/* CSS Variables */
:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a26;
    --bg-card: #16161f;
    --bg-hover: #1e1e2a;
    
    --text-primary: #f0f0f5;
    --text-secondary: #8888a0;
    --text-muted: #55556a;
    
    --accent: #6366f1;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --accent-soft: rgba(99, 102, 241, 0.15);
    
    --success: #22c55e;
    --success-soft: rgba(34, 197, 94, 0.15);
    
    --danger: #ef4444;
    --danger-soft: rgba(239, 68, 68, 0.2);
    
    --gift-accent: #f472b6;
    --gift-soft: rgba(244, 114, 182, 0.15);
    
    --border: rgba(255, 255, 255, 0.06);
    --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
    
    --safe-top: env(safe-area-inset-top);
    --safe-bottom: env(safe-area-inset-bottom);
    --safe-left: env(safe-area-inset-left);
    --safe-right: env(safe-area-inset-right);
    
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-spring: 400ms cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}

html {
    font-size: 16px;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: 'DM Sans', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.5;
    overflow: hidden;
    position: fixed;
    width: 100%;
    height: 100%;
    overscroll-behavior: none;
}

/* App Container */
.app {
    display: flex;
    flex-direction: column;
    height: 100%;
    max-width: 500px;
    margin: 0 auto;
    background: var(--bg-primary);
    position: relative;
}

/* Header */
.header {
    padding: calc(var(--safe-top) + 16px) 20px 12px;
    background: linear-gradient(to bottom, var(--bg-secondary), var(--bg-primary));
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    z-index: 10;
}

.header-title {
    font-size: 1.75rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-count {
    font-size: 0.875rem;
    color: var(--text-secondary);
    background: var(--bg-tertiary);
    padding: 6px 12px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
}

.header-count span {
    font-weight: 600;
    color: var(--accent);
}

/* Tab Navigation */
.tabs {
    display: flex;
    padding: 4px;
    margin: 8px 16px 0;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    position: relative;
    border: 1px solid var(--border);
}

.tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 16px;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-family: inherit;
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: color var(--transition-fast);
    position: relative;
    z-index: 2;
}

.tab.active {
    color: var(--text-primary);
}

.tab-icon {
    font-size: 1.125rem;
}

.tab-indicator {
    position: absolute;
    top: 4px;
    left: 4px;
    width: calc(50% - 4px);
    height: calc(100% - 8px);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    transition: transform var(--transition-smooth);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    z-index: 1;
}

.tabs[data-active="gifts"] .tab-indicator {
    transform: translateX(100%);
}

/* Content Area */
.content {
    flex: 1;
    overflow: hidden;
    position: relative;
    margin-top: 8px;
}

.lists-container {
    display: flex;
    width: 200%;
    height: 100%;
    transition: transform var(--transition-smooth);
}

.lists-container.show-gifts {
    transform: translateX(-50%);
}

.list-panel {
    width: 50%;
    height: 100%;
    overflow-y: auto;
    overflow-x: hidden;
    padding: 8px 16px;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior: contain;
}

/* Item List */
.item-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 8px;
    padding-bottom: 100px;
}

/* List Item */
.list-item {
    position: relative;
    overflow: hidden;
    border-radius: var(--radius-md);
    background: var(--bg-card);
    border: 1px solid var(--border);
    transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.list-item.removing {
    animation: removeItem 300ms ease-out forwards;
}

@keyframes removeItem {
    0% {
        transform: translateX(0);
        opacity: 1;
        max-height: 80px;
        margin-bottom: 8px;
    }
    50% {
        transform: translateX(-100%);
        opacity: 0;
    }
    100% {
        transform: translateX(-100%);
        opacity: 0;
        max-height: 0;
        margin-bottom: 0;
        padding: 0;
        border: none;
    }
}

.list-item.adding {
    animation: addItem 400ms var(--transition-spring) forwards;
}

@keyframes addItem {
    0% {
        transform: translateY(-20px) scale(0.95);
        opacity: 0;
    }
    100% {
        transform: translateY(0) scale(1);
        opacity: 1;
    }
}

/* Delete Background */
.item-delete-bg {
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg, transparent 0%, var(--danger) 50%, var(--danger) 100%);
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 20px;
    color: white;
    font-weight: 500;
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.list-item.swiping .item-delete-bg {
    opacity: 1;
}

.delete-icon {
    font-size: 1.25rem;
}

/* Item Content */
.item-content {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 16px;
    background: var(--bg-card);
    position: relative;
    z-index: 1;
    transition: transform var(--transition-fast), background var(--transition-fast);
    touch-action: pan-y;
}

.list-item.swiping .item-content {
    transition: none;
}

/* Checkbox */
.item-checkbox {
    position: relative;
    width: 24px;
    height: 24px;
    flex-shrink: 0;
}

.item-checkbox input {
    position: absolute;
    opacity: 0;
    width: 100%;
    height: 100%;
    cursor: pointer;
    z-index: 1;
}

.checkbox-visual {
    position: absolute;
    inset: 0;
    border: 2px solid var(--text-muted);
    border-radius: 50%;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.checkbox-visual svg {
    width: 14px;
    height: 14px;
    stroke: white;
    stroke-width: 3;
    opacity: 0;
    transform: scale(0.5);
    transition: all var(--transition-spring);
}

.item-checkbox input:checked + .checkbox-visual {
    background: var(--success);
    border-color: var(--success);
}

.item-checkbox input:checked + .checkbox-visual svg {
    opacity: 1;
    transform: scale(1);
}

/* Item Text Container */
.item-text-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 4px;
    min-width: 0;
}

.item-text {
    font-size: 1rem;
    color: var(--text-primary);
    transition: all var(--transition-fast);
    word-break: break-word;
}

.item-description {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.4;
    word-break: break-word;
}

.list-item.completed .item-text {
    color: var(--text-muted);
    text-decoration: line-through;
    text-decoration-color: var(--text-muted);
}

.list-item.completed .item-description {
    color: var(--text-muted);
    opacity: 0.7;
}

/* Edit Button */
.item-edit-btn {
    width: 36px;
    height: 36px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    border-radius: var(--radius-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    transition: all var(--transition-fast);
    margin-left: 8px;
}

.item-edit-btn:active {
    background: var(--bg-hover);
    color: var(--text-secondary);
    transform: scale(0.9);
}

/* Gift styling */
.list-panel[data-category="gifts"] .item-checkbox input:checked + .checkbox-visual {
    background: var(--gift-accent);
    border-color: var(--gift-accent);
}

/* Add Item Container */
.add-item-container {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: 12px 16px calc(var(--safe-bottom) + 12px);
    background: linear-gradient(to top, var(--bg-primary) 70%, transparent);
    max-width: 500px;
    margin: 0 auto;
}

.add-item-form {
    display: flex;
    gap: 10px;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 6px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}

.add-item-input {
    flex: 1;
    background: transparent;
    border: none;
    padding: 12px 14px;
    font-family: inherit;
    font-size: 1rem;
    color: var(--text-primary);
    outline: none;
}

.add-item-input::placeholder {
    color: var(--text-muted);
}

.add-item-btn {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: var(--accent);
    border: none;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

.add-item-btn:active {
    transform: scale(0.92);
    background: #5558e3;
}

.add-item-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

/* Gift mode button color */
.app[data-category="gifts"] .add-item-btn {
    background: var(--gift-accent);
}

.app[data-category="gifts"] .add-item-btn:active {
    background: #e255a3;
}

/* Delete hint overlay */
.delete-hint {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%) scale(0.9);
    background: var(--danger);
    color: white;
    padding: 16px 24px;
    border-radius: var(--radius-lg);
    font-weight: 600;
    opacity: 0;
    pointer-events: none;
    transition: all var(--transition-fast);
    z-index: 1000;
    box-shadow: 0 8px 32px rgba(239, 68, 68, 0.4);
}

.delete-hint.visible {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
}

/* Empty State */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 60px 20px;
    text-align: center;
    color: var(--text-muted);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: 16px;
    opacity: 0.5;
}

.empty-state-text {
    font-size: 1rem;
}

/* Loading state */
.loading {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
}

.loading-spinner {
    width: 32px;
    height: 32px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* Completed section */
.completed-divider {
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 20px 0 12px;
    color: var(--text-muted);
    font-size: 0.8125rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.completed-divider::before,
.completed-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border);
}

/* Scrollbar */
.list-panel::-webkit-scrollbar {
    width: 4px;
}

.list-panel::-webkit-scrollbar-track {
    background: transparent;
}

.list-panel::-webkit-scrollbar-thumb {
    background: var(--text-muted);
    border-radius: 2px;
}

/* Touch feedback */
@media (hover: hover) {
    .list-item:hover .item-content {
        background: var(--bg-hover);
    }
    
    .tab:hover:not(.active) {
        color: var(--text-primary);
    }
}

/* Edit Modal */
.edit-modal {
    position: fixed;
    inset: 0;
    z-index: 2000;
    display: flex;
    align-items: flex-end;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-smooth), visibility var(--transition-smooth);
}

.edit-modal.visible {
    opacity: 1;
    visibility: visible;
}

.edit-modal-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    -webkit-backdrop-filter: blur(4px);
}

.edit-modal-content {
    position: relative;
    width: 100%;
    max-width: 500px;
    background: var(--bg-secondary);
    border-radius: var(--radius-xl) var(--radius-xl) 0 0;
    padding: 20px;
    padding-bottom: calc(var(--safe-bottom) + 20px);
    transform: translateY(100%);
    transition: transform var(--transition-smooth);
    border: 1px solid var(--border);
    border-bottom: none;
}

.edit-modal.visible .edit-modal-content {
    transform: translateY(0);
}

.edit-modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
}

.edit-modal-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.edit-modal-close {
    width: 40px;
    height: 40px;
    border: none;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
}

.edit-modal-close:active {
    background: var(--bg-hover);
    transform: scale(0.9);
}

.edit-modal-form {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.edit-field {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.edit-field label {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.edit-field input,
.edit-field textarea {
    width: 100%;
    padding: 14px 16px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 1rem;
    color: var(--text-primary);
    outline: none;
    transition: border-color var(--transition-fast);
    resize: none;
}

.edit-field input:focus,
.edit-field textarea:focus {
    border-color: var(--accent);
}

.edit-field input::placeholder,
.edit-field textarea::placeholder {
    color: var(--text-muted);
}

.edit-modal-save {
    width: 100%;
    padding: 16px;
    background: var(--accent);
    border: none;
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 1rem;
    font-weight: 600;
    color: white;
    cursor: pointer;
    transition: all var(--transition-fast);
    margin-top: 8px;
}

.edit-modal-save:active {
    background: #5558e3;
    transform: scale(0.98);
}

/* Gift mode modal button */
.app[data-category="gifts"] .edit-modal-save {
    background: var(--gift-accent);
}

.app[data-category="gifts"] .edit-modal-save:active {
    background: #e255a3;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
    }
}