/* ============================================
   Root Variables & Reset
   ============================================ */
:root {
    /* Colors */
    --color-primary: #FF385C;
    --color-primary-dark: #E31C5F;
    --color-secondary: #00A699;
    --color-success: #00C851;
    --color-warning: #FFB300;
    --color-error: #FF3547;
    --color-dark: #000000;
    --color-light: #FFFFFF;
    --color-gray-100: #F7F7F7;
    --color-gray-200: #E5E5E5;
    --color-gray-300: #D4D4D4;
    --color-gray-400: #A3A3A3;
    --color-gray-500: #737373;
    --color-gray-600: #525252;
    --color-gray-700: #404040;
    --color-gray-800: #262626;
    --color-gray-900: #171717;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Layout */
    --header-height: 60px;
    --bottom-nav-height: 65px;
    --max-content-width: 600px;
    
    /* Animations */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.16), 0 3px 6px rgba(0, 0, 0, 0.23);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
    --shadow-xl: 0 14px 28px rgba(0, 0, 0, 0.25), 0 10px 10px rgba(0, 0, 0, 0.22);
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.5;
    color: var(--color-gray-900);
    background-color: var(--color-light);
    overflow-x: hidden;
    -webkit-tap-highlight-color: transparent;
}

/* ============================================
   App Container
   ============================================ */
.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
}

/* ============================================
   Header
   ============================================ */
.app-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: var(--color-light);
    border-bottom: 1px solid var(--color-gray-200);
    z-index: 100;
    backdrop-filter: blur(10px);
    background: rgba(255, 255, 255, 0.95);
}

.header-content {
    height: 100%;
    max-width: var(--max-content-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-primary);
    letter-spacing: -0.5px;
}

.header-nav {
    display: flex;
    gap: var(--spacing-sm);
}

.nav-btn {
    position: relative;
    width: 40px;
    height: 40px;
    border: none;
    background: transparent;
    color: var(--color-gray-700);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.nav-btn:hover {
    background: var(--color-gray-100);
}

.nav-btn:active {
    transform: scale(0.95);
}

.notification-badge {
    position: absolute;
    top: 6px;
    right: 6px;
    width: 18px;
    height: 18px;
    background: var(--color-error);
    color: var(--color-light);
    border-radius: 50%;
    font-size: var(--font-size-xs);
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
}

/* ============================================
   Feed Container
   ============================================ */
.feed-container {
    flex: 1;
    padding-top: var(--header-height);
    padding-bottom: var(--bottom-nav-height);
    background: var(--color-gray-100);
    min-height: calc(100vh - var(--header-height) - var(--bottom-nav-height));
    position: relative;
}

/* ============================================
   Pull to Refresh
   ============================================ */
.pull-refresh {
    position: absolute;
    top: var(--header-height);
    left: 50%;
    transform: translateX(-50%) translateY(-100%);
    padding: var(--spacing-md);
    transition: transform var(--transition-base);
    z-index: 90;
}

.pull-refresh.active {
    transform: translateX(-50%) translateY(0);
}

.pull-refresh-icon {
    width: 40px;
    height: 40px;
    background: var(--color-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
}

.spinner {
    animation: rotate 1s linear infinite;
}

@keyframes rotate {
    to { transform: rotate(360deg); }
}

/* ============================================
   Product Feed
   ============================================ */
.product-feed {
    max-width: var(--max-content-width);
    margin: 0 auto;
    padding: var(--spacing-md);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

/* Product Card */
.product-card {
    background: var(--color-light);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
    cursor: pointer;
    position: relative;
    transform-origin: center;
}

.product-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.product-card.entering {
    animation: slideUp 0.4s ease-out;
}

.product-card.exiting {
    animation: slideOut 0.3s ease-in forwards;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideOut {
    to {
        opacity: 0;
        transform: translateX(-100%) rotate(-5deg);
    }
}

/* Product Image Container */
.product-image-container {
    position: relative;
    width: 100%;
    padding-bottom: 100%; /* 1:1 Aspect Ratio */
    background: var(--color-gray-200);
    overflow: hidden;
}

.product-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.product-card:hover .product-image {
    transform: scale(1.05);
}

.product-badge {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    background: var(--color-error);
    color: var(--color-light);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 20px;
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Product Content */
.product-content {
    padding: var(--spacing-lg);
}

.product-header {
    margin-bottom: var(--spacing-md);
}

.product-title {
    font-size: var(--font-size-lg);
    font-weight: 600;
    color: var(--color-gray-900);
    margin-bottom: var(--spacing-xs);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.product-price {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
}

.product-original-price {
    font-size: var(--font-size-base);
    color: var(--color-gray-500);
    text-decoration: line-through;
    margin-left: var(--spacing-sm);
}

/* Product Meta */
.product-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

.product-rating {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.stars {
    display: flex;
    gap: 2px;
}

.star {
    width: 16px;
    height: 16px;
    fill: var(--color-warning);
}

.star.empty {
    fill: var(--color-gray-300);
}

/* Product Actions */
.product-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.product-action-btn {
    width: 48px;
    height: 48px;
    border: 2px solid var(--color-gray-200);
    background: var(--color-light);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    color: var(--color-gray-600);
}

.product-action-btn:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
    transform: scale(1.1);
}

.product-action-btn:active {
    transform: scale(0.95);
}

.product-action-btn.active {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--color-light);
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: none;
    border-radius: 25px;
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    min-height: 48px;
    text-decoration: none;
    white-space: nowrap;
}

.btn-primary {
    background: var(--color-primary);
    color: var(--color-light);
    flex: 1;
}

.btn-primary:hover {
    background: var(--color-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--color-gray-200);
    color: var(--color-gray-900);
}

.btn-secondary:hover {
    background: var(--color-gray-300);
}

.btn-text {
    background: transparent;
    color: var(--color-gray-600);
    padding: var(--spacing-sm) var(--spacing-md);
}

.btn-text:hover {
    color: var(--color-gray-900);
}

/* ============================================
   Loading States
   ============================================ */
.loading-indicator {
    padding: var(--spacing-xl);
    max-width: var(--max-content-width);
    margin: 0 auto;
}

.loading-skeleton {
    background: var(--color-light);
    border-radius: 16px;
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.skeleton-image {
    width: 100%;
    padding-bottom: 100%;
    background: linear-gradient(90deg, var(--color-gray-200) 25%, var(--color-gray-100) 50%, var(--color-gray-200) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: 12px;
    margin-bottom: var(--spacing-lg);
}

.skeleton-line {
    height: 20px;
    background: linear-gradient(90deg, var(--color-gray-200) 25%, var(--color-gray-100) 50%, var(--color-gray-200) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: 4px;
    margin-bottom: var(--spacing-sm);
}

.skeleton-title {
    width: 70%;
}

.skeleton-price {
    width: 40%;
    height: 28px;
}

.skeleton-description {
    width: 90%;
}

.skeleton-button {
    width: 100%;
    height: 48px;
    margin-top: var(--spacing-lg);
    background: linear-gradient(90deg, var(--color-gray-200) 25%, var(--color-gray-100) 50%, var(--color-gray-200) 75%);
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: 24px;
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

/* ============================================
   Empty & Error States
   ============================================ */
.empty-state,
.error-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: var(--spacing-2xl);
    min-height: 400px;
    color: var(--color-gray-600);
}

.empty-state svg,
.error-state svg {
    margin-bottom: var(--spacing-xl);
    opacity: 0.3;
}

.empty-state h2,
.error-state h2 {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-gray-900);
    margin-bottom: var(--spacing-sm);
}

.empty-state p,
.error-state p {
    font-size: var(--font-size-base);
    margin-bottom: var(--spacing-xl);
    max-width: 300px;
}

/* ============================================
   Bottom Navigation
   ============================================ */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: var(--bottom-nav-height);
    background: var(--color-light);
    border-top: 1px solid var(--color-gray-200);
    display: flex;
    align-items: center;
    justify-content: space-around;
    z-index: 100;
    padding-bottom: env(safe-area-inset-bottom);
}

.bottom-nav-item {
    flex: 1;
    height: 100%;
    border: none;
    background: transparent;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    color: var(--color-gray-500);
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
}

.bottom-nav-item:hover {
    color: var(--color-gray-700);
}

.bottom-nav-item.active {
    color: var(--color-primary);
}

.bottom-nav-item.active::before {
    content: '';
    position: absolute;
    top: 0;
    left: 20%;
    right: 20%;
    height: 2px;
    background: var(--color-primary);
    border-radius: 0 0 2px 2px;
}

.bottom-nav-item span {
    font-size: var(--font-size-xs);
    font-weight: 500;
}

/* ============================================
   Consent Banner
   ============================================ */
.consent-banner {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--color-light);
    border-top: 1px solid var(--color-gray-200);
    box-shadow: var(--shadow-xl);
    z-index: 1000;
    transform: translateY(100%);
    transition: transform var(--transition-base);
}

.consent-banner:not(.hidden) {
    transform: translateY(0);
}

.consent-content {
    max-width: var(--max-content-width);
    margin: 0 auto;
    padding: var(--spacing-lg);
}

.consent-content h3 {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.consent-content p {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
    margin-bottom: var(--spacing-lg);
}

.consent-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* ============================================
   Modals
   ============================================ */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    padding: var(--spacing-md);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
}

.modal:not(.hidden) {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--color-light);
    border-radius: 16px;
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    transform: scale(0.9);
    transition: transform var(--transition-base);
}

.modal:not(.hidden) .modal-content {
    transform: scale(1);
}

.modal-close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    width: 32px;
    height: 32px;
    border: none;
    background: var(--color-gray-100);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    cursor: pointer;
    transition: all var(--transition-fast);
    z-index: 1;
}

.modal-close:hover {
    background: var(--color-gray-200);
    transform: rotate(90deg);
}

.modal-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-gray-200);
}

.modal-header h2 {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.modal-body {
    padding: var(--spacing-lg);
}

.modal-footer {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--color-gray-200);
}

/* Privacy Options */
.privacy-option {
    padding: var(--spacing-md) 0;
    border-bottom: 1px solid var(--color-gray-100);
}

.privacy-option:last-child {
    border-bottom: none;
}

.switch-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    gap: var(--spacing-md);
}

.switch {
    position: relative;
    width: 48px;
    height: 24px;
    background: var(--color-gray-300);
    border-radius: 12px;
    transition: background var(--transition-fast);
}

.switch::after {
    content: '';
    position: absolute;
    top: 2px;
    left: 2px;
    width: 20px;
    height: 20px;
    background: var(--color-light);
    border-radius: 50%;
    transition: transform var(--transition-fast);
}

input[type="checkbox"]:checked + .switch {
    background: var(--color-success);
}

input[type="checkbox"]:checked + .switch::after {
    transform: translateX(24px);
}

input[type="checkbox"] {
    position: absolute;
    opacity: 0;
    pointer-events: none;
}

.option-info {
    flex: 1;
}

.option-info strong {
    display: block;
    font-size: var(--font-size-base);
    margin-bottom: var(--spacing-xs);
}

.option-info p {
    font-size: var(--font-size-sm);
    color: var(--color-gray-600);
}

/* Product Detail Modal */
.product-modal-content {
    max-width: 600px;
    padding: 0;
}

#product-detail-content {
    padding: var(--spacing-lg);
}

/* ============================================
   Utilities
   ============================================ */
.hidden {
    display: none !important;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* ============================================
   Responsive Design
   ============================================ */
@media (min-width: 768px) {
    .product-feed {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: var(--spacing-lg);
    }
}

@media (min-width: 1024px) {
    :root {
        --max-content-width: 1000px;
    }
    
    .product-feed {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ============================================
   Dark Mode Support
   ============================================ */
@media (prefers-color-scheme: dark) {
    :root {
        --color-gray-100: #171717;
        --color-gray-200: #262626;
        --color-gray-300: #404040;
        --color-gray-400: #525252;
        --color-gray-500: #737373;
        --color-gray-600: #A3A3A3;
        --color-gray-700: #D4D4D4;
        --color-gray-800: #E5E5E5;
        --color-gray-900: #F7F7F7;
    }
    
    body {
        background-color: var(--color-dark);
        color: var(--color-gray-100);
    }
    
    .app-header,
    .bottom-nav,
    .product-card,
    .modal-content,
    .consent-banner {
        background: var(--color-gray-900);
    }
}

/* ============================================
   Accessibility
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Focus Styles */
*:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
    :root {
        --color-primary: #FF0040;
        --color-gray-200: #000000;
        --color-gray-700: #FFFFFF;
    }
}