/* Music Lab: shared, local-only visual system. */
:root {
    color-scheme: light;
    --bg: #f5f3eb;
    --paper: #fffef9;
    --ink: #242c28;
    --muted: #5b655f;
    --green: #254f3e;
    --green-soft: #e7eee5;
    --orange: #aa481f;
    --orange-soft: #fae8d9;
    --line: #d6d9cf;
    --radius: 12px;
    font-family:
        ui-sans-serif,
        system-ui,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;
    color: var(--ink);
    background: var(--bg);
}
*,
*::before,
*::after {
    box-sizing: border-box;
}
body {
    margin: 0;
    line-height: 1.6;
}
h1,
h2,
h3,
p {
    margin: 0;
}
h1,
h2,
h3 {
    line-height: 1.15;
    letter-spacing: -0.035em;
}
h1 {
    font-size: clamp(2.8rem, 5.6vw, 5rem);
    font-weight: 750;
}
h2 {
    font-size: clamp(1.6rem, 3vw, 2rem);
}
h3 {
    font-size: 1.2rem;
}
a {
    color: var(--green);
    text-underline-offset: 4px;
}
button,
input {
    font: inherit;
}
button,
a,
input {
    -webkit-tap-highlight-color: transparent;
}
button {
    cursor: pointer;
}
button:disabled {
    cursor: not-allowed;
    opacity: 0.65;
}
a:hover {
    text-decoration-thickness: 2px;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
[tabindex]:focus-visible {
    outline: 3px solid var(--orange);
    outline-offset: 4px;
}
button:active:not(:disabled):not(.piano-key),
.button:active {
    transform: translateY(1px);
}
[hidden] {
    display: none !important;
}
::selection {
    background: #d9e6c9;
}
.skip-link {
    position: absolute;
    left: 1rem;
    top: -100px;
    z-index: 10;
    padding: 0.7rem 1rem;
    background: var(--paper);
    border: 2px solid var(--green);
}
.skip-link:focus {
    top: 1rem;
}
.container {
    width: min(1180px, calc(100% - 64px));
    margin-inline: auto;
}
.site-header {
    border-bottom: 1px solid var(--line);
    background: var(--paper);
}
.site-nav {
    max-width: 1244px;
    margin: auto;
    padding: 20px 32px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}
.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.3rem;
    font-weight: 800;
    letter-spacing: -0.06em;
    text-decoration: none;
    color: var(--ink);
    white-space: nowrap;
}
.brand-mark {
    display: grid;
    place-items: center;
    width: 32px;
    height: 32px;
    border-radius: 7px;
    background: var(--green);
    color: var(--paper);
    font-size: 1.3rem;
    letter-spacing: 0;
}
.nav-links {
    display: flex;
    gap: 28px;
    align-items: center;
}
.nav-links a {
    font-size: 0.88rem;
    font-weight: 650;
    color: var(--muted);
    text-decoration: none;
    padding: 6px 0;
}
.nav-links a:hover,
.nav-links [aria-current] {
    color: var(--green);
    text-decoration: underline;
}
.nav-links .nav-lab {
    border: 1px solid var(--line);
    border-radius: 6px;
    padding: 8px 14px;
    color: var(--green);
}
.hero {
    display: grid;
    grid-template-columns: 1.05fr 1fr;
    gap: 64px;
    align-items: center;
    padding: 64px 0 54px;
}
.hero h1 span {
    color: var(--green);
}
.hero-copy > p {
    font-size: 1.06rem;
    max-width: 480px;
    color: var(--muted);
    margin-top: 24px;
}
.hero-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-top: 28px;
}
.button,
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    border: 1px solid var(--green);
    border-radius: 6px;
    background: var(--green);
    color: var(--paper);
    font-weight: 650;
    font-size: 0.9rem;
    padding: 11px 18px;
    min-height: 44px;
    text-decoration: none;
}
.button:hover,
.btn:hover {
    background: #193d2e;
}
.button.secondary,
.btn.danger {
    background: transparent;
    color: var(--green);
    border-color: var(--line);
}
.button.secondary:hover,
.btn.danger:hover {
    background: var(--green-soft);
    border-color: var(--green);
}
.small-note {
    font-size: 0.78rem !important;
    color: var(--muted);
    line-height: 1.5;
}
.hero-copy .small-note {
    margin-top: 20px;
}
.piano-panel {
    background: var(--green);
    color: var(--paper);
    padding: 28px;
    border-radius: var(--radius);
}
.piano-top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 24px;
}
.piano-top h2 {
    font-size: 1.2rem;
    letter-spacing: -0.02em;
}
.piano-top span {
    font-size: 0.75rem;
    color: #d0ddcf;
}
.piano-panel p {
    color: #dbe6d8;
    font-size: 0.83rem;
    margin-top: 18px;
    line-height: 1.6;
}
.piano-panel .audio-status {
    min-height: 1.6em;
    color: #fff1cb;
}
.keyboard {
    position: relative;
    height: 176px;
    display: flex;
    isolation: isolate;
}
.piano-key {
    border: 1px solid #aeb7a9;
    box-shadow: 0 4px 0 #c8cec1;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: center;
    padding: 0 0 12px;
    gap: 5px;
    color: var(--ink);
    background: #fffef5;
    border-radius: 0 0 6px 6px;
    min-width: 0;
    flex: 1;
    touch-action: manipulation;
    user-select: none;
}
.piano-key b {
    font-size: 0.9rem;
}
.piano-key span {
    font-size: 0.68rem;
    color: var(--muted);
}
.piano-key.black {
    position: absolute;
    top: 0;
    left: var(--position);
    transform: translateX(-50%);
    width: 8%;
    height: 62%;
    background: #202b25;
    color: white;
    border-color: #111e17;
    z-index: 1;
    box-shadow: 0 3px 0 #0f1e15;
    padding-bottom: 10px;
}
.piano-key.black span {
    color: #c2d0c3;
}
.piano-key.is-playing {
    background: #e4b880;
    box-shadow: 0 1px 0 #ac7840;
}
.piano-key.black.is-playing {
    background: #b7612b;
}
.piano-key:focus-visible {
    outline-color: #ffb96a;
    z-index: 2;
    outline-offset: -4px;
}
.keyboard:focus-visible {
    outline-color: #ffb96a;
}
.progress-strip {
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
    padding: 22px 0;
    display: grid;
    grid-template-columns: auto minmax(100px, 1fr) auto;
    align-items: center;
    gap: 28px;
}
.progress-copy strong {
    display: block;
    font-size: 0.93rem;
}
.progress-copy p {
    font-size: 0.78rem;
    color: var(--muted);
}
progress {
    appearance: none;
    width: 100%;
    height: 8px;
    border: 0;
    border-radius: 10px;
    overflow: hidden;
    background: var(--line);
    accent-color: var(--green);
}
progress::-webkit-progress-bar {
    background: var(--line);
}
progress::-webkit-progress-value {
    background: var(--green);
    border-radius: 10px;
}
progress::-moz-progress-bar {
    background: var(--green);
}
.progress-count {
    font-size: 0.85rem;
    font-weight: 700;
    color: var(--green);
}
.library {
    padding: 48px 0;
}
.section-heading {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 24px;
    margin-bottom: 24px;
}
.section-heading p {
    font-size: 0.9rem;
    color: var(--muted);
    margin-top: 10px;
}
.search-label {
    display: block;
    font-size: 0.78rem;
    font-weight: 650;
    margin-bottom: 5px;
}
.search-input {
    width: 280px;
    max-width: 100%;
    background: var(--paper);
    border: 1px solid #a3afa4;
    border-radius: 6px;
    padding: 10px 14px;
    min-height: 44px;
    color: var(--ink);
}
.library-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
    gap: 16px;
    font-size: 0.78rem;
    color: var(--muted);
}
.text-button {
    background: none;
    border: 0;
    color: var(--green);
    padding: 8px 0;
    text-decoration: underline;
    text-underline-offset: 4px;
    min-height: 44px;
}
.topic-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 16px;
}
.topic-card {
    display: flex;
    flex-direction: column;
    min-width: 0;
    min-height: 232px;
    padding: 24px;
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    text-decoration: none;
    color: var(--ink);
}
.topic-card:hover {
    border-color: var(--green);
    background: #fcfdf5;
}
.card-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 10px;
    margin-bottom: 25px;
}
.topic-symbol {
    font-size: 1.5rem;
    line-height: 1;
    color: var(--green);
    font-weight: 650;
}
.topic-type {
    font-size: 0.72rem;
    color: var(--muted);
}
.topic-card p {
    font-size: 0.85rem;
    color: var(--muted);
    margin-top: 10px;
    line-height: 1.6;
    flex: 1;
}
.card-bottom {
    display: flex;
    justify-content: space-between;
    gap: 10px;
    margin-top: 24px;
    font-size: 0.76rem;
    font-weight: 650;
    color: var(--green);
}
.completion-label {
    font-weight: 450;
    color: var(--muted);
}
.topic-card.is-complete {
    border-color: #8ca48b;
}
.topic-card.is-complete .completion-label {
    color: var(--green);
    font-weight: 650;
}
.empty-state {
    padding: 40px;
    border: 1px dashed var(--line);
    border-radius: var(--radius);
    text-align: center;
}
.empty-state p {
    margin-top: 12px;
    color: var(--muted);
}
.practice {
    display: grid;
    grid-template-columns: 0.8fr 1.2fr;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--paper);
    overflow: hidden;
    margin-bottom: 56px;
}
.practice-intro {
    padding: 32px;
    background: var(--green-soft);
}
.practice-intro h2 {
    margin: 16px 0;
}
.practice-intro p {
    color: var(--muted);
    font-size: 0.9rem;
}
.section-index {
    color: var(--orange);
    font-size: 0.76rem;
    letter-spacing: 0.08em;
    font-weight: 750;
    text-transform: uppercase;
}
.quiz-body {
    padding: 32px;
    min-width: 0;
}
.quiz-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.78rem;
    color: var(--muted);
    margin-bottom: 16px;
}
.quiz-body h3 {
    font-size: 1.2rem;
    line-height: 1.4;
}
.quiz-body fieldset {
    padding: 0;
    border: 0;
    margin: 18px 0;
}
.quiz-body legend {
    font-weight: 650;
    font-size: 1.1rem;
    margin-bottom: 16px;
    line-height: 1.5;
}
.quiz-choice {
    display: flex;
    align-items: center;
    gap: 10px;
    border: 1px solid var(--line);
    padding: 10px 12px;
    border-radius: 6px;
    margin-bottom: 8px;
    font-size: 0.88rem;
    cursor: pointer;
    min-height: 44px;
}
.quiz-choice:has(input:checked) {
    background: var(--green-soft);
    border-color: var(--green);
}
.quiz-choice input {
    accent-color: var(--green);
    width: 16px;
    height: 16px;
    flex-shrink: 0;
}
.quiz-feedback {
    padding: 14px;
    background: var(--orange-soft);
    border-left: 3px solid var(--orange);
    font-size: 0.88rem;
    margin-bottom: 18px;
}
.quiz-feedback:empty {
    padding: 0;
    border: 0;
    margin: 0;
}
.quiz-feedback.correct {
    background: var(--green-soft);
    border-color: var(--green);
}
.quiz-result p {
    margin: 16px 0;
    color: var(--muted);
}
.site-footer {
    border-top: 1px solid var(--line);
    padding: 26px 0;
    background: var(--paper);
    font-size: 0.8rem;
    color: var(--muted);
}
.footer-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
    flex-wrap: wrap;
}
.footer-inner strong {
    color: var(--ink);
}
.no-script {
    padding: 16px;
    background: var(--orange-soft);
    color: var(--ink);
}
/* Lesson reading layout */
.lesson-header {
    width: min(900px, calc(100% - 64px));
    margin: auto;
    padding: 40px 0 32px;
}
.breadcrumb {
    font-size: 0.8rem;
    color: var(--muted);
    margin-bottom: 22px;
}
.lesson-header h1 {
    font-size: clamp(2.3rem, 5vw, 3.7rem);
    margin-bottom: 18px;
}
.lesson-header > p {
    max-width: 720px;
    color: var(--muted);
    font-size: 1.05rem;
}
.lesson-tools {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
    margin-top: 26px;
    padding-top: 20px;
    border-top: 1px solid var(--line);
}
.lesson-tools p {
    max-width: 440px;
}
.lesson-layout {
    width: min(900px, calc(100% - 64px));
    margin: 0 auto 60px;
}
.lesson-toc {
    display: flex;
    gap: 8px 20px;
    flex-wrap: wrap;
    border-block: 1px solid var(--line);
    padding: 16px 0;
    margin-bottom: 32px;
    font-size: 0.8rem;
}
.content {
    min-width: 0;
}
.topic-section {
    margin-bottom: 36px;
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    padding: 28px;
}
.topic-section h2 {
    font-size: 1.4rem;
    border-bottom: 1px solid var(--line);
    padding-bottom: 16px;
    margin-bottom: 20px;
    scroll-margin-top: 20px;
}
.topic-section p {
    font-size: 0.95rem;
    color: #424e46;
    line-height: 1.85;
    margin-bottom: 16px;
}
.topic-section p:last-child {
    margin-bottom: 0;
}
.table-scroll {
    overflow-x: auto;
    max-width: 100%;
    margin: 20px 0 8px;
    border: 1px solid var(--line);
    border-radius: 6px;
}
.ref-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.87rem;
    text-align: left;
    line-height: 1.6;
}
.ref-table th {
    background: var(--green-soft);
    color: var(--green);
    font-size: 0.75rem;
    padding: 12px 16px;
}
.ref-table td {
    padding: 12px 16px;
    border-top: 1px solid var(--line);
    min-width: 95px;
}
.ref-table tr:hover td {
    background: #f7f8f0;
}
.tip-box {
    background: var(--green-soft);
    border-left: 3px solid var(--green);
    padding: 16px 20px;
    margin-top: 20px;
    font-size: 0.88rem;
    color: #364f3e;
}
.lesson-end {
    padding: 24px 0;
    display: flex;
    justify-content: space-between;
    gap: 16px;
    border-top: 1px solid var(--line);
}
.status-message {
    font-size: 0.8rem;
    color: var(--orange);
    margin-top: 10px;
}
.completion-button {
    flex-shrink: 0;
}
/* Sequencer has a locally scrolling canvas, never a scrolling page. */
.sequencer-wrap {
    width: min(1180px, calc(100% - 64px));
    margin: 0 auto 36px;
    padding: 24px;
    background: var(--paper);
    border: 1px solid var(--line);
    border-radius: var(--radius);
}
.seq-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 16px;
}
.seq-title {
    font-size: 1.3rem;
    font-weight: 750;
}
.controls {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
}
.tempo-wrap {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 0.8rem;
}
.tempo-wrap input {
    width: 100px;
    accent-color: var(--green);
    min-height: 44px;
}
.tempo-val {
    min-width: 26px;
    font-weight: 700;
}
.instrument-row {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin: 16px 0;
}
.inst-btn {
    border: 1px solid var(--line);
    border-radius: 6px;
    padding: 8px 14px;
    min-height: 44px;
    background: var(--bg);
    color: var(--green);
    font-size: 0.8rem;
    font-weight: 650;
}
.inst-btn.active {
    background: var(--green);
    color: var(--paper);
    border-color: var(--green);
}
.grid-outer {
    overflow-x: auto;
    padding: 5px 4px 12px;
}
.grid-labels {
    display: flex;
    margin-left: 64px;
    min-width: 704px;
}
.beat-label {
    flex: 1;
    text-align: center;
    font-size: 0.7rem;
    min-width: 44px;
    color: var(--muted);
}
.beat-label.bar-start {
    font-weight: 750;
    color: var(--green);
}
.note-row,
.perc-row {
    display: flex;
    min-width: 768px;
    gap: 3px;
    margin-bottom: 3px;
}
.note-label {
    width: 61px;
    flex-shrink: 0;
    align-self: center;
    font-size: 0.75rem;
    text-align: right;
    padding-right: 10px;
    color: var(--muted);
}
.note-label.c-note {
    font-weight: 750;
    color: var(--green);
}
.note-cell,
.perc-cell {
    flex: 1;
    min-width: 41px;
    height: 36px;
    background: var(--bg);
    border: 1px solid #a9b4a5;
    border-radius: 3px;
    padding: 0;
}
.note-cell:hover,
.perc-cell:hover {
    border-color: var(--ink);
}
.note-cell.on {
    background: var(--green);
    border-color: var(--green);
}
.perc-cell.on {
    background: var(--orange);
    border-color: var(--orange);
}
.note-cell.on::after,
.perc-cell.on::after {
    content: "•";
    color: white;
}
.note-cell.playing,
.perc-cell.playing {
    outline: 3px solid var(--orange);
    outline-offset: -4px;
    background: #e5b775;
}
.note-cell.playing::after,
.perc-cell.playing::after {
    color: var(--ink);
}
.perc-divider {
    border: 0;
    border-top: 1px solid var(--line);
    margin: 16px 0;
}
.perc-section-label {
    font-size: 0.72rem;
    color: var(--muted);
}
@media (min-width: 1450px) {
    .hero {
        padding-block: 80px;
    }
}
@media (max-width: 1000px) {
    .hero {
        gap: 32px;
    }
    h1 {
        font-size: 3.3rem;
    }
    .piano-panel {
        padding: 20px;
    }
    .topic-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
    .practice {
        grid-template-columns: 0.8fr 1fr;
    }
    .nav-links {
        gap: 18px;
    }
}
@media (max-width: 720px) {
    .container,
    .lesson-header,
    .lesson-layout,
    .sequencer-wrap {
        width: calc(100% - 40px);
    }
    .site-nav {
        padding: 16px 20px;
        flex-wrap: wrap;
        gap: 14px;
    }
    .nav-links {
        gap: 20px;
        flex-wrap: wrap;
    }
    .nav-links a {
        font-size: 0.8rem;
    }
    .nav-links .nav-lab {
        padding: 6px 10px;
    }
    .hero {
        grid-template-columns: 1fr;
        padding: 36px 0;
        gap: 32px;
    }
    .hero h1 {
        font-size: clamp(2.7rem, 9vw, 4rem);
        max-width: 550px;
    }
    .hero-copy > p {
        margin-top: 18px;
    }
    .piano-panel {
        padding: 24px;
    }
    .progress-strip {
        grid-template-columns: 1fr auto;
        gap: 12px;
    }
    .progress-strip progress {
        grid-row: 2;
        grid-column: 1/-1;
    }
    .progress-count {
        grid-column: 2;
        grid-row: 1;
    }
    .section-heading {
        align-items: stretch;
        flex-direction: column;
        gap: 20px;
    }
    .search-input {
        width: 100%;
    }
    .library {
        padding: 32px 0;
    }
    .practice {
        grid-template-columns: 1fr;
    }
    .practice-intro,
    .quiz-body {
        padding: 24px;
    }
    .practice-intro h2 {
        margin: 10px 0;
    }
    .lesson-header {
        padding-top: 28px;
    }
    .lesson-tools {
        flex-direction: column;
        align-items: flex-start;
        gap: 16px;
    }
    .topic-section {
        padding: 20px;
    }
    .lesson-toc {
        gap: 12px 20px;
    }
    .sequencer-wrap {
        padding: 16px;
    }
    .lesson-end {
        flex-wrap: wrap;
    }
    .footer-inner {
        align-items: flex-start;
        flex-direction: column;
        gap: 6px;
    }
}
@media (max-width: 480px) {
    .topic-grid {
        grid-template-columns: 1fr;
    }
    .topic-card {
        min-height: 210px;
    }
    .card-top {
        margin-bottom: 20px;
    }
    .brand {
        font-size: 1.2rem;
    }
    .site-nav {
        gap: 10px;
    }
    .nav-links {
        gap: 16px;
    }
    .piano-panel {
        padding: 18px;
    }
    .keyboard {
        height: 156px;
    }
    .piano-top {
        gap: 8px;
    }
    .piano-top span {
        font-size: 0.68rem;
    }
    .piano-key.black b {
        font-size: 0.68rem;
    }
    .piano-key span {
        font-size: 0.6rem;
    }
    .ref-table th,
    .ref-table td {
        padding: 10px;
    }
    .completion-button {
        white-space: normal;
    }
}
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        scroll-behavior: auto !important;
        transition: none !important;
        animation: none !important;
    }
}