diff --git a/.env.example b/.env.example
index 9a50945..7cdfeed 100644
--- a/.env.example
+++ b/.env.example
@@ -2,6 +2,7 @@
 SECRET_KEY=django-insecure-change-me
 DEBUG=True
 ALLOWED_HOSTS=localhost,127.0.0.1
+S3_ENABLE=False
 
 # PostgreSQL (por defecto habilitado; si POSTGRES_ENABLED=False se usa SQLite)
 POSTGRES_ENABLED=True
@@ -14,6 +15,17 @@ POSTGRES_PORT=5432
 # Redis
 REDIS_URL=redis://127.0.0.1:6379/1
 
+# S3 (activar con S3_ENABLE=True)
+AWS_STORAGE_BUCKET_NAME=
+AWS_ACCESS_KEY_ID=
+AWS_SECRET_ACCESS_KEY=
+AWS_S3_REGION_NAME=
+AWS_S3_ENDPOINT_URL=
+AWS_S3_CUSTOM_DOMAIN=
+AWS_S3_USE_SSL=True
+AWS_QUERYSTRING_AUTH=False
+AWS_DEFAULT_ACL=public-read
+
 # Stripe
 STRIPE_PUBLISHABLE_KEY=
 STRIPE_SECRET_KEY=
diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
index b3470d7..b9cdc65 100644
--- a/.github/copilot-instructions.md
+++ b/.github/copilot-instructions.md
@@ -35,6 +35,7 @@ Templates use Django's inheritance pattern:
 - **Image uploads**: Organized in `tienda/static/media/images/` via `upload_to='images/'` in ImageField
 - **Access**: Media files served automatically in development via Django's static file handler
 - **Image model**: Located in [tienda/models.py](tienda/models.py) with `ImageField(upload_to='images/')`
+- **S3 mode**: if `S3_ENABLE=True` (case-insensitive), static and media switch to S3 storages instead of the local filesystem; Nginx should proxy the app only and the browser should load asset URLs from the bucket or CDN
 
 ## Shipping Restrictions
 - **Zona de envío**: Solo se vende/envía dentro de la provincia de Almería
diff --git a/.github/workflows/opencode.yml b/.github/workflows/opencode.yml
new file mode 100644
index 0000000..515af89
--- /dev/null
+++ b/.github/workflows/opencode.yml
@@ -0,0 +1,33 @@
+name: opencode
+
+on:
+  issue_comment:
+    types: [created]
+  pull_request_review_comment:
+    types: [created]
+
+jobs:
+  opencode:
+    if: |
+      contains(github.event.comment.body, ' /oc') ||
+      startsWith(github.event.comment.body, '/oc') ||
+      contains(github.event.comment.body, ' /opencode') ||
+      startsWith(github.event.comment.body, '/opencode')
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
+      pull-requests: read
+      issues: read
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Run opencode
+        uses: anomalyco/opencode/github@latest
+        env:
+          OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}
+        with:
+          model: openai/gpt-5.3-codex
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index afb4ca3..1fe2ba1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ __pycache__/
 *.pyc
 tienda/__pycache__/
 proyecto/__pycache__/
+media
\ No newline at end of file
diff --git a/nginx.conf b/nginx.conf
index a2a3e58..7e100bf 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -34,7 +34,9 @@ http {
         listen 80;
         server_name _;
 
-        # Archivos estáticos generados por collectstatic.
+        # Modo local: sirve static/media desde volúmenes montados.
+        # Si S3_ENABLE=True, estos bloques no se usan y el navegador debe
+        # cargar los assets directamente desde el bucket o CDN.
         location /static/ {
             alias /static/;
             expires 30d;
@@ -42,7 +44,7 @@ http {
             access_log off;
         }
 
-        # Archivos subidos por usuarios.
+        # Archivos subidos por usuarios en modo local.
         location /media/ {
             alias /media/;
             expires 7d;
diff --git a/proyecto/settings.py b/proyecto/settings.py
index 2732df4..6e66468 100644
--- a/proyecto/settings.py
+++ b/proyecto/settings.py
@@ -53,6 +53,21 @@ def env_int(name: str, default: int) -> int:
         return default
     return int(value)
 
+
+def env_str(name: str, default: str = '') -> str:
+    value = os.getenv(name)
+    if value is None:
+        return default
+    return value.strip()
+
+
+def env_optional_str(name: str) -> str | None:
+    value = os.getenv(name)
+    if value is None:
+        return None
+    value = value.strip()
+    return value or None
+
 # Build paths inside the project like this: BASE_DIR / 'subdir'.
 BASE_DIR = Path(__file__).resolve().parent.parent
 load_dotenv(BASE_DIR / '.env')
@@ -66,6 +81,8 @@ SECRET_KEY = os.getenv('SECRET_KEY', 'django-insecure-#g((q@lvnkt(j6)2(gvtn0px)r
 
 # SECURITY WARNING: don't run with debug turned on in production!
 DEBUG = env_bool('DEBUG', True)
+S3_ENABLE = env_bool('S3_ENABLE', False)
+S3_USE_LOCAL_URLS = env_bool('S3_USE_LOCAL_URLS', False)
 
 ALLOWED_HOSTS = env_list('ALLOWED_HOSTS', [
     '192.168.1.142',
@@ -87,9 +104,11 @@ INSTALLED_APPS = [
     'compressor',
 ]
 
+if S3_ENABLE:
+    INSTALLED_APPS.append('storages')
+
 MIDDLEWARE = [
     'django.middleware.security.SecurityMiddleware',
-    'whitenoise.middleware.WhiteNoiseMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',
@@ -98,6 +117,9 @@ MIDDLEWARE = [
     'django.middleware.clickjacking.XFrameOptionsMiddleware',
 ]
 
+if not S3_ENABLE:
+    MIDDLEWARE.insert(1, 'whitenoise.middleware.WhiteNoiseMiddleware')
+
 ROOT_URLCONF = 'proyecto.urls'
 
 TEMPLATES = [
@@ -211,6 +233,27 @@ STORAGES = {
     },
 }
 
+if S3_ENABLE:
+    AWS_STORAGE_BUCKET_NAME = env_str('AWS_STORAGE_BUCKET_NAME') or None
+    AWS_ACCESS_KEY_ID = env_optional_str('AWS_ACCESS_KEY_ID')
+    AWS_SECRET_ACCESS_KEY = env_optional_str('AWS_SECRET_ACCESS_KEY')
+    AWS_S3_REGION_NAME = env_optional_str('AWS_S3_REGION_NAME')
+    AWS_S3_ENDPOINT_URL = env_optional_str('AWS_S3_ENDPOINT_URL')
+    AWS_S3_CUSTOM_DOMAIN = env_optional_str('AWS_S3_CUSTOM_DOMAIN')
+    AWS_S3_USE_SSL = env_bool('AWS_S3_USE_SSL', True)
+    AWS_QUERYSTRING_AUTH = env_bool('AWS_QUERYSTRING_AUTH', False)
+    AWS_DEFAULT_ACL = env_str('AWS_DEFAULT_ACL', 'public-read') or None
+    AWS_S3_OBJECT_PARAMETERS = {}
+
+    STORAGES = {
+        'default': {
+            'BACKEND': 'tienda.storage_backends.MediaStorage',
+        },
+        'staticfiles': {
+            'BACKEND': 'tienda.storage_backends.StaticStorage',
+        },
+    }
+
 STATICFILES_FINDERS = [
     'django.contrib.staticfiles.finders.FileSystemFinder',
     'django.contrib.staticfiles.finders.AppDirectoriesFinder',
@@ -384,6 +427,4 @@ CELERY_RESULT_SERIALIZER = 'json'
 SECURE_PROXY_SSL_HEADER = ("HTTP_X_FORWARDED_PROTO", "https")
 
 USE_X_FORWARDED_HOST = True
-SECURE_REFERER_POLICY = "strict-origin-when-cross-origin"
-
-print(f"DEBUG: ALLOWED_HOSTS is {ALLOWED_HOSTS}")
\ No newline at end of file
+SECURE_REFERER_POLICY = "strict-origin-when-cross-origin"
\ No newline at end of file
diff --git a/proyecto/urls.py b/proyecto/urls.py
index ca32905..d7813f5 100644
--- a/proyecto/urls.py
+++ b/proyecto/urls.py
@@ -26,5 +26,7 @@ urlpatterns = [
     path('tienda/', include('tienda.urls'))
 ]
 
-if settings.DEBUG:
+if settings.DEBUG and (
+    not settings.S3_ENABLE or getattr(settings, 'S3_USE_LOCAL_URLS', False)
+):
     urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
diff --git a/requirements.txt b/requirements.txt
index 4b6da18..b1b1161 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -14,6 +14,7 @@ Django==6.0.4
 django-appconf==1.2.0
 django-redis==5.4.0
 django_compressor==4.6.0
+django-storages[boto3]==1.14.6
 gunicorn==25.1.0
 idna==3.11
 Jinja2==3.1.6
@@ -22,6 +23,7 @@ MarkupSafe==3.0.3
 packaging==26.0
 paypalrestsdk==1.13.3
 pillow==12.2.0
+boto3==1.42.97
 prompt_toolkit==3.0.52
 pycparser==3.0
 pyOpenSSL==26.0.0
diff --git a/tienda/models.py b/tienda/models.py
index 56d986e..f15a28f 100644
--- a/tienda/models.py
+++ b/tienda/models.py
@@ -25,6 +25,11 @@ class User(AbstractUser):
         choices = RegisterStatus.choices,
         default = RegisterStatus.CONFIRMATION_REQUIRED
     )
+    def to_dict(self):
+        return {
+            "username": self.username,
+            "fullname": self.get_full_name()
+        }
 
 class VerificationCode(models.Model):
     class VerificationModes(models.TextChoices):
@@ -41,7 +46,7 @@ class VerificationCode(models.Model):
     
     def generate(user: User, code_mode: str) -> VerificationCode:
         while True:
-            code = "".join(random.choices(string.ascii_letters+string.digits+string.punctuation))
+            code = "".join(random.choices(string.ascii_letters+string.digits, k=64))
             if not VerificationCode.objects.filter(code=code).exists():
                 return VerificationCode.objects.create(
                     code = code,
@@ -55,6 +60,11 @@ class Category(models.Model):
 
     def __str__(self):
         return self.name
+    
+    def to_dict(self):
+        return {
+            "name": self.name
+        }
 
 class Image(models.Model):
     name = models.CharField(max_length=200, default="")
@@ -63,6 +73,13 @@ class Image(models.Model):
 
     def __str__(self):
         return self.name
+    
+    def to_dict(self):
+        return {
+            "name": self.name,
+            "image": self.image.url,
+            "alt": self.alt
+        }
 
 class Product(models.Model):
     name = models.CharField(max_length=200, default="")
@@ -85,6 +102,19 @@ class Product(models.Model):
     def get_vat_amount(self):
         """Retorna la cantidad de IVA"""
         return round(self.price * VAT_RATE, 2)
+    
+    def to_dict(self):
+        return {
+            "name": self.name,
+            "description": self.description,
+            "briefdesc": self.briefdesc,
+            "price": self.price,
+            "stock": self.stock,
+            "category": self.category.to_dict(),
+            "primary_image": self.primary_image.to_dict() if self.primary_image else None,
+            "secondary_images": [secondary_image.to_dict() for secondary_image in self.secondary_images.all()],
+            "creator": self.creator.to_dict() if self.creator else None
+        }
 
 
 class StockReservation(models.Model):
diff --git a/tienda/static/css/custom.css b/tienda/static/css/custom.css
index 5a77645..56a7bce 100644
--- a/tienda/static/css/custom.css
+++ b/tienda/static/css/custom.css
@@ -1,3 +1,28 @@
+.skip-link {
+  position: fixed;
+  top: -100%;
+  left: 50%;
+  transform: translateX(-50%);
+  background: #fff;
+  color: #513CB0;
+  padding: 8px 24px;
+  font-weight: 700;
+  font-size: 0.9rem;
+  z-index: 10001;
+  text-decoration: none;
+  border-radius: 0 0 8px 8px;
+  border: 2px solid #513CB0;
+  border-top: none;
+  box-shadow: 0 4px 12px rgba(81, 60, 176, 0.25);
+  transition: top 0.2s ease;
+  outline: none;
+  white-space: nowrap;
+}
+.skip-link:focus,
+.skip-link:focus-visible {
+  top: 0;
+}
+
 @media (min-width: 1250px) {
   .grid {
     display: grid;
@@ -63,8 +88,9 @@ p.price {
 .navbar.header .site-title-mobile {
   color: #FFF;
   position: absolute;
+  top: calc(var(--bs-navbar-padding-y) + 20px);
   left: 50%;
-  transform: translateX(-50%);
+  transform: translate(-50%, -50%);
   margin: 0;
   max-width: calc(100% - 9rem);
   overflow: hidden;
diff --git a/tienda/storage_backends.py b/tienda/storage_backends.py
new file mode 100644
index 0000000..bad7897
--- /dev/null
+++ b/tienda/storage_backends.py
@@ -0,0 +1,44 @@
+from __future__ import annotations
+
+import os
+
+from django.utils.encoding import iri_to_uri
+from storages.backends.s3 import S3Storage
+
+
+def _use_local_asset_urls() -> bool:
+    return os.getenv('S3_USE_LOCAL_URLS', '').strip().lower() in {'1', 'true', 'yes', 'on'}
+
+
+def _local_asset_url(prefix: str, name: str) -> str:
+    return iri_to_uri(f'/{prefix}/{name.lstrip("/")}')
+
+
+class StaticStorage(S3Storage):
+    location = 'static'
+    default_acl = 'public-read'
+    querystring_auth = False
+    file_overwrite = True
+    object_parameters = {
+        'CacheControl': 'public, max-age=31536000, immutable',
+    }
+
+    def url(self, name: str) -> str:
+        if _use_local_asset_urls():
+            return _local_asset_url('static', name)
+        return super().url(name)
+
+
+class MediaStorage(S3Storage):
+    location = 'media'
+    default_acl = 'public-read'
+    querystring_auth = False
+    file_overwrite = False
+    object_parameters = {
+        'CacheControl': 'public, max-age=604800',
+    }
+
+    def url(self, name: str) -> str:
+        if _use_local_asset_urls():
+            return _local_asset_url('media', name)
+        return super().url(name)
\ No newline at end of file
diff --git a/tienda/templates/tienda/base.html b/tienda/templates/tienda/base.html
index f4d6708..8cc1491 100644
--- a/tienda/templates/tienda/base.html
+++ b/tienda/templates/tienda/base.html
@@ -50,8 +50,11 @@
             transition: background-color 0.2s;
         }
         
-        .search-suggestion-item:hover {
+        .search-suggestion-item:hover,
+        .search-suggestion-item.active {
             background-color: #f8f9fa;
+            outline: 2px solid #0d6efd;
+            outline-offset: -2px;
         }
         
         .search-suggestion-item:last-child {
@@ -78,6 +81,7 @@
     {% block head %}{% endblock %}
 </head>
 <body class="d-flex flex-column min-vh-100">
+    <a href="#main-content" class="skip-link">Saltar al contenido</a>
     {% cache 500 sidebar request.user.username %}
     <nav class="navbar navbar-expand-md header" role="banner">
         <div class="container-fluid">
@@ -107,10 +111,10 @@
                 <!-- Barra de búsqueda con sugerencias -->
                 <form class="search-suggestions-container" method="GET" action="{% url 'search' %}" role="search" id="searchForm">
                     <div class="input-group">
-                        <input class="form-control" type="search" name="q" id="searchInput" placeholder="Buscar productos..." aria-label="Buscar" autocomplete="off">
-                        <button class="btn btn-outline-primary" type="submit">🔍</button>
+                        <input class="form-control" type="search" name="q" id="searchInput" placeholder="Buscar productos..." aria-label="Buscar" autocomplete="off" role="combobox" aria-expanded="false" aria-autocomplete="list" aria-controls="searchSuggestions" aria-activedescendant="" aria-haspopup="listbox">
+                        <button class="btn btn-outline-primary" type="submit" aria-label="Buscar productos">🔍 Buscar</button>
                     </div>
-                    <div class="search-suggestions" id="searchSuggestions"></div>
+                    <div class="search-suggestions" id="searchSuggestions" role="listbox" aria-label="Sugerencias de búsqueda"></div>
                 </form>
                 
                 <div class="navbar-nav ms-auto d-flex align-items-md-center gap-2 flex-wrap" role="navigation">
@@ -137,7 +141,7 @@
     </nav>
     {% endcache %}
 
-    <div class="container-fluid flex-grow-1 d-flex flex-column" role="main">
+    <div id="main-content" class="container-fluid flex-grow-1 d-flex flex-column" role="main">
         <!-- Mensajes -->
         {% if messages %}
         <div class="row mt-3">
@@ -201,6 +205,35 @@
         const searchSuggestions = document.getElementById('searchSuggestions');
         const searchForm = document.getElementById('searchForm');
         let searchTimeout;
+        let currentFocusIndex = -1;
+
+        // Helpers para gestionar el estado ARIA del combobox
+        function openSuggestions() {
+            searchSuggestions.classList.add('show');
+            searchInput.setAttribute('aria-expanded', 'true');
+        }
+
+        function closeSuggestions() {
+            searchSuggestions.classList.remove('show');
+            searchInput.setAttribute('aria-expanded', 'false');
+            searchInput.setAttribute('aria-activedescendant', '');
+            currentFocusIndex = -1;
+        }
+
+        function updateFocus(options) {
+            options.forEach((option, index) => {
+                const active = index === currentFocusIndex;
+                option.classList.toggle('active', active);
+                option.setAttribute('aria-selected', active ? 'true' : 'false');
+            });
+            if (currentFocusIndex >= 0) {
+                const activeOption = options[currentFocusIndex];
+                searchInput.setAttribute('aria-activedescendant', activeOption.id);
+                activeOption.scrollIntoView({ block: 'nearest' });
+            } else {
+                searchInput.setAttribute('aria-activedescendant', '');
+            }
+        }
 
         // Escuchar cambios en el input
         searchInput.addEventListener('input', function() {
@@ -208,7 +241,7 @@
             const query = this.value.trim();
 
             if (query.length < 2) {
-                searchSuggestions.classList.remove('show');
+                closeSuggestions();
                 return;
             }
 
@@ -218,6 +251,31 @@
             }, 300);
         });
 
+        // Navegación por teclado (ArrowDown/ArrowUp/Enter/Escape)
+        searchInput.addEventListener('keydown', function(event) {
+            const options = searchSuggestions.querySelectorAll('[role="option"]');
+            if (!options.length || !searchSuggestions.classList.contains('show')) {
+                return;
+            }
+
+            if (event.key === 'ArrowDown') {
+                event.preventDefault();
+                currentFocusIndex = Math.min(currentFocusIndex + 1, options.length - 1);
+                updateFocus(options);
+            } else if (event.key === 'ArrowUp') {
+                event.preventDefault();
+                currentFocusIndex = Math.max(currentFocusIndex - 1, -1);
+                updateFocus(options);
+            } else if (event.key === 'Enter' && currentFocusIndex >= 0) {
+                event.preventDefault();
+                const selected = options[currentFocusIndex];
+                window.location.href = selected.dataset.href;
+            } else if (event.key === 'Escape') {
+                closeSuggestions();
+                searchInput.focus();
+            }
+        });
+
         // Función para obtener sugerencias del servidor
         function fetchSuggestions(query) {
             fetch(`{% url 'search_suggestions' %}?q=${encodeURIComponent(query)}`)
@@ -227,33 +285,37 @@
                 })
                 .catch(error => {
                     console.error('Error fetching suggestions:', error);
-                    searchSuggestions.classList.remove('show');
+                    closeSuggestions();
                 });
         }
 
         // Función para mostrar las sugerencias
         function displaySuggestions(suggestions, query) {
+            currentFocusIndex = -1;
             if (suggestions.length === 0) {
                 searchSuggestions.innerHTML = '<div class="search-suggestion-item text-muted">No se encontraron productos</div>';
-                searchSuggestions.classList.add('show');
+                openSuggestions();
                 return;
             }
 
             let html = '';
-            suggestions.forEach(suggestion => {
+            suggestions.forEach((suggestion, index) => {
                 // Resaltar la coincidencia en el nombre
                 const highlightedName = highlightMatch(suggestion.name, query);
                 const priceWithVAT = (suggestion.price * 1.21).toFixed(2);
                 html += `
-                    <a href="/tienda/producto/${suggestion.id}" class="search-suggestion-item text-decoration-none">
+                    <div class="search-suggestion-item" role="option" id="search-option-${index}"
+                         aria-selected="false" tabindex="-1"
+                         data-href="/tienda/producto/${suggestion.id}"
+                         onclick="window.location.href=this.dataset.href">
                         <span class="suggestion-name">${highlightedName}</span>
                         <span class="suggestion-price">€${priceWithVAT}</span>
-                    </a>
+                    </div>
                 `;
             });
 
             searchSuggestions.innerHTML = html;
-            searchSuggestions.classList.add('show');
+            openSuggestions();
         }
 
         // Función para resaltar el texto que coincide
@@ -265,19 +327,19 @@
         // Cerrar sugerencias cuando se hace clic fuera
         document.addEventListener('click', function(event) {
             if (!searchForm.contains(event.target)) {
-                searchSuggestions.classList.remove('show');
+                closeSuggestions();
             }
         });
 
         // Cerrar sugerencias al enviar el formulario
         searchForm.addEventListener('submit', function() {
-            searchSuggestions.classList.remove('show');
+            closeSuggestions();
         });
 
         // Mostrar sugerencias al hacer clic en el input (si hay texto)
         searchInput.addEventListener('focus', function() {
             if (this.value.trim().length >= 2 && searchSuggestions.innerHTML) {
-                searchSuggestions.classList.add('show');
+                openSuggestions();
             }
         });
     </script>
diff --git a/tienda/templates/tienda/cart.html b/tienda/templates/tienda/cart.html
index bcde235..5f2bd7b 100644
--- a/tienda/templates/tienda/cart.html
+++ b/tienda/templates/tienda/cart.html
@@ -51,7 +51,7 @@
               <td>
                 <form method="post" action="{% url 'update_cart_item' item.id %}" class="d-flex align-items-center" style="max-width: 150px;">
                   {% csrf_token %}
-                  <input type="number" name="quantity" value="{{ item.quantity }}" min="1" max="{{ item.product.stock }}" class="form-control form-control-sm me-2" style="width: 70px;">
+                  <input type="number" name="quantity" value="{{ item.quantity }}" min="1" max="{{ item.product.stock }}" class="form-control form-control-sm me-2" style="width: 70px;" aria-label="Cantidad para {{ item.product.name }}">
                   <button type="submit" class="btn btn-sm btn-primary">Actualizar</button>
                 </form>
               </td>
@@ -59,7 +59,7 @@
                 {% if item.product.stock > 0 %}
                 {{ item.product.stock }}
                 {% else %}
-                <span class="text-danger">0</span>
+                <span class="text-danger" role="status"><span aria-hidden="true">✗</span> Sin stock</span>
                 {% endif %}
               </td>
               <td class="price">{{ item.get_subtotal_with_vat|format_price }} €</td>
@@ -89,7 +89,7 @@
         </div>
         <div class="d-flex justify-content-between mb-2">
           <span>IVA (21%)</span>
-          <span class="price text-success">{{ cart.get_vat_amount|format_price }} €</span>
+          <span class="price text-success"><span aria-hidden="true">ℹ️</span> {{ cart.get_vat_amount|format_price }} €</span>
         </div>
         <div class="d-flex justify-content-between mb-2">
           <span>Envío</span>
diff --git a/tienda/templates/tienda/checkout.html b/tienda/templates/tienda/checkout.html
index 1b88ee9..b1135e5 100644
--- a/tienda/templates/tienda/checkout.html
+++ b/tienda/templates/tienda/checkout.html
@@ -127,22 +127,25 @@
                 <!-- Tabs -->
                 <ul class="nav nav-tabs mb-3" id="paymentTabs" role="tablist">
                     <li class="nav-item" role="presentation">
-                        <button class="nav-link active" id="tab-card" data-tab="pane-card" type="button" role="tab">
+                        <button class="nav-link active" id="tab-card" data-tab="pane-card" type="button"
+                                role="tab" aria-selected="true" aria-controls="pane-card" tabindex="0">
                             💳 Tarjeta
                         </button>
                     </li>
                     <li class="nav-item" role="presentation">
-                        <button class="nav-link" id="tab-paypal" data-tab="pane-paypal" type="button" role="tab">
+                        <button class="nav-link" id="tab-paypal" data-tab="pane-paypal" type="button"
+                                role="tab" aria-selected="false" aria-controls="pane-paypal" tabindex="-1">
                             🅿️ PayPal
                         </button>
                     </li>
                 </ul>
 
                 <!-- Tarjeta tab -->
-                <div id="pane-card" class="payment-tab-content active">
+                <div id="pane-card" class="payment-tab-content active"
+                     role="tabpanel" aria-labelledby="tab-card" tabindex="0">
                     {% if saved_cards %}
-                    <div class="mb-3">
-                        <p class="fw-semibold">Tarjetas guardadas:</p>
+                    <fieldset class="mb-3">
+                        <legend class="fw-semibold fs-6 mb-2">Selección de tarjeta</legend>
                         {% for card in saved_cards %}
                         <div class="form-check mb-2">
                             <input class="form-check-input" type="radio" name="saved_card_choice" id="card-{{ card.id }}" value="{{ card.id }}" data-pm-id="{{ card.stripe_payment_method_id }}" {% if card.is_default %}checked{% endif %}>
@@ -156,7 +159,7 @@
                             <input class="form-check-input" type="radio" name="saved_card_choice" id="card-new" value="new">
                             <label class="form-check-label" for="card-new">Usar nueva tarjeta</label>
                         </div>
-                    </div>
+                    </fieldset>
                     {% endif %}
 
                     <div id="new-card-section" {% if saved_cards %}style="display:none;"{% endif %}>
@@ -183,7 +186,8 @@
                 </div>
 
                 <!-- PayPal tab -->
-                <div id="pane-paypal" class="payment-tab-content">
+                <div id="pane-paypal" class="payment-tab-content"
+                     role="tabpanel" aria-labelledby="tab-paypal" tabindex="0">
                     {% if saved_paypal %}
                     <div class="alert alert-light border mb-3">
                         <small class="text-muted">Cuenta PayPal guardada:</small>
@@ -196,6 +200,7 @@
                             Guardar esta cuenta de PayPal para futuras compras
                         </label>
                     </div>
+                    <div id="paypal-errors" class="alert alert-danger d-none mt-2" role="alert"></div>
                     <div id="paypal-button-container"></div>
                     {% if not addresses or stock_issues %}
                     <div class="alert alert-warning mt-2">Selecciona una dirección de envío válida para activar el pago.</div>
@@ -221,12 +226,42 @@ const HAS_STOCK_ISSUES = {{ stock_issues|yesno:"true,false" }};
 const HAS_ADDRESS = {{ addresses|yesno:"true,false" }};
 
 // ---- Tab switching ----
-document.querySelectorAll('#paymentTabs .nav-link').forEach(btn => {
-    btn.addEventListener('click', () => {
-        document.querySelectorAll('#paymentTabs .nav-link').forEach(b => b.classList.remove('active'));
-        document.querySelectorAll('.payment-tab-content').forEach(p => p.classList.remove('active'));
-        btn.classList.add('active');
-        document.getElementById(btn.dataset.tab).classList.add('active');
+const paymentTabs = Array.from(document.querySelectorAll('#paymentTabs .nav-link[role="tab"]'));
+
+function activateTab(tab) {
+    paymentTabs.forEach(b => {
+        const isSelected = b === tab;
+        b.classList.toggle('active', isSelected);
+        b.setAttribute('aria-selected', isSelected ? 'true' : 'false');
+        b.setAttribute('tabindex', isSelected ? '0' : '-1');
+    });
+    document.querySelectorAll('.payment-tab-content').forEach(p => p.classList.remove('active'));
+    document.getElementById(tab.dataset.tab).classList.add('active');
+}
+
+paymentTabs.forEach(btn => {
+    btn.addEventListener('click', () => activateTab(btn));
+    btn.addEventListener('keydown', e => {
+        const idx = paymentTabs.indexOf(e.currentTarget);
+        if (e.key === 'ArrowRight') {
+            e.preventDefault();
+            const next = paymentTabs[(idx + 1) % paymentTabs.length];
+            activateTab(next);
+            next.focus();
+        } else if (e.key === 'ArrowLeft') {
+            e.preventDefault();
+            const prev = paymentTabs[(idx - 1 + paymentTabs.length) % paymentTabs.length];
+            activateTab(prev);
+            prev.focus();
+        } else if (e.key === 'Home') {
+            e.preventDefault();
+            activateTab(paymentTabs[0]);
+            paymentTabs[0].focus();
+        } else if (e.key === 'End') {
+            e.preventDefault();
+            activateTab(paymentTabs[paymentTabs.length - 1]);
+            paymentTabs[paymentTabs.length - 1].focus();
+        }
     });
 });
 
@@ -254,10 +289,13 @@ document.getElementById('pay-card-btn').addEventListener('click', async () => {
 
     const addressId = document.getElementById('shipping-address').value;
     if (!addressId) {
-        alert('Selecciona una dirección de envío para continuar.');
+        const cardErrors = document.getElementById('card-errors');
+        if (cardErrors) cardErrors.textContent = 'Selecciona una dirección de envío para continuar.';
         return;
     }
 
+    const cardErrorsEl = document.getElementById('card-errors');
+    if (cardErrorsEl) cardErrorsEl.textContent = '';
     const btn = document.getElementById('pay-card-btn');
     const spinner = document.getElementById('card-spinner');
     btn.disabled = true;
@@ -335,9 +373,15 @@ paypal.Buttons({
     createOrder: async () => {
         const addressId = document.getElementById('shipping-address').value;
         if (!addressId) {
-            alert('Selecciona una dirección de envío para continuar.');
+            const paypalErrors = document.getElementById('paypal-errors');
+            if (paypalErrors) {
+                paypalErrors.textContent = 'Selecciona una dirección de envío para continuar.';
+                paypalErrors.classList.remove('d-none');
+            }
             return Promise.reject(new Error('Sin dirección'));
         }
+        const paypalErrorsEl = document.getElementById('paypal-errors');
+        if (paypalErrorsEl) paypalErrorsEl.classList.add('d-none');
         const resp = await fetch('{% url "crear_orden_paypal" %}', {
             method: 'POST',
             headers: { 'Content-Type': 'application/json', 'X-CSRFToken': CSRF_TOKEN },
@@ -359,7 +403,11 @@ paypal.Buttons({
         showSuccess(result.transaction_code);
     },
     onError: (err) => {
-        alert('Error en el pago con PayPal: ' + err);
+        const paypalErrors = document.getElementById('paypal-errors');
+        if (paypalErrors) {
+            paypalErrors.textContent = 'Error en el pago con PayPal: ' + err;
+            paypalErrors.classList.remove('d-none');
+        }
     },
 }).render('#paypal-button-container');
 {% endif %}
diff --git a/tienda/templates/tienda/home.html b/tienda/templates/tienda/home.html
index 4465721..3e28fb3 100644
--- a/tienda/templates/tienda/home.html
+++ b/tienda/templates/tienda/home.html
@@ -196,9 +196,11 @@
                                 <a href="{% url 'producto' product.id %}" class="btn btn-primary btn-sm flex-grow-1">
                                     Ver detalles
                                 </a>
-                                <a href="{% url 'add_to_cart' product.id %}" class="btn btn-outline-primary btn-sm">
-                                    🛒
-                                </a>
+                                <form method="post" action="{% url 'add_to_cart' product.id %}" style="display:inline;">
+                                    {% csrf_token %}
+                                    <input type="hidden" name="quantity" value="1">
+                                    <button type="submit" class="btn btn-outline-primary btn-sm">🛒</button>
+                                </form>
                             </div>
                         </div>
                     </div>
diff --git a/tienda/templates/tienda/producto.html b/tienda/templates/tienda/producto.html
index fca8dd8..117aa9f 100644
--- a/tienda/templates/tienda/producto.html
+++ b/tienda/templates/tienda/producto.html
@@ -34,16 +34,16 @@
             
             <div class="small text-primary font-weight-bold mb-2">Precio total (IVA incluido):</div>
             <span class="price" style="font-size: 2rem; color: #28a745;">€{{ product.get_price_with_vat|format_price }}</span>
-            <div class="small text-success mt-2">IVA: €{{ product.get_vat_amount|format_price }}</div>
+            <div class="small text-success mt-2"><span aria-hidden="true">ℹ️</span> IVA incluido: €{{ product.get_vat_amount|format_price }}</div>
         </div>
         <div id="descripcion" class="texto-ajustado">
             {{ product.briefdesc }}
         </div>
         <div class="mt-3">
             {% if product.stock > 0 %}
-            <span class="badge bg-success">Stock disponible: {{ product.stock }}</span>
+            <span class="badge bg-success" role="status"><span aria-hidden="true">✓</span> Stock disponible: {{ product.stock }}</span>
             {% else %}
-            <span class="badge bg-danger">Sin stock</span>
+            <span class="badge bg-danger" role="status"><span aria-hidden="true">✗</span> Sin stock</span>
             {% endif %}
         </div>
         
diff --git a/tienda/templates/tienda/register.html b/tienda/templates/tienda/register.html
index ce794d8..c648827 100644
--- a/tienda/templates/tienda/register.html
+++ b/tienda/templates/tienda/register.html
@@ -36,7 +36,7 @@
           <div class="mb-3 form-check">
             <input type="checkbox" class="form-check-input" id="acceptTerms" name="terms" required>
             <label class="form-check-label" for="acceptTerms">
-              Acepto los <a href="#" target="_blank">términos y condiciones</a>
+              Acepto los <a href="{% url 'terminos' %}" target="_blank">términos y condiciones</a>
             </label>
           </div>
           
diff --git a/tienda/templates/tienda/search.html b/tienda/templates/tienda/search.html
index 3641bdd..7fc8385 100644
--- a/tienda/templates/tienda/search.html
+++ b/tienda/templates/tienda/search.html
@@ -79,9 +79,11 @@
                                     <a href="{% url 'producto' product.id %}" class="btn btn-primary btn-sm flex-grow-1">
                                         Ver detalles
                                     </a>
-                                    <a href="{% url 'add_to_cart' product.id %}" class="btn btn-outline-primary btn-sm">
-                                        🛒
-                                    </a>
+                                    <form method="post" action="{% url 'add_to_cart' product.id %}" style="display:inline;">
+                                        {% csrf_token %}
+                                        <input type="hidden" name="quantity" value="1">
+                                        <button type="submit" class="btn btn-outline-primary btn-sm">🛒</button>
+                                    </form>
                                 </div>
                             </div>
                         </div>
diff --git a/tienda/tests.py b/tienda/tests.py
index 2c0b210..284ddc2 100644
--- a/tienda/tests.py
+++ b/tienda/tests.py
@@ -1,4 +1,6 @@
 import json
+from pathlib import Path
+import re
 from unittest.mock import MagicMock, patch
 
 from django.test import TestCase, override_settings
@@ -1371,6 +1373,16 @@ class EndpointViewTests(TestCase):
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, 'site-title-mobile d-md-none')
         self.assertContains(response, 'site-title-desktop')
+
+    def test_mobile_site_title_css_keeps_title_pinned_to_header_row(self):
+        css_path = Path(__file__).resolve().parent / "static" / "css" / "custom.css"
+        css_content = css_path.read_text(encoding="utf-8")
+        selector_match = re.search(r"\.navbar\.header \.site-title-mobile\s*\{(?P<body>[^}]*)\}", css_content, re.DOTALL)
+        self.assertIsNotNone(selector_match)
+
+        rule_block = selector_match.group("body")
+        self.assertRegex(rule_block, r"top:\s*calc\(var\(--bs-navbar-padding-y\)\s*\+\s*20px\);")
+        self.assertRegex(rule_block, r"transform:\s*translate\(-50%,\s*-50%\);")
     def test_home_mobile_welcome_title_centered(self):
         response = self.client.get(reverse("home"))
         html = response.content.decode()
diff --git a/tienda/views.py b/tienda/views.py
index a44db6b..001dfa8 100644
--- a/tienda/views.py
+++ b/tienda/views.py
@@ -16,6 +16,7 @@ from .vars import (
 )
 from django.conf import settings
 from django.views.decorators.csrf import csrf_exempt
+from django.views.decorators.http import require_POST
 from django.urls import reverse
 from django.utils import timezone
 from decimal import Decimal, ROUND_HALF_UP
@@ -239,6 +240,9 @@ def login(request: HttpRequest):
         
         # Autenticar usuario
         user = authenticate(request, username=username, password=password)
+        if user is None: # Bug de error 500 en caso de fallar la contra
+            messages.error(request, "Correo electrónico o contraseña incorrectos.")
+            return render(request, "tienda/login.html") 
         user = User.objects.get(username=user.username)
         if user.registration_status == "CR":
             audit_logger.info(
@@ -704,6 +708,7 @@ def create_order_from_cart(request, payment_method, payment_reference="", shippi
     return order, ""
 
 
+@require_POST
 def add_to_cart(request: HttpRequest, product_id: int):
     """Agrega un producto al carrito"""
     try:
@@ -2253,13 +2258,6 @@ def verify(request: HttpRequest, code: str):
         return HttpResponse("<h1>Error</h1><p>No existe el codigo de verificación</p>")
 
 
-def reset_password(request: HttpRequest):
-    if request.user.is_authenticated:
-        return redirect("index")
-    
-        
-    return render(request, "tienda/reset_password", {})
-
 def rgpd(request: HttpRequest):
     return render(request, "tienda/rgpd.html", {})
 
@@ -2312,6 +2310,7 @@ def reset_password_phase2(request: HttpRequest, code: str):
         user = ver_code.user
         user.set_password(password)
         user.save()
+        ver_code.delete() # Delete Verification code after changing password
         messages.success(request, "Se ha cambiado la contraseña!")
         return redirect(reverse("index"))