/* 피아노 코드 마스터 모던 스타일시트 */
:root {
    --bg-primary: #0f1117;
    --bg-secondary: #181b24;
    --bg-card: rgba(28, 32, 45, 0.85);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-active: rgba(255, 215, 0, 0.6);
    
    --text-primary: #f0f3f8;
    --text-secondary: #9aa5b8;
    --text-muted: #64748b;

    /* 하이라이트 컬러 */
    --gold: #f59e0b;
    --gold-glow: rgba(245, 158, 11, 0.5);
    --cyan: #06b6d4;
    --cyan-glow: rgba(6, 182, 212, 0.45);
    --purple: #8b5cf6;
    --accent: #3b82f6;

    /* 피아노 건반 치수 */
    --piano-height: 230px;
    --white-key-bg: linear-gradient(to bottom, #ffffff 0%, #f3f4f6 85%, #e2e8f0 100%);
    --white-key-border: #cbd5e1;
    --black-key-bg: linear-gradient(to bottom, #2d3748 0%, #1a202c 60%, #111827 100%);
    --black-key-width: 2.7%;
    --black-key-height: 60%;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-primary);
    background-image: 
        radial-gradient(at 10% 20%, rgba(59, 130, 246, 0.12) 0px, transparent 40%),
        radial-gradient(at 90% 85%, rgba(139, 92, 246, 0.12) 0px, transparent 40%);
    color: var(--text-primary);
    min-height: 100vh;
    padding: 1rem 1.5rem 3rem 1.5rem;
    overflow-x: hidden;
}

.app-container {
    max-width: 1280px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* 1. 헤더 영역 */
.header-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border-color);
}

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

.logo-icon {
    font-size: 2rem;
    filter: drop-shadow(0 0 10px rgba(245, 158, 11, 0.4));
}

.logo-text h1 {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #ffffff 30%, #93c5fd 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-text p {
    font-size: 0.82rem;
    color: var(--text-secondary);
}

.global-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.volume-control {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
    background: var(--bg-secondary);
    padding: 0.35rem 0.75rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.volume-control input[type="range"] {
    width: 80px;
    accent-color: var(--cyan);
    cursor: pointer;
}

.toggle-group {
    display: flex;
    gap: 0.4rem;
}

.btn-toggle {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.4rem 0.75rem;
    border-radius: 8px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-toggle:hover {
    color: var(--text-primary);
    border-color: rgba(255, 255, 255, 0.2);
}

.btn-toggle.active {
    background: rgba(6, 182, 212, 0.2);
    border-color: var(--cyan);
    color: var(--cyan);
    font-weight: 600;
}

/* 2. 피아노 섹션 */
.piano-section {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.25rem 1.5rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.piano-top-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.25rem;
}

.key-size-selector {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    background: var(--bg-secondary);
    padding: 0.3rem 0.6rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.key-size-label {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--cyan);
}

.btn-key-size {
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-secondary);
    padding: 0.25rem 0.55rem;
    border-radius: 6px;
    font-size: 0.78rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s;
}

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

.btn-key-size.active {
    background: linear-gradient(135deg, #0284c7, #06b6d4);
    color: #000;
    border-color: #38bdf8;
    box-shadow: 0 0 10px var(--cyan-glow);
}

.octave-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-secondary);
    padding: 0.3rem 0.6rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.octave-selector span {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.octave-selector span strong {
    color: var(--text-primary);
}

.btn-octave {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    width: 28px;
    height: 28px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 700;
}

.btn-octave:hover:not(:disabled) {
    background: var(--cyan);
    color: #000;
}

.btn-octave:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.playback-controls {
    display: flex;
    align-items: center;
    gap: 0.6rem;
}

.btn-play {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    background: linear-gradient(135deg, #2563eb, #1d4ed8);
    color: white;
    border: none;
    padding: 0.5rem 1.1rem;
    border-radius: 8px;
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.35);
    transition: all 0.2s;
}

.btn-play:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(37, 99, 235, 0.5);
}

.btn-play:active {
    transform: translateY(1px);
}

.btn-play-secondary {
    background: linear-gradient(135deg, #7c3aed, #6d28d9);
    box-shadow: 0 4px 12px rgba(124, 58, 237, 0.35);
}

.btn-play-secondary:hover {
    box-shadow: 0 6px 16px rgba(124, 58, 237, 0.5);
}

.btn-sustain {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 0.9rem;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    transition: all 0.2s;
}

.btn-sustain.active {
    background: rgba(245, 158, 11, 0.2);
    border-color: var(--gold);
    color: var(--gold);
    box-shadow: 0 0 10px var(--gold-glow);
}

.btn-sustain .sustain-status {
    font-size: 0.75rem;
    padding: 0.1rem 0.4rem;
    background: rgba(0,0,0,0.3);
    border-radius: 4px;
}

/* 33건반 피아노 건반 그래픽 */
.piano-wrapper-outer {
    position: relative;
    width: 100%;
    overflow-x: auto;
    padding-bottom: 0.5rem;
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) transparent;
}

.piano-container {
    position: relative;
    width: 100%;
    min-width: 820px;
    height: var(--piano-height);
    background: #090a0f;
    border-radius: 10px;
    padding: 12px 10px 8px 10px;
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.9), 0 4px 12px rgba(0, 0, 0, 0.5);
    user-select: none;
}

.piano-keys-wrapper {
    position: relative;
    width: 100%;
    height: 100%;
}

.white-keys-container {
    display: flex;
    width: 100%;
    height: 100%;
}

.black-keys-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

/* 흰건반 */
.piano-key.white-key {
    position: relative;
    height: 100%;
    background: var(--white-key-bg);
    border: 1px solid var(--white-key-border);
    border-bottom: 5px solid #94a3b8;
    border-radius: 0 0 6px 6px;
    box-shadow: inset 0 -3px 4px rgba(0, 0, 0, 0.15), 0 2px 5px rgba(0, 0, 0, 0.3);
    cursor: pointer;
    transition: background 0.1s, transform 0.05s, border-color 0.15s;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
    padding-bottom: 8px;
    box-sizing: border-box;
}

.piano-key.white-key:hover {
    background: linear-gradient(to bottom, #ffffff 0%, #f1f5f9 85%, #e2e8f0 100%);
}

.piano-key.white-key.is-pressed,
.piano-key.white-key.is-playing-flash {
    transform: translateY(3px);
    border-bottom: 2px solid #64748b;
    background: linear-gradient(to bottom, #e2e8f0 0%, #cbd5e1 100%);
    box-shadow: inset 0 2px 5px rgba(0, 0, 0, 0.3);
}

/* 검은건반 */
.piano-key.black-key {
    position: absolute;
    width: var(--black-key-width);
    height: var(--black-key-height);
    background: var(--black-key-bg);
    border: 1px solid #1e293b;
    border-bottom: 4px solid #0f172a;
    border-radius: 0 0 4px 4px;
    box-shadow: 2px 4px 8px rgba(0, 0, 0, 0.7), inset 0 -2px 3px rgba(255, 255, 255, 0.1);
    z-index: 10;
    pointer-events: auto;
    cursor: pointer;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
    padding-bottom: 6px;
    transition: background 0.1s, transform 0.05s, border-color 0.15s;
}

.piano-key.black-key:hover {
    background: linear-gradient(to bottom, #374151 0%, #1f2937 60%, #111827 100%);
}

.piano-key.black-key.is-pressed,
.piano-key.black-key.is-playing-flash {
    transform: translateY(2px);
    border-bottom: 2px solid #020617;
    background: linear-gradient(to bottom, #1f2937 0%, #111827 100%);
    box-shadow: 1px 2px 4px rgba(0, 0, 0, 0.8);
}

/* 건반 위 하이라이트 (코드 구성음) */
.piano-key.chord-highlight.white-key {
    background: linear-gradient(to bottom, #e0f2fe 0%, #bae6fd 60%, #7dd3fc 100%);
    border-color: #38bdf8;
    box-shadow: 0 0 14px var(--cyan-glow), inset 0 -3px 4px rgba(6, 182, 212, 0.3);
}

.piano-key.chord-highlight.black-key {
    background: linear-gradient(to bottom, #0e7490 0%, #0891b2 60%, #06b6d4 100%);
    border-color: #67e8f9;
    box-shadow: 0 0 14px var(--cyan-glow);
}

/* 근음(Root) 특별 강조 */
.piano-key.chord-root.white-key {
    background: linear-gradient(to bottom, #fef3c7 0%, #fde68a 60%, #fcd34d 100%);
    border-color: #f59e0b;
    box-shadow: 0 0 18px var(--gold-glow), inset 0 -3px 4px rgba(245, 158, 11, 0.4);
}

.piano-key.chord-root.black-key {
    background: linear-gradient(to bottom, #b45309 0%, #d97706 60%, #f59e0b 100%);
    border-color: #fde047;
    box-shadow: 0 0 18px var(--gold-glow);
}

/* 실제 연주 보이싱 (Voiced) 강조 */
.piano-key.chord-voiced {
    border-width: 2px;
}

/* 건반 라벨 및 배지 */
.key-label-wrapper {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 3px;
    pointer-events: none;
}

.chord-note-badge {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 3px 5px;
    border-radius: 6px;
    font-weight: 700;
    line-height: 1.1;
    min-width: 24px;
    animation: popIn 0.2s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.chord-note-badge.member-badge {
    background: #0284c7;
    color: #ffffff;
    box-shadow: 0 2px 6px rgba(2, 132, 199, 0.4);
}

.chord-note-badge.root-badge {
    background: #d97706;
    color: #ffffff;
    box-shadow: 0 2px 6px rgba(217, 119, 6, 0.5);
}

.black-key .chord-note-badge {
    padding: 2px 3px;
    min-width: 20px;
}

.badge-name {
    font-size: 0.78rem;
}

.black-key .badge-name {
    font-size: 0.68rem;
}

.badge-degree {
    font-size: 0.64rem;
    opacity: 0.9;
}

.black-key .badge-degree {
    font-size: 0.58rem;
}

.default-note-label {
    font-size: 0.72rem;
    color: #64748b;
    font-weight: 600;
}

.c-note-label {
    color: #2563eb;
    font-weight: 800;
}

.black-key .default-note-label {
    color: #94a3b8;
    font-size: 0.62rem;
}

.key-shortcut-hint {
    font-size: 0.6rem;
    color: #94a3b8;
    background: rgba(0, 0, 0, 0.08);
    padding: 1px 4px;
    border-radius: 3px;
}

.black-key .key-shortcut-hint {
    background: rgba(255, 255, 255, 0.15);
    color: #e2e8f0;
}

@keyframes popIn {
    0% { transform: scale(0.6); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}

/* 3. 코드 상세 정보 카드 */
.chord-info-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.25rem 1.5rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 1.5rem;
    align-items: center;
}

@media (max-width: 768px) {
    .chord-info-card {
        grid-template-columns: 1fr;
    }
}

.chord-main-meta {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.chord-title-row {
    display: flex;
    align-items: baseline;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.chord-big-title {
    font-size: 2.2rem;
    font-weight: 800;
    color: var(--gold);
    text-shadow: 0 0 20px var(--gold-glow);
    letter-spacing: -0.02em;
}

.chord-korean-name {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.chord-inversion-badge {
    background: rgba(255, 255, 255, 0.07);
    border: 1px solid var(--border-color);
    color: var(--cyan);
    font-size: 0.75rem;
    padding: 0.2rem 0.5rem;
    border-radius: 6px;
    font-weight: 600;
}

.chord-desc {
    font-size: 0.9rem;
    color: var(--text-muted);
    line-height: 1.4;
}

.chord-notes-row {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-top: 0.4rem;
    flex-wrap: wrap;
}

.chord-notes-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.notes-badges-list {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.note-pill {
    display: inline-flex;
    align-items: baseline;
    gap: 0.35rem;
    background: var(--bg-secondary);
    border: 1px solid var(--cyan);
    color: var(--cyan);
    padding: 0.35rem 0.7rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.15s ease;
}

.note-pill:hover {
    background: var(--cyan);
    color: #000;
    transform: translateY(-2px);
}

.note-pill.is-root {
    border-color: var(--gold);
    color: var(--gold);
}

.note-pill.is-root:hover {
    background: var(--gold);
    color: #000;
}

.pill-name {
    font-weight: 700;
    font-size: 0.95rem;
}

.pill-degree {
    font-size: 0.7rem;
    opacity: 0.8;
}

.chord-formula-box {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.6rem;
    border-left: 1px solid var(--border-color);
    padding-left: 1.5rem;
}

@media (max-width: 768px) {
    .chord-formula-box {
        align-items: flex-start;
        border-left: none;
        border-top: 1px solid var(--border-color);
        padding-left: 0;
        padding-top: 1rem;
    }
}

.formula-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.formula-value {
    font-family: monospace;
    font-size: 1.1rem;
    color: #a7f3d0;
    background: rgba(16, 185, 129, 0.15);
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    border: 1px solid rgba(16, 185, 129, 0.3);
}

.inversion-selector {
    display: flex;
    align-items: center;
    gap: 0.3rem;
}

.inversion-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-right: 0.3rem;
}

.inv-btn {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.3rem 0.55rem;
    border-radius: 6px;
    font-size: 0.75rem;
    cursor: pointer;
    transition: all 0.2s;
}

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

.inv-btn.active {
    background: var(--purple);
    border-color: var(--purple);
    color: #fff;
    font-weight: 700;
}

/* 4. 코드 선택 패널 (Root 및 Chord Type) */
.chord-selector-panel {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

/* 근음(Root) 선택 바 */
.root-selector-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1rem 1.25rem;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.section-label {
    font-size: 0.82rem;
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.root-buttons-container {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: 0.4rem;
}

@media (max-width: 900px) {
    .root-buttons-container {
        grid-template-columns: repeat(6, 1fr);
    }
}

@media (max-width: 480px) {
    .root-buttons-container {
        grid-template-columns: repeat(4, 1fr);
    }
}

.btn-root {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.7rem 0.2rem;
    border-radius: 10px;
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s ease;
    text-align: center;
}

.btn-root:hover {
    border-color: rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.06);
    transform: translateY(-2px);
}

.btn-root.active {
    background: linear-gradient(135deg, #d97706, #f59e0b);
    border-color: #fbbf24;
    color: #000;
    box-shadow: 0 4px 14px var(--gold-glow);
    transform: translateY(-2px);
}

/* 2. 코드 조합기 (Chord Builder) 모던 칩 UI */
.chord-builder-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.25rem;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.builder-header-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 0.6rem;
}

.builder-header-row .section-label {
    margin-bottom: 0;
}

.btn-reset-chord {
    background: rgba(239, 68, 68, 0.15);
    border: 1px solid rgba(239, 68, 68, 0.4);
    color: #fca5a5;
    padding: 0.35rem 0.75rem;
    border-radius: 8px;
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-reset-chord:hover {
    background: rgba(239, 68, 68, 0.3);
    color: #fff;
    transform: translateY(-1px);
}

.chip-row-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.chip-group-label {
    min-width: 80px;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--text-secondary);
}

.chip-buttons-wrap {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    flex: 1;
}

/* 칩 버튼 기본 스타일 */
.btn-chip {
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.12);
    color: var(--text-primary);
    padding: 0.55rem 1rem;
    border-radius: 20px;
    font-size: 0.88rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.18s cubic-bezier(0.16, 1, 0.3, 1);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.btn-chip:hover {
    border-color: rgba(255, 255, 255, 0.3);
    background: rgba(255, 255, 255, 0.08);
    transform: translateY(-2px);
}

.btn-chip:active {
    transform: translateY(1px);
}

/* 1) Quality: Major / Minor 활성화 (블루/사이언) */
.quality-chip.active {
    background: linear-gradient(135deg, #0284c7, #06b6d4);
    border-color: #38bdf8;
    color: #000;
    box-shadow: 0 0 14px var(--cyan-glow);
    font-weight: 800;
}

/* 2) Modifier: sus4, sus2, dim, aug 활성화 (에메랄드 그린) */
.modifier-chip.active {
    background: linear-gradient(135deg, #059669, #10b981);
    border-color: #34d399;
    color: #000;
    box-shadow: 0 0 14px rgba(16, 185, 129, 0.5);
    font-weight: 800;
}

/* 3) 7th / 6th: 7, maj7, 6, dim7 활성화 (퍼플/바이올렛) */
.seventh-chip.active {
    background: linear-gradient(135deg, #7c3aed, #a855f7);
    border-color: #c084fc;
    color: #fff;
    box-shadow: 0 0 14px rgba(168, 85, 247, 0.5);
    font-weight: 800;
}

/* 4) Tension: 9, 11, 13, b9 활성화 (로즈/핑크) */
.tension-chip.active {
    background: linear-gradient(135deg, #db2777, #f43f5e);
    border-color: #fb7185;
    color: #fff;
    box-shadow: 0 0 14px rgba(244, 63, 94, 0.5);
    font-weight: 800;
}

/* 3. 빠른 프리셋 섹션 */
.quick-preset-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    padding: 0.9rem 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.quick-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 700;
    white-space: nowrap;
}

.quick-chips-wrap {
    display: flex;
    gap: 0.4rem;
    flex-wrap: wrap;
}

.quick-btn {
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.3rem 0.65rem;
    border-radius: 8px;
    font-size: 0.78rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.15s;
}

.quick-btn:hover {
    color: var(--text-primary);
    border-color: var(--cyan);
    background: rgba(6, 182, 212, 0.15);
    transform: translateY(-1px);
}

/* 악기 선택 셀렉터 스타일 */
.instrument-selector-wrap {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    padding: 0.35rem 0.75rem;
    border-radius: 8px;
}

.inst-label {
    font-size: 0.82rem;
    font-weight: 700;
    color: var(--gold);
}

.instrument-select {
    background: #0f172a;
    color: var(--text-primary);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 6px;
    padding: 0.35rem 0.6rem;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    outline: none;
    transition: border-color 0.2s;
}

.instrument-select:focus {
    border-color: var(--cyan);
}

/* 4. 추천 코드 진행 (Chord Progressions) 섹션 */
.progressions-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.progressions-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1rem;
}

.prog-title-wrap {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.prog-icon {
    font-size: 2rem;
}

.prog-title-wrap h2 {
    font-size: 1.25rem;
    font-weight: 700;
    color: #e2e8f0;
}

.prog-title-wrap p {
    font-size: 0.82rem;
    color: var(--text-muted);
}

.prog-playback-bar {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.bpm-control {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-secondary);
    padding: 0.35rem 0.75rem;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.bpm-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.bpm-label strong {
    color: var(--cyan);
}

.bpm-control input[type="range"] {
    width: 80px;
    accent-color: var(--cyan);
    cursor: pointer;
}

.btn-prog-ctrl {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.45rem 0.85rem;
    border-radius: 8px;
    font-size: 0.82rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-prog-ctrl.active {
    background: rgba(6, 182, 212, 0.2);
    border-color: var(--cyan);
    color: var(--cyan);
}

.btn-prog-ctrl.btn-stop {
    background: rgba(239, 68, 68, 0.15);
    border-color: rgba(239, 68, 68, 0.4);
    color: #fca5a5;
}

.btn-prog-ctrl.btn-stop:hover {
    background: rgba(239, 68, 68, 0.3);
    color: #fff;
}

/* 장르 필터 탭 */
.prog-genre-tabs {
    display: flex;
    gap: 0.5rem;
    overflow-x: auto;
    padding-bottom: 0.25rem;
}

.genre-tab {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.45rem 0.9rem;
    border-radius: 20px;
    font-size: 0.84rem;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
    transition: all 0.2s;
}

.genre-tab:hover {
    color: var(--text-primary);
    border-color: rgba(255, 255, 255, 0.3);
}

.genre-tab.active {
    background: linear-gradient(135deg, #7c3aed, #9333ea);
    border-color: #a855f7;
    color: #fff;
    box-shadow: 0 2px 10px rgba(168, 85, 247, 0.4);
}

/* 진행 카드 그리드 */
.progressions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1rem;
}

.prog-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem 1.15rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    position: relative;
    overflow: hidden;
}

.prog-card:hover {
    border-color: rgba(255, 255, 255, 0.25);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.4);
}

.prog-card.is-playing {
    border-color: var(--gold);
    box-shadow: 0 0 16px var(--gold-glow);
}

.prog-card-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 0.5rem;
}

.prog-card-title {
    font-size: 0.98rem;
    font-weight: 700;
    color: var(--text-primary);
}

.prog-card-formula {
    font-size: 0.72rem;
    color: var(--cyan);
    font-family: monospace;
    background: rgba(6, 182, 212, 0.1);
    padding: 0.15rem 0.45rem;
    border-radius: 4px;
    border: 1px solid rgba(6, 182, 212, 0.3);
}

.prog-card-desc {
    font-size: 0.78rem;
    color: var(--text-muted);
    line-height: 1.35;
}

/* 코드 블록 나열 */
.prog-chord-flow {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    flex-wrap: wrap;
    margin: 0.2rem 0;
}

.prog-chord-badge {
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--border-color);
    padding: 0.35rem 0.65rem;
    border-radius: 6px;
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: all 0.15s;
}

.prog-chord-arrow {
    color: var(--text-muted);
    font-size: 0.75rem;
}

/* 연주 중인 코드 하이라이트 */
.prog-chord-badge.active-step {
    background: var(--gold);
    color: #000;
    border-color: #fbbf24;
    box-shadow: 0 0 12px var(--gold-glow);
    transform: scale(1.1);
}

.prog-play-btn {
    align-self: flex-start;
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: linear-gradient(135deg, #0284c7, #06b6d4);
    border: none;
    color: #000;
    padding: 0.45rem 1rem;
    border-radius: 8px;
    font-size: 0.84rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: 0 2px 8px var(--cyan-glow);
}

.prog-play-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px var(--cyan-glow);
}

.prog-card.is-playing .prog-play-btn {
    background: linear-gradient(135deg, #ef4444, #dc2626);
    color: #fff;
    box-shadow: 0 2px 8px rgba(239, 68, 68, 0.4);
}

/* 푸터 영역 */
.footer-bar {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.8rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}