diff --git a/Assets/CriticalCSS/responsive.critical.css b/Assets/CriticalCSS/responsive.critical.css
new file mode 100644
index 00000000..53898bd8
--- /dev/null
+++ b/Assets/CriticalCSS/responsive.critical.css
@@ -0,0 +1 @@
+@media (max-width:575.98px){:root{--bs-gutter-x:1rem}body{font-size:14px}h1{font-size:24px}h2{font-size:20px}h3{font-size:18px}.container-fluid{padding:0 10px}.navbar{padding:0.5rem 0}.navbar-brand{font-size:18px}main{padding:0.5rem}.sidebar{margin-top:2rem}table{font-size:12px;margin-bottom:1rem;overflow-x:auto}.table-responsive{margin-bottom:1rem}.btn{padding:0.375rem 0.75rem;font-size:14px}.btn-lg{padding:0.5rem 1rem;font-size:16px}.card{margin-bottom:1rem}.form-group{margin-bottom:1rem}.form-control{padding:0.375rem 0.75rem;font-size:16px}.modal-dialog{margin:0.5rem}.modal-content{border-radius:4px}img{max-width:100%;height:auto}ul,ol{padding-left:1.5rem}.mt-1,.my-1{margin-top:0.25rem !important}.mb-1,.my-1{margin-bottom:0.25rem !important}.p-1{padding:0.25rem !important}}@media (min-width:576px){body{font-size:14px}h1{font-size:28px}h2{font-size:22px}h3{font-size:18px}}@media (min-width:768px){body{font-size:15px}h1{font-size:32px}h2{font-size:26px}h3{font-size:20px}.row-md-2{display:grid;grid-template-columns:1fr 1fr;gap:1.5rem}.navbar{padding:1rem 0}.main-content{display:grid;grid-template-columns:1fr 300px;gap:2rem}.main-content.no-sidebar{grid-template-columns:1fr}}@media (min-width:992px){body{font-size:16px}h1{font-size:36px}h2{font-size:28px}h3{font-size:22px}.row-lg-3{display:grid;grid-template-columns:repeat(3,1fr);gap:2rem}.main-content{display:grid;grid-template-columns:1fr 300px;gap:2rem}.main-content.with-left-sidebar{grid-template-columns:250px 1fr 300px}.content-wrapper{max-width:1200px;margin:0 auto}}
\ No newline at end of file
diff --git a/Assets/CriticalCSS/variables.critical.css b/Assets/CriticalCSS/variables.critical.css
new file mode 100644
index 00000000..593b9c27
--- /dev/null
+++ b/Assets/CriticalCSS/variables.critical.css
@@ -0,0 +1 @@
+:root{--color-navy-dark:#0E2337;--color-navy-primary:#1e3a5f;--color-navy-light:#2c5282;--color-blue-primary:#1e3a5f;--color-blue-secondary:#2c5282;--color-blue-light:#1a73e8;--color-cyan-primary:#61c7cd;--color-cyan-dark:#4db8c4;--color-cyan-darker:#4fb3b9;--color-orange-primary:#FF8600;--color-orange-secondary:#FFB800;--color-orange-light:#FFB800;--color-orange-button:#FF6B35;--color-orange-button-end:#FF8C42;--color-orange-hover:#FF6B35;--color-neutral-50:#f8f9fa;--color-neutral-100:#e9ecef;--color-neutral-600:#495057;--color-neutral-700:#6c757d;--color-slate-gray:#4C5C6B;--color-gray-50:#f8f9fa;--color-gray-100:#f7fafc;--color-gray-200:#e9ecef;--color-gray-300:#dee2e6;--color-gray-400:#cbd5e0;--color-gray-500:#a0aec0;--color-gray-600:#6c757d;--color-gray-700:#495057;--color-gray-800:#333;--color-gray-900:#212529;--color-gray-dark:#1a1a1a;--color-white:#ffffff;--color-black:#000000;--font-family-base:'Poppins',sans-serif;--font-family-monospace:SFMono-Regular,Menlo,Monaco,Consolas,"Liberation Mono","Courier New",monospace;--font-size-base:1rem;--font-size-sm:0.875rem;--font-size-lg:1.125rem;--font-size-xl:1.25rem;--font-weight-normal:400;--font-weight-medium:500;--font-weight-semibold:600;--font-weight-bold:700;--line-height-base:1.5;--line-height-tight:1.25;--line-height-loose:1.8;--spacing-xs:0.25rem;--spacing-sm:0.5rem;--spacing-md:1rem;--spacing-lg:1.5rem;--spacing-xl:2rem;--spacing-2xl:3rem;--spacing-3xl:4rem;--border-width:1px;--border-width-thick:2px;--border-width-thicker:3px;--border-width-lateral:4px;--border-radius-sm:4px;--border-radius-md:8px;--border-radius-lg:12px;--border-radius-xl:16px;--border-color-light:var(--color-gray-200);--border-color-default:var(--color-gray-300);--shadow-xs:0 1px 2px rgba(0,0,0,0.05);--shadow-sm:0 2px 4px rgba(0,0,0,0.1);--shadow-md:0 4px 12px rgba(0,0,0,0.15);--shadow-lg:0 8px 24px rgba(0,0,0,0.2);--shadow-xl:0 12px 32px rgba(0,0,0,0.25);--shadow-2xl:0 20px 60px rgba(0,0,0,0.3);--shadow-navbar:0 2px 4px rgba(0,0,0,0.15);--shadow-navbar-scrolled:0 4px 12px rgba(0,0,0,0.25);--shadow-dropdown:0 8px 24px rgba(0,0,0,0.12);--shadow-cta:0 8px 24px rgba(255,133,0,0.3);--shadow-cta-hover:0 12px 32px rgba(255,133,0,0.4);--shadow-button:0 4px 12px rgba(255,107,53,0.3);--shadow-related-posts:0 12px 32px rgba(26,115,232,0.15);--shadow-pagination:0 4px 12px rgba(26,115,232,0.3);--transition-fast:0.15s ease;--transition-base:0.3s ease;--transition-slow:0.5s ease;--transition-cubic:cubic-bezier(0.4,0,0.2,1);--z-dropdown:1000;--z-sticky:1020;--z-navbar:1030;--z-modal-backdrop:1040;--z-modal:1050;--z-popover:1060;--z-tooltip:1070;--gradient-hero:linear-gradient(135deg,var(--color-blue-primary) 0%,var(--color-blue-secondary) 100%);--gradient-cta:linear-gradient(135deg,var(--color-orange-primary) 0%,var(--color-orange-secondary) 100%);--gradient-button-lets-talk:linear-gradient(135deg,var(--color-orange-button) 0%,var(--color-orange-button-end) 100%);--gradient-pagination:linear-gradient(135deg,var(--color-blue-primary) 0%,var(--color-blue-secondary) 100%);--gradient-underline:linear-gradient(90deg,var(--color-cyan-primary) 0%,var(--color-cyan-dark) 100%);--gradient-border-related:linear-gradient(180deg,var(--color-blue-primary) 0%,var(--color-blue-light) 100%);--opacity-disabled:0.5;--opacity-hover:0.8;--opacity-backdrop:0.5;--breakpoint-sm:576px;--breakpoint-md:768px;--breakpoint-lg:992px;--breakpoint-xl:1200px;--breakpoint-xxl:1400px}
\ No newline at end of file
diff --git a/Assets/Js/lazy-css-loader.js b/Assets/Js/lazy-css-loader.js
new file mode 100644
index 00000000..a73c938a
--- /dev/null
+++ b/Assets/Js/lazy-css-loader.js
@@ -0,0 +1,135 @@
+/**
+ * TIPO 5: Lazy CSS Loader
+ *
+ * Carga CSS no critico despues del evento load usando:
+ * - requestIdleCallback para CSS de baja prioridad
+ * - Event listeners para CSS condicional
+ *
+ * @package ROITheme
+ * @since 1.0.20
+ */
+(function() {
+    'use strict';
+
+    // Configuracion de CSS lazy (inyectada desde PHP)
+    var config = window.roiLazyCSSConfig || {
+        baseUrl: '',
+        version: '1.0.0',
+        idleTimeout: 2000,
+        cssFiles: []
+    };
+
+    /**
+     * Carga un archivo CSS de forma asincrona
+     *
+     * @param {string} href URL del archivo CSS
+     * @param {string} id ID del elemento link
+     * @returns {Promise}
+     */
+    function loadCSS(href, id) {
+        // Evitar duplicados
+        if (document.getElementById(id)) {
+            return Promise.resolve();
+        }
+
+        return new Promise(function(resolve, reject) {
+            var link = document.createElement('link');
+            link.id = id;
+            link.rel = 'stylesheet';
+            link.href = href;
+            link.onload = resolve;
+            link.onerror = reject;
+            document.head.appendChild(link);
+        });
+    }
+
+    /**
+     * Carga CSS cuando el navegador esta idle
+     *
+     * @param {Array} files Lista de archivos a cargar
+     */
+    function loadOnIdle(files) {
+        var load = function() {
+            files.forEach(function(file) {
+                loadCSS(
+                    config.baseUrl + file.path + '?ver=' + config.version,
+                    'roi-lazy-' + file.id
+                );
+            });
+        };
+
+        if ('requestIdleCallback' in window) {
+            requestIdleCallback(load, { timeout: config.idleTimeout });
+        } else {
+            // Fallback para Safari
+            setTimeout(load, config.idleTimeout);
+        }
+    }
+
+    /**
+     * Carga CSS de print solo cuando se va a imprimir
+     *
+     * @param {Object} file Archivo de print CSS
+     */
+    function setupPrintCSS(file) {
+        var loaded = false;
+
+        var load = function() {
+            if (loaded) return;
+            loaded = true;
+            loadCSS(
+                config.baseUrl + file.path + '?ver=' + config.version,
+                'roi-lazy-print'
+            );
+        };
+
+        // Evento antes de imprimir
+        window.addEventListener('beforeprint', load);
+
+        // Fallback: detectar Ctrl+P / Cmd+P
+        document.addEventListener('keydown', function(e) {
+            if ((e.ctrlKey || e.metaKey) && e.key === 'p') {
+                load();
+            }
+        });
+    }
+
+    /**
+     * Inicializacion
+     */
+    function init() {
+        var idleFiles = [];
+        var printFile = null;
+
+        config.cssFiles.forEach(function(file) {
+            switch (file.trigger) {
+                case 'idle':
+                    idleFiles.push(file);
+                    break;
+                case 'print':
+                    printFile = file;
+                    break;
+            }
+        });
+
+        // Cargar CSS idle despues de que la pagina este lista
+        if (idleFiles.length > 0) {
+            if (document.readyState === 'complete') {
+                loadOnIdle(idleFiles);
+            } else {
+                window.addEventListener('load', function() {
+                    loadOnIdle(idleFiles);
+                });
+            }
+        }
+
+        // Configurar CSS de print
+        if (printFile) {
+            setupPrintCSS(printFile);
+        }
+    }
+
+    // Iniciar
+    init();
+
+})();
diff --git a/Inc/enqueue-scripts.php b/Inc/enqueue-scripts.php
index c500efc7..7469da8c 100644
--- a/Inc/enqueue-scripts.php
+++ b/Inc/enqueue-scripts.php
@@ -512,14 +512,16 @@ function roi_enqueue_theme_styles() {
     // );
 
     // Theme Animations
-    // DIFERIDO: Fase 4.2 PageSpeed - mejoras visuales no críticas
-    wp_enqueue_style(
-        'roi-animations',
-        get_template_directory_uri() . '/Assets/Css/css-global-animations.css',
-        array('roi-bootstrap'),
-        '1.0.0',
-        'print' // Diferido para no bloquear renderizado
-    );
+    // MIGRADO A TIPO 5: Lazy loading via LazyCSSRegistrar (requestIdleCallback)
+    // Fecha: 2025-12-01
+    // @see Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php
+    // wp_enqueue_style(
+    //     'roi-animations',
+    //     get_template_directory_uri() . '/Assets/Css/css-global-animations.css',
+    //     array('roi-bootstrap'),
+    //     '1.0.0',
+    //     'print'
+    // );
 
     // Theme Responsive Styles
     // DIFERIDO: Fase 4.3 - media queries no críticas para primer paint
@@ -542,13 +544,16 @@ function roi_enqueue_theme_styles() {
     );
 
     // Print Styles
-    wp_enqueue_style(
-        'roi-print',
-        get_template_directory_uri() . '/Assets/Css/css-global-print.css',
-        array(),
-        '1.0.0',
-        'print'
-    );
+    // MIGRADO A TIPO 5: Lazy loading via LazyCSSRegistrar (beforeprint event)
+    // Fecha: 2025-12-01
+    // @see Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php
+    // wp_enqueue_style(
+    //     'roi-print',
+    //     get_template_directory_uri() . '/Assets/Css/css-global-print.css',
+    //     array(),
+    //     '1.0.0',
+    //     'print'
+    // );
 }
 
 add_action('wp_enqueue_scripts', 'roi_enqueue_theme_styles', 13);
diff --git a/Public/CriticalCSS/Application/UseCases/GetCriticalCSSUseCase.php b/Public/CriticalCSS/Application/UseCases/GetCriticalCSSUseCase.php
new file mode 100644
index 00000000..d2b1f8e2
--- /dev/null
+++ b/Public/CriticalCSS/Application/UseCases/GetCriticalCSSUseCase.php
@@ -0,0 +1,49 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Application\UseCases;
+
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSCacheInterface;
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSExtractorInterface;
+
+/**
+ * Caso de uso para obtener/generar CSS critico
+ *
+ * Cumple DIP: depende de interfaces, no de clases concretas
+ *
+ * @package ROITheme\Public\CriticalCSS\Application\UseCases
+ */
+final class GetCriticalCSSUseCase
+{
+    public function __construct(
+        private readonly CriticalCSSCacheInterface $cache,
+        private readonly CriticalCSSExtractorInterface $extractor
+    ) {}
+
+    /**
+     * Obtiene CSS critico, regenerando si es necesario
+     *
+     * @param string $type Tipo de CSS critico ('variables', 'responsive')
+     * @return string CSS critico o vacio si no existe
+     */
+    public function execute(string $type): string
+    {
+        // Si no existe en cache, generar
+        if (!$this->cache->has($type)) {
+            $this->extractor->generateAll();
+        }
+
+        return $this->cache->get($type) ?? '';
+    }
+
+    /**
+     * Fuerza regeneracion de todo el CSS critico
+     *
+     * @return array<string, int> Mapa de tipo => bytes generados
+     */
+    public function regenerate(): array
+    {
+        $this->cache->clear();
+        return $this->extractor->generateAll();
+    }
+}
diff --git a/Public/CriticalCSS/Domain/Contracts/CriticalCSSCacheInterface.php b/Public/CriticalCSS/Domain/Contracts/CriticalCSSCacheInterface.php
new file mode 100644
index 00000000..f615583c
--- /dev/null
+++ b/Public/CriticalCSS/Domain/Contracts/CriticalCSSCacheInterface.php
@@ -0,0 +1,59 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Domain\Contracts;
+
+/**
+ * Interface para cache de CSS critico
+ *
+ * Define el contrato para almacenamiento y recuperacion
+ * de CSS critico generado (TIPO 4).
+ *
+ * @package ROITheme\Public\CriticalCSS\Domain\Contracts
+ */
+interface CriticalCSSCacheInterface
+{
+    /**
+     * Obtiene CSS del cache
+     *
+     * @param string $key Clave del cache (ej: 'variables', 'responsive')
+     * @return string|null CSS cacheado o null si no existe
+     */
+    public function get(string $key): ?string;
+
+    /**
+     * Guarda CSS en cache
+     *
+     * @param string $key Clave del cache
+     * @param string $css Contenido CSS a guardar
+     * @return bool True si se guardo correctamente
+     */
+    public function set(string $key, string $css): bool;
+
+    /**
+     * Verifica si existe en cache
+     *
+     * @param string $key Clave del cache
+     * @return bool True si existe
+     */
+    public function has(string $key): bool;
+
+    /**
+     * Limpia todo el cache
+     *
+     * @return void
+     */
+    public function clear(): void;
+
+    /**
+     * Verifica si el cache esta desactualizado respecto al archivo fuente
+     *
+     * Compara filemtime del archivo fuente vs archivo cache.
+     * Si el fuente es mas nuevo, el cache esta desactualizado.
+     *
+     * @param string $key Clave del cache
+     * @param string $sourceFile Ruta absoluta al archivo fuente
+     * @return bool True si el cache es mas viejo que el fuente
+     */
+    public function isStale(string $key, string $sourceFile): bool;
+}
diff --git a/Public/CriticalCSS/Domain/Contracts/CriticalCSSExtractorInterface.php b/Public/CriticalCSS/Domain/Contracts/CriticalCSSExtractorInterface.php
new file mode 100644
index 00000000..1d9b4677
--- /dev/null
+++ b/Public/CriticalCSS/Domain/Contracts/CriticalCSSExtractorInterface.php
@@ -0,0 +1,54 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Domain\Contracts;
+
+/**
+ * Interface para extraccion de CSS critico
+ *
+ * Define el contrato para extraer CSS critico de archivos fuente
+ * y generar versiones optimizadas para inline (TIPO 4).
+ *
+ * @package ROITheme\Public\CriticalCSS\Domain\Contracts
+ */
+interface CriticalCSSExtractorInterface
+{
+    /**
+     * Extrae CSS de variables
+     *
+     * El archivo css-global-variables.css completo es critico
+     * porque define las variables CSS usadas en todo el sitio.
+     *
+     * @return string CSS de variables minificado
+     */
+    public function extractVariables(): string;
+
+    /**
+     * Extrae media queries criticas
+     *
+     * Solo extrae breakpoints mobile-first criticos de
+     * css-global-responsive.css para evitar layout shift.
+     *
+     * @return string CSS responsive critico minificado
+     */
+    public function extractResponsive(): string;
+
+    /**
+     * Genera y cachea todo el CSS critico
+     *
+     * Extrae variables y responsive, los minifica y guarda en cache.
+     *
+     * @return array<string, int> Mapa de tipo => bytes generados
+     */
+    public function generateAll(): array;
+
+    /**
+     * Verifica si algun archivo fuente ha cambiado
+     * respecto al cache generado
+     *
+     * Usado para auto-regeneracion en el bootstrap.
+     *
+     * @return bool True si se necesita regenerar
+     */
+    public function needsRegeneration(): bool;
+}
diff --git a/Public/CriticalCSS/Infrastructure/Cache/CriticalCSSFileCache.php b/Public/CriticalCSS/Infrastructure/Cache/CriticalCSSFileCache.php
new file mode 100644
index 00000000..412c4be8
--- /dev/null
+++ b/Public/CriticalCSS/Infrastructure/Cache/CriticalCSSFileCache.php
@@ -0,0 +1,117 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Infrastructure\Cache;
+
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSCacheInterface;
+
+/**
+ * Cache de CSS critico en filesystem con auto-invalidacion
+ *
+ * Almacena CSS critico generado en archivos .critical.css
+ * dentro de Assets/CriticalCSS/
+ *
+ * @package ROITheme\Public\CriticalCSS\Infrastructure\Cache
+ */
+final class CriticalCSSFileCache implements CriticalCSSCacheInterface
+{
+    private readonly string $cacheDir;
+
+    public function __construct()
+    {
+        $this->cacheDir = get_template_directory() . '/Assets/CriticalCSS';
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function get(string $key): ?string
+    {
+        $file = $this->getFilePath($key);
+
+        if (!file_exists($file)) {
+            return null;
+        }
+
+        $content = file_get_contents($file);
+
+        return $content !== false ? $content : null;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function set(string $key, string $css): bool
+    {
+        $this->ensureDirectoryExists();
+        $file = $this->getFilePath($key);
+
+        return file_put_contents($file, $css) !== false;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function has(string $key): bool
+    {
+        return file_exists($this->getFilePath($key));
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function clear(): void
+    {
+        $files = glob($this->cacheDir . '/*.critical.css');
+
+        if ($files === false) {
+            return;
+        }
+
+        foreach ($files as $file) {
+            unlink($file);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * Compara timestamps para detectar cache desactualizado.
+     * Costo: ~0.1ms (2 llamadas a filemtime)
+     */
+    public function isStale(string $key, string $sourceFile): bool
+    {
+        $cacheFile = $this->getFilePath($key);
+
+        // Si no existe cache, esta desactualizado
+        if (!file_exists($cacheFile)) {
+            return true;
+        }
+
+        // Si no existe fuente, no esta desactualizado (nada que regenerar)
+        if (!file_exists($sourceFile)) {
+            return false;
+        }
+
+        // Comparar timestamps
+        return filemtime($sourceFile) > filemtime($cacheFile);
+    }
+
+    /**
+     * Genera ruta del archivo cache
+     */
+    private function getFilePath(string $key): string
+    {
+        return $this->cacheDir . '/' . $key . '.critical.css';
+    }
+
+    /**
+     * Asegura que el directorio de cache existe
+     */
+    private function ensureDirectoryExists(): void
+    {
+        if (!is_dir($this->cacheDir)) {
+            mkdir($this->cacheDir, 0755, true);
+        }
+    }
+}
diff --git a/Public/CriticalCSS/Infrastructure/Services/CriticalCSSExtractor.php b/Public/CriticalCSS/Infrastructure/Services/CriticalCSSExtractor.php
new file mode 100644
index 00000000..40850a79
--- /dev/null
+++ b/Public/CriticalCSS/Infrastructure/Services/CriticalCSSExtractor.php
@@ -0,0 +1,147 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Infrastructure\Services;
+
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSCacheInterface;
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSExtractorInterface;
+
+/**
+ * Extrae CSS critico de archivos fuente
+ *
+ * Estrategia simple:
+ * - Variables: Todo el archivo (siempre critico)
+ * - Responsive: Solo breakpoints mobile-first criticos
+ *
+ * @package ROITheme\Public\CriticalCSS\Infrastructure\Services
+ */
+final class CriticalCSSExtractor implements CriticalCSSExtractorInterface
+{
+    // Archivos fuente
+    private const SOURCE_VARIABLES = '/Assets/Css/css-global-variables.css';
+    private const SOURCE_RESPONSIVE = '/Assets/Css/css-global-responsive.css';
+
+    // Breakpoints criticos (mobile-first)
+    // NOTA: El regex maneja 1 nivel de anidamiento.
+    // Si el CSS tiene @supports dentro de @media, no se capturara correctamente.
+    // Esto es aceptable para css-global-responsive.css que es simple.
+    private const CRITICAL_BREAKPOINTS = [
+        '@media (max-width: 575.98px)',
+        '@media (min-width: 576px)',
+        '@media (max-width: 767.98px)',
+        '@media (min-width: 768px)',
+        '@media (min-width: 992px)',
+    ];
+
+    public function __construct(
+        private readonly CriticalCSSCacheInterface $cache
+    ) {}
+
+    /**
+     * {@inheritDoc}
+     */
+    public function extractVariables(): string
+    {
+        $sourceFile = get_template_directory() . self::SOURCE_VARIABLES;
+
+        if (!file_exists($sourceFile)) {
+            return '';
+        }
+
+        $css = file_get_contents($sourceFile);
+
+        if ($css === false) {
+            return '';
+        }
+
+        // Para variables, todo el contenido es critico
+        return $this->minify($css);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function extractResponsive(): string
+    {
+        $sourceFile = get_template_directory() . self::SOURCE_RESPONSIVE;
+
+        if (!file_exists($sourceFile)) {
+            return '';
+        }
+
+        $css = file_get_contents($sourceFile);
+
+        if ($css === false) {
+            return '';
+        }
+
+        $criticalCSS = '';
+
+        // Extraer solo media queries criticas
+        // Regex: captura @media (...) { contenido con 1 nivel de {} }
+        foreach (self::CRITICAL_BREAKPOINTS as $breakpoint) {
+            $pattern = '/' . preg_quote($breakpoint, '/') . '\s*\{([^{}]*(?:\{[^{}]*\}[^{}]*)*)\}/s';
+
+            if (preg_match_all($pattern, $css, $matches)) {
+                foreach ($matches[0] as $match) {
+                    $criticalCSS .= $match . "\n";
+                }
+            }
+        }
+
+        return $this->minify($criticalCSS);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function generateAll(): array
+    {
+        $results = [];
+
+        // Variables CSS
+        $variablesCSS = $this->extractVariables();
+        if (!empty($variablesCSS)) {
+            $this->cache->set('variables', $variablesCSS);
+            $results['variables'] = strlen($variablesCSS);
+        }
+
+        // Responsive critico
+        $responsiveCSS = $this->extractResponsive();
+        if (!empty($responsiveCSS)) {
+            $this->cache->set('responsive', $responsiveCSS);
+            $results['responsive'] = strlen($responsiveCSS);
+        }
+
+        return $results;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function needsRegeneration(): bool
+    {
+        $templateDir = get_template_directory();
+
+        return $this->cache->isStale('variables', $templateDir . self::SOURCE_VARIABLES)
+            || $this->cache->isStale('responsive', $templateDir . self::SOURCE_RESPONSIVE);
+    }
+
+    /**
+     * Minifica CSS eliminando espacios y comentarios innecesarios
+     */
+    private function minify(string $css): string
+    {
+        // Eliminar comentarios
+        $css = preg_replace('/\/\*[\s\S]*?\*\//', '', $css) ?? $css;
+
+        // Eliminar espacios innecesarios
+        $css = preg_replace('/\s+/', ' ', $css) ?? $css;
+        $css = preg_replace('/\s*([{};:,>+~])\s*/', '$1', $css) ?? $css;
+
+        // Eliminar ultimo punto y coma antes de }
+        $css = preg_replace('/;}/', '}', $css) ?? $css;
+
+        return trim($css);
+    }
+}
diff --git a/Public/CriticalCSS/Infrastructure/Services/CriticalCSSInjector.php b/Public/CriticalCSS/Infrastructure/Services/CriticalCSSInjector.php
new file mode 100644
index 00000000..72c19cca
--- /dev/null
+++ b/Public/CriticalCSS/Infrastructure/Services/CriticalCSSInjector.php
@@ -0,0 +1,86 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\CriticalCSS\Infrastructure\Services;
+
+use ROITheme\Public\CriticalCSS\Domain\Contracts\CriticalCSSCacheInterface;
+
+/**
+ * Inyecta CSS critico en wp_head
+ *
+ * Prioridades:
+ * - P:-1 Variables CSS (antes de todo)
+ * - P:1  Responsive critico (despues de Bootstrap critico)
+ *
+ * @package ROITheme\Public\CriticalCSS\Infrastructure\Services
+ */
+final class CriticalCSSInjector
+{
+    public function __construct(
+        private readonly CriticalCSSCacheInterface $cache
+    ) {}
+
+    /**
+     * Registra hooks de WordPress
+     */
+    public function register(): void
+    {
+        // Variables CSS: P:-1 (antes de CriticalBootstrapService P:0)
+        add_action('wp_head', [$this, 'injectVariables'], -1);
+
+        // Responsive critico: P:2 (despues de CriticalCSSService P:1)
+        // NOTA: Cambiado de P:1 a P:2 para evitar colision con roi-critical-css
+        add_action('wp_head', [$this, 'injectResponsive'], 2);
+
+        // Deshabilitar enqueue de archivos que ahora son inline
+        add_action('wp_enqueue_scripts', [$this, 'dequeueInlinedCSS'], 999);
+    }
+
+    /**
+     * Inyecta variables CSS criticas
+     */
+    public function injectVariables(): void
+    {
+        $css = $this->cache->get('variables');
+
+        if (empty($css)) {
+            return;
+        }
+
+        printf(
+            '<!-- TIPO 4: Variables CSS criticas -->' . "\n" .
+            '<style id="roi-critical-variables">%s</style>' . "\n",
+            $css
+        );
+    }
+
+    /**
+     * Inyecta media queries criticas
+     */
+    public function injectResponsive(): void
+    {
+        $css = $this->cache->get('responsive');
+
+        if (empty($css)) {
+            return;
+        }
+
+        printf(
+            '<!-- TIPO 4: Responsive critico -->' . "\n" .
+            '<style id="roi-critical-responsive">%s</style>' . "\n",
+            $css
+        );
+    }
+
+    /**
+     * Deshabilita enqueue de archivos que ahora estan inline
+     */
+    public function dequeueInlinedCSS(): void
+    {
+        // Variables ya inline - no cargar archivo externo
+        if ($this->cache->has('variables')) {
+            wp_dequeue_style('roi-variables');
+            wp_deregister_style('roi-variables');
+        }
+    }
+}
diff --git a/Public/CustomCSSManager/Infrastructure/Services/CustomCSSInjector.php b/Public/CustomCSSManager/Infrastructure/Services/CustomCSSInjector.php
index 288935df..cf6da9e6 100644
--- a/Public/CustomCSSManager/Infrastructure/Services/CustomCSSInjector.php
+++ b/Public/CustomCSSManager/Infrastructure/Services/CustomCSSInjector.php
@@ -23,8 +23,9 @@ final class CustomCSSInjector
      */
     public function register(): void
     {
-        // CSS crítico: priority 2 (después de componentes, antes de theme-settings)
-        add_action('wp_head', [$this, 'injectCriticalCSS'], 2);
+        // CSS crítico: priority 3 (después de TIPO 4 responsive P:2, antes de theme-settings P:5)
+        // NOTA: Cambiado de P:2 a P:3 para evitar colision con roi-critical-responsive
+        add_action('wp_head', [$this, 'injectCriticalCSS'], 3);
 
         // CSS diferido: priority alta en footer
         add_action('wp_footer', [$this, 'injectDeferredCSS'], 10);
diff --git a/Public/LazyCSSLoader/Infrastructure/Contracts/LazyCSSRegistrarInterface.php b/Public/LazyCSSLoader/Infrastructure/Contracts/LazyCSSRegistrarInterface.php
new file mode 100644
index 00000000..203c148b
--- /dev/null
+++ b/Public/LazyCSSLoader/Infrastructure/Contracts/LazyCSSRegistrarInterface.php
@@ -0,0 +1,34 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\LazyCSSLoader\Infrastructure\Contracts;
+
+/**
+ * Interface para registrar CSS lazy (TIPO 5)
+ *
+ * Cumple DIP: permite inyeccion de dependencias y testing
+ *
+ * @package ROITheme\Public\LazyCSSLoader\Infrastructure\Contracts
+ */
+interface LazyCSSRegistrarInterface
+{
+    /**
+     * Registra hooks de WordPress para lazy loading
+     */
+    public function register(): void;
+
+    /**
+     * Remueve CSS que ahora es TIPO 5 del enqueue normal
+     */
+    public function dequeueType5CSS(): void;
+
+    /**
+     * Encola el loader JavaScript con configuracion
+     */
+    public function enqueueLoader(): void;
+
+    /**
+     * Agrega fallback noscript para accesibilidad
+     */
+    public function addNoscriptFallback(): void;
+}
diff --git a/Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php b/Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php
new file mode 100644
index 00000000..dd85d7b8
--- /dev/null
+++ b/Public/LazyCSSLoader/Infrastructure/Services/LazyCSSRegistrar.php
@@ -0,0 +1,124 @@
+<?php
+declare(strict_types=1);
+
+namespace ROITheme\Public\LazyCSSLoader\Infrastructure\Services;
+
+use ROITheme\Public\LazyCSSLoader\Infrastructure\Contracts\LazyCSSRegistrarInterface;
+
+/**
+ * Registra CSS para carga lazy (TIPO 5)
+ *
+ * Separa CSS de TIPO 2 (diferido inmediato) vs TIPO 5 (lazy loading)
+ *
+ * CSS incluidos en TIPO 5:
+ * - Animaciones: requestIdleCallback (2s timeout)
+ * - Print: beforeprint event
+ *
+ * @package ROITheme\Public\LazyCSSLoader\Infrastructure\Services
+ */
+final class LazyCSSRegistrar implements LazyCSSRegistrarInterface
+{
+    /**
+     * CSS que se mueve de TIPO 2 a TIPO 5
+     *
+     * @var array<int, array{id: string, path: string, trigger: string, handle: string}>
+     */
+    private const LAZY_CSS_FILES = [
+        [
+            'id' => 'animations',
+            'path' => '/Assets/Css/css-global-animations.css',
+            'trigger' => 'idle',
+            'handle' => 'roi-animations',
+        ],
+        [
+            'id' => 'print',
+            'path' => '/Assets/Css/css-global-print.css',
+            'trigger' => 'print',
+            'handle' => 'roi-print',
+        ],
+    ];
+
+    /**
+     * Timeout en ms para requestIdleCallback
+     */
+    private const IDLE_TIMEOUT = 2000;
+
+    /**
+     * Registra hooks de WordPress
+     */
+    public function register(): void
+    {
+        // Dequeue CSS que ahora es TIPO 5
+        add_action('wp_enqueue_scripts', [$this, 'dequeueType5CSS'], 999);
+
+        // Agregar script loader y configuracion
+        add_action('wp_enqueue_scripts', [$this, 'enqueueLoader'], 20);
+
+        // Agregar fallback noscript
+        add_action('wp_head', [$this, 'addNoscriptFallback'], 99);
+    }
+
+    /**
+     * Remueve CSS que ahora es TIPO 5 del enqueue normal
+     */
+    public function dequeueType5CSS(): void
+    {
+        foreach (self::LAZY_CSS_FILES as $file) {
+            wp_dequeue_style($file['handle']);
+            wp_deregister_style($file['handle']);
+        }
+    }
+
+    /**
+     * Encola el loader JavaScript con configuracion
+     */
+    public function enqueueLoader(): void
+    {
+        $loaderPath = get_template_directory() . '/Assets/Js/lazy-css-loader.js';
+
+        // Solo encolar si el archivo existe
+        if (!file_exists($loaderPath)) {
+            if (defined('WP_DEBUG') && WP_DEBUG) {
+                error_log('ROI Theme TIPO 5: lazy-css-loader.js not found');
+            }
+            return;
+        }
+
+        wp_enqueue_script(
+            'roi-lazy-css-loader',
+            get_template_directory_uri() . '/Assets/Js/lazy-css-loader.js',
+            [],
+            ROI_VERSION,
+            true // En footer
+        );
+
+        // Pasar configuracion al JS
+        wp_localize_script('roi-lazy-css-loader', 'roiLazyCSSConfig', [
+            'baseUrl' => get_template_directory_uri(),
+            'version' => ROI_VERSION,
+            'idleTimeout' => self::IDLE_TIMEOUT,
+            'cssFiles' => self::LAZY_CSS_FILES,
+        ]);
+    }
+
+    /**
+     * Agrega fallback noscript para accesibilidad
+     */
+    public function addNoscriptFallback(): void
+    {
+        echo '<noscript>' . "\n";
+
+        foreach (self::LAZY_CSS_FILES as $file) {
+            $href = esc_url(get_template_directory_uri() . $file['path'] . '?ver=' . ROI_VERSION);
+            $media = $file['trigger'] === 'print' ? 'print' : 'all';
+
+            printf(
+                '<link rel="stylesheet" href="%s" media="%s">' . "\n",
+                $href,
+                $media
+            );
+        }
+
+        echo '</noscript>' . "\n";
+    }
+}
diff --git a/bin/generate-critical-css.php b/bin/generate-critical-css.php
new file mode 100644
index 00000000..a27e372b
--- /dev/null
+++ b/bin/generate-critical-css.php
@@ -0,0 +1,73 @@
+<?php
+/**
+ * WP-CLI Command para generar CSS critico TIPO 4
+ *
+ * Uso:
+ *   wp roi-theme generate-critical-css
+ *   wp roi-theme generate-critical-css --clear
+ *
+ * @package ROITheme
+ */
+
+if (!defined('WP_CLI')) {
+    return;
+}
+
+use ROITheme\Public\CriticalCSS\Infrastructure\Cache\CriticalCSSFileCache;
+use ROITheme\Public\CriticalCSS\Infrastructure\Services\CriticalCSSExtractor;
+use ROITheme\Public\CriticalCSS\Application\UseCases\GetCriticalCSSUseCase;
+
+/**
+ * Comandos para gestionar CSS critico TIPO 4
+ */
+class ROI_CriticalCSS_Command
+{
+    /**
+     * Genera CSS critico para todas las paginas
+     *
+     * ## OPTIONS
+     *
+     * [--clear]
+     * : Limpia cache antes de regenerar
+     *
+     * ## EXAMPLES
+     *
+     *     wp roi-theme generate-critical-css
+     *     wp roi-theme generate-critical-css --clear
+     *
+     * @when after_wp_load
+     */
+    public function __invoke($args, $assoc_args)
+    {
+        $cache = new CriticalCSSFileCache();
+        $extractor = new CriticalCSSExtractor($cache);
+        $useCase = new GetCriticalCSSUseCase($cache, $extractor);
+
+        // Limpiar cache si se solicita
+        if (isset($assoc_args['clear'])) {
+            $cache->clear();
+            WP_CLI::log('Cache limpiado.');
+        }
+
+        WP_CLI::log('Generando CSS critico TIPO 4...');
+
+        $results = $useCase->regenerate();
+
+        if (empty($results)) {
+            WP_CLI::warning('No se genero CSS critico. Verifica que existan los archivos fuente.');
+            return;
+        }
+
+        foreach ($results as $type => $size) {
+            WP_CLI::success(sprintf(
+                '%s.critical.css: %s bytes',
+                $type,
+                number_format($size)
+            ));
+        }
+
+        WP_CLI::success('CSS critico TIPO 4 generado exitosamente.');
+    }
+}
+
+WP_CLI::add_command('roi-theme generate-critical-css', 'ROI_CriticalCSS_Command');
diff --git a/functions.php b/functions.php
index 64f2a59f..ab25190e 100644
--- a/functions.php
+++ b/functions.php
@@ -338,6 +338,64 @@ if (defined('WP_DEBUG') && WP_DEBUG) {
     error_log('ROI Theme: Bootstrap completed successfully');
 }
 
+// =============================================================================
+// 5.4. CRITICAL CSS TIPO 4 (CSS Below-the-fold)
+// =============================================================================
+
+/**
+ * Bootstrap CriticalCSS TIPO 4
+ *
+ * Inyecta CSS critico (variables, responsive) inline en wp_head
+ * antes de cualquier otro CSS para evitar FOUC.
+ *
+ * Incluye auto-regeneracion: si los archivos fuente cambian,
+ * el cache se regenera automaticamente sin intervencion manual.
+ * Costo: ~0.1ms (2 llamadas a filemtime())
+ */
+if (!is_admin()) {
+    $criticalCSSCache = new \ROITheme\Public\CriticalCSS\Infrastructure\Cache\CriticalCSSFileCache();
+    $criticalCSSExtractor = new \ROITheme\Public\CriticalCSS\Infrastructure\Services\CriticalCSSExtractor(
+        $criticalCSSCache
+    );
+
+    // Auto-regenerar si archivos fuente cambiaron
+    if ($criticalCSSExtractor->needsRegeneration()) {
+        $criticalCSSExtractor->generateAll();
+    }
+
+    $criticalCSSInjector = new \ROITheme\Public\CriticalCSS\Infrastructure\Services\CriticalCSSInjector(
+        $criticalCSSCache
+    );
+    $criticalCSSInjector->register();
+}
+
+// Registrar comando WP-CLI (util para forzar regeneracion o limpiar cache)
+if (defined('WP_CLI') && WP_CLI) {
+    require_once get_template_directory() . '/bin/generate-critical-css.php';
+}
+
+// =============================================================================
+// 5.5. LAZY CSS LOADER TIPO 5 (CSS No Critico)
+// =============================================================================
+
+/**
+ * Bootstrap LazyCSSLoader TIPO 5
+ *
+ * Carga CSS no critico de forma lazy:
+ * - Animaciones: requestIdleCallback o timeout 2s
+ * - Print: solo cuando usuario va a imprimir (beforeprint event)
+ *
+ * @since 1.0.20
+ */
+if (!is_admin()) {
+    $lazyCSSRegistrar = new \ROITheme\Public\LazyCSSLoader\Infrastructure\Services\LazyCSSRegistrar();
+    $lazyCSSRegistrar->register();
+
+    if (defined('WP_DEBUG') && WP_DEBUG) {
+        error_log('ROI Theme: TIPO 5 LazyCSSLoader registered');
+    }
+}
+
 // =============================================================================
 // 6. INSTALACIÓN DE TABLAS DEL TEMA
 // =============================================================================