:root {
    --primary-blue: #2196F3;
    --success-green: #4CAF50;
    --warning-yellow: #FFC107;
    --danger-red: #F44336;
    --accent-purple: #9C27B0;
    --background: #f5f5f5;
    --surface: #ffffff;
    --text-primary: #212121;
    --text-secondary: #757575;
    --border: #e0e0e0;
    --shadow: rgba(0, 0, 0, 0.1);
    --border-radius: 8px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    padding-bottom: 140px;
    min-height: 100vh;
    position: relative;
}

.app-header {
    background: linear-gradient(135deg, var(--primary-blue), var(--accent-purple));
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 8px var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.language-btn {
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.language-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

.main-content {
    padding: 1rem;
    max-width: 800px;
    margin: 0 auto;
}

.app-section {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.app-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.mood-selector {
    background: var(--surface);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 8px var(--shadow);
}

.mood-selector h2 {
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
    font-size: 1.5rem;
}

.mood-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
}

.mood-btn {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: var(--border-radius);
    padding: 1rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    font-size: 1rem;
    color: var(--text-primary);
}

.mood-btn:hover {
    border-color: var(--primary-blue);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.mood-btn.active {
    background: var(--primary-blue);
    border-color: var(--primary-blue);
    color: white;
}

.composition-area {
    background: var(--surface);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: 0 2px 8px var(--shadow);
}

.chord-display {
    margin-bottom: 1.5rem;
}

.chord-display h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.chord-sequence {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
    min-height: 60px;
    align-items: center;
}

.chord-item {
    background: var(--primary-blue);
    color: white;
    padding: 0.75rem 1rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    font-size: 1.1rem;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from { opacity: 0; transform: scale(0.8); }
    to { opacity: 1; transform: scale(1); }
}

.action-btn {
    background: var(--success-green);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1rem;
    width: 100%;
    justify-content: center;
}

.action-btn:hover {
    background: #45a049;
    transform: translateY(-1px);
}

.instrument-selector {
    margin-bottom: 1.5rem;
}

.instrument-selector h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.instrument-selector select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border);
    border-radius: var(--border-radius);
    background: var(--surface);
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
}

.playback-controls {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.control-btn {
    flex: 1;
    min-width: 120px;
    background: var(--primary-blue);
    color: white;
    border: none;
    padding: 0.75rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-size: 0.9rem;
}

.control-btn:hover {
    background: #1976D2;
    transform: translateY(-1px);
}

.control-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.tempo-control {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.tempo-control label {
    font-weight: 600;
    color: var(--text-primary);
}

.tempo-control input[type="range"] {
    flex: 1;
    min-width: 150px;
}

#tempoValue {
    font-weight: 600;
    color: var(--primary-blue);
    min-width: 40px;
}

.compositions-list {
    display: grid;
    gap: 1rem;
}

.composition-card {
    background: var(--surface);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: 0 2px 8px var(--shadow);
    border-left: 4px solid var(--primary-blue);
}

.composition-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.composition-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.composition-mood {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.composition-actions {
    display: flex;
    gap: 0.5rem;
}

.composition-actions button {
    background: none;
    border: 1px solid var(--border);
    color: var(--text-secondary);
    padding: 0.5rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.composition-actions button:hover {
    background: var(--primary-blue);
    color: white;
    border-color: var(--primary-blue);
}

.composition-actions button.delete:hover {
    background: var(--danger-red);
    border-color: var(--danger-red);
}

.composition-chords {
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
    margin-bottom: 1rem;
}

.composition-chord {
    background: var(--background);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.composition-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
}

.empty-state i {
    font-size: 4rem;
    margin-bottom: 1rem;
    color: var(--border);
}

.empty-state p {
    margin-bottom: 0.5rem;
}

.education-content {
    display: grid;
    gap: 1.5rem;
}

.theory-card {
    background: var(--surface);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: 0 2px 8px var(--shadow);
}

.theory-card h3 {
    color: var(--primary-blue);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.theory-card p {
    margin-bottom: 1rem;
    line-height: 1.7;
}

.theory-card ul {
    padding-left: 1.5rem;
}

.theory-card li {
    margin-bottom: 0.5rem;
}

.chord-examples {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.chord-example {
    background: var(--primary-blue);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 600;
}

.chord-example:hover {
    background: #1976D2;
    transform: translateY(-1px);
}

.faq-container {
    display: grid;
    gap: 1rem;
}

.faq-item {
    background: var(--surface);
    border-radius: var(--border-radius);
    box-shadow: 0 2px 8px var(--shadow);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    background: none;
    border: none;
    padding: 1.5rem;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-primary);
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--background);
}

.faq-question[aria-expanded="true"] {
    background: var(--primary-blue);
    color: white;
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-icon {
    font-size: 1.5rem;
    transition: var(--transition);
}

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.7;
    animation: slideDown 0.3s ease-out;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.bottom-nav {
    position: fixed;
    bottom: 60px;
    left: 0;
    right: 0;
    background: var(--surface);
    border-top: 1px solid var(--border);
    display: flex;
    z-index: 100;
    box-shadow: 0 -2px 8px var(--shadow);
}

.nav-item {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.75rem 0.5rem;
    text-decoration: none;
    color: var(--text-secondary);
    transition: var(--transition);
    font-size: 0.8rem;
}

.nav-item:hover {
    color: var(--primary-blue);
    background: rgba(33, 150, 243, 0.1);
}

.nav-item.active {
    color: var(--primary-blue);
    background: rgba(33, 150, 243, 0.1);
}

.nav-item i {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}

footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: 1rem;
    font-size: 0.9rem;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 200;
    box-shadow: 0 -2px 8px var(--shadow);
}

footer p {
    margin: 0;
}

footer a {
    color: var(--primary-blue);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

footer a:hover {
    color: #64B5F6;
    text-decoration: underline;
}

@media (max-width: 768px) {
    .app-header h1 {
        font-size: 1.2rem;
    }
    
    .mood-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .playback-controls {
        flex-direction: column;
    }
    
    .control-btn {
        min-width: auto;
    }
    
    .tempo-control {
        flex-direction: column;
        align-items: stretch;
    }
    
    .composition-header {
        flex-direction: column;
        gap: 1rem;
    }
    
    .composition-actions {
        align-self: flex-end;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 0.5rem;
    }
    
    .mood-selector,
    .composition-area,
    .theory-card,
    .faq-item {
        padding: 1rem;
    }
    
    .nav-item {
        padding: 0.5rem 0.25rem;
    }
    
    .nav-item span {
        font-size: 0.7rem;
    }
}

.loading {
    opacity: 0.6;
    pointer-events: none;
}

.success {
    background: var(--success-green) !important;
}

.error {
    background: var(--danger-red) !important;
}

.pulse {
    animation: pulse 1s infinite;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.05); }
    100% { transform: scale(1); }
}