:root {
    --bg-base: #0C0A09;
    --bg-surface: #1C1917;
    --bg-surface-elevated: #292524;
    
    --text-primary: #FAFAF9;
    --text-secondary: #A8A29E;
    
    --primary: #8B5CF6; /* Violets for focus */
    --primary-hover: #7C3AED;
    --secondary: #64748B;
    --accent: #F59E0B; /* Amber for breaks */
    
    --border-radius: 16px;
    --border-radius-pill: 9999px;
    
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;
    
    --transition: 250ms cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    user-select: none;
}

body {
    background-color: var(--bg-base);
    color: var(--text-primary);
    font-family: var(--font-family);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}

/* App Layout */
.app-container {
    width: 100%;
    max-width: 1100px;
    height: 100vh;
    max-height: 800px;
    display: flex;
    flex-direction: column;
    padding: 2rem;
    gap: 2rem;
}

/* Navbar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    color: var(--primary);
    width: 28px;
    height: 28px;
}

.logo h1 {
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: -0.025em;
}

.nav-actions {
    display: flex;
    gap: 1rem;
}

.action-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition);
}

.action-btn:hover {
    color: var(--text-primary);
    background: var(--bg-surface);
}

.action-btn i {
    width: 20px;
    height: 20px;
}

/* Main Content Grid */
.main-content {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

@media (max-width: 860px) {
    .main-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        overflow-y: auto;
    }
    .app-container {
        height: auto;
        min-height: 100vh;
        max-height: none;
        padding: 1rem;
    }
}

/* Left Panel: Timer */
.timer-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    background: var(--bg-surface);
    padding: 3rem 2rem;
    border-radius: var(--border-radius);
    box-shadow: 0 20px 40px rgba(0,0,0,0.2);
    border: 1px solid rgba(255,255,255,0.05);
}

.timer-mode-selector {
    display: flex;
    background: var(--bg-surface-elevated);
    border-radius: var(--border-radius-pill);
    padding: 0.25rem;
    gap: 0.25rem;
}

.mode-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 0.5rem 1.25rem;
    border-radius: var(--border-radius-pill);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition);
}

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

.mode-btn.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.3);
}

.mode-btn[data-mode="shortBreak"].active,
.mode-btn[data-mode="longBreak"].active {
    background: var(--accent);
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.3);
}

/* Timer Display SVG Ring */
.timer-display {
    position: relative;
    width: 300px;
    height: 300px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.progress-ring {
    position: absolute;
    top: 0;
    left: 0;
    transform: rotate(-90deg);
}

.progress-ring__circle.bg {
    stroke: var(--bg-surface-elevated);
}

.progress-ring__circle.fg {
    stroke: var(--primary);
    stroke-linecap: round;
    transition: stroke-dashoffset 1s linear, stroke 0.5s ease;
}

.timer-display.break .progress-ring__circle.fg {
    stroke: var(--accent);
}

#timeDisplay {
    font-size: 4.5rem;
    font-weight: 800;
    font-variant-numeric: tabular-nums;
    letter-spacing: -0.05em;
    z-index: 2;
}

/* Controls */
.timer-controls {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.control-btn {
    border: none;
    border-radius: var(--border-radius-pill);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 1rem;
    transition: all var(--transition);
    gap: 0.5rem;
}

.control-btn.primary {
    background: var(--primary);
    color: white;
    padding: 1rem 2.5rem;
    box-shadow: 0 10px 20px rgba(139, 92, 246, 0.2);
}

.control-btn.primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 14px 24px rgba(139, 92, 246, 0.3);
}

.control-btn.primary.active-timer {
    background: var(--bg-surface-elevated);
    color: var(--text-primary);
    box-shadow: none;
}

.control-btn.secondary {
    background: var(--bg-surface-elevated);
    color: var(--text-primary);
    width: 3.5rem;
    height: 3.5rem;
    padding: 0;
}

.control-btn.secondary:hover {
    background: #3a3431;
}

/* Session Info */
.session-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

.session-info p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

.session-dots {
    display: flex;
    gap: 6px;
}

.dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--bg-surface-elevated);
    transition: background var(--transition);
}

.dot.filled {
    background: var(--primary);
}

/* Right Panel: Mixer */
.mixer-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 2rem;
}

.mixer-header {
    display: flex;
    flex-direction: column;
    position: relative;
}

.mixer-header h3 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
}

.mixer-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.mixer-header #masterMuteBtn {
    position: absolute;
    right: 0;
    top: 0;
    padding: 0.5rem;
    background: var(--bg-surface);
    border-radius: 50%;
}

.sound-channels {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.sound-channel {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    background: var(--bg-surface);
    padding: 1.25rem 1.5rem;
    border-radius: var(--border-radius);
    transition: all var(--transition);
    border: 1px solid transparent;
}

.sound-channel.active {
    border-color: rgba(139, 92, 246, 0.3);
    background: rgba(139, 92, 246, 0.05);
}

.channel-icon {
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--bg-surface-elevated);
    display: flex;
    justify-content: center;
    align-items: center;
    color: var(--text-secondary);
    transition: color var(--transition);
}

.sound-channel.active .channel-icon {
    color: var(--primary);
}

.channel-controls {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.channel-title {
    font-weight: 600;
    font-size: 1rem;
}

/* Range Sliders */
.volume-slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: var(--bg-surface-elevated);
    border-radius: 3px;
    outline: none;
    transition: background-color 0.2s;
}

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

.sound-channel.active .volume-slider::-webkit-slider-thumb {
    background: var(--primary);
    box-shadow: 0 0 10px rgba(139, 92, 246, 0.4);
}

/* Settings Modal */
.modal-overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.8);
    backdrop-filter: blur(4px);
    display: flex;
    justify-content: center;
    align-items: center;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    z-index: 100;
}

.modal-overlay.open {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-surface);
    width: 100%;
    max-width: 400px;
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
    box-shadow: 0 25px 50px -12px rgba(0,0,0,0.5);
    transform: translateY(20px);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.modal-overlay.open .modal {
    transform: translateY(0);
}

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

.close-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
}

.modal-body {
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.setting-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.setting-group.toggle-group {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
}

.setting-group label {
    font-weight: 500;
    font-size: 0.95rem;
}

.setting-group input[type="number"] {
    background: var(--bg-surface-elevated);
    border: 1px solid rgba(255,255,255,0.1);
    color: var(--text-primary);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-size: 1rem;
    outline: none;
}

.setting-group input[type="number"]:focus {
    border-color: var(--primary);
}

/* Checkbox Toggle */
input[type="checkbox"] {
    appearance: none;
    width: 44px;
    height: 24px;
    background: var(--bg-surface-elevated);
    border-radius: 12px;
    position: relative;
    cursor: pointer;
    outline: none;
    transition: all var(--transition);
}

input[type="checkbox"]::after {
    content: '';
    position: absolute;
    top: 2px;
    left: 2px;
    width: 20px;
    height: 20px;
    background: white;
    border-radius: 50%;
    transition: all var(--transition);
}

input[type="checkbox"]:checked {
    background: var(--primary);
}

input[type="checkbox"]:checked::after {
    transform: translateX(20px);
}

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

.btn-primary {
    background: var(--primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition);
}

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