diff --git a/config/sinau-c-tail.json b/config/sinau-c-tail.json
index c3607b7..43087d8 100644
--- a/config/sinau-c-tail.json
+++ b/config/sinau-c-tail.json
@@ -9,6 +9,9 @@
       "Handlers": {
         "/": {
           "Proxy": "http://elemes-frontend:3000"
+        },
+        "/assets/": {
+          "Proxy": "http://elemes:5000/assets/"
         }
       }
     }
diff --git a/documentation.md b/documentation.md
index bdd3b80..05c3476 100644
--- a/documentation.md
+++ b/documentation.md
@@ -185,6 +185,41 @@ Semua endpoint Flask diakses via SvelteKit proxy (`/api/*` → Flask `:5000`):
 
 ---
 
+## Anti Copy-Paste System
+
+Sistem berlapis untuk mencegah siswa meng-copy konten pelajaran dan mem-paste kode dari sumber eksternal ke editor.
+
+### Selection & Copy Prevention (Halaman Lesson)
+
+**File:** `frontend/src/routes/lesson/[slug]/+page.svelte`
+
+Mencegah siswa men-select dan meng-copy teks dari konten pelajaran (termasuk code blocks).
+
+| Layer | Mekanisme | Target |
+|-------|-----------|--------|
+| CSS | `user-select: none`, `-webkit-touch-callout: none` | `.lesson-content`, `.lesson-info` |
+| Events | `onselectstart`, `oncopy`, `oncut`, `oncontextmenu` → `preventDefault()` | `.lesson-content`, `.lesson-info` |
+| JS | `selectionchange` + `mouseup` + `touchend` → `getSelection().removeAllRanges()` | Fallback aktif — clear selection jika terjadi di area konten (scoped, tidak mengganggu editor) |
+
+### Paste Prevention (CodeEditor)
+
+**File:** `frontend/src/lib/components/CodeEditor.svelte`
+
+Mencegah siswa mem-paste kode dari sumber eksternal ke code editor. Diaktifkan via prop `noPaste={true}`.
+
+| Layer | Mekanisme | Menangani |
+|-------|-----------|-----------|
+| 1 | `EditorView.domEventHandlers` — `paste`, `drop`, `beforeinput` → `preventDefault()` | Desktop paste, iOS paste |
+| A | `EditorState.transactionFilter` — block `input.paste` + heuristik ukuran (>2 baris atau >20 chars untuk 2 baris) | Standard paste + **GBoard clipboard panel** (paste via IME yang menyamar sebagai `input.type.compose`) |
+| C | `EditorView.clipboardInputFilter` — replace clipboard text → `''` (runtime check) | Standard paste (jika API tersedia) |
+| D | `EditorView.inputHandler` — block multi-line insertion >20 chars | GBoard clipboard via DOM mutations |
+| 2 | DOM capture-phase listeners — `paste`, `copy`, `cut`, `contextmenu`, `drop` → `preventDefault()` | Backup DOM-level |
+| B | `input` event listener — `CM.undo()` jika `insertFromPaste` | Fallback post-hoc revert |
+
+**Limitasi:** GBoard clipboard panel menyuntikkan teks lewat IME composition system (bukan clipboard API), sehingga tidak bisa dibedakan 100% dari ketikan biasa. Heuristik ukuran teks digunakan untuk mendeteksi dan memblokir mayoritas kasus paste, namun paste 1 baris pendek (<20 chars) masih bisa lolos.
+
+---
+
 ## Status Implementasi
 
 - [x] **Phase 0:** Backend decomposition (monolith → Blueprints + services)
diff --git a/frontend/src/hooks.server.ts b/frontend/src/hooks.server.ts
index dc7e972..56b735b 100644
--- a/frontend/src/hooks.server.ts
+++ b/frontend/src/hooks.server.ts
@@ -17,8 +17,14 @@ function resolveBackend(): string {
 const API_BACKEND = resolveBackend();
 
 export const handle: Handle = async ({ event, resolve }) => {
-	if (event.url.pathname.startsWith('/api/')) {
-		const backendPath = event.url.pathname.replace(/^\/api/, '');
+	// Proxy /api/* and /assets/* to Flask backend
+	const isApi = event.url.pathname.startsWith('/api/');
+	const isAsset = event.url.pathname.startsWith('/assets/');
+
+	if (isApi || isAsset) {
+		const backendPath = isApi
+			? event.url.pathname.replace(/^\/api/, '')
+			: event.url.pathname; // /assets/* kept as-is
 		const backendUrl = `${API_BACKEND}${backendPath}${event.url.search}`;
 
 		try {
@@ -38,13 +44,15 @@ export const handle: Handle = async ({ event, resolve }) => {
 			}
 
 			const res = await fetch(backendUrl, init);
-			const body = await res.text();
+
+			// Use arrayBuffer for binary content (images), text for API JSON
+			const resContentType = res.headers.get('content-type') ?? 'application/json';
+			const isBinary = !resContentType.startsWith('text/') && !resContentType.includes('json');
+			const body = isBinary ? await res.arrayBuffer() : await res.text();
 
 			return new Response(body, {
 				status: res.status,
-				headers: {
-					'content-type': res.headers.get('content-type') ?? 'application/json',
-				},
+				headers: { 'content-type': resContentType },
 			});
 		} catch (err) {
 			console.error(`API proxy error (${backendUrl}):`, err);
diff --git a/frontend/src/lib/components/CodeEditor.svelte b/frontend/src/lib/components/CodeEditor.svelte
index bbc7a49..32f51f3 100644
--- a/frontend/src/lib/components/CodeEditor.svelte
+++ b/frontend/src/lib/components/CodeEditor.svelte
@@ -6,17 +6,20 @@
 		code?: string;
 		language?: string;
 		readonly?: boolean;
+		noPaste?: boolean;
 		onchange?: (value: string) => void;
 	}
 
-	let { code = '', language = 'c', readonly = false, onchange }: Props = $props();
+	let { code = '', language = 'c', readonly = false, noPaste = false, onchange }: Props = $props();
 
 	let container: HTMLDivElement;
 	let view: any;
 	let ready = $state(false);
+	let lastThemeDark: boolean | undefined;
 
 	// Store module references after dynamic import
 	let CM: any;
+	let cleanupNoPaste: (() => void) | undefined;
 
 	async function loadCodeMirror() {
 		const [viewMod, stateMod, cmdsMod, langMod, autoMod, cppMod, pyMod, themeMod] =
@@ -76,6 +79,86 @@
 			);
 		}
 
+		if (noPaste) {
+			// Layer 1: DOM event handlers (catches standard paste/drop on desktop)
+			exts.push(
+				CM.EditorView.domEventHandlers({
+					paste(event: ClipboardEvent) {
+						event.preventDefault();
+						return true;
+					},
+					drop(event: DragEvent) {
+						event.preventDefault();
+						return true;
+					},
+					// Mobile browsers may use beforeinput with insertFromPaste/Drop
+					beforeinput(event: InputEvent) {
+						if (event.inputType === 'insertFromPaste' ||
+							event.inputType === 'insertFromDrop' ||
+							event.inputType === 'insertFromPasteAsQuotation') {
+							event.preventDefault();
+							return true;
+						}
+						return false;
+					},
+				})
+			);
+
+			// Layer A: Transaction filter — blocks paste at CM6 abstraction level.
+			// 1) Blocks transactions explicitly tagged 'input.paste' / 'input.drop'
+			//    (standard long-press → "Paste" on Android, and all desktop paste).
+			// 2) Heuristic for GBoard clipboard panel: GBoard injects clipboard
+			//    text through the IME as 'input.type.compose', indistinguishable
+			//    from regular typing at the event level. We detect it by checking
+			//    for unusually large insertions (multi-line or long single chunk)
+			//    that cannot come from normal keyboard input.
+			exts.push(
+				CM.EditorState.transactionFilter.of((tr: any) => {
+					if (tr.isUserEvent('input.paste') || tr.isUserEvent('input.drop')) {
+						return [];
+					}
+					// Heuristic: detect paste disguised as typing via mobile IME
+					if (tr.isUserEvent('input.type') || tr.isUserEvent('input.type.compose')) {
+						let dominated = false;
+						tr.changes.iterChanges(
+							(_fA: number, _tA: number, _fB: number, _tB: number, inserted: any) => {
+								// 3+ lines → definitely paste
+								// 2 lines with >20 chars → likely paste (Enter+indent is ~5-10 chars)
+								if (inserted.lines > 2 || (inserted.lines > 1 && inserted.length > 20)) {
+									dominated = true;
+								}
+							}
+						);
+						if (dominated) return [];
+					}
+					return tr;
+				})
+			);
+
+			// Layer C: Clipboard input filter — replaces clipboard text with ''
+			// before CM6 processes it (available since @codemirror/view 6.17.0)
+			if (CM.EditorView.clipboardInputFilter) {
+				exts.push(
+					CM.EditorView.clipboardInputFilter.of(() => '')
+				);
+			}
+
+			// Layer D: Input handler — intercepts text from DOM mutations.
+			// GBoard clipboard panel injects text via DOM mutations tagged as
+			// 'input.type.compose'. inputHandler fires for these mutations and
+			// can block them if the text looks like paste (multi-line).
+			exts.push(
+				CM.EditorView.inputHandler.of(
+					(_view: any, _from: number, _to: number, text: string) => {
+						if (text.includes('\n') && text.length > 20) {
+							return true; // block: multi-line insertion = paste
+						}
+						return false; // allow normal typing
+					}
+				)
+			);
+		}
+
 		return exts;
 	}
 
@@ -92,24 +175,66 @@
 		});
 	}
 
+	function setupNoPasteListeners() {
+		if (!noPaste || !container) return;
+		const prevent = (e: Event) => { e.preventDefault(); e.stopPropagation(); };
+		container.addEventListener('paste', prevent, true);
+		container.addEventListener('copy', prevent, true);
+		container.addEventListener('cut', prevent, true);
+		container.addEventListener('contextmenu', prevent, true);
+		container.addEventListener('drop', prevent, true);
+
+		// Layer B: Post-hoc paste revert via input event.
+		// The 'input' event fires AFTER content has been inserted, making it
+		// reliable on mobile where beforeinput may be non-cancelable.
+		// If Layer A (transactionFilter) blocks the paste, no input event fires,
+		// so there is no double-undo risk.
+		const revertPaste = (e: Event) => {
+			const ie = e as InputEvent;
+			if (ie.inputType === 'insertFromPaste' ||
+				ie.inputType === 'insertFromDrop' ||
+				ie.inputType === 'insertFromPasteAsQuotation') {
+				if (view && CM) {
+					CM.undo(view);
+				}
+			}
+		};
+		container.addEventListener('input', revertPaste, true);
+
+		cleanupNoPaste = () => {
+			container.removeEventListener('paste', prevent, true);
+			container.removeEventListener('copy', prevent, true);
+			container.removeEventListener('cut', prevent, true);
+			container.removeEventListener('contextmenu', prevent, true);
+			container.removeEventListener('drop', prevent, true);
+			container.removeEventListener('input', revertPaste, true);
+		};
+	}
+
 	onMount(async () => {
 		await loadCodeMirror();
+		lastThemeDark = $themeDark;
 		createEditor();
+		setupNoPasteListeners();
 		ready = true;
 	});
 
 	onDestroy(() => {
+		cleanupNoPaste?.();
 		view?.destroy();
 	});
 
-	// Recreate editor when theme changes
+	// Recreate editor ONLY when theme actually changes (not on ready/container changes)
 	$effect(() => {
-		const _dark = $themeDark;
-		if (ready && container && view) {
-			const currentCode = view.state.doc.toString();
-			code = currentCode;
-			createEditor();
-		}
+		const dark = $themeDark;
+		if (!ready || !container || !view) return;
+		if (lastThemeDark === dark) return;
+		lastThemeDark = dark;
+		const currentCode = view.state.doc.toString();
+		code = currentCode;
+		createEditor();
+		// Restore focus after theme-driven recreation
+		requestAnimationFrame(() => view?.focus());
 	});
 
 	/** Replace editor content programmatically (e.g. reset / load solution). */
@@ -126,7 +251,7 @@
 	}
 </script>
 
-<div class="editor-wrapper" bind:this={container}>
+<div class="editor-wrapper" class:no-paste={noPaste} bind:this={container}>
 	{#if !ready}
 		<div class="editor-loading">Memuat editor...</div>
 	{/if}
@@ -138,6 +263,7 @@
 		border-radius: var(--radius);
 		overflow: hidden;
 		font-size: 0.9rem;
+		-webkit-touch-callout: none;
 	}
 	.editor-wrapper :global(.cm-editor) {
 		min-height: 200px;
@@ -155,6 +281,9 @@
 		font-size: 0.85rem;
 		background: var(--color-bg-secondary);
 	}
+	.editor-wrapper.no-paste :global(.cm-content) {
+		-webkit-touch-callout: none;
+	}
 	@media (max-width: 768px) {
 		.editor-wrapper :global(.cm-editor) {
 			min-height: 150px;
diff --git a/frontend/src/routes/lesson/[slug]/+page.svelte b/frontend/src/routes/lesson/[slug]/+page.svelte
index e054dc6..5f4cdc2 100644
--- a/frontend/src/routes/lesson/[slug]/+page.svelte
+++ b/frontend/src/routes/lesson/[slug]/+page.svelte
@@ -9,10 +9,12 @@
 
 	// Data from +page.ts load function (SSR + client)
 	let { data: pageData } = $props();
-	let data = $state<LessonContent | null>(pageData.lesson);
 
-	// Editor state
-	let currentCode = $state(data?.initial_code ?? '');
+	// Derive lesson reactively so navigation updates propagate
+	let lesson = $derived(pageData.lesson);
+
+	let data = $state<LessonContent | null>(null);
+	let currentCode = $state('');
 	let compileOutput = $state('');
 	let compileError = $state('');
 	let compiling = $state(false);
@@ -22,13 +24,183 @@
 	let showSolution = $state(false);
 	let activeTab = $state<'editor' | 'output'>('editor');
 
-	let editor: CodeEditor;
+	let editor = $state<CodeEditor | null>(null);
+	let showCelebration = $state(false);
+
+	// Floating editor state
+	let editorFloating = $state(false);
+	let editorMinimized = $state(false);
+	let isMobile = $state(false);
+	let mobileExpanded = $state(true);
+	let touchStartY = 0;
+	let lessonContentEl = $state<HTMLDivElement>();
+	let lessonInfoEl = $state<HTMLDetailsElement>();
+
+	// Drag & resize state for floating panel
+	let dragging = $state(false);
+	let dragOffset = { x: 0, y: 0 };
+	let floatPos = $state<{ top: number; left: number } | null>(null);
+	let floatSize = $state<{ width: number; height: number } | null>(null);
+
+	// Computed inline style for position & size only (visibility handled via CSS class)
+	let floatStyle = $derived.by(() => {
+		if (editorFloating && !editorMinimized) {
+			let s = '';
+			if (floatPos) s += `top:${floatPos.top}px;left:${floatPos.left}px;bottom:auto;right:auto;`;
+			if (floatSize) s += `width:${floatSize.width}px;height:${floatSize.height}px;`;
+			return s;
+		}
+		return '';
+	});
+
+	function getFloatingPanel(e: MouseEvent): HTMLElement | null {
+		return (e.currentTarget as HTMLElement).closest('.editor-area') as HTMLElement | null;
+	}
+
+	function onDragStart(e: MouseEvent) {
+		if (!editorFloating || isMobile) return;
+		const panel = getFloatingPanel(e);
+		if (!panel) return;
+		dragging = true;
+		const rect = panel.getBoundingClientRect();
+		dragOffset = { x: e.clientX - rect.left, y: e.clientY - rect.top };
+		// Capture current size so it's preserved during/after drag
+		if (!floatSize) {
+			floatSize = { width: rect.width, height: rect.height };
+		}
+
+		const onMove = (ev: MouseEvent) => {
+			if (!dragging) return;
+			const newLeft = Math.max(0, Math.min(window.innerWidth - 100, ev.clientX - dragOffset.x));
+			const newTop = Math.max(0, Math.min(window.innerHeight - 48, ev.clientY - dragOffset.y));
+			floatPos = { top: newTop, left: newLeft };
+		};
+		const onUp = () => {
+			dragging = false;
+			window.removeEventListener('mousemove', onMove);
+			window.removeEventListener('mouseup', onUp);
+		};
+		window.addEventListener('mousemove', onMove);
+		window.addEventListener('mouseup', onUp);
+	}
+
+	function onResizeStart(e: MouseEvent) {
+		if (!editorFloating || isMobile) return;
+		e.preventDefault();
+		const panel = (e.currentTarget as HTMLElement).closest('.editor-area') as HTMLElement;
+		if (!panel) return;
+		const rect = panel.getBoundingClientRect();
+		const startX = e.clientX;
+		const startY = e.clientY;
+		const startW = rect.width;
+		const startH = rect.height;
+		const startLeft = rect.left;
+		const startTop = rect.top;
+
+		const onMove = (ev: MouseEvent) => {
+			// Handle grows left+up from top-left corner
+			const dx = startX - ev.clientX;
+			const dy = startY - ev.clientY;
+			const newW = Math.max(320, startW + dx);
+			const newH = Math.max(200, startH + dy);
+			floatSize = { width: newW, height: newH };
+			floatPos = {
+				left: startLeft - (newW - startW),
+				top: startTop - (newH - startH),
+			};
+		};
+		const onUp = () => {
+			window.removeEventListener('mousemove', onMove);
+			window.removeEventListener('mouseup', onUp);
+		};
+		window.addEventListener('mousemove', onMove);
+		window.addEventListener('mouseup', onUp);
+	}
+
+	// Media query detection
+	$effect(() => {
+		if (typeof window === 'undefined') return;
+		const mql = window.matchMedia('(max-width: 768px)');
+		isMobile = mql.matches;
+		const handler = (e: MediaQueryListEvent) => {
+			isMobile = e.matches;
+			if (isMobile) {
+				editorFloating = false;
+				editorMinimized = false;
+			}
+		};
+		mql.addEventListener('change', handler);
+		return () => mql.removeEventListener('change', handler);
+	});
+
+	// Selection prevention: clear any text selection inside lesson content
+	// CSS user-select:none may be bypassed on some mobile browsers, so we
+	// use JS as a fallback — detect selection via getSelection() and clear it.
+	$effect(() => {
+		if (typeof window === 'undefined') return;
+
+		function clearIfInProtectedArea() {
+			const sel = window.getSelection();
+			if (!sel || sel.isCollapsed) return;
+
+			const node = sel.anchorNode;
+			if (!node) return;
+
+			// Only clear if selection is inside lesson content or lesson info
+			const inLesson = lessonContentEl?.contains(node);
+			const inInfo = lessonInfoEl?.contains(node);
+			if (inLesson || inInfo) {
+				sel.removeAllRanges();
+			}
+		}
+
+		// selectionchange: fires during selection (real-time)
+		document.addEventListener('selectionchange', clearIfInProtectedArea);
+		// mouseup: backup for desktop (fires after mouse release)
+		document.addEventListener('mouseup', clearIfInProtectedArea);
+		// touchend: backup for mobile (fires after long-press select)
+		document.addEventListener('touchend', clearIfInProtectedArea);
+
+		return () => {
+			document.removeEventListener('selectionchange', clearIfInProtectedArea);
+			document.removeEventListener('mouseup', clearIfInProtectedArea);
+			document.removeEventListener('touchend', clearIfInProtectedArea);
+		};
+	});
+
+	function toggleFloat() {
+		editorFloating = !editorFloating;
+		editorMinimized = false;
+		floatPos = null;
+		floatSize = null;
+	}
+
+	function minimizeFloat() {
+		editorMinimized = true;
+	}
+
+	function restoreFloat() {
+		editorMinimized = false;
+	}
+
+	function toggleMobileSheet() {
+		mobileExpanded = !mobileExpanded;
+	}
+
+	function onSheetTouchStart(e: TouchEvent) {
+		touchStartY = e.touches[0].clientY;
+	}
+
+	function onSheetTouchEnd(e: TouchEvent) {
+		const delta = e.changedTouches[0].clientY - touchStartY;
+		if (delta > 60) mobileExpanded = false;
+		else if (delta < -60) mobileExpanded = true;
+	}
 
 	const slug = $derived($page.params.slug);
 
-	// Update data when navigating between lessons (pageData changes)
+	// Sync lesson data when navigating between lessons
 	$effect(() => {
-		const lesson = pageData.lesson;
 		if (lesson) {
 			data = lesson;
 			currentCode = lesson.initial_code ?? '';
@@ -37,9 +209,17 @@
 			compileSuccess = null;
 			showSolution = false;
 			activeTab = 'editor';
+			mobileExpanded = true;
 		}
 	});
 
+	/** Check if student code contains all required key_text keywords. */
+	function checkKeyText(code: string, keyText: string): boolean {
+		if (!keyText.trim()) return true;
+		const keys = keyText.split('\n').map(k => k.trim()).filter(k => k.length > 0);
+		return keys.every(key => code.includes(key));
+	}
+
 	async function handleRun() {
 		if (!data) return;
 		compiling = true;
@@ -56,14 +236,20 @@
 				compileOutput = res.output;
 				compileSuccess = true;
 
-				// Check if output matches expected output for auto-completion
-				if (data.expected_output && auth.isLoggedIn) {
-					const actual = res.output.trim();
-					const expected = data.expected_output.trim();
-					if (actual === expected) {
-						const lessonName = slug.replace('.md', '');
-						await trackProgress(auth.token, lessonName);
-						data.lesson_completed = true;
+				// Check completion: output must match AND code must contain all key_text keywords
+				if (data.expected_output) {
+					const outputMatch = res.output.trim() === data.expected_output.trim();
+					const keyTextMatch = checkKeyText(code, data.key_text ?? '');
+					if (outputMatch && keyTextMatch) {
+						// Celebration for everyone
+						showCelebration = true;
+						setTimeout(() => (showCelebration = false), 3000);
+						// Track progress only for logged-in users
+						if (auth.isLoggedIn) {
+							const lessonName = slug.replace('.md', '');
+							await trackProgress(auth.token, lessonName);
+							data.lesson_completed = true;
+						}
 					}
 				}
 			} else {
@@ -102,6 +288,16 @@
 	<title>{data?.lesson_title ?? 'Pelajaran'} - Elemes LMS</title>
 </svelte:head>
 
+<!-- Celebration overlay -->
+{#if showCelebration}
+	<div class="celebration-overlay">
+		<div class="celebration-content">
+			<div class="celebration-icon">&#10003;</div>
+			<p class="celebration-text">Selamat! Latihan Selesai!</p>
+		</div>
+	</div>
+{/if}
+
 {#if data}
 	<!-- Navigation breadcrumb -->
 	<div class="lesson-nav">
@@ -113,18 +309,28 @@
 
 	<h1 class="lesson-title">{data.lesson_title}</h1>
 
-	<!-- Lesson info (collapsible) -->
+	<!-- Lesson info (collapsible, selection prevented) -->
 	{#if data.lesson_info}
-		<details class="lesson-info">
+		<details class="lesson-info" bind:this={lessonInfoEl}
+			onselectstart={(e) => e.preventDefault()}
+			oncopy={(e) => e.preventDefault()}
+			oncontextmenu={(e) => e.preventDefault()}>
 			<summary>Informasi Pelajaran</summary>
 			<div class="info-content">{@html data.lesson_info}</div>
 		</details>
 	{/if}
 
-	<!-- Main content area: 2-col on desktop, stacked on mobile -->
-	<div class="lesson-layout">
-		<!-- Left: Lesson content -->
-		<div class="lesson-content">
+	<!-- Main content area -->
+	<div class="lesson-layout" class:single-col={editorFloating || isMobile}>
+		<!-- Left: Lesson content (selection & copy prevention) -->
+		<!-- svelte-ignore a11y_no_static_element_interactions -->
+		<div class="lesson-content" bind:this={lessonContentEl}
+			role="region" aria-label="Konten pelajaran"
+			class:full-width={editorFloating || isMobile}
+			onselectstart={(e) => e.preventDefault()}
+			oncopy={(e) => e.preventDefault()}
+			oncut={(e) => e.preventDefault()}
+			oncontextmenu={(e) => e.preventDefault()}>
 			<div class="prose">{@html data.lesson_content}</div>
 
 			{#if data.exercise_content}
@@ -135,67 +341,104 @@
 			{/if}
 		</div>
 
-		<!-- Right: Editor + Output -->
-		<div class="editor-area">
-			<!-- Mobile tabs -->
-			<div class="mobile-tabs">
-				<button
-					class="tab"
-					class:active={activeTab === 'editor'}
-					onclick={() => (activeTab = 'editor')}
-				>
-					Editor
+		<!-- Floating restore button (visible when minimized) -->
+		{#if editorFloating && editorMinimized && !isMobile}
+			<button type="button" class="float-restore-btn" onclick={restoreFloat}
+				title="Tampilkan Code Editor">
+				&#9654; Editor
+			</button>
+		{/if}
+
+		<!-- Editor + Output -->
+		<!-- svelte-ignore a11y_no_static_element_interactions -->
+		<div class="editor-area"
+			class:floating={editorFloating && !isMobile && !editorMinimized}
+			class:floating-hidden={editorFloating && editorMinimized && !isMobile}
+			class:mobile-sheet={isMobile}
+			class:mobile-collapsed={isMobile && !mobileExpanded}
+			style={floatStyle}>
+
+			<!-- Floating/Sheet header -->
+			{#if isMobile}
+				<button class="panel-header sheet-handle"
+					ontouchstart={onSheetTouchStart}
+					ontouchend={onSheetTouchEnd}
+					onclick={toggleMobileSheet}>
+					<div class="sheet-handle-bar"></div>
+					<span class="panel-title">Code Editor</span>
 				</button>
-				<button
-					class="tab"
-					class:active={activeTab === 'output'}
-					onclick={() => (activeTab = 'output')}
-				>
-					Output
-				</button>
-			</div>
-
-			<!-- Toolbar -->
-			<div class="toolbar">
-				<button class="btn btn-success" onclick={handleRun} disabled={compiling}>
-					{compiling ? 'Compiling...' : '&#9654; Run'}
-				</button>
-				<button class="btn btn-secondary" onclick={handleReset}>Reset</button>
-				{#if data.solution_code}
-					<button class="btn btn-secondary" onclick={handleShowSolution}>
-						{showSolution ? 'Sembunyikan Solusi' : 'Lihat Solusi'}
-					</button>
-				{/if}
-				<span class="lang-label">{data.language_display_name}</span>
-			</div>
-
-			<!-- Editor panel -->
-			<div class="panel" class:hidden-mobile={activeTab !== 'editor'}>
-				<CodeEditor
-					bind:this={editor}
-					code={currentCode}
-					language={data.language}
-					onchange={(val) => (currentCode = val)}
-				/>
-			</div>
-
-			<!-- Output panel -->
-			<div class="panel" class:hidden-mobile={activeTab !== 'output'}>
-				<OutputPanel
-					output={compileOutput}
-					error={compileError}
-					loading={compiling}
-					success={compileSuccess}
-				/>
-			</div>
-
-			<!-- Expected output hint -->
-			{#if data.expected_output}
-				<details class="expected-output">
-					<summary>Expected Output</summary>
-					<pre>{data.expected_output}</pre>
-				</details>
+			{:else if editorFloating && !editorMinimized}
+				<!-- svelte-ignore a11y_no_static_element_interactions -->
+				<div class="panel-header draggable" onmousedown={onDragStart}>
+					<!-- svelte-ignore a11y_no_static_element_interactions -->
+					<span class="resize-handle" onmousedown={(e) => { e.stopPropagation(); onResizeStart(e); }} title="Resize">&#x25F3;</span>
+					<span class="panel-title">Code Editor</span>
+					<div class="panel-actions">
+						<button type="button" class="panel-btn" onclick={minimizeFloat}
+							title="Minimize">▽</button>
+						<button type="button" class="panel-btn" onclick={toggleFloat}
+							title="Dock editor">⊡</button>
+					</div>
+				</div>
 			{/if}
+
+			<!-- Editor body -->
+			<div class="editor-body" class:body-hidden={isMobile && !mobileExpanded}>
+				{#if isMobile}
+					<div class="mobile-tabs">
+						<button class="tab" class:active={activeTab === 'editor'}
+							onclick={() => (activeTab = 'editor')}>Editor</button>
+						<button class="tab" class:active={activeTab === 'output'}
+							onclick={() => (activeTab = 'output')}>Output</button>
+					</div>
+				{/if}
+
+				<!-- Toolbar -->
+				<div class="toolbar">
+					<button type="button" class="btn btn-success" onclick={handleRun} disabled={compiling}>
+						{compiling ? 'Compiling...' : '&#9654; Run'}
+					</button>
+					<button type="button" class="btn btn-secondary" onclick={handleReset}>Reset</button>
+					{#if data.solution_code && auth.isLoggedIn && data.lesson_completed}
+						<button type="button" class="btn btn-secondary" onclick={handleShowSolution}>
+							{showSolution ? 'Sembunyikan Solusi' : 'Lihat Solusi'}
+						</button>
+					{/if}
+					<span class="lang-label">{data.language_display_name}</span>
+					{#if !isMobile && !editorFloating}
+						<button type="button" class="btn-float-toggle" onclick={toggleFloat} title="Float editor">&#x229E;</button>
+					{/if}
+				</div>
+
+				<!-- Editor panel -->
+				<div class="panel" class:hidden-mobile={isMobile && activeTab !== 'editor'}>
+					<CodeEditor
+						bind:this={editor}
+						code={currentCode}
+						language={data.language}
+						noPaste={true}
+						onchange={(val) => (currentCode = val)}
+					/>
+				</div>
+
+				<!-- Output panel -->
+				<div class="panel" class:hidden-mobile={isMobile && activeTab !== 'output'}>
+					<OutputPanel
+						output={compileOutput}
+						error={compileError}
+						loading={compiling}
+						success={compileSuccess}
+					/>
+				</div>
+
+				<!-- Expected output hint -->
+				{#if data.expected_output}
+					<details class="expected-output">
+						<summary>Expected Output</summary>
+						<pre>{data.expected_output}</pre>
+					</details>
+				{/if}
+			</div>
 		</div>
 	</div>
 
@@ -259,6 +502,15 @@
 		overflow-y: auto;
 		max-height: 80vh;
 		padding-right: 0.5rem;
+		-webkit-user-select: none;
+		user-select: none;
+		-webkit-touch-callout: none;
+	}
+
+	.lesson-info {
+		-webkit-user-select: none;
+		user-select: none;
+		-webkit-touch-callout: none;
 	}
 
 	.prose :global(pre) {
@@ -290,12 +542,23 @@
 		font-size: 1.1rem;
 	}
 
-	/* ── Editor area ───────────────────────────────────────── */
+	/* ── Editor area (inline mode) ─────────────────────────── */
 	.editor-area {
 		position: sticky;
 		top: 4rem;
 	}
 
+	/* ── Single-column layout ──────────────────────────────── */
+	.lesson-layout.single-col {
+		grid-template-columns: 1fr;
+	}
+	.lesson-content.full-width {
+		max-height: none;
+		padding-right: 0;
+		padding-bottom: 60px;
+	}
+
+	/* ── Toolbar ───────────────────────────────────────────── */
 	.toolbar {
 		display: flex;
 		align-items: center;
@@ -318,11 +581,9 @@
 		font-weight: 600;
 		text-transform: uppercase;
 	}
-
 	.panel {
 		margin-bottom: 0.75rem;
 	}
-
 	.expected-output {
 		font-size: 0.8rem;
 		color: var(--color-text-muted);
@@ -334,6 +595,203 @@
 		margin-top: 0.5rem;
 	}
 
+	/* ── Floating restore button (when minimized) ────────── */
+	.float-restore-btn {
+		position: fixed;
+		bottom: 1rem;
+		right: 1rem;
+		z-index: 50;
+		background: var(--color-primary);
+		color: #fff;
+		border: none;
+		border-radius: var(--radius);
+		padding: 0.6rem 1rem;
+		font-size: 0.85rem;
+		font-weight: 600;
+		cursor: pointer;
+		box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
+		transition: background 0.15s, transform 0.1s;
+	}
+	.float-restore-btn:hover {
+		background: var(--color-primary-dark);
+	}
+	.float-restore-btn:active {
+		transform: scale(0.95);
+	}
+
+	/* ── Float toggle button ───────────────────────────────── */
+	.btn-float-toggle {
+		background: none;
+		border: 1px solid var(--color-border);
+		border-radius: 4px;
+		padding: 0.2rem 0.5rem;
+		cursor: pointer;
+		font-size: 0.95rem;
+		color: var(--color-text-muted);
+		line-height: 1;
+	}
+	.btn-float-toggle:hover {
+		background: var(--color-bg-secondary);
+		color: var(--color-text);
+	}
+
+	/* ── Panel header (floating & sheet) ───────────────────── */
+	.panel-header {
+		display: flex;
+		align-items: center;
+		gap: 0.5rem;
+		padding: 0.5rem 0.75rem;
+		background: var(--color-bg-secondary);
+		border-bottom: 1px solid var(--color-border);
+		user-select: none;
+		cursor: default;
+		flex-wrap: wrap;
+	}
+	.panel-header.draggable {
+		cursor: grab;
+	}
+	.panel-header.draggable:active {
+		cursor: grabbing;
+	}
+	.panel-title {
+		font-size: 0.85rem;
+		font-weight: 600;
+		flex: 1;
+	}
+	.panel-actions {
+		display: flex;
+		gap: 0.25rem;
+	}
+	.panel-btn {
+		background: none;
+		border: 1px solid var(--color-border);
+		border-radius: 4px;
+		padding: 0.15rem 0.5rem;
+		cursor: pointer;
+		font-size: 0.8rem;
+		color: var(--color-text);
+		line-height: 1;
+	}
+	.panel-btn:hover {
+		background: var(--color-border);
+	}
+
+	/* ── Desktop floating mode ─────────────────────────────── */
+	.editor-area.floating {
+		position: fixed;
+		bottom: 1rem;
+		right: 1rem;
+		top: auto;
+		width: 45vw;
+		min-width: 320px;
+		max-width: 90vw;
+		max-height: 85vh;
+		z-index: 50;
+		background: var(--color-bg);
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius);
+		box-shadow: 0 8px 32px rgba(0, 0, 0, 0.18);
+		display: flex;
+		flex-direction: column;
+		overflow: auto;
+	}
+	.resize-handle {
+		cursor: nwse-resize;
+		font-size: 0.9rem;
+		color: var(--color-text-muted);
+		line-height: 1;
+		padding: 0.1rem 0.3rem;
+		border-radius: 3px;
+	}
+	.resize-handle:hover {
+		background: var(--color-border);
+		color: var(--color-text);
+	}
+	.editor-area.floating .editor-body {
+		flex: 1;
+		overflow-y: auto;
+		padding: 0.5rem;
+		min-height: 0;
+	}
+	.editor-area.floating-hidden {
+		display: none !important;
+	}
+
+	/* ── Mobile bottom sheet ───────────────────────────────── */
+	.editor-area.mobile-sheet {
+		position: fixed;
+		bottom: 0;
+		left: 0;
+		right: 0;
+		top: auto;
+		z-index: 50;
+		background: var(--color-bg);
+		border-top: 2px solid var(--color-primary);
+		border-radius: 12px 12px 0 0;
+		box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.15);
+		max-height: 70vh;
+		display: flex;
+		flex-direction: column;
+		transition: transform 0.3s ease;
+	}
+	.editor-area.mobile-collapsed {
+		transform: translateY(calc(100% - 48px));
+	}
+	.mobile-sheet .editor-body {
+		flex: 1;
+		overflow-y: auto;
+		padding: 0.5rem;
+		overscroll-behavior: contain;
+	}
+	.sheet-handle {
+		flex-direction: column;
+		border: none;
+		border-bottom: 1px solid var(--color-border);
+		cursor: pointer;
+		width: 100%;
+		color: inherit;
+		font: inherit;
+		text-align: center;
+	}
+	.sheet-handle-bar {
+		width: 36px;
+		height: 4px;
+		background: var(--color-border);
+		border-radius: 2px;
+		margin: 0 auto 0.25rem;
+	}
+
+	/* ── Mobile tabs ───────────────────────────────────────── */
+	.mobile-tabs {
+		display: flex;
+		gap: 0;
+		margin-bottom: 0.5rem;
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius);
+		overflow: hidden;
+	}
+	.tab {
+		flex: 1;
+		padding: 0.5rem;
+		border: none;
+		background: var(--color-bg-secondary);
+		cursor: pointer;
+		font-weight: 500;
+		font-size: 0.85rem;
+	}
+	.tab.active {
+		background: var(--color-primary);
+		color: #fff;
+	}
+
+	/* ── Utility ───────────────────────────────────────────── */
+	.hidden-mobile {
+		display: none;
+	}
+	.editor-body.body-hidden {
+		display: none;
+	}
+
 	/* ── Footer nav ────────────────────────────────────────── */
 	.lesson-footer-nav {
 		display: flex;
@@ -343,46 +801,54 @@
 		border-top: 1px solid var(--color-border);
 	}
 
-	/* ── Mobile tabs (hidden on desktop) ───────────────────── */
-	.mobile-tabs {
-		display: none;
+	/* ── Celebration overlay ──────────────────────────────── */
+	.celebration-overlay {
+		position: fixed;
+		inset: 0;
+		z-index: 200;
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		background: rgba(0, 0, 0, 0.4);
+		animation: celebFadeIn 0.3s ease-out;
+		pointer-events: none;
 	}
-
-	/* ── Mobile responsive ─────────────────────────────────── */
-	@media (max-width: 768px) {
-		.lesson-layout {
-			grid-template-columns: 1fr;
-		}
-		.lesson-content {
-			max-height: none;
-			padding-right: 0;
-		}
-		.editor-area {
-			position: static;
-		}
-		.mobile-tabs {
-			display: flex;
-			gap: 0;
-			margin-bottom: 0.5rem;
-			border: 1px solid var(--color-border);
-			border-radius: var(--radius);
-			overflow: hidden;
-		}
-		.tab {
-			flex: 1;
-			padding: 0.5rem;
-			border: none;
-			background: var(--color-bg-secondary);
-			cursor: pointer;
-			font-weight: 500;
-			font-size: 0.85rem;
-		}
-		.tab.active {
-			background: var(--color-primary);
-			color: #fff;
-		}
-		.hidden-mobile {
-			display: none;
-		}
+	.celebration-content {
+		text-align: center;
+		animation: celebPop 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
+	}
+	.celebration-icon {
+		width: 80px;
+		height: 80px;
+		margin: 0 auto 1rem;
+		background: var(--color-success);
+		color: #fff;
+		border-radius: 50%;
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		font-size: 2.5rem;
+		font-weight: 700;
+		box-shadow: 0 0 0 0 rgba(25, 135, 84, 0.4);
+		animation: celebRing 1.5s ease-out;
+	}
+	.celebration-text {
+		font-size: 1.4rem;
+		font-weight: 700;
+		color: #fff;
+		text-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
+	}
+	@keyframes celebFadeIn {
+		from { opacity: 0; }
+		to { opacity: 1; }
+	}
+	@keyframes celebPop {
+		0% { transform: scale(0.5); opacity: 0; }
+		100% { transform: scale(1); opacity: 1; }
+	}
+	@keyframes celebRing {
+		0% { box-shadow: 0 0 0 0 rgba(25, 135, 84, 0.6); }
+		70% { box-shadow: 0 0 0 30px rgba(25, 135, 84, 0); }
+		100% { box-shadow: 0 0 0 0 rgba(25, 135, 84, 0); }
 	}
 </style>
diff --git a/frontend/vite.config.ts b/frontend/vite.config.ts
index 0baff38..2991feb 100644
--- a/frontend/vite.config.ts
+++ b/frontend/vite.config.ts
@@ -9,6 +9,10 @@ export default defineConfig({
 				target: 'http://elemes:5000',
 				changeOrigin: true,
 				rewrite: (path) => path.replace(/^\/api/, '')
+			},
+			'/assets': {
+				target: 'http://elemes:5000',
+				changeOrigin: true
 			}
 		}
 	}
diff --git a/podman-compose.yml b/podman-compose.yml
index d2f1133..c6c96d3 100644
--- a/podman-compose.yml
+++ b/podman-compose.yml
@@ -10,29 +10,23 @@ services:
       - ../assets:/app/assets
     env_file:
       - ../.env
-    networks:
-      lms_net:
-        ipv4_address: 10.89.100.10
 
     # production
-    # command: gunicorn --config gunicorn.conf.py "app:create_app()"
+    command: gunicorn --config gunicorn.conf.py "app:create_app()"
 
     # debug
-    command: python app.py
+    # command: python app.py
 
   elemes-frontend:
     build: ./frontend
     container_name: elemes-frontend
-    ports:
-      - 3000:3000
+    # ports:
+    #  - 3000:3000
     environment:
       - ORIGIN=http://localhost:3000
-      - API_BACKEND=http://10.89.100.10:5000
+      - API_BACKEND=http://elemes:5000
     depends_on:
       - elemes
-    networks:
-      lms_net:
-        ipv4_address: 10.89.100.11
 
   elemes-ts:
     image: docker.io/tailscale/tailscale:latest
@@ -55,13 +49,8 @@ services:
       - elemes-frontend
     env_file:
       - ../.env
-    networks:
-      lms_net:
-        ipv4_address: 10.89.100.12
 
 networks:
-  lms_net:
-    driver: bridge
-    ipam:
-      config:
-        - subnet: 10.89.100.0/24
+  main_network:
+    drive: bridge
+    network_mode: service:elemes-ts