/* ============================
   CSS Variables & Reset
   ============================ */
:root {
    --sidebar-width: 220px;
    --primary: #7c3aed;
    --primary-light: #a78bfa;
    --primary-dark: #5b21b6;
    --primary-bg: #f5f3ff;
    --bg: #f8f9fa;
    --bg-white: #ffffff;
    --text: #1a1a2e;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --border: #e5e7eb;
    --border-light: #f0f0f0;
    --success: #10b981;
    --success-bg: #ecfdf5;
    --danger: #ef4444;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -1px rgba(0,0,0,0.04);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.03);
    --radius: 12px;
    --radius-sm: 8px;
    --transition: all 0.2s ease;
    --sidebar-bg: #1e1b3a;
    --sidebar-hover: #2d2a4a;
    --sidebar-active: #7c3aed;
    --sidebar-text: #c4b5fd;
    --sidebar-text-active: #ffffff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    display: flex;
}

/* ============================
   Sidebar
   ============================ */
.sidebar {
    width: var(--sidebar-width);
    min-width: var(--sidebar-width);
    background: var(--sidebar-bg);
    color: var(--sidebar-text);
    display: flex;
    flex-direction: column;
    height: 100vh;
    position: fixed;
    left: 0;
    top: 0;
    z-index: 100;
    transition: transform 0.3s ease;
}

.sidebar-header {
    padding: 20px 16px;
    border-bottom: 1px solid rgba(255,255,255,0.08);
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 18px;
    font-weight: 700;
    color: #fff;
}

.logo svg {
    flex-shrink: 0;
}

.sidebar-nav {
    flex: 1;
    padding: 12px 8px;
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.nav-btn {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 14px;
    border: none;
    background: transparent;
    color: var(--sidebar-text);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition);
    width: 100%;
    text-align: left;
    font-family: inherit;
}

.nav-btn:hover {
    background: var(--sidebar-hover);
    color: #fff;
}

.nav-btn.active {
    background: var(--sidebar-active);
    color: var(--sidebar-text-active);
    box-shadow: 0 2px 8px rgba(124,58,237,0.4);
}

.nav-btn svg {
    flex-shrink: 0;
    opacity: 0.8;
}

.nav-btn.active svg {
    opacity: 1;
}

.sidebar-footer {
    padding: 16px;
    border-top: 1px solid rgba(255,255,255,0.08);
}

.server-status {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 12px;
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--text-muted);
}

.status-dot.online {
    background: var(--success);
    box-shadow: 0 0 6px rgba(16,185,129,0.5);
}

.status-dot.offline {
    background: var(--danger);
}

.status-text {
    color: var(--sidebar-text);
    opacity: 0.7;
}

/* ============================
   Main Content
   ============================ */
.main-content {
    margin-left: var(--sidebar-width);
    flex: 1;
    display: flex;
    flex-direction: column;
    height: 100vh;
    overflow: hidden;
}

/* ============================
   Top Bar
   ============================ */
.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 32px;
    background: var(--bg-white);
    border-bottom: 1px solid var(--border);
    min-height: 64px;
}

.top-bar-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

.tool-title {
    font-size: 20px;
    font-weight: 600;
    color: var(--text);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
    color: var(--text);
}

.lang-selector {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 6px 12px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.lang-selector:hover {
    background: var(--bg);
}

/* ============================
   Tool Panels
   ============================ */
.tool-panel {
    display: none;
    flex: 1;
    padding: 32px;
    overflow-y: auto;
}

.tool-panel.active {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.panel-header {
    text-align: center;
    padding-bottom: 8px;
}

.panel-header h2 {
    font-size: 28px;
    font-weight: 700;
    color: var(--text);
    margin-bottom: 8px;
}

.panel-header p {
    font-size: 15px;
    color: var(--text-secondary);
}

/* ============================
   Upload Zone
   ============================ */
.upload-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 48px 32px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    background: var(--bg-white);
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
}

.upload-zone:hover {
    border-color: var(--primary);
    background: var(--primary-bg);
}

.upload-zone.drag-over {
    border-color: var(--primary);
    background: var(--primary-bg);
    transform: scale(1.01);
}

.upload-icon {
    margin-bottom: 16px;
}

.upload-text {
    font-size: 16px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 4px;
}

.upload-hint {
    font-size: 14px;
    color: var(--primary);
    font-weight: 500;
    margin-bottom: 12px;
}

.upload-formats {
    font-size: 12px;
    color: var(--text-muted);
}

/* ============================
   Processing Area
   ============================ */
.processing-area {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 24px;
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
    box-shadow: var(--shadow-sm);
}

.processing-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.processing-filename {
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
}

.processing-status {
    font-size: 13px;
    color: var(--primary);
    font-weight: 500;
}

.progress-bar {
    height: 6px;
    background: var(--border-light);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 16px;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--primary-light));
    border-radius: 3px;
    width: 0%;
    transition: width 0.3s ease;
}

.btn-cancel {
    background: none;
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-cancel:hover {
    border-color: var(--danger);
    color: var(--danger);
}

/* ============================
   Result Area
   ============================ */
.result-area {
    max-width: 700px;
    margin: 0 auto;
    width: 100%;
}

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

.result-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.result-header h3 {
    font-size: 20px;
    font-weight: 600;
    color: var(--success);
    display: flex;
    align-items: center;
    gap: 8px;
}

.result-header h3::before {
    content: '✓';
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    background: var(--success);
    color: white;
    border-radius: 50%;
    font-size: 14px;
}

.btn-restart {
    display: flex;
    align-items: center;
    gap: 6px;
    background: none;
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-restart:hover {
    border-color: var(--primary);
    color: var(--primary);
}

/* ============================
   Track Cards
   ============================ */
.result-tracks {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.track-card {
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--bg-white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 20px;
    transition: var(--transition);
}

.track-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary-light);
}

.track-icon {
    width: 44px;
    height: 44px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.vocal-icon {
    background: #ede9fe;
    color: var(--primary);
}

.music-icon {
    background: #ecfdf5;
    color: var(--success);
}

.drum-icon {
    background: #fff7ed;
    color: #f97316;
}

.bass-icon {
    background: #eff6ff;
    color: #3b82f6;
}

.piano-icon {
    background: #fef2f2;
    color: #ef4444;
}

.other-icon {
    background: #f0fdf4;
    color: #22c55e;
}

.track-info {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.track-label {
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
    display: block;
}

.track-waveform {
    height: 32px;
    background: var(--bg);
    border-radius: 4px;
    position: relative;
    overflow: hidden;
}

.track-waveform canvas {
    width: 100%;
    height: 100%;
}

.track-controls {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-shrink: 0;
}

.track-volume-control {
    display: flex;
    align-items: center;
    gap: 10px;
    min-width: 0;
}

.track-volume-label {
    font-size: 12px;
    color: var(--text-secondary);
    white-space: nowrap;
    flex-shrink: 0;
}

.track-volume {
    flex: 1;
    min-width: 120px;
    accent-color: var(--primary);
}

.track-volume-value {
    width: 44px;
    text-align: right;
    font-size: 12px;
    color: var(--text-secondary);
    flex-shrink: 0;
}

.btn-play {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: none;
    background: var(--primary);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.btn-play:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.btn-play.playing {
    background: var(--danger);
}

.btn-download {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 8px 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-white);
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-download:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--primary-bg);
}

/* ============================
   Engine Selector
   ============================ */
.engine-selector {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
    padding: 16px;
    background: var(--bg-white);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}

.engine-label {
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    white-space: nowrap;
}

.engine-option {
    cursor: pointer;
    flex: 1;
}

.engine-option input {
    display: none;
}

.engine-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    padding: 10px 16px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    transition: var(--transition);
    background: var(--bg);
}

.engine-option input:checked + .engine-card {
    border-color: var(--primary);
    background: var(--primary-bg);
    box-shadow: 0 0 0 1px var(--primary);
}

.engine-card:hover {
    border-color: var(--primary-light);
}

.engine-name {
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
}

.engine-desc {
    font-size: 12px;
    color: var(--text-muted);
}

/* ============================
   Splitter Mode Cards
   ============================ */
.splitter-modes {
    display: flex;
    gap: 16px;
    justify-content: center;
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
}

.mode-option {
    flex: 1;
    cursor: pointer;
}

.mode-option input {
    display: none;
}

.mode-card {
    background: var(--bg-white);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 16px;
    text-align: center;
    transition: var(--transition);
}

.mode-option input:checked + .mode-card {
    border-color: var(--primary);
    background: var(--primary-bg);
    box-shadow: 0 0 0 1px var(--primary);
}

.mode-card:hover {
    border-color: var(--primary-light);
}

.mode-icon {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--primary-bg);
    color: var(--primary);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 8px;
}

.mode-name {
    display: block;
    font-size: 15px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 4px;
}

.mode-desc {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
}

/* ============================
   Cutter Workspace
   ============================ */
.cutter-workspace {
    background: var(--bg-white);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    max-width: 800px;
    margin: 0 auto;
    width: 100%;
}

.cutter-player {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 20px;
}

.player-controls {
    display: flex;
    gap: 8px;
}

.btn-transport {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    border: none;
    background: var(--primary);
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.btn-transport:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.time-display {
    font-size: 14px;
    color: var(--text-secondary);
    font-variant-numeric: tabular-nums;
    letter-spacing: 0.5px;
}

/* Waveform Container */
.waveform-container {
    position: relative;
    height: 120px;
    background: var(--bg);
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin-bottom: 16px;
    border: 1px solid var(--border-light);
}

.waveform-container canvas {
    width: 100%;
    height: 100%;
}

.selection-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 24px;
    pointer-events: none;
}

.selection-region {
    position: absolute;
    top: 0;
    bottom: 0;
    background: rgba(124, 58, 237, 0.15);
    border-left: 2px solid var(--primary);
    border-right: 2px solid var(--primary);
}

.selection-handle {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 10px;
    cursor: ew-resize;
    pointer-events: all;
    z-index: 2;
}

.selection-handle::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 4px;
    height: 24px;
    background: var(--primary);
    border-radius: 2px;
}

.left-handle {
    left: -5px;
}

.right-handle {
    right: -5px;
}

.time-ruler {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 24px;
    background: rgba(0,0,0,0.03);
    border-top: 1px solid var(--border-light);
    display: flex;
    align-items: center;
    padding: 0 8px;
    font-size: 10px;
    color: var(--text-muted);
}

/* ============================
   Selection Info
   ============================ */
.selection-info {
    text-align: center;
    font-size: 13px;
    color: var(--text-secondary);
    margin-bottom: 12px;
    padding: 8px;
    background: var(--primary-bg);
    border-radius: var(--radius-sm);
    font-variant-numeric: tabular-nums;
}

/* ============================
   Fade Controls
   ============================ */
.fade-controls {
    display: flex;
    gap: 24px;
    margin-bottom: 16px;
}

.fade-option {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    color: var(--text-secondary);
    cursor: pointer;
}

.fade-option input[type="checkbox"] {
    accent-color: var(--primary);
}

.fade-option input[type="range"] {
    width: 80px;
    accent-color: var(--primary);
}

.fade-option input[type="range"]:disabled {
    opacity: 0.4;
}

.fade-value {
    font-size: 12px;
    min-width: 30px;
    font-variant-numeric: tabular-nums;
}

/* Output Options */
.output-options {
    display: flex;
    gap: 16px;
    margin-bottom: 20px;
}

.output-options > div {
    flex: 1;
}

.output-options label {
    display: block;
    font-size: 12px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.output-options select {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 13px;
    color: var(--text);
    background: var(--bg-white);
    font-family: inherit;
    cursor: pointer;
}

/* Cutter Actions */
.cutter-actions {
    display: flex;
    gap: 12px;
    justify-content: flex-end;
}

.btn-primary {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 24px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

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

.btn-secondary {
    padding: 10px 24px;
    background: none;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
}

.btn-secondary:hover {
    border-color: var(--text-secondary);
    color: var(--text);
}

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

/* ============================
   Responsive
   ============================ */
@media (max-width: 768px) {
    .sidebar {
        transform: translateX(-100%);
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .main-content {
        margin-left: 0;
    }

    .mobile-menu-btn {
        display: block;
    }

    .tool-panel {
        padding: 20px 16px;
    }

    .splitter-modes {
        flex-direction: column;
    }

    .upload-zone {
        padding: 32px 16px;
    }

    .panel-header h2 {
        font-size: 22px;
    }

    .track-card {
        flex-wrap: wrap;
    }

    .track-volume-control {
        width: 100%;
    }

    .output-options {
        flex-direction: column;
    }

    .fade-controls {
        flex-direction: column;
        gap: 12px;
    }
}

/* Scrollbar */
.tool-panel::-webkit-scrollbar {
    width: 6px;
}

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

.tool-panel::-webkit-scrollbar-thumb {
    background: var(--border);
    border-radius: 3px;
}

.tool-panel::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}