diff --git a/src/main.ts b/src/main.ts
index 8f95c50..1b11adb 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -203,14 +203,24 @@ document.getElementById('file')!.addEventListener('change', (ev) => {
   (ev.target as HTMLInputElement).value = '';
 });
 let dark = true;
+document.getElementById('fit')?.addEventListener('click', () => {
+  viewer.fit();
+});
 document.getElementById('theme')!.addEventListener('click', () => {
   dark = !dark;
   viewer.setTheme(dark);
+  fillLayers();
 });
 document.getElementById('layersBtn')!.addEventListener('click', () => {
   layersPanel.style.display = layersPanel.style.display === 'block' ? 'none' : 'block';
 });
 
+window.addEventListener('keydown', (e) => {
+  if ((e.key === 'f' || e.key === 'F') && (e.target as HTMLElement)?.tagName !== 'INPUT') {
+    viewer.fit();
+  }
+});
+
 window.addEventListener('dragover', (e) => e.preventDefault());
 window.addEventListener('drop', (e) => {
   e.preventDefault();
@@ -219,7 +229,11 @@ window.addEventListener('drop', (e) => {
 });
 
 const model = new URLSearchParams(location.search).get('model');
-if (model) void run(model, () => loadUrl(model));
-else void run('C0060202-001-평면및종단면도.dwg', () => loadUrl(civilFile, 'C0060202-001-평면및종단면도.dwg'));
+if (model) {
+  void run(model, () => loadUrl(model));
+} else {
+  setStatus('ready');
+}
 
 window.addEventListener('resize', () => viewer.resize());
+
diff --git a/src/viewer2d/Viewer2D.d.ts b/src/viewer2d/Viewer2D.d.ts
index a8a60a0..4565721 100644
--- a/src/viewer2d/Viewer2D.d.ts
+++ b/src/viewer2d/Viewer2D.d.ts
@@ -5,7 +5,7 @@ import type { CadSpace } from './cadSpaces';
 export class Viewer2D {
   constructor(container: HTMLElement);
   /** Render a DWG/DXF parseResult. `keepView` preserves pan/zoom on re-render. */
-  load(result: unknown, opts?: { keepView?: boolean; spaceHandle?: string | number | null }): void;
+  load(result: unknown, opts?: { keepView?: boolean; keepTheme?: boolean; spaceHandle?: string | number | null }): void;
   /** Zoom-extents to the loaded drawing. */
   fit(): void;
   /** Resync renderer/camera to the container size (call after un-hiding). */
diff --git a/src/viewer2d/Viewer2D.js b/src/viewer2d/Viewer2D.js
index b2f503b..c34705c 100644
--- a/src/viewer2d/Viewer2D.js
+++ b/src/viewer2d/Viewer2D.js
@@ -50,6 +50,8 @@ export class Viewer2D {
 
     this._scene = new THREE.Scene();
     this._scene.background = new THREE.Color(0x0d1117);
+    this._isDark = true;
+    this._isLoading = false;
 
     const w = container.clientWidth  || 800;
     const h = container.clientHeight || 600;
@@ -243,43 +245,46 @@ export class Viewer2D {
   }
 
   load(result, opts = {}) {
-    this._lastResult = result;
-    this._selMeta = null;
-    this._clear();
-    this._entityMeta = [];
-    this._buildLayerMap(result?.tables?.layers);
-    this._buildStyleMap(result?.tables?.styles || result?.tables?.textStyles);
-    this._buildLinetypeMap(result);
-    // Sheet orientation: the active model-space viewport's VIEWTWIST rotates the
-    // view so a drawing stored tilted in WCS (rotated survey sheets — header UCS
-    // stays identity) displays with its title border upright. Applied as a
-    // camera-up rotation in _fit (geometry untouched → picking stays exact).
-    this._viewTwist = this._readViewTwist(result);
-    // Geometric pick index — the ACTUAL rendered geometry, not a bounds proxy.
-    // _pickSegs: flat [ax,ay,bx,by,…] of every line segment (lines, arcs, circles,
-    // polylines, block wires, dimension leaders/arrows) with a parallel owner-meta
-    // index. _pickFills: filled regions (hatch loops, SOLID quads, text quads)
-    // tested by even-odd point-in-polygon. _onClick raycasts these directly.
-    this._pickSegs = [];
-    this._pickSegMeta = [];
-    this._pickFills = [];
-    this._pickCurIdx = -1;
+    this._isLoading = true;
+    try {
+      this._lastResult = result;
+      this._selMeta = null;
+      this._clear();
+      this._entityMeta = [];
 
-    // Model vs Paper (Layout): never draw both spaces at once.
-    // - opts.spaceHandle provided (including null) → set active space
-    // - omitted → keep previous _activeSpaceHex if still valid for this file
-    if (Object.prototype.hasOwnProperty.call(opts, 'spaceHandle')) {
-      const sh = opts.spaceHandle;
-      if (sh == null || sh === '') this._activeSpaceHex = null;
-      else this._activeSpaceHex = typeof sh === 'number' ? sh.toString(16) : String(sh).toLowerCase();
-    }
+      // Model vs Paper (Layout): never draw both spaces at once.
+      // - opts.spaceHandle provided (including null) → set active space
+      // - omitted → keep previous _activeSpaceHex if still valid for this file
+      if (Object.prototype.hasOwnProperty.call(opts, 'spaceHandle')) {
+        const sh = opts.spaceHandle;
+        if (sh == null || sh === '') this._activeSpaceHex = null;
+        else this._activeSpaceHex = typeof sh === 'number' ? sh.toString(16) : String(sh).toLowerCase();
+      }
 
-    if (!opts.keepTheme) {
-      const spacesList = listCadSpaces(result);
-      const activeSp = spacesList.find((s) => s.handleHex === this._activeSpaceHex);
-      const isPaper = activeSp?.kind === 'paper';
-      this.setTheme(!isPaper);
-    }
+      if (!opts.keepTheme) {
+        const spacesList = listCadSpaces(result);
+        const activeSp = spacesList.find((s) => s.handleHex === this._activeSpaceHex);
+        const isPaper = activeSp?.kind === 'paper';
+        this.setTheme(!isPaper);
+      }
+
+      this._buildLayerMap(result?.tables?.layers);
+      this._buildStyleMap(result?.tables?.styles || result?.tables?.textStyles);
+      this._buildLinetypeMap(result);
+      // Sheet orientation: the active model-space viewport's VIEWTWIST rotates the
+      // view so a drawing stored tilted in WCS (rotated survey sheets — header UCS
+      // stays identity) displays with its title border upright. Applied as a
+      // camera-up rotation in _fit (geometry untouched → picking stays exact).
+      this._viewTwist = this._readViewTwist(result);
+      // Geometric pick index — the ACTUAL rendered geometry, not a bounds proxy.
+      // _pickSegs: flat [ax,ay,bx,by,…] of every line segment (lines, arcs, circles,
+      // polylines, block wires, dimension leaders/arrows) with a parallel owner-meta
+      // index. _pickFills: filled regions (hatch loops, SOLID quads, text quads)
+      // tested by even-odd point-in-polygon. _onClick raycasts these directly.
+      this._pickSegs = [];
+      this._pickSegMeta = [];
+      this._pickFills = [];
+      this._pickCurIdx = -1;
 
     const entities    = result?.entities || [];
     const lineVerts   = [];
@@ -1049,14 +1054,24 @@ export class Viewer2D {
     const fitBox = box.isEmpty() ? null : (this._trimmedContentBox(fitSamples, box) || box);
     this._contentBox = fitBox ? fitBox.clone() : null;
     if (!opts.keepView && fitBox && !fitBox.isEmpty()) this._fit(fitBox);
+    } finally {
+      this._isLoading = false;
+    }
   }
 
   // ── UI integration ─────────────────────────────────────────────────────────
 
   /** Swap canvas background for theme. dark=true → near-black (Model), false → white (Layout). */
   setTheme(dark) {
-    this._scene.background = new THREE.Color(dark ? 0x0a0b0d : 0xffffff);
+    const isDarkBool = !!dark;
+    const changed = (this._isDark !== isDarkBool);
+    this._isDark = isDarkBool;
+    this._scene.background = new THREE.Color(this._isDark ? 0x0a0b0d : 0xffffff);
     if (this._gridVisible) this._rebuildGrid();
+
+    if (changed && this._lastResult && !this._isLoading) {
+      this.load(this._lastResult, { keepView: true, keepTheme: true, spaceHandle: this._activeSpaceHex });
+    }
   }
 
   setGrid(visible) {
@@ -1547,7 +1562,7 @@ export class Viewer2D {
       const aci  = Math.abs(l.colorIndex ?? l.color ?? l.colorNumber ?? 7);
       return {
         name,
-        colorHex: '#' + ((aciToHex(aci) ?? DEFAULT_COLOR).toString(16).padStart(6, '0')),
+        colorHex: '#' + ((aciToHex(aci, this._isDark) ?? DEFAULT_COLOR).toString(16).padStart(6, '0')),
         count: counts.get(name) || 0,
         visible: !hidden.has(name),
       };
@@ -1914,7 +1929,7 @@ export class Viewer2D {
       const handle = l.handle?.value ?? l.handle;
       const name   = l.name ?? l.layerName;
       const aci    = Math.abs(l.colorIndex ?? l.color ?? l.colorNumber ?? 7);
-      const hex    = aciToHex(aci) ?? DEFAULT_COLOR;
+      const hex    = aciToHex(aci, this._isDark) ?? DEFAULT_COLOR;
       if (handle != null) this._layerByHandle.set(String(handle), hex);
       if (name)           this._layerByName.set(name, hex);
       if (handle != null && name) this._layerNameByHandle.set(String(handle), name);
@@ -2006,7 +2021,7 @@ export class Viewer2D {
     const aci = entity.entityHeader?.colorIndex
              ?? entity.color ?? entity.colorIndex ?? entity.colorNumber ?? 256;
     if (aci != null) {
-      const hex = aciToHex(aci);
+      const hex = aciToHex(aci, this._isDark);
       if (hex !== null) return hex;
     }
     const lh = entity.layerHandle?.value ?? entity.layerHandle;
@@ -2900,7 +2915,7 @@ export class Viewer2D {
     } else if (t.bgColorRgb && (t.bgColorRgb.r != null)) {
       bgColor = ((t.bgColorRgb.r & 255) << 16) | ((t.bgColorRgb.g & 255) << 8) | (t.bgColorRgb.b & 255);
     } else if (t.bgColorIndex != null) {
-      const hex = aciToHex(t.bgColorIndex);
+      const hex = aciToHex(t.bgColorIndex, this._isDark);
       if (hex != null) bgColor = hex;
     }
 
diff --git a/src/viewer2d/aciColors.js b/src/viewer2d/aciColors.js
index 59bceba..cb01809 100644
--- a/src/viewer2d/aciColors.js
+++ b/src/viewer2d/aciColors.js
@@ -47,8 +47,9 @@ const VARIANTS_SL = [
   [0.00, 0.30],  // 9: dark gray
 ];
 
-export function aciToHex(aci) {
+export function aciToHex(aci, isDark = true) {
   if (aci == null || aci === 0 || aci === 256) return null;
+  if (aci === 7) return isDark ? 0xFFFFFF : 0x000000;
   if (aci <= 9) return FIXED[aci] ?? null;
   if (aci >= 250 && aci <= 255) {
     const v = Math.round(40 + (aci - 250) * 43);