
     `;
diff --git a/server/src/wled_controller/static/locales/en.json b/server/src/wled_controller/static/locales/en.json
index 4db2b40..187dd4e 100644
--- a/server/src/wled_controller/static/locales/en.json
+++ b/server/src/wled_controller/static/locales/en.json
@@ -552,6 +552,7 @@
   "color_strip.interpolation.dominant": "Dominant",
   "color_strip.smoothing": "Smoothing:",
   "color_strip.smoothing.hint": "Temporal blending between frames (0=none, 1=full). Reduces flicker.",
+  "color_strip.color_corrections": "Color Corrections",
   "color_strip.brightness": "Brightness:",
   "color_strip.brightness.hint": "Output brightness multiplier (0=off, 1=unchanged, 2=double). Applied after color extraction.",
   "color_strip.saturation": "Saturation:",
@@ -561,6 +562,8 @@
   "color_strip.test_device": "Test on Device:",
   "color_strip.test_device.hint": "Select a device to send test pixels to when clicking edge toggles",
   "color_strip.leds": "LED count",
+  "color_strip.led_count": "LED Count:",
+  "color_strip.led_count.hint": "Total number of LEDs on the physical strip. Set to 0 to use the sum from calibration. Useful when the strip has LEDs behind the TV that are not mapped to screen edges — those LEDs will be sent black.",
   "color_strip.created": "Color strip source created",
   "color_strip.updated": "Color strip source updated",
   "color_strip.deleted": "Color strip source deleted",
diff --git a/server/src/wled_controller/static/locales/ru.json b/server/src/wled_controller/static/locales/ru.json
index d1b6189..12a4f05 100644
--- a/server/src/wled_controller/static/locales/ru.json
+++ b/server/src/wled_controller/static/locales/ru.json
@@ -552,6 +552,7 @@
   "color_strip.interpolation.dominant": "Доминирующий",
   "color_strip.smoothing": "Сглаживание:",
   "color_strip.smoothing.hint": "Временное смешивание кадров (0=без смешивания, 1=полное). Уменьшает мерцание.",
+  "color_strip.color_corrections": "Цветокоррекция",
   "color_strip.brightness": "Яркость:",
   "color_strip.brightness.hint": "Множитель яркости (0=выкл, 1=без изменений, 2=двойная). Применяется после извлечения цвета.",
   "color_strip.saturation": "Насыщенность:",
@@ -561,6 +562,8 @@
   "color_strip.test_device": "Тестировать на устройстве:",
   "color_strip.test_device.hint": "Выберите устройство для отправки тестовых пикселей при нажатии на рамку",
   "color_strip.leds": "Количество светодиодов",
+  "color_strip.led_count": "Количество LED:",
+  "color_strip.led_count.hint": "Общее число светодиодов на физической полосе. 0 = взять из калибровки. Укажите явно, если на полосе есть светодиоды за телевизором, не привязанные к краям экрана — им будет отправлен чёрный цвет.",
   "color_strip.created": "Источник цветовой полосы создан",
   "color_strip.updated": "Источник цветовой полосы обновлён",
   "color_strip.deleted": "Источник цветовой полосы удалён",
diff --git a/server/src/wled_controller/storage/color_strip_source.py b/server/src/wled_controller/storage/color_strip_source.py
index 3ef6d37..7782252 100644
--- a/server/src/wled_controller/storage/color_strip_source.py
+++ b/server/src/wled_controller/storage/color_strip_source.py
@@ -20,7 +20,6 @@ from wled_controller.core.capture.calibration import (
     CalibrationConfig,
     calibration_from_dict,
     calibration_to_dict,
-    create_default_calibration,
 )
 
 
@@ -53,6 +52,7 @@ class ColorStripSource:
             "smoothing": None,
             "interpolation_mode": None,
             "calibration": None,
+            "led_count": None,
         }
 
     @staticmethod
@@ -82,7 +82,7 @@ class ColorStripSource:
         calibration = (
             calibration_from_dict(calibration_data)
             if calibration_data
-            else create_default_calibration(0)
+            else CalibrationConfig(layout="clockwise", start_position="bottom_left")
         )
 
         # Only "picture" type for now; extend with elif branches for future types
@@ -97,6 +97,7 @@ class ColorStripSource:
             smoothing=data["smoothing"] if data.get("smoothing") is not None else 0.3,
             interpolation_mode=data.get("interpolation_mode") or "average",
             calibration=calibration,
+            led_count=data.get("led_count") or 0,
         )
 
 
@@ -115,7 +116,10 @@ class PictureColorStripSource(ColorStripSource):
     gamma: float = 1.0               # 1.0 = no correction; <1 = brighter, >1 = darker mids
     smoothing: float = 0.3           # temporal smoothing (0.0 = none, 1.0 = full)
     interpolation_mode: str = "average"   # "average" | "median" | "dominant"
-    calibration: CalibrationConfig = field(default_factory=lambda: create_default_calibration(0))
+    calibration: CalibrationConfig = field(
+        default_factory=lambda: CalibrationConfig(layout="clockwise", start_position="bottom_left")
+    )
+    led_count: int = 0               # explicit LED count; 0 = auto (derived from calibration)
 
     def to_dict(self) -> dict:
         d = super().to_dict()
@@ -127,4 +131,5 @@ class PictureColorStripSource(ColorStripSource):
         d["smoothing"] = self.smoothing
         d["interpolation_mode"] = self.interpolation_mode
         d["calibration"] = calibration_to_dict(self.calibration)
+        d["led_count"] = self.led_count
         return d
diff --git a/server/src/wled_controller/storage/color_strip_store.py b/server/src/wled_controller/storage/color_strip_store.py
index d506b0c..f204ae2 100644
--- a/server/src/wled_controller/storage/color_strip_store.py
+++ b/server/src/wled_controller/storage/color_strip_store.py
@@ -6,7 +6,7 @@ from datetime import datetime
 from pathlib import Path
 from typing import Dict, List, Optional
 
-from wled_controller.core.capture.calibration import calibration_to_dict
+from wled_controller.core.capture.calibration import CalibrationConfig, calibration_to_dict
 from wled_controller.storage.color_strip_source import (
     ColorStripSource,
     PictureColorStripSource,
@@ -98,6 +98,7 @@ class ColorStripStore:
         smoothing: float = 0.3,
         interpolation_mode: str = "average",
         calibration=None,
+        led_count: int = 0,
         description: Optional[str] = None,
     ) -> ColorStripSource:
         """Create a new color strip source.
@@ -105,8 +106,6 @@ class ColorStripStore:
         Raises:
             ValueError: If validation fails
         """
-        from wled_controller.core.capture.calibration import create_default_calibration
-
         if not name or not name.strip():
             raise ValueError("Name is required")
 
@@ -115,7 +114,7 @@ class ColorStripStore:
                 raise ValueError(f"Color strip source with name '{name}' already exists")
 
         if calibration is None:
-            calibration = create_default_calibration(0)
+            calibration = CalibrationConfig(layout="clockwise", start_position="bottom_left")
 
         source_id = f"css_{uuid.uuid4().hex[:8]}"
         now = datetime.utcnow()
@@ -135,6 +134,7 @@ class ColorStripStore:
             smoothing=smoothing,
             interpolation_mode=interpolation_mode,
             calibration=calibration,
+            led_count=led_count,
         )
 
         self._sources[source_id] = source
@@ -155,6 +155,7 @@ class ColorStripStore:
         smoothing: Optional[float] = None,
         interpolation_mode: Optional[str] = None,
         calibration=None,
+        led_count: Optional[int] = None,
         description: Optional[str] = None,
     ) -> ColorStripSource:
         """Update an existing color strip source.
@@ -193,6 +194,8 @@ class ColorStripStore:
                 source.interpolation_mode = interpolation_mode
             if calibration is not None:
                 source.calibration = calibration
+            if led_count is not None:
+                source.led_count = led_count
 
         source.updated_at = datetime.utcnow()
         self._save()
diff --git a/server/src/wled_controller/templates/modals/calibration.html b/server/src/wled_controller/templates/modals/calibration.html
index c083340..28ef749 100644
--- a/server/src/wled_controller/templates/modals/calibration.html
+++ b/server/src/wled_controller/templates/modals/calibration.html
@@ -18,6 +18,16 @@
                 <small class="input-hint" style="display:none" data-i18n="color_strip.test_device.hint">Select a device to send test pixels to when clicking edge toggles</small>
                 <select id="calibration-test-device"></select>
             </div>
+            <!-- LED count input (CSS calibration mode only) -->
+            <div id="cal-css-led-count-group" class="form-group" style="display:none; margin-bottom: 12px; padding: 0 4px;">
+                <div class="label-row">
+                    <label for="cal-css-led-count" data-i18n="color_strip.led_count">LED Count:</label>
+                    <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                </div>
+                <small class="input-hint" style="display:none" data-i18n="color_strip.led_count.hint">Total number of LEDs on the physical strip. Set to 0 to use the sum from calibration. If your strip has LEDs behind the TV that are not mapped to screen edges, set the exact count here and they will be filled with black.</small>
+                <input type="number" id="cal-css-led-count" min="0" max="1500" step="1" value="0" oninput="updateCalibrationPreview()">
+            </div>
+
             <!-- Interactive Preview with integrated LED inputs and test toggles -->
             <div style="margin-bottom: 12px; padding: 0 24px;">
                 <div class="calibration-preview">
diff --git a/server/src/wled_controller/templates/modals/css-editor.html b/server/src/wled_controller/templates/modals/css-editor.html
index 2d0fbfa..97c3df8 100644
--- a/server/src/wled_controller/templates/modals/css-editor.html
+++ b/server/src/wled_controller/templates/modals/css-editor.html
@@ -63,40 +63,54 @@
                     <input type="range" id="css-editor-smoothing" min="0.0" max="1.0" step="0.05" value="0.3" oninput="document.getElementById('css-editor-smoothing-value').textContent = parseFloat(this.value).toFixed(2)">
                 </div>
 
-                <div class="form-group">
-                    <div class="label-row">
-                        <label for="css-editor-brightness">
-                            <span data-i18n="color_strip.brightness">Brightness:</span>
-                            <span id="css-editor-brightness-value">1.00</span>
-                        </label>
-                        <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                <details class="form-collapse">
+                    <summary data-i18n="color_strip.color_corrections">Color Corrections</summary>
+                    <div class="form-collapse-body">
+                        <div class="form-group">
+                            <div class="label-row">
+                                <label for="css-editor-brightness">
+                                    <span data-i18n="color_strip.brightness">Brightness:</span>
+                                    <span id="css-editor-brightness-value">1.00</span>
+                                </label>
+                                <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                            </div>
+                            <small class="input-hint" style="display:none" data-i18n="color_strip.brightness.hint">Output brightness multiplier (0=off, 1=unchanged, 2=double). Applied after color extraction.</small>
+                            <input type="range" id="css-editor-brightness" min="0.0" max="2.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-brightness-value').textContent = parseFloat(this.value).toFixed(2)">
+                        </div>
+
+                        <div class="form-group">
+                            <div class="label-row">
+                                <label for="css-editor-saturation">
+                                    <span data-i18n="color_strip.saturation">Saturation:</span>
+                                    <span id="css-editor-saturation-value">1.00</span>
+                                </label>
+                                <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                            </div>
+                            <small class="input-hint" style="display:none" data-i18n="color_strip.saturation.hint">Color saturation (0=grayscale, 1=unchanged, 2=double saturation)</small>
+                            <input type="range" id="css-editor-saturation" min="0.0" max="2.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-saturation-value').textContent = parseFloat(this.value).toFixed(2)">
+                        </div>
+
+                        <div class="form-group">
+                            <div class="label-row">
+                                <label for="css-editor-gamma">
+                                    <span data-i18n="color_strip.gamma">Gamma:</span>
+                                    <span id="css-editor-gamma-value">1.00</span>
+                                </label>
+                                <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
+                            </div>
+                            <small class="input-hint" style="display:none" data-i18n="color_strip.gamma.hint">Gamma correction (1=none, &lt;1=brighter midtones, &gt;1=darker midtones)</small>
+                            <input type="range" id="css-editor-gamma" min="0.1" max="3.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-gamma-value').textContent = parseFloat(this.value).toFixed(2)">
+                        </div>
                     </div>
-                    <small class="input-hint" style="display:none" data-i18n="color_strip.brightness.hint">Output brightness multiplier (0=off, 1=unchanged, 2=double). Applied after color extraction.</small>
-                    <input type="range" id="css-editor-brightness" min="0.0" max="2.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-brightness-value').textContent = parseFloat(this.value).toFixed(2)">
-                </div>
+                </details>
 
                 <div class="form-group">
                     <div class="label-row">
-                        <label for="css-editor-saturation">
-                            <span data-i18n="color_strip.saturation">Saturation:</span>
-                            <span id="css-editor-saturation-value">1.00</span>
-                        </label>
+                        <label for="css-editor-led-count" data-i18n="color_strip.led_count">LED Count:</label>
                         <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
                     </div>
-                    <small class="input-hint" style="display:none" data-i18n="color_strip.saturation.hint">Color saturation (0=grayscale, 1=unchanged, 2=double saturation)</small>
-                    <input type="range" id="css-editor-saturation" min="0.0" max="2.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-saturation-value').textContent = parseFloat(this.value).toFixed(2)">
-                </div>
-
-                <div class="form-group">
-                    <div class="label-row">
-                        <label for="css-editor-gamma">
-                            <span data-i18n="color_strip.gamma">Gamma:</span>
-                            <span id="css-editor-gamma-value">1.00</span>
-                        </label>
-                        <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
-                    </div>
-                    <small class="input-hint" style="display:none" data-i18n="color_strip.gamma.hint">Gamma correction (1=none, &lt;1=brighter midtones, &gt;1=darker midtones)</small>
-                    <input type="range" id="css-editor-gamma" min="0.1" max="3.0" step="0.05" value="1.0" oninput="document.getElementById('css-editor-gamma-value').textContent = parseFloat(this.value).toFixed(2)">
+                    <small class="input-hint" style="display:none" data-i18n="color_strip.led_count.hint">Total number of LEDs on the strip. Set to 0 to use the sum from calibration. If your strip has LEDs behind the TV that are not mapped to screen edges, set the exact count here and they will be filled with black.</small>
+                    <input type="number" id="css-editor-led-count" min="0" max="1500" step="1" value="0">
                 </div>
 
                 <div id="css-editor-error" class="error-message" style="display: none;"></div>