diff --git a/Dockerfile b/Dockerfile
index c06359b..f3fa1d3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,7 +18,7 @@ RUN pip install --no-cache-dir -r backend/requirements.txt
 COPY backend/ /app/backend/
 
 # Copy frontend files
-COPY index.html manage.html /usr/share/nginx/html/
+COPY index.html manage.html yaml-validator.js /usr/share/nginx/html/
 
 # Configure nginx
 RUN echo 'server {\n\
@@ -27,8 +27,10 @@ RUN echo 'server {\n\
     root /usr/share/nginx/html;\n\
     index index.html;\n\
     \n\
-    location / {\n\
-        try_files $uri $uri/ /index.html;\n\
+    # Serve JavaScript files with correct MIME type (must come before location /)\n\
+    location ~* \\.js$ {\n\
+        default_type application/javascript;\n\
+        try_files $uri =404;\n\
     }\n\
     \n\
     location /api {\n\
@@ -36,6 +38,10 @@ RUN echo 'server {\n\
         proxy_set_header Host $host;\n\
         proxy_set_header X-Real-IP $remote_addr;\n\
     }\n\
+    \n\
+    location / {\n\
+        try_files $uri $uri/ /index.html;\n\
+    }\n\
 }' > /etc/nginx/sites-available/default
 
 # Configure supervisor
diff --git a/docker-compose.yml b/docker-compose.yml
index bc1f59f..1463917 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -15,6 +15,7 @@ services:
       # Hot reload frontend (optional, for development)
       - ./index.html:/usr/share/nginx/html/index.html:ro,z
       - ./manage.html:/usr/share/nginx/html/manage.html:ro,z
+      - ./yaml-validator.js:/usr/share/nginx/html/yaml-validator.js:ro,z
     environment:
       # Set working directory for database
       - PWD=/app/data
diff --git a/index.html b/index.html
index 59a77d7..3cedc93 100644
--- a/index.html
+++ b/index.html
@@ -5,6 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Stronghold - Minecraft Server Generator</title>
     <script src="https://cdn.jsdelivr.net/npm/js-yaml@4.1.0/dist/js-yaml.min.js"></script>
+    <script src="yaml-validator.js"></script>
     <style>
         * {
             margin: 0;
@@ -697,138 +698,78 @@
         const yamlStatus = document.getElementById('yamlStatus');
         let currentYaml = '';
 
-        // Docker Compose structure validation
-        function validateDockerCompose(config) {
-            const errors = [];
-
-            // Check for required top-level keys
-            if (!config.services) {
-                errors.push('Missing "services" section');
-                return errors;
-            }
-
-            // Check services
-            const serviceNames = Object.keys(config.services);
-            if (serviceNames.length === 0) {
-                errors.push('No services defined');
-            }
-
-            // Validate each service
-            serviceNames.forEach(serviceName => {
-                const service = config.services[serviceName];
-
-                // Check for required service fields
-                if (!service.image && !service.build) {
-                    errors.push(`Service "${serviceName}": Missing "image" or "build"`);
-                }
-
-                // Check volume references match defined volumes
-                if (service.volumes && Array.isArray(service.volumes)) {
-                    service.volumes.forEach(volume => {
-                        // Extract volume name from volume string (format: "volume_name:/path" or "/host:/path")
-                        if (typeof volume === 'string') {
-                            const parts = volume.split(':');
-                            const volumeName = parts[0];
-                            
-                            // Check if it's a named volume (not a bind mount starting with / or ./)
-                            if (volumeName && !volumeName.startsWith('/') && !volumeName.startsWith('./') && volumeName !== '~') {
-                                // Check if volume is defined
-                                if (config.volumes && !config.volumes.hasOwnProperty(volumeName)) {
-                                    errors.push(`Service "${serviceName}": Volume "${volumeName}" is referenced but not defined in "volumes" section`);
-                                }
-                            }
-                        }
-                    });
-                }
-
-                // Validate port format
-                if (service.ports && Array.isArray(service.ports)) {
-                    service.ports.forEach(port => {
-                        if (typeof port === 'string') {
-                            // Basic port format check: "host:container" or just number
-                            const parts = port.split(':');
-                            if (parts.length === 2 && (!parts[0].match(/^\d+$/) || !parts[1].match(/^\d+\/?\w*$/))) {
-                                errors.push(`Service "${serviceName}": Invalid port format "${port}" (expected "host:container")`);
-                            }
-                        }
-                    });
-                }
-
-                // Check environment variables format
-                if (service.environment) {
-                    if (typeof service.environment !== 'object') {
-                        errors.push(`Service "${serviceName}": "environment" must be an object or array`);
-                    }
-                }
-            });
-
-            return errors;
-        }
-
-        // YAML validation function
+        // YAML validation function (wrapper that handles DOM updates)
         function validateYAML(yamlText) {
-            yamlError.classList.remove('show');
-            yamlSuccess.classList.remove('show');
+            const errorElement = document.getElementById('yamlError');
+            const successElement = document.getElementById('yamlSuccess');
+            
+            errorElement.classList.remove('show');
+            successElement.classList.remove('show');
             yamlEditor.classList.remove('error', 'valid');
             yamlStatus.textContent = '';
             yamlStatus.classList.remove('valid', 'invalid');
 
-            if (!yamlText || yamlText.trim() === '') {
-                yamlStatus.textContent = 'YAML is empty';
+            // Get the pure validation function from yaml-validator.js
+            // yaml-validator.js exposes it as window._validateYAMLPure to avoid shadowing
+            const pureValidateFn = (typeof window !== 'undefined' && window._validateYAMLPure) 
+                ? window._validateYAMLPure 
+                : null;
+            
+            if (!pureValidateFn) {
+                errorElement.textContent = 'Error: YAML validator library not loaded. Please refresh the page.';
+                errorElement.classList.add('show');
+                yamlStatus.textContent = '✗ Validation Error';
                 yamlStatus.classList.add('invalid');
-                return { valid: false, error: 'YAML is empty' };
+                console.error('Cannot access _validateYAMLPure from yaml-validator.js');
+                return { valid: false, error: 'YAML validator not loaded', config: null };
             }
+            
+            // Call the pure function from yaml-validator.js
+            const result = pureValidateFn(yamlText);
 
-            let parsedConfig;
-            let yamlError = null;
-
-            // First, check YAML syntax
-            try {
-                parsedConfig = jsyaml.load(yamlText);
-            } catch (error) {
+            if (!result.valid) {
+                // Show error
+                errorElement.textContent = result.error;
+                errorElement.classList.add('show');
+                successElement.classList.remove('show');
                 yamlEditor.classList.add('error');
                 yamlEditor.classList.remove('valid');
-                yamlError = error;
-            }
-
-            if (yamlError) {
-                // YAML syntax error
-                document.getElementById('yamlError').textContent = `YAML Syntax Error: ${yamlError.message}`;
-                document.getElementById('yamlError').classList.add('show');
-                yamlSuccess.classList.remove('show');
-                yamlStatus.textContent = '✗ Invalid YAML Syntax';
+                
+                // Determine status text based on error type
+                if (result.error.includes('Syntax Error')) {
+                    yamlStatus.textContent = '✗ Invalid YAML Syntax';
+                } else if (result.error.includes('Docker Compose')) {
+                    yamlStatus.textContent = '✗ Docker Compose Validation Failed';
+                } else {
+                    yamlStatus.textContent = '✗ Validation Error';
+                }
                 yamlStatus.classList.add('invalid');
-                return { valid: false, error: yamlError.message };
+            } else {
+                // All valid!
+                yamlEditor.classList.add('valid');
+                yamlEditor.classList.remove('error');
+                errorElement.classList.remove('show');
+                successElement.classList.add('show');
+                yamlStatus.textContent = '✓ Valid Docker Compose YAML';
+                yamlStatus.classList.add('valid');
             }
 
-            // YAML is syntactically valid, now check Docker Compose structure
-            const composeErrors = validateDockerCompose(parsedConfig);
+            return result;
+        }
 
-            if (composeErrors.length > 0) {
-                // Docker Compose structure errors
-                yamlEditor.classList.add('error');
-                yamlEditor.classList.remove('valid');
-                document.getElementById('yamlError').textContent = `Docker Compose Errors:\n• ${composeErrors.join('\n• ')}`;
-                document.getElementById('yamlError').classList.add('show');
-                yamlSuccess.classList.remove('show');
-                yamlStatus.textContent = '✗ Docker Compose Validation Failed';
-                yamlStatus.classList.add('invalid');
-                return { valid: false, error: composeErrors.join('; ') };
-            }
-
-            // All valid!
-            yamlEditor.classList.add('valid');
-            yamlEditor.classList.remove('error');
-            document.getElementById('yamlError').classList.remove('show');
-            yamlSuccess.classList.add('show');
-            yamlStatus.textContent = '✓ Valid Docker Compose YAML';
-            yamlStatus.classList.add('valid');
-            return { valid: true };
+        // Check if js-yaml is loaded
+        if (typeof jsyaml === 'undefined') {
+            console.error('js-yaml library not loaded!');
+            yamlStatus.textContent = 'Error: YAML library not loaded';
+            yamlStatus.classList.add('invalid');
         }
 
         // Real-time YAML linting with debounce
         let lintTimeout;
         yamlEditor.addEventListener('input', () => {
+            if (typeof jsyaml === 'undefined') {
+                return; // Don't validate if library isn't loaded
+            }
             clearTimeout(lintTimeout);
             lintTimeout = setTimeout(() => {
                 validateYAML(yamlEditor.value);
diff --git a/yaml-validator.js b/yaml-validator.js
new file mode 100644
index 0000000..1469492
--- /dev/null
+++ b/yaml-validator.js
@@ -0,0 +1,137 @@
+/**
+ * YAML Linting and Docker Compose Validation
+ * 
+ * Pure validation functions for YAML syntax, formatting, and Docker Compose structure.
+ * Requires js-yaml library to be loaded globally.
+ * 
+ * Note: We rely on js-yaml for ALL syntax and formatting validation, including indentation.
+ * The js-yaml parser is comprehensive and handles all YAML edge cases correctly.
+ */
+
+// Docker Compose structure validation
+function validateDockerCompose(config) {
+    const errors = [];
+
+    // Check for required top-level keys
+    if (!config.services) {
+        errors.push('Missing "services" section');
+        return errors;
+    }
+
+    // Check services
+    const serviceNames = Object.keys(config.services);
+    if (serviceNames.length === 0) {
+        errors.push('No services defined');
+    }
+
+    // Validate each service
+    serviceNames.forEach(serviceName => {
+        const service = config.services[serviceName];
+
+        // Check for required service fields
+        if (!service.image && !service.build) {
+            errors.push(`Service "${serviceName}": Missing "image" or "build"`);
+        }
+
+        // Check volume references match defined volumes
+        if (service.volumes && Array.isArray(service.volumes)) {
+            service.volumes.forEach(volume => {
+                // Extract volume name from volume string (format: "volume_name:/path" or "/host:/path")
+                if (typeof volume === 'string') {
+                    const parts = volume.split(':');
+                    const volumeName = parts[0];
+                    
+                    // Check if it's a named volume (not a bind mount starting with / or ./)
+                    if (volumeName && !volumeName.startsWith('/') && !volumeName.startsWith('./') && volumeName !== '~') {
+                        // Check if volume is defined
+                        if (config.volumes && !config.volumes.hasOwnProperty(volumeName)) {
+                            errors.push(`Service "${serviceName}": Volume "${volumeName}" is referenced but not defined in "volumes" section`);
+                        }
+                    }
+                }
+            });
+        }
+
+        // Validate port format
+        if (service.ports && Array.isArray(service.ports)) {
+            service.ports.forEach(port => {
+                if (typeof port === 'string') {
+                    // Basic port format check: "host:container" or just number
+                    const parts = port.split(':');
+                    if (parts.length === 2 && (!parts[0].match(/^\d+$/) || !parts[1].match(/^\d+\/?\w*$/))) {
+                        errors.push(`Service "${serviceName}": Invalid port format "${port}" (expected "host:container")`);
+                    }
+                }
+            });
+        }
+
+        // Check environment variables format
+        if (service.environment) {
+            if (typeof service.environment !== 'object') {
+                errors.push(`Service "${serviceName}": "environment" must be an object or array`);
+            }
+        }
+    });
+
+    return errors;
+}
+
+/**
+ * Main YAML validation function (pure function, no DOM manipulation)
+ * @param {string} yamlText - The YAML text to validate
+ * @returns {Object} Validation result with {valid: boolean, error: string|null, config: Object|null}
+ */
+function validateYAMLPure(yamlText) {
+    // Check if js-yaml is available
+    if (typeof jsyaml === 'undefined') {
+        return { valid: false, error: 'YAML validation library not loaded', config: null };
+    }
+
+    if (!yamlText || yamlText.trim() === '') {
+        return { valid: true, error: null, config: null }; // Treat empty as valid (no errors)
+    }
+
+    let parsedConfig;
+
+    // 1. Rely on js-yaml for ALL syntax/formatting checks (Indentation, spacing, etc.)
+    try {
+        parsedConfig = jsyaml.load(yamlText);
+    } catch (error) {
+        // Extract precise location data from the js-yaml error object
+        const line = error.mark ? error.mark.line + 1 : 'Unknown';
+        const column = error.mark ? error.mark.column + 1 : 'Unknown';
+
+        return { 
+            valid: false, 
+            error: `YAML Syntax Error (Line ${line}, Col ${column}): ${error.reason}`, 
+            config: null 
+        };
+    }
+
+    // A valid YAML parse might return null or undefined for an empty file
+    if (!parsedConfig) {
+        return { valid: true, error: null, config: null };
+    }
+
+    // 2. YAML is syntactically valid, now check Docker Compose structure
+    const composeErrors = validateDockerCompose(parsedConfig);
+
+    if (composeErrors.length > 0) {
+        return { 
+            valid: false, 
+            error: `Docker Compose Structural Errors:\n• ${composeErrors.join('\n• ')}`, 
+            config: parsedConfig 
+        };
+    }
+
+    // All valid!
+    return { valid: true, error: 'YAML is valid and meets basic Docker Compose requirements.', config: parsedConfig };
+}
+
+// Expose the function on window with a unique name to avoid conflicts
+// This must happen at the end of the script, after the function is defined
+if (typeof window !== 'undefined') {
+    window._validateYAMLPure = validateYAMLPure;
+    console.log('Exposed _validateYAMLPure on window');
+}
+