/* Design System Variables */
:root {
    /* Dark Theme Default variables */
    --bg-main: #0E1015;
    --bg-sidebar: #131720;
    --bg-surface: #171B26;
    --border-color: #242A38;
    --border-hover: #333B4F;
    
    --primary: #3B82F6;
    --primary-hover: #60A5FA;
    --accent: #10B981;
    --accent-hover: #34D399;
    --danger: #EF4444;
    --danger-hover: #F87171;
    
    --text-primary: #F3F4F6;
    --text-secondary: #9CA3AF;
    
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    --border-radius: 6px;
}

/* Light Theme overrides */
body.light-theme {
    --bg-main: #F9FAFB;
    --bg-sidebar: #F3F4F6;
    --bg-surface: #FFFFFF;
    --border-color: #E5E7EB;
    --border-hover: #D1D5DB;
    
    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --accent: #059669;
    --accent-hover: #047857;
    --danger: #DC2626;
    --danger-hover: #B91C1C;
    
    --text-primary: #111827;
    --text-secondary: #4B5563;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-font-smoothing: antialiased;
}

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-family: var(--font-sans);
    height: 100vh;
    overflow: hidden;
    transition: background-color 0.2s, color 0.2s;
}

/* Layout Framework */
.app-container {
    display: grid;
    grid-template-columns: 260px 1fr;
    height: 100vh;
    width: 100vw;
}

/* Sidebar Navigation */
.sidebar {
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 20px;
    justify-content: space-between;
    transition: background-color 0.2s, border-color 0.2s;
}

.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 30px;
}

.brand-icon {
    font-size: 20px;
    color: var(--primary);
}

.brand h1 {
    font-size: 16px;
    font-weight: 600;
    letter-spacing: -0.2px;
    color: var(--text-primary);
}

.nav-menu {
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex-grow: 1;
}

.nav-item {
    background: transparent;
    border: 1px solid transparent;
    border-radius: var(--border-radius);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-sans);
    font-size: 13px;
    font-weight: 500;
    padding: 10px 14px;
    text-align: left;
    transition: all 0.15s ease;
    width: 100%;
}

.nav-item:hover {
    background: rgba(255, 255, 255, 0.04);
    color: var(--text-primary);
}

body.light-theme .nav-item:hover {
    background: rgba(0, 0, 0, 0.03);
}

.nav-item.active {
    background: var(--bg-surface);
    border-color: var(--border-color);
    color: var(--text-primary);
    font-weight: 600;
}

.ad-placeholder-sidebar {
    background: rgba(0, 0, 0, 0.05);
    border: 1px dashed var(--border-color);
    border-radius: var(--border-radius);
    height: 250px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 16px;
    text-align: center;
}

.ad-label {
    font-size: 10px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    opacity: 0.6;
}

/* Main Panel Layout */
.main-content {
    display: grid;
    grid-template-rows: 64px 1fr 140px;
    height: 100vh;
    overflow: hidden;
}

.top-bar {
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 30px;
    background: var(--bg-surface);
    transition: background-color 0.2s, border-color 0.2s;
}

.active-title-container h2 {
    font-size: 16px;
    font-weight: 600;
}

.active-title-container p {
    color: var(--text-secondary);
    font-size: 12px;
    margin-top: 1px;
}

.top-bar-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

/* Theme Toggle Button styling */
.theme-toggle-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    cursor: pointer;
    font-size: 14px;
    height: 34px;
    width: 34px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.15s ease;
}

.theme-toggle-btn:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--border-hover);
}

body.light-theme .theme-toggle-btn:hover {
    background: rgba(0, 0, 0, 0.03);
}

.audio-status {
    background: rgba(16, 185, 129, 0.08);
    border: 1px solid rgba(16, 185, 129, 0.15);
    border-radius: 4px;
    color: var(--accent);
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 11px;
    font-weight: 500;
    padding: 4px 10px;
}

.status-dot {
    background: var(--accent);
    border-radius: 50%;
    height: 6px;
    width: 6px;
    display: inline-block;
}

/* Stage Area & Grid Layouts */
.tool-stage {
    padding: 30px;
    overflow-y: auto;
}

.tool-pane {
    display: none;
}

.tool-pane.active {
    display: block;
}

.controls-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 24px;
}

.control-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 24px;
    transition: background-color 0.2s, border-color 0.2s;
}

.control-card h3 {
    font-size: 13px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

/* Numeric Readouts & Displays (JetBrains Mono) */
.dial-container {
    display: flex;
    justify-content: center;
    margin: 15px 0;
}

.freq-display {
    font-family: var(--font-mono);
    font-size: 48px;
    font-weight: 700;
    letter-spacing: -1.5px;
    color: var(--text-primary);
}

.freq-display .unit {
    font-family: var(--font-sans);
    font-size: 16px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-left: 2px;
}

/* Hardware-like flat slider */
.slider {
    -webkit-appearance: none;
    width: 100%;
    height: 4px;
    border-radius: 2px;
    background: var(--border-color);
    outline: none;
    margin: 20px 0;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--primary);
    cursor: pointer;
    transition: transform 0.1s;
}

.slider::-webkit-slider-thumb:hover {
    transform: scale(1.15);
}

.quick-presets {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}

.preset-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 12px;
    padding: 8px;
    transition: all 0.15s;
}

.preset-btn:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--border-hover);
}

body.light-theme .preset-btn:hover {
    background: rgba(0, 0, 0, 0.03);
}

.wave-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 8px;
    margin-bottom: 20px;
}

.wave-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-secondary);
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 13px;
    font-weight: 500;
    padding: 10px;
    transition: all 0.15s;
}

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

.wave-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: #FFF;
}

.volume-container h3 {
    margin-top: 10px;
    margin-bottom: 5px;
}

/* Action Buttons */
.action-bar {
    display: flex;
    justify-content: center;
}

.btn {
    border: 1px solid transparent;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 13px;
    font-weight: 600;
    padding: 12px 30px;
    transition: all 0.15s;
}

.btn-primary {
    background: var(--primary);
    color: #FFF;
}

.btn-primary:hover {
    background: var(--primary-hover);
}

.btn-danger {
    background: var(--danger);
    color: #FFF;
}

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

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--border-hover);
}

body.light-theme .btn-secondary:hover {
    background: rgba(0, 0, 0, 0.03);
}

/* Sweep Progress Bar */
.range-inputs {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.input-group label {
    display: block;
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.input-group input {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 14px;
    padding: 8px 12px;
    width: 100%;
    outline: none;
}

.slider-label {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: var(--text-secondary);
}

.sweep-progress-container {
    background: rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    height: 50px;
    margin-bottom: 24px;
    position: relative;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
}

.sweep-progress-bar {
    background: rgba(59, 130, 246, 0.15);
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 0%;
    transition: width 0.1s linear;
}

.sweep-current-freq {
    font-family: var(--font-mono);
    font-size: 15px;
    font-weight: 600;
    position: relative;
    z-index: 10;
}

/* BPM Tapper Panel */
.tapper-layout {
    display: grid;
    grid-template-columns: 1fr 240px;
    gap: 20px;
    margin-bottom: 20px;
}

.tap-area-card {
    border: 1px dashed var(--border-color);
    border-radius: var(--border-radius);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 200px;
    transition: all 0.15s;
    user-select: none;
}

.tap-area-card:hover {
    border-color: var(--primary);
    background: rgba(255, 255, 255, 0.02);
}

body.light-theme .tap-area-card:hover {
    background: rgba(0, 0, 0, 0.01);
}

.tap-instruction {
    font-size: 11px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.bpm-large-display {
    font-family: var(--font-mono);
    font-size: 72px;
    font-weight: 700;
    letter-spacing: -2px;
    margin: 4px 0;
    color: var(--text-primary);
}

.bpm-label {
    font-size: 12px;
    color: var(--text-secondary);
}

.tapper-stats {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.stat-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 16px;
}

.stat-card h4 {
    font-size: 10px;
    color: var(--text-secondary);
    text-transform: uppercase;
    margin-bottom: 4px;
}

.stat-card p {
    font-size: 18px;
    font-weight: 600;
}

.tap-history {
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 16px;
    max-height: 160px;
    overflow-y: auto;
}

.tap-history h3 {
    font-size: 12px;
    color: var(--text-secondary);
    margin-bottom: 10px;
}

.history-list {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.history-list li {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 4px 10px;
    font-size: 12px;
    font-family: var(--font-mono);
}

body.light-theme .history-list li {
    background: rgba(0, 0, 0, 0.03);
}

.history-list .empty-state {
    color: var(--text-secondary);
    font-style: italic;
    background: none;
    border: none;
    padding: 0;
}

/* Tuner Styles */
.tuner-layout {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

.tuner-dial-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    width: 360px;
    padding: 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.tuner-meter {
    background: rgba(0, 0, 0, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 80px 80px 0 0;
    height: 100px;
    width: 220px;
    position: relative;
    overflow: hidden;
}

.tuner-needle {
    background: var(--primary);
    height: 80px;
    width: 1px;
    position: absolute;
    bottom: 0;
    left: 50%;
    transform-origin: bottom center;
    transform: translateX(-50%) rotate(0deg);
    transition: transform 0.15s ease-out;
}

.tuner-center-mark {
    background: var(--accent);
    height: 12px;
    width: 2px;
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
}

.pitch-display {
    margin-top: 20px;
    text-align: center;
}

.note-val {
    font-family: var(--font-mono);
    font-size: 56px;
    font-weight: 700;
    color: var(--text-primary);
}

.cents-val {
    font-size: 13px;
    color: var(--text-secondary);
    margin-top: 2px;
}

/* Bottom Canvas visualizer styles */
.visualizer-bar {
    background: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    display: grid;
    grid-template-rows: 40px 1fr;
    padding: 10px 30px;
}

.visualizer-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.visualizer-header h3 {
    font-size: 12px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
}

.visualizer-options {
    display: flex;
    gap: 4px;
}

.vis-opt-btn {
    background: transparent;
    border: 1px solid transparent;
    border-radius: var(--border-radius);
    color: var(--text-secondary);
    cursor: pointer;
    font-family: var(--font-sans);
    font-size: 11px;
    font-weight: 500;
    padding: 2px 8px;
    transition: all 0.15s;
}

.vis-opt-btn.active {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--border-color);
    color: var(--text-primary);
}

body.light-theme .vis-opt-btn.active {
    background: rgba(0, 0, 0, 0.04);
}

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

#visualizer-canvas {
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
}

/* /* Mobile Drawer Menu Layout (Desktop hidden defaults) */
.menu-toggle-btn {
    display: none;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    cursor: pointer;
    font-size: 16px;
    height: 34px;
    width: 34px;
    align-items: center;
    justify-content: center;
}

.mobile-menu-drawer {
    display: none;
    background: var(--bg-sidebar);
    border-bottom: 1px solid var(--border-color);
    position: absolute;
    top: 52px;
    left: 0;
    width: 100%;
    z-index: 1000;
    flex-direction: column;
    padding: 8px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.mobile-menu-drawer.open {
    display: flex;
}

.mobile-nav-item {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-family: var(--font-sans);
    font-size: 13px;
    font-weight: 500;
    padding: 12px 16px;
    text-align: left;
    width: 100%;
    cursor: pointer;
    border-radius: var(--border-radius);
}

.mobile-nav-item:hover {
    background: rgba(255, 255, 255, 0.03);
    color: var(--text-primary);
}

body.light-theme .mobile-nav-item:hover {
    background: rgba(0, 0, 0, 0.02);
}

.mobile-nav-item.active {
    background: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    font-weight: 600;
}

/* Responsive Mobile Layout */
@media (max-width: 768px) {
    body {
        height: 100dvh;
        overflow: hidden;
    }

    .app-container {
        grid-template-columns: 1fr;
        grid-template-rows: 1fr; /* Single viewport, no bottom nav bar */
        height: 100dvh;
        overflow: hidden;
    }

    .sidebar {
        display: none !important; /* Hide sidebar completely on mobile */
    }

    .main-content {
        grid-row: 1;
        grid-template-rows: 52px 1fr 100px; /* Fixed header, body stage, and visualizer */
        height: 100dvh;
        overflow: hidden;
        position: relative;
    }

    .menu-toggle-btn {
        display: flex; /* Make burger button visible */
    }

    .top-bar {
        grid-row: 1; /* Explicitly place in row 1 */
        padding: 0 16px;
        height: 52px;
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
    }

    .top-bar-left {
        display: flex;
        align-items: center;
        gap: 12px;
    }

    .mobile-menu-drawer {
        position: absolute; /* Take out of grid flow */
        top: 52px;
        left: 0;
        width: 100%;
        z-index: 1000;
    }

    .active-title-container h2 {
        font-size: 14px;
    }

    .active-title-container p {
        display: none; /* Hide subtitle description on mobile header */
    }

    .audio-status {
        font-size: 10px;
        padding: 3px 8px;
    }

    .tool-stage {
        grid-row: 2; /* Explicitly place in row 2 */
        padding: 16px 12px;
        overflow-y: auto;
    }

    .controls-grid {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .control-card {
        padding: 16px;
    }

    .freq-display {
        font-size: 36px;
    }

    .quick-presets {
        grid-template-columns: repeat(4, 1fr);
    }

    .tapper-layout {
        grid-template-columns: 1fr;
        gap: 12px;
    }

    .tap-area-card {
        height: 140px;
    }

    .bpm-large-display {
        font-size: 56px;
    }

    .tuner-dial-card {
        width: 100%;
        padding: 16px;
    }

    .tuner-meter {
        width: 180px;
        height: 80px;
    }

    .tuner-needle {
        height: 65px;
    }

    .note-val {
        font-size: 40px;
    }

    .visualizer-bar {
        grid-row: 3; /* Explicitly place in row 3 */
        padding: 6px 16px;
        grid-template-rows: 24px 1fr;
        height: 100px;
        background: var(--bg-surface);
        z-index: 10;
    }

    .visualizer-header h3 {
        font-size: 10px;
    }

    .vis-opt-btn {
        font-size: 9px;
        padding: 1px 6px;
    }

    .tool-info-section {
        margin-top: 20px;
        padding-top: 16px;
        font-size: 11px;
    }
}