/* ==========================================================================
   CSS Variables & Theming
   ========================================================================== */
:root[data-theme="dark"] {
    --clr-bg-main: #0f172a; /* Slate 900 */
    --clr-bg-card: rgba(30, 41, 59, 0.6); /* Slate 800 Glass */
    --clr-bg-input: rgba(15, 23, 42, 0.8);
    --clr-bg-hover: rgba(51, 65, 85, 0.5); /* Slate 700 */
    
    --clr-primary: #3b82f6; /* Blue 500 */
    --clr-primary-hover: #2563eb;
    --clr-success: #10b981; /* Emerald 500 */
    --clr-success-hover: #059669;
    --clr-danger: #ef4444; /* Red 500 */
    
    --clr-text-main: #f8fafc; /* Slate 50 */
    --clr-text-muted: #94a3b8; /* Slate 400 */
    
    --clr-border: rgba(255, 255, 255, 0.1);
    --clr-border-highlight: rgba(255, 255, 255, 0.2);
    
    --shadow-glass: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.2);
    
    --bg-gradient-1: rgba(59, 130, 246, 0.15);
    --bg-gradient-2: rgba(16, 185, 129, 0.15);
}

:root[data-theme="light"] {
    --clr-bg-main: #f1f5f9; /* Slate 100 */
    --clr-bg-card: rgba(255, 255, 255, 0.7); /* White Glass */
    --clr-bg-input: rgba(241, 245, 249, 0.8);
    --clr-bg-hover: rgba(226, 232, 240, 0.6); /* Slate 200 */
    
    --clr-primary: #2563eb; /* Blue 600 */
    --clr-primary-hover: #1d4ed8;
    --clr-success: #059669; /* Emerald 600 */
    --clr-success-hover: #047857;
    --clr-danger: #dc2626; /* Red 600 */
    
    --clr-text-main: #0f172a; /* Slate 900 */
    --clr-text-muted: #64748b; /* Slate 500 */
    
    --clr-border: rgba(0, 0, 0, 0.08);
    --clr-border-highlight: rgba(0, 0, 0, 0.15);
    
    --shadow-glass: 0 8px 32px 0 rgba(30, 41, 59, 0.1);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    
    --bg-gradient-1: rgba(59, 130, 246, 0.08);
    --bg-gradient-2: rgba(16, 185, 129, 0.08);
}

:root {
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==========================================================================
   Global Resets & Structure
   ========================================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--clr-bg-main);
    color: var(--clr-text-main);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 2rem 1rem;
    overflow-x: hidden;
    transition: background-color 0.4s ease, color 0.4s ease;
}

.app-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    background-image: 
        radial-gradient(circle at 15% 10%, var(--bg-gradient-1) 0px, transparent 40%),
        radial-gradient(circle at 85% 90%, var(--bg-gradient-2) 0px, transparent 40%);
    transition: opacity 0.4s ease;
}

.app-container {
    width: 100%;
    max-width: 900px;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* ==========================================================================
   Typography & Header
   ========================================================================== */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 0.5rem;
}

.header-left .logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.75rem;
    font-weight: 700;
}

.logo i {
    color: var(--clr-primary);
    background: linear-gradient(135deg, var(--clr-primary), var(--clr-success));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.global-stats {
    animation: fadeIn 0.4s ease;
}

.stat-badge {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--clr-bg-card);
    border: 1px solid var(--clr-border);
    padding: 0.5rem 1rem;
    border-radius: 999px;
    font-size: 0.9rem;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
}

.stat-badge i {
    color: var(--clr-success);
}

/* ==========================================================================
   UI Components
   ========================================================================== */
.card {
    background: var(--clr-bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--clr-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-glass);
    padding: 1.5rem;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.hidden {
    display: none !important;
}

/* Buttons */
button, .btn-primary, .btn-success, .btn-danger {
    font-family: inherit;
    font-weight: 500;
    border: none;
    border-radius: var(--radius-md);
    padding: 0.75rem 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 1rem;
}

.btn-primary { background: var(--clr-primary); color: white; }
.btn-primary:hover { background: var(--clr-primary-hover); transform: translateY(-2px); box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3); }

.btn-success { background: var(--clr-success); color: white; }
.btn-success:hover:not(:disabled) { background: var(--clr-success-hover); transform: translateY(-2px); box-shadow: 0 4px 12px rgba(16, 185, 129, 0.3); }

.btn-success:disabled, .btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.btn-full { width: 100%; }

.btn-icon {
    background: transparent;
    color: var(--clr-text-main);
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--clr-border);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
}

.btn-icon:hover {
    background: var(--clr-bg-hover);
    border-color: var(--clr-border-highlight);
}

.btn-danger { color: #fff; background: var(--clr-danger); border: none; }
.btn-danger:hover { filter: brightness(1.1); }

/* ==========================================================================
   Upload Section (Drag & Drop)
   ========================================================================== */
.upload-section {
    animation: fadeIn 0.5s ease;
}

.drop-zone {
    border: 2px dashed var(--clr-border);
    border-radius: var(--radius-lg);
    background: rgba(0, 0, 0, 0.05);
    padding: 4rem 2rem;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    outline: none;
}

.drop-zone:focus-visible {
    border-color: var(--clr-primary);
    box-shadow: 0 0 0 4px rgba(59, 130, 246, 0.2);
}

.drop-zone.dragover, .drop-zone:hover {
    border-color: var(--clr-primary);
    background: rgba(59, 130, 246, 0.05);
}

.drop-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    pointer-events: none;
}

.upload-icon-wrapper {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: rgba(59, 130, 246, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    color: var(--clr-primary);
    margin-bottom: 0.5rem;
}

.drop-content h3 { font-size: 1.5rem; font-weight: 600; }
.drop-content p { color: var(--clr-text-muted); }
.drop-content .btn-primary { pointer-events: auto; margin-top: 0.5rem; }
.file-limits { font-size: 0.85rem; margin-top: 1rem; }

/* ==========================================================================
   Workspace Section (Queue & Controls)
   ========================================================================== */
.workspace-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    animation: fadeIn 0.5s ease;
}

.controls-panel {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
    gap: 2rem;
    padding: 1rem 1.5rem;
}

.control-header h3 { font-size: 1.1rem; }

.quality-slider-container {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    max-width: 400px;
    width: 100%;
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    font-size: 0.9rem;
    color: var(--clr-text-muted);
}

.quality-value { color: var(--clr-primary); font-weight: 600; }

.slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    border-radius: 3px;
    background: var(--clr-bg-input);
    outline: none;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: var(--clr-primary);
    cursor: pointer;
    transition: transform 0.2s;
}

.slider::-webkit-slider-thumb:hover { transform: scale(1.2); }

.action-buttons {
    display: flex;
    gap: 0.75rem;
}

/* Queue List */
.queue-container { padding: 0; overflow: hidden; }

.queue-header {
    display: flex;
    justify-content: space-between;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--clr-border);
    background: rgba(0,0,0,0.02);
}

.queue-count {
    color: var(--clr-text-muted);
    font-size: 0.9rem;
    font-weight: 500;
}

.queue-list {
    max-height: 500px;
    overflow-y: auto;
}

/* Custom Scrollbar */
.queue-list::-webkit-scrollbar { width: 8px; }
.queue-list::-webkit-scrollbar-track { background: transparent; }
.queue-list::-webkit-scrollbar-thumb { background: var(--clr-border-highlight); border-radius: 4px; }

/* Queue Item */
.queue-item {
    display: grid;
    grid-template-columns: auto auto 1fr auto auto;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--clr-border);
    transition: background 0.2s ease;
    cursor: pointer;
}

.queue-item:hover {
    background: var(--clr-bg-hover);
}

.queue-item:last-child { border-bottom: none; }

.drag-handle {
    cursor: grab;
    color: var(--clr-text-muted);
    font-size: 1.25rem;
    padding: 0.5rem;
}
.drag-handle:active { cursor: grabbing; }

.item-thumbnail {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-sm);
    object-fit: cover;
    background: var(--clr-bg-input);
    border: 1px solid var(--clr-border);
}

.item-details {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    min-width: 0; /* allows truncation */
}

.item-name {
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.item-meta {
    font-size: 0.85rem;
    color: var(--clr-text-muted);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.item-progress {
    width: 100px;
    height: 6px;
    background: var(--clr-bg-input);
    border-radius: 3px;
    overflow: hidden;
    display: none;
}
.item-progress .bar {
    height: 100%;
    background: var(--clr-primary);
    width: 0%;
    transition: width 0.3s;
}
.queue-item.compressing .item-progress { display: block; }
.queue-item.compressing .item-meta { display: none; }

.item-savings {
    font-size: 0.9rem;
    font-weight: 600;
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
}

.savings-positive { color: var(--clr-success); background: rgba(16, 185, 129, 0.1); }
.savings-neutral { color: var(--clr-text-muted); background: var(--clr-bg-input); }
.savings-negative { color: var(--clr-danger); background: rgba(239, 68, 68, 0.1); }

.item-actions button {
    background: transparent;
    border: none;
    color: var(--clr-text-muted);
    font-size: 1.25rem;
    padding: 0.5rem;
    cursor: pointer;
    transition: color 0.2s;
}
.item-actions button:hover { color: var(--clr-danger); }

/* ==========================================================================
   Image Comparison Modal
   ========================================================================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(5px);
    z-index: 100;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    animation: fadeIn 0.3s ease;
}

.modal-content {
    width: 100%;
    max-width: 900px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    padding: 0;
    overflow: hidden;
    background: var(--clr-bg-main);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--clr-border);
}

.modal-header h3 {
    font-weight: 600;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.modal-body {
    padding: 1.5rem;
    flex: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.comparison-stats {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.stat-pill {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 999px;
    font-size: 0.9rem;
    background: var(--clr-bg-input);
    border: 1px solid var(--clr-border);
}

.stat-pill .label { color: var(--clr-text-muted); }
.stat-pill.success { border-color: var(--clr-success); }
.stat-pill.success strong { color: var(--clr-success); }
.stat-pill .savings {
    font-size: 0.8rem;
    background: var(--clr-success);
    color: white;
    padding: 0.1rem 0.4rem;
    border-radius: 4px;
}

/* Before/After Slider */
.image-compare-container {
    position: relative;
    width: 100%;
    height: 50vh;
    min-height: 300px;
    background: repeating-conic-gradient(var(--clr-bg-input) 0% 25%, transparent 0% 50%) 50% / 20px 20px;
    border-radius: var(--radius-md);
    overflow: hidden;
    user-select: none;
    border: 1px solid var(--clr-border);
}

.compare-img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;
}

.compare-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 50%;
    height: 100%;
    overflow: hidden;
}

.compare-overlay img {
    width: 200%; /* Important for slider aspect */
    max-width: none;
}

.compare-slider-handle {
    position: absolute;
    top: 0;
    left: 50%;
    width: 40px;
    height: 100%;
    transform: translateX(-50%);
    cursor: ew-resize;
    z-index: 10;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.handle-line {
    position: absolute;
    width: 2px;
    height: 100%;
    background: white;
    box-shadow: 0 0 5px rgba(0,0,0,0.5);
}

.handle-button {
    position: relative;
    width: 40px;
    height: 40px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #0f172a;
    box-shadow: 0 2px 10px rgba(0,0,0,0.3);
    font-size: 1.2rem;
    gap: 2px;
}

.modal-footer {
    padding: 1.5rem;
    border-top: 1px solid var(--clr-border);
    display: flex;
    justify-content: flex-end;
}

/* ==========================================================================
   Toast Notifications
   ========================================================================== */
.toast-container {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    z-index: 1000;
}

.toast {
    background: var(--clr-bg-card);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--clr-border);
    border-radius: var(--radius-md);
    padding: 1rem 1.5rem;
    color: var(--clr-text-main);
    box-shadow: var(--shadow-glass);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    animation: slideIn 0.3s ease forwards;
    max-width: 350px;
}

.toast-error { border-left: 4px solid var(--clr-danger); }
.toast-error i { color: var(--clr-danger); }
.toast-success { border-left: 4px solid var(--clr-success); }
.toast-success i { color: var(--clr-success); }
.toast-info { border-left: 4px solid var(--clr-primary); }
.toast-info i { color: var(--clr-primary); }
.toast.fade-out { animation: slideOut 0.3s ease forwards; }

/* ==========================================================================
   Animations & Responsive
   ========================================================================== */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideIn { from { opacity: 0; transform: translateX(100%); } to { opacity: 1; transform: translateX(0); } }
@keyframes slideOut { from { opacity: 1; transform: translateX(0); } to { opacity: 0; transform: translateX(100%); } }
@keyframes spin { 100% { transform: rotate(360deg); } }

@media (max-width: 768px) {
    .controls-panel {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .action-buttons {
        width: 100%;
        display: grid;
        grid-template-columns: 1fr auto;
    }
    
    .queue-item {
        grid-template-columns: auto auto 1fr auto;
        padding: 1rem;
    }
    .item-savings { display: none; } /* Hide on small mobile to save space */
    
    .comparison-stats { flex-direction: column; gap: 0.5rem; align-items: stretch; }
    .stat-pill { justify-content: space-between; }
}