feat: Add adaptive multi-column layout for categories and tags checkboxes

Implemented responsive grid system for product form checkboxes to improve UX
when dealing with multiple categories and tags.

Changes:
- Added CSS Grid layout with adaptive columns (1-4 based on screen width)
- Mobile (< 768px): 1 column
- Tablet (≥ 768px): 2 columns
- Desktop (≥ 1200px): 3 columns
- Wide screens (≥ 1600px): 4 columns
- Compact spacing (0.35rem gap) for better density
- Enhanced checkbox styling with hover effects and selected state
- JavaScript fallback for forced grid application and responsive resizing
- Improved form container width (col-12 col-xl-10) for better space usage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

myproject/products/templates/products/product_form.html

@@ -2,10 +2,116 @@
 
 {% block title %}{% if object %}Редактировать товар{% else %}Создать товар{% endif %}{% endblock %}
 
+{% block extra_css %}
+<style>
+    /* Адаптивная grid-система для чекбоксов категорий и тегов */
+    /* Нацеливаемся на любой UL внутри .checkbox-grid */
+    #id_categories,
+    #id_tags,
+    .checkbox-grid ul,
+    .checkbox-grid > ul,
+    .checkbox-grid div > ul,
+    .checkbox-grid * ul {
+        display: grid !important;
+        gap: 0.35rem !important;
+        list-style: none !important;
+        padding: 0 !important;
+        margin: 0 !important;
+        /* 1 столбец на маленьких экранах */
+        grid-template-columns: 1fr !important;
+    }
+
+    /* 2 столбца на средних экранах (≥768px) */
+    @media (min-width: 768px) {
+        #id_categories,
+        #id_tags,
+        .checkbox-grid ul,
+        .checkbox-grid > ul,
+        .checkbox-grid div > ul,
+        .checkbox-grid * ul {
+            grid-template-columns: repeat(2, 1fr) !important;
+        }
+    }
+
+    /* 3 столбца на больших экранах (≥1200px) */
+    @media (min-width: 1200px) {
+        #id_categories,
+        #id_tags,
+        .checkbox-grid ul,
+        .checkbox-grid > ul,
+        .checkbox-grid div > ul,
+        .checkbox-grid * ul {
+            grid-template-columns: repeat(3, 1fr) !important;
+        }
+    }
+
+    /* 4 столбца на очень больших экранах (≥1600px) */
+    @media (min-width: 1600px) {
+        #id_categories,
+        #id_tags,
+        .checkbox-grid ul,
+        .checkbox-grid > ul,
+        .checkbox-grid div > ul,
+        .checkbox-grid * ul {
+            grid-template-columns: repeat(4, 1fr) !important;
+        }
+    }
+
+    /* Стилизация элементов списка */
+    #id_categories li,
+    #id_tags li,
+    .checkbox-grid li {
+        margin: 0 !important;
+        padding: 0 !important;
+    }
+
+    /* Стилизация чекбоксов */
+    #id_categories label,
+    #id_tags label,
+    .checkbox-grid label {
+        display: flex !important;
+        align-items: center !important;
+        margin-bottom: 0 !important;
+        padding: 0.4rem 0.6rem !important;
+        background: white !important;
+        border-radius: 0.375rem !important;
+        transition: all 0.2s ease !important;
+        cursor: pointer !important;
+        height: 100% !important;
+    }
+
+    #id_categories label:hover,
+    #id_tags label:hover,
+    .checkbox-grid label:hover {
+        background: #e9ecef !important;
+        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05) !important;
+    }
+
+    #id_categories input[type="checkbox"],
+    #id_tags input[type="checkbox"],
+    .checkbox-grid input[type="checkbox"] {
+        margin-right: 0.5rem !important;
+        cursor: pointer !important;
+        width: 18px !important;
+        height: 18px !important;
+        flex-shrink: 0 !important;
+    }
+
+    /* Стиль для выбранных чекбоксов */
+    #id_categories li:has(input[type="checkbox"]:checked) label,
+    #id_tags li:has(input[type="checkbox"]:checked) label,
+    .checkbox-grid li:has(input[type="checkbox"]:checked) label {
+        background: #e7f3ff !important;
+        border-left: 3px solid #0d6efd !important;
+        font-weight: 500 !important;
+    }
+</style>
+{% endblock %}
+
 {% block content %}
 <div class="container mt-5">
     <div class="row justify-content-center">
-        <div class="col-md-8">
+        <div class="col-12 col-xl-10">
             <div class="card">
                 <div class="card-body">
                     <form method="post" enctype="multipart/form-data">
@@ -76,7 +182,7 @@
                                         <i class="bi bi-plus-circle"></i> Новая
                                     </a>
                                 </div>
-                                <div class="p-3 bg-light rounded">
+                                <div class="p-3 bg-light rounded checkbox-grid">
                                     {{ form.categories }}
                                 </div>
                                 {% if form.categories.help_text %}
@@ -90,7 +196,7 @@
                             <!-- Теги -->
                             <div class="mb-3">
                                 {{ form.tags.label_tag }}
-                                <div class="p-3 bg-light rounded">
+                                <div class="p-3 bg-light rounded checkbox-grid">
                                     {{ form.tags }}
                                 </div>
                                 {% if form.tags.help_text %}
@@ -400,3 +506,78 @@
     </div>
 </div>
 {% endblock %}
+
+{% block extra_js %}
+<script>
+// Диагностика и принудительное применение grid для чекбоксов
+document.addEventListener('DOMContentLoaded', function() {
+    console.log('=== Checkbox Grid Diagnostic ===');
+
+    // Ищем все UL элементы внутри .checkbox-grid
+    const checkboxGrids = document.querySelectorAll('.checkbox-grid');
+
+    checkboxGrids.forEach((grid, index) => {
+        console.log(`Grid ${index}:`, grid);
+
+        // Ищем все UL внутри этого grid
+        const lists = grid.querySelectorAll('ul');
+        console.log(`  Found ${lists.length} UL elements`);
+
+        lists.forEach((ul, ulIndex) => {
+            console.log(`  UL ${ulIndex}:`, ul);
+            console.log(`    ID: ${ul.id}`);
+            console.log(`    Current display: ${window.getComputedStyle(ul).display}`);
+            console.log(`    Current grid-template-columns: ${window.getComputedStyle(ul).gridTemplateColumns}`);
+
+            // Принудительно применяем grid стили
+            ul.style.setProperty('display', 'grid', 'important');
+            ul.style.setProperty('list-style', 'none', 'important');
+            ul.style.setProperty('padding', '0', 'important');
+            ul.style.setProperty('margin', '0', 'important');
+            ul.style.setProperty('gap', '0.35rem', 'important');
+
+            // Определяем количество колонок на основе ширины экрана
+            const width = window.innerWidth;
+            let columns = 1;
+            if (width >= 1600) columns = 4;
+            else if (width >= 1200) columns = 3;
+            else if (width >= 768) columns = 2;
+
+            ul.style.setProperty('grid-template-columns', `repeat(${columns}, 1fr)`, 'important');
+
+            console.log(`    Applied ${columns} columns`);
+            console.log(`    New display: ${window.getComputedStyle(ul).display}`);
+        });
+    });
+
+    // Также проверяем прямые ID
+    ['id_categories', 'id_tags'].forEach(id => {
+        const element = document.getElementById(id);
+        if (element) {
+            console.log(`Found element with ID: ${id}`, element);
+            console.log(`  Tag name: ${element.tagName}`);
+            console.log(`  Parent: ${element.parentElement.className}`);
+        } else {
+            console.log(`Element with ID ${id} NOT found`);
+        }
+    });
+
+    // Пересчитываем при изменении размера окна
+    let resizeTimeout;
+    window.addEventListener('resize', function() {
+        clearTimeout(resizeTimeout);
+        resizeTimeout = setTimeout(function() {
+            const width = window.innerWidth;
+            let columns = 1;
+            if (width >= 1600) columns = 4;
+            else if (width >= 1200) columns = 3;
+            else if (width >= 768) columns = 2;
+
+            document.querySelectorAll('.checkbox-grid ul, #id_categories, #id_tags').forEach(ul => {
+                ul.style.setProperty('grid-template-columns', `repeat(${columns}, 1fr)`, 'important');
+            });
+        }, 250);
+    });
+});
+</script>
+{% endblock %}