feat: Complete mobile UX/UI overhaul

Major improvements:
- New CSS design system with custom properties (tokens)
- Consistent spacing scale (4px base)
- Touch-friendly sizing (44px min targets)
- Improved Carousel with better touch handling and rubber-band effect
- Enhanced FilterControls (auto-collapse on mobile)
- Better stat card styling with change indicators
- Refined chart cards and toggle switches
- Smoother transitions and micro-interactions
- Better RTL support
- Print styles
- Responsive breakpoints for tablet (1024px), mobile (768px), and small mobile (375px)
- Cleaner typography hierarchy
- Subtle shadows and depth

Components updated:
- App.css: Complete rewrite with design tokens
- Carousel.jsx: Better touch gestures with velocity detection
- StatCard.jsx: Improved change indicator styling
- FilterControls.jsx: Auto-collapse on mobile
- EmptyState.jsx: Better accessibility
- ChartExport.js: Cleaned up unused imports

src/components/shared/Carousel.jsx

@@ -1,4 +1,4 @@
-import React, { useRef, useCallback } from 'react';
+import React, { useRef, useCallback, useState } from 'react';
 
 function Carousel({ 
   children, 
@@ -8,25 +8,66 @@ function Carousel({
   showLabels = true,
   className = ''
 }) {
-  const touchStart = useRef(null);
+  const touchStartX = useRef(null);
+  const touchStartY = useRef(null);
+  const trackRef = useRef(null);
+  const [isDragging, setIsDragging] = useState(false);
+  const [dragOffset, setDragOffset] = useState(0);
   const itemCount = React.Children.count(children);
-
+  
+  // Threshold for swipe detection
+  const SWIPE_THRESHOLD = 50;
+  const VELOCITY_THRESHOLD = 0.3;
+  
   const handleTouchStart = useCallback((e) => {
-    touchStart.current = e.touches[0].clientX;
+    touchStartX.current = e.touches[0].clientX;
+    touchStartY.current = e.touches[0].clientY;
+    setIsDragging(true);
+    setDragOffset(0);
   }, []);
 
+  const handleTouchMove = useCallback((e) => {
+    if (!touchStartX.current || !isDragging) return;
+    
+    const currentX = e.touches[0].clientX;
+    const currentY = e.touches[0].clientY;
+    const diffX = currentX - touchStartX.current;
+    const diffY = currentY - touchStartY.current;
+    
+    // Only handle horizontal swipes
+    if (Math.abs(diffX) > Math.abs(diffY)) {
+      e.preventDefault();
+      // Add resistance at edges
+      let offset = diffX;
+      if ((activeIndex === 0 && diffX > 0) || (activeIndex === itemCount - 1 && diffX < 0)) {
+        offset = diffX * 0.3; // Rubber band effect
+      }
+      setDragOffset(offset);
+    }
+  }, [isDragging, activeIndex, itemCount]);
+
   const handleTouchEnd = useCallback((e) => {
-    if (!touchStart.current) return;
-    const diff = touchStart.current - e.changedTouches[0].clientX;
-    if (Math.abs(diff) > 50) {
+    if (!touchStartX.current || !isDragging) return;
+    
+    const endX = e.changedTouches[0].clientX;
+    const diff = touchStartX.current - endX;
+    const velocity = Math.abs(diff) / 200; // Rough velocity calc
+    
+    // Determine if we should change slide
+    if (Math.abs(diff) > SWIPE_THRESHOLD || velocity > VELOCITY_THRESHOLD) {
       if (diff > 0 && activeIndex < itemCount - 1) {
         setActiveIndex(activeIndex + 1);
       } else if (diff < 0 && activeIndex > 0) {
         setActiveIndex(activeIndex - 1);
       }
     }
-    touchStart.current = null;
-  }, [activeIndex, setActiveIndex, itemCount]);
+    
+    // Reset
+    touchStartX.current = null;
+    touchStartY.current = null;
+    setIsDragging(false);
+    setDragOffset(0);
+  }, [isDragging, activeIndex, setActiveIndex, itemCount]);
 
   const handleKeyDown = useCallback((e) => {
     if (e.key === 'ArrowLeft' && activeIndex > 0) {
@@ -36,18 +77,40 @@ function Carousel({
     }
   }, [activeIndex, setActiveIndex, itemCount]);
 
+  // Calculate transform
+  const baseTransform = -(activeIndex * 100);
+  const dragPercentage = trackRef.current ? (dragOffset / trackRef.current.offsetWidth) * 100 : 0;
+  const transform = baseTransform + dragPercentage;
+
   return (
-    <div className={`carousel ${className}`} onKeyDown={handleKeyDown} tabIndex={0}>
+    <div 
+      className={`carousel ${className}`} 
+      onKeyDown={handleKeyDown} 
+      tabIndex={0}
+      role="region"
+      aria-label="Carousel"
+    >
       <div className="carousel-container">
         <div className="carousel-viewport">
           <div 
+            ref={trackRef}
             className="carousel-track"
-            style={{ transform: `translateX(-${activeIndex * 100}%)` }}
+            style={{ 
+              transform: `translateX(${transform}%)`,
+              transition: isDragging ? 'none' : 'transform 400ms cubic-bezier(0.25, 0.46, 0.45, 0.94)'
+            }}
             onTouchStart={handleTouchStart}
+            onTouchMove={handleTouchMove}
             onTouchEnd={handleTouchEnd}
           >
             {React.Children.map(children, (child, i) => (
-              <div className="carousel-slide" key={i}>
+              <div 
+                className="carousel-slide" 
+                key={i}
+                role="tabpanel"
+                aria-hidden={activeIndex !== i}
+                aria-label={labels[i] || `Slide ${i + 1}`}
+              >
                 {child}
               </div>
             ))}
@@ -64,6 +127,7 @@ function Carousel({
             role="tab"
             aria-selected={activeIndex === i}
             aria-label={labels[i] || `Slide ${i + 1}`}
+            aria-controls={`slide-${i}`}
           >
             {showLabels && labels[i] && (
               <span className="dot-label">{labels[i]}</span>

src/components/shared/EmptyState.jsx

@@ -2,18 +2,29 @@ import React from 'react';
 
 function EmptyState({ 
   icon = '📊', 
-  title = 'No data found', 
-  message = 'Try adjusting your filters',
-  action,
-  actionLabel = 'Reset Filters'
+  title, 
+  message, 
+  action = null, 
+  actionLabel = 'Try Again',
+  className = ''
 }) {
   return (
-    <div className="empty-state">
-      <div className="empty-state-icon">{icon}</div>
-      <h3 className="empty-state-title">{title}</h3>
-      <p className="empty-state-message">{message}</p>
+    <div className={`empty-state ${className}`}>
+      <div className="empty-state-icon" role="img" aria-hidden="true">
+        {icon}
+      </div>
+      {title && (
+        <h3 className="empty-state-title">{title}</h3>
+      )}
+      {message && (
+        <p className="empty-state-message">{message}</p>
+      )}
       {action && (
-        <button className="empty-state-action" onClick={action}>
+        <button 
+          className="empty-state-action"
+          onClick={action}
+          type="button"
+        >
           {actionLabel}
         </button>
       )}

src/components/shared/FilterControls.jsx

@@ -1,33 +1,86 @@
-import React, { useState } from 'react';
+import React, { useState, useEffect } from 'react';
+import { useLanguage } from '../../contexts/LanguageContext';
 
 function FilterControls({ 
   children, 
-  title = 'Filters',
+  title,
   defaultExpanded = true,
   onReset = null,
   className = ''
 }) {
-  const [expanded, setExpanded] = useState(defaultExpanded);
+  const { t } = useLanguage();
+  const displayTitle = title || t('filters.title');
+  
+  // Start collapsed on mobile
+  const [expanded, setExpanded] = useState(() => {
+    if (typeof window !== 'undefined') {
+      return window.innerWidth > 768 ? defaultExpanded : false;
+    }
+    return defaultExpanded;
+  });
+
+  // Handle resize
+  useEffect(() => {
+    const handleResize = () => {
+      // Auto-expand on desktop, keep user preference on mobile
+      if (window.innerWidth > 768) {
+        setExpanded(true);
+      }
+    };
+    
+    window.addEventListener('resize', handleResize);
+    return () => window.removeEventListener('resize', handleResize);
+  }, []);
+
+  const toggleExpanded = () => {
+    setExpanded(!expanded);
+  };
 
   return (
     <div className={`controls ${expanded ? 'expanded' : 'collapsed'} ${className}`}>
-      <div className="controls-header" onClick={() => setExpanded(!expanded)}>
-        <h3>{title}</h3>
+      <div 
+        className="controls-header" 
+        onClick={toggleExpanded}
+        role="button"
+        aria-expanded={expanded}
+        tabIndex={0}
+        onKeyDown={(e) => {
+          if (e.key === 'Enter' || e.key === ' ') {
+            e.preventDefault();
+            toggleExpanded();
+          }
+        }}
+      >
+        <h3>{displayTitle}</h3>
         <div className="controls-header-actions">
           {onReset && expanded && (
             <button 
               className="controls-reset"
-              onClick={(e) => { e.stopPropagation(); onReset(); }}
+              onClick={(e) => { 
+                e.stopPropagation(); 
+                onReset(); 
+              }}
+              aria-label={t('filters.reset') || 'Reset filters'}
             >
-              Reset
+              {t('filters.reset') || 'Reset'}
             </button>
           )}
-          <button className="controls-toggle">
-            {expanded ? '▲ Hide' : '▼ Show'}
+          <button 
+            className="controls-toggle"
+            aria-hidden="true"
+          >
+            {expanded ? '▲' : '▼'}
           </button>
         </div>
       </div>
-      <div className="controls-body">
+      
+      <div 
+        className="controls-body"
+        style={{
+          display: expanded ? 'block' : 'none',
+          animation: expanded ? 'fadeIn 200ms ease' : 'none'
+        }}
+      >
         {children}
       </div>
     </div>
@@ -37,7 +90,7 @@ function FilterControls({
 function FilterGroup({ label, children }) {
   return (
     <div className="control-group">
-      <label>{label}</label>
+      {label && <label>{label}</label>}
       {children}
     </div>
   );

src/components/shared/StatCard.jsx

@@ -1,15 +1,20 @@
 import React from 'react';
 
-function StatCard({ title, value, change = null, changeLabel = 'YoY' }) {
+function StatCard({ title, value, change = null, changeLabel = 'YoY', subtitle = null }) {
   const isPositive = change !== null && change >= 0;
   
   return (
     <div className="stat-card">
       <h3>{title}</h3>
       <div className="stat-value">{value}</div>
+      {subtitle && (
+        <div className="stat-subtitle">{subtitle}</div>
+      )}
       {change !== null && (
         <div className={`stat-change ${isPositive ? 'positive' : 'negative'}`}>
-          {isPositive ? '↑' : '↓'} {Math.abs(change).toFixed(1)}% {changeLabel}
+          <span className="stat-change-arrow">{isPositive ? '↑' : '↓'}</span>
+          <span className="stat-change-value">{Math.abs(change).toFixed(1)}%</span>
+          <span className="stat-change-label">{changeLabel}</span>
         </div>
       )}
     </div>