*{box-sizing:border-box}html{color-scheme:light;scroll-behavior:smooth}body{margin:0;background:var(--site-canvas);color:var(--site-ink);font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Noto Sans CJK SC",sans-serif;font-size:15px;line-height:1.6}button,select,input{font:inherit;color:inherit}button,select{min-height:44px;border:1px solid var(--site-line);border-radius:10px;background:var(--site-raised);padding:8px 14px}button{cursor:pointer;touch-action:manipulation}button:hover:not(:disabled){border-color:var(--site-accent);background:var(--site-soft)}button:disabled{cursor:default;opacity:.55}button.primary,button[aria-pressed=true]{background:var(--site-accent);border-color:var(--site-accent);color:var(--site-on)}button.primary:hover:not(:disabled){background:var(--site-accent);filter:brightness(.95)}button.quiet{background:transparent}select{width:100%;max-width:100%;text-overflow:ellipsis}input[type=range]{accent-color:var(--site-accent);min-height:44px;max-width:100%;margin:0}input[type=checkbox]{width:20px;height:20px;accent-color:var(--site-accent);margin:0}label{font-size:12px;color:var(--site-muted);display:flex;flex-direction:column;gap:5px;min-width:0}label select{font-size:14px;color:var(--site-ink)}a{color:var(--site-accent)}h1,h2,h3,p{margin:0}h1{font-size:28px;line-height:1.3}h2{font-size:18px;line-height:1.4;font-weight:650}p+p{margin-top:8px}strong{font-weight:650}.small{font-size:12px;line-height:1.6}.muted{color:var(--site-muted)}.eyebrow{display:block;font-size:11px;letter-spacing:.06em;color:var(--site-muted);margin-bottom:4px}[hidden]{display:none!important}:focus-visible{outline:3px solid var(--site-accent);outline-offset:3px}.container{width:100%;max-width:1920px;margin-inline:auto;padding-inline:clamp(28px,3vw,58px)}.page-header{height:72px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--site-line);gap:12px}.brand{display:flex;align-items:center;gap:12px;font-size:17px}.brand-mark{display:grid;place-items:center;background:var(--site-ink);color:var(--site-canvas);width:32px;height:32px;border-radius:9px;font-size:21px;font-weight:750}.brand-divider{padding:0 12px;color:var(--site-line)}.page-intro{display:flex;justify-content:space-between;align-items:center;padding:20px 0 10px;font-size:13px;color:var(--site-muted)}.preview-tag{font-size:11px;padding:2px 8px;border-radius:20px;background:var(--site-surface);border:1px solid var(--site-line)}.tabs{display:flex;gap:24px;border-bottom:1px solid var(--site-line);margin-bottom:20px}.tabs button{border:0;border-radius:0;background:none;font-weight:550;padding:8px 0 13px;color:var(--site-muted);min-width:70px;border-bottom:3px solid transparent}.tabs button[aria-current=page]{color:var(--site-accent);border-color:var(--site-accent)}.selectors{display:grid;grid-template-columns:minmax(150px,1fr) minmax(220px,1.7fr) minmax(100px,.5fr);gap:14px;margin-bottom:20px;max-width:1000px}.explorer-grid{display:grid;grid-template-columns:minmax(300px,.78fr) minmax(0,1.22fr);gap:20px}.panel{background:var(--site-raised);border:1px solid var(--site-line);border-radius:16px;min-width:0;padding:22px}.panel-heading{display:flex;justify-content:space-between;align-items:center;gap:12px}.segmented{display:flex;gap:3px;padding:3px;background:var(--site-surface);border:1px solid var(--site-line);border-radius:11px}.segmented button{min-width:48px;border:0;padding:6px 10px;border-radius:7px;font-size:12px}.ring{width:100%;max-width:420px;aspect-ratio:1;margin:6px auto 0;position:relative}.ring-lines{width:100%;height:100%;overflow:visible}.ring-lines .guide{fill:none;stroke:var(--site-line);stroke-width:1}.ring-lines .polygon{fill:var(--site-soft);stroke:var(--site-accent);stroke-width:1.7}.ring-center{position:absolute;inset:33% 23%;display:flex;align-items:center;justify-content:center;flex-direction:column;text-align:center;pointer-events:none;line-height:1.3}.ring-center>span{font-size:38px;letter-spacing:-.05em;font-weight:650}.ring-center>strong{font-size:clamp(14px,1.5vw,20px);margin:6px 0;max-width:100%;overflow-wrap:anywhere}.ring-center>small{font-size:11px;color:var(--site-muted)}.ring-note{position:absolute;transform:translate(-50%,-50%);width:49px;height:49px;min-height:49px;padding:0;border-radius:50%;display:flex;align-items:center;justify-content:center;flex-direction:column;line-height:1.2;font-size:13px;z-index:2;color:var(--site-muted)}.ring-note span{font-size:10px;margin-top:2px}.ring-note.member{background:var(--site-surface);color:var(--site-ink);border-color:var(--site-ink);font-weight:600}.ring-note.tonic{border:3px double var(--site-ink);background:var(--site-ink);color:var(--site-canvas)}.ring-note.feature{border:2px dashed var(--site-accent);color:var(--site-accent);background:var(--site-soft)}.ring-note.playing{background:var(--site-accent);color:var(--site-on);outline:3px solid var(--site-accent);outline-offset:3px}.ring-legend{display:flex;justify-content:center;gap:14px;flex-wrap:wrap;font-size:11px;color:var(--site-muted)}.ring-legend span{display:flex;align-items:center;gap:5px}.ring-legend i{display:inline-block;width:13px;height:13px;border-radius:50%}.legend-tonic{border:3px double var(--site-ink)}.legend-feature{border:2px dashed var(--site-accent)}.legend-playing{background:var(--site-accent)}.ring-caption{text-align:center;margin-top:9px}.study-column{display:flex;flex-direction:column;gap:16px;min-width:0}.score-panel{flex:1}.score-description{margin-top:9px}.score-scroll{overflow-x:auto;overflow-y:hidden;max-width:100%;margin:8px -4px 0;scrollbar-color:var(--site-line) transparent;padding:4px}.score-scroll svg{display:block;width:100%;height:auto;min-width:550px;color:var(--site-ink)}.score-scroll [data-note-index].active,.score-scroll [data-degree-index].active{color:var(--site-accent);filter:drop-shadow(0 0 1px currentColor)}.score-scroll [data-note-index].feature{color:var(--site-accent)}.scroll-hint{font-size:11px;color:var(--site-muted);display:none;margin:4px 0}.degree-buttons{display:flex;flex-wrap:wrap;gap:6px;margin-top:12px}.degree-buttons button{flex:1 0 46px;padding:5px;min-width:46px;max-width:90px;display:flex;flex-direction:column;align-items:center;line-height:1.3;font-size:15px}.degree-buttons small{font-size:10px;color:var(--site-muted)}.degree-buttons .feature{border-style:dashed;border-color:var(--site-accent);color:var(--site-accent)}.degree-buttons .tonic{border-bottom:3px double var(--site-ink)}.degree-buttons .playing{background:var(--site-accent);color:var(--site-on)}.degree-buttons .playing small{color:inherit}.note-readout{display:flex;align-items:center;justify-content:space-between;gap:8px;min-height:32px;font-size:12px;color:var(--site-muted);margin-top:10px;border-top:1px solid var(--site-line);padding-top:8px}.comparison-heading{display:flex;align-items:end;gap:12px;margin-bottom:12px}.comparison-heading label{flex:1}.comparison-heading button{flex-shrink:0;font-size:13px}.comparison-panel>p{font-size:13px}.comparison-panel>p.small{font-size:11px}.difference-chips{display:flex;gap:7px;flex-wrap:wrap;margin:10px 0}.difference-chips span{padding:4px 9px;border:1px dashed var(--site-accent);border-radius:7px;background:var(--site-soft);font-size:12px;color:var(--site-accent)}.transport-panel{margin-top:20px;display:grid;grid-template-columns:1fr 1fr;gap:16px}.transport-actions{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.transport-settings{display:flex;align-items:center;justify-content:flex-end;gap:18px}.transport-settings>label:first-child{display:grid;grid-template-columns:1fr auto;gap:0 4px;width:135px}.transport-settings>label:first-child input{grid-column:1/-1;width:100%}.check{display:flex;flex-direction:row;align-items:center;min-height:44px;gap:7px}.melody-details{grid-column:1/-1;border-top:1px solid var(--site-line);padding-top:14px;display:grid;grid-template-columns:240px 1fr;gap:8px 20px}.melody-details label{grid-row:1/3}.melody-details details{grid-column:1/-1}.melody-details details[open]{margin-top:6px}.melody-row{display:flex;gap:14px;overflow:auto;max-width:100%;padding:12px 0}.melody-bar{display:flex;gap:4px;padding-right:10px;border-right:2px solid var(--site-line);flex-shrink:0;align-items:center}.melody-bar>span{min-width:34px;text-align:center;line-height:1.3;border-radius:5px;padding:4px}.melody-bar small{display:block;font-size:10px;color:var(--site-muted)}.melody-bar .active{background:var(--site-accent);color:var(--site-on)}.melody-bar .active small{color:inherit}summary{cursor:pointer;min-height:44px;display:flex;align-items:center;font-size:12px;color:var(--site-muted)}summary:before{content:'＋';margin-right:6px;font-size:15px}details[open]>summary:before{content:'−'}.audio-status-bar{display:flex;justify-content:space-between;align-items:center;gap:20px;margin-top:20px;padding:15px 0;border-top:1px solid var(--site-line);border-bottom:1px solid var(--site-line);font-size:12px}.audio-status-bar>div:first-child{display:flex;align-items:center;gap:10px;min-width:0}.audio-status-bar [data-state=error]{color:var(--site-accent);font-weight:600}.volume-control{display:flex;align-items:center;gap:10px;flex-shrink:0}.volume-control button{font-size:12px}.volume-control label{flex-direction:row;align-items:center;gap:8px}.volume-control input{width:100px}.volume-control output{font-size:11px;min-width:34px}.page-footer{padding:18px 0 28px;color:var(--site-muted);font-size:11px}.page-footer details{max-width:1000px}.page-footer details p{margin-bottom:8px}.lesson-picker{display:flex;align-items:center;justify-content:space-between;gap:15px;margin-bottom:16px}.lesson-picker label{max-width:400px;width:100%}.lesson-picker span{font-size:12px;color:var(--site-muted)}.lesson-card{display:grid;grid-template-columns:1.5fr 1fr;gap:30px;padding:22px;background:var(--site-soft);border-radius:14px;margin-bottom:20px}.lesson-question{font-size:16px;margin:8px 0;color:var(--site-accent);font-weight:600}.lesson-card p:not(.lesson-question){font-size:13px}.lesson-next{border-left:1px solid var(--site-line);padding-left:24px;display:flex;flex-direction:column;justify-content:center;align-items:start;gap:12px}.quiz-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:24px;padding:6px 0 20px}.quiz-main{padding:28px}.quiz-number{font-size:28px;color:var(--site-muted);font-variant-numeric:tabular-nums}.quiz-setup{display:grid;grid-template-columns:1fr 1.4fr .55fr;gap:12px;margin:22px 0}.quiz-prompt{font-size:16px;margin-bottom:20px}.blind-stage{min-height:160px;display:flex;align-items:center;justify-content:center;flex-direction:column;background:var(--site-surface);border:1px solid var(--site-line);border-radius:12px;gap:7px;padding:20px;text-align:center}.listening-glyph{height:35px;display:flex;align-items:center;gap:5px;margin-bottom:4px}.listening-glyph i{width:4px;height:14px;border-radius:2px;background:var(--site-muted)}.listening-glyph i:nth-child(2n){height:24px}.listening-glyph i:nth-child(3){height:35px}.quiz-play{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}.hint{padding:12px;background:var(--site-soft);border-radius:9px;font-size:13px;margin-bottom:15px}.quiz-choices{display:flex;gap:12px;margin:16px 0 8px;flex-wrap:wrap}.quiz-choices button{flex:1;min-width:110px;min-height:56px;font-size:16px}.quiz-choices button.selected{border:2px solid var(--site-accent);background:var(--site-soft)}.quiz-feedback{padding:18px;background:var(--site-soft);border-radius:12px;margin-top:18px}.quiz-feedback h3{font-size:18px;margin-bottom:8px}.quiz-feedback p{font-size:13px}.quiz-feedback .score-scroll{margin-top:12px}.quiz-footer{display:flex;justify-content:space-between;gap:12px;margin-top:18px}.progress-panel{align-self:start}.progress-panel h2{margin-bottom:20px}.stat-line{display:flex;justify-content:space-between;border-top:1px solid var(--site-line);padding:12px 0;font-size:13px}.stat-line strong{font-size:19px;font-variant-numeric:tabular-nums}.progress-panel>p{margin:10px 0}.progress-panel button{width:100%;font-size:12px;margin-top:12px}.progress-panel ol{padding-left:20px;font-size:11px;line-height:1.7}.progress-panel li{margin-bottom:8px}.skip-link{position:fixed;top:-100px;left:20px;background:var(--site-accent);color:var(--site-on);padding:12px;z-index:100}.skip-link:focus{top:12px}dialog{max-width:450px;width:calc(100% - 40px);padding:24px;border:1px solid var(--site-line);border-radius:18px;background:var(--site-raised);color:var(--site-ink)}dialog::backdrop{background:#0006}dialog p{font-size:13px;margin:12px 0}dialog label{margin-top:16px}.dialog-actions{display:flex;gap:10px;justify-content:flex-end;margin-top:20px}
@media(max-width:1050px){.container{padding-inline:20px}.explorer-grid{grid-template-columns:minmax(290px,.85fr) minmax(0,1.15fr);gap:14px}.panel{padding:18px}.transport-panel{grid-template-columns:1fr}.transport-settings{justify-content:flex-start}.melody-details{grid-column:1}.score-scroll svg{min-width:520px}.scroll-hint{display:block}.ring-note{width:45px;height:45px;min-height:45px;font-size:12px}.ring-center>span{font-size:32px}.quiz-layout{grid-template-columns:minmax(0,1fr) 250px;gap:14px}.quiz-setup{grid-template-columns:1fr 1fr}.quiz-setup label:last-child{grid-column:1/-1;max-width:120px}}
/* Every narrow score is engraved by LilyPond; CSS only scales and highlights its SVG. */
.mobile-compact-score{display:none}
.mobile-compact-score svg{display:block;width:100%;height:100%;color:var(--site-ink)}
.mobile-compact-score [data-note-index].feature,.mobile-compact-score [data-degree-index].feature{color:var(--site-accent)}
.mobile-compact-score [data-degree-index].feature text,.score-scroll [data-degree-index].feature text{font-weight:700;text-decoration:underline;text-underline-offset:2px}
.score-scroll [data-degree-index].feature{color:var(--site-accent)}
.score-feature-key.has-features{color:var(--site-accent);font-weight:700;white-space:nowrap}
.score-presentation.compact{position:relative;width:100%;height:138px}
.score-presentation.compact .score-scroll{display:none}
.score-presentation.compact .mobile-compact-score{display:block;width:100%;height:138px;overflow:hidden}
.score-presentation.compact .degree-buttons{position:absolute;inset:0;display:block;margin:0;width:auto;height:138px;z-index:1}
.score-presentation.compact .degree-buttons button{position:absolute;top:0;width:100%;max-width:none;min-width:0;min-height:138px;height:138px;padding:0;border:0;border-radius:0;background:transparent!important;color:transparent!important;box-shadow:none;font-size:0}
.score-presentation.compact .degree-buttons button.tonic,.score-presentation.compact .degree-buttons button.feature{border:0}
.score-presentation.compact .degree-buttons button span,.score-presentation.compact .degree-buttons button small{display:none}
.score-presentation.compact .degree-buttons button:hover:not(:disabled),.score-presentation.compact .degree-buttons button:focus-visible,.score-presentation.compact .degree-buttons button.playing{background:transparent!important;box-shadow:inset 0 0 0 1px var(--site-accent)}
.score-presentation.compact .degree-buttons button:focus-visible{outline:2px solid var(--site-accent);outline-offset:-2px}
@media(max-width:760px){.page-header{height:64px}.brand{font-size:15px;gap:8px}.brand-divider{padding:0 7px}.page-intro{padding-top:14px}.tabs{gap:22px;margin-bottom:18px}.selectors{grid-template-columns:1fr 100px;gap:10px}.selectors>label:first-child{grid-column:1/-1}.selectors .mode-select-label{grid-column:1}.explorer-grid{grid-template-columns:1fr}.ring{max-width:345px}.ring-panel{padding-top:16px}.ring-center>strong{font-size:20px}.ring-caption{font-size:11px}.ring-note{width:47px;height:47px;min-height:47px}.study-column{gap:14px}.panel-heading h2{font-size:18px}.score-description{font-size:11px}.transport-panel{margin-top:14px;gap:12px}.transport-actions{display:grid;grid-template-columns:1fr 1fr;gap:8px}.transport-actions button{font-size:13px}.transport-settings{gap:13px;flex-wrap:wrap;justify-content:space-between}.transport-settings label:first-child{width:116px}.transport-settings select{font-size:12px;padding-inline:8px}.melody-details{grid-template-columns:1fr;gap:8px}.melody-details label{grid-row:auto}.melody-details details{grid-column:1}.comparison-heading button{padding-inline:10px}.audio-status-bar{flex-direction:column;align-items:stretch;gap:8px}.volume-control{justify-content:space-between}.volume-control label{flex:1}.volume-control input{width:100%;max-width:170px}.audio-status-bar>div:first-child{min-height:36px}.page-footer{font-size:10px}.lesson-card{grid-template-columns:1fr;gap:16px;padding:18px}.lesson-next{padding:16px 0 0;border-left:0;border-top:1px solid var(--site-line)}.lesson-picker span{min-width:50px}.quiz-layout{grid-template-columns:1fr}.quiz-main{padding:18px}.quiz-main h1{font-size:24px}.quiz-setup{gap:10px}.quiz-setup label:nth-child(2){grid-column:1/-1;grid-row:2}.quiz-setup label:last-child{grid-column:2;grid-row:1}.quiz-choices button{min-width:100px;font-size:15px}.quiz-prompt{font-size:14px}.blind-stage{min-height:150px;padding:16px}.quiz-play button{font-size:13px;padding-inline:12px}.quiz-footer button{font-size:12px}.progress-panel{margin-top:2px}.page-header button{padding:8px 10px}.ring-legend{gap:10px;font-size:10px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*:before,*:after{animation:none!important;transition:none!important}}

/* Core playback precedes the ring on every viewport. */
.page-intro h1{font-size:18px;font-weight:650;color:var(--site-ink);line-height:1.4}.selectors{margin-bottom:12px}#explore-view>.transport-actions{margin:0 0 20px;padding-bottom:16px;border-bottom:1px solid var(--site-line)}.transport-panel{display:block}.transport-settings{justify-content:flex-start;margin-bottom:14px}.melody-details{display:grid}.lesson-card p:not(.lesson-question),.comparison-panel>p{font-size:15px}.comparison-panel>p.small{font-size:12px}@media(max-width:760px){body{font-size:16px}.lesson-card p:not(.lesson-question),.lesson-question,.comparison-panel>p:not(.small),.quiz-prompt,.quiz-feedback p:not(.small){font-size:16px}.transport-actions button{font-size:15px}.page-intro h1{font-size:16px}.tabs button{font-size:15px}.selectors label select{font-size:15px}.panel-heading h2{font-size:19px}}
/* Integration contract: shared site-shell owns navigation; this page owns its scroll area. */
body.has-site-shell.mode-lab-integrated{display:flex;flex-direction:column;height:100dvh;min-height:0;overflow:hidden;padding-bottom:var(--site-bottom)}
body.has-site-shell.mode-lab-integrated>main.container{flex:1 1 auto;min-height:0;height:auto;overflow-x:hidden;overflow-y:auto;overscroll-behavior:contain;max-width:1920px;width:100%;margin-inline:auto;padding-bottom:24px}
.mode-lab-integrated>.mode-lab-mobile-header{display:flex;align-items:center;justify-content:space-between;gap:14px;min-height:64px;flex:0 0 auto;padding:8px 20px;width:100%;border-bottom:1px solid var(--site-line);background:var(--site-surface)}
.mode-lab-mobile-header>strong{font-size:16px;line-height:1.4}.mode-lab-mobile-header>.global-account{margin-left:auto}
@media(min-width:901px){.mode-lab-integrated>.mode-lab-mobile-header{display:none}}

/* Melody-driven ring: the polygon is stable; the playhead snaps only to sounding notes. */
.showcase-strip{display:grid;grid-template-columns:minmax(220px,.8fr) minmax(0,1.2fr);gap:10px 22px;margin:18px 0 20px;padding:17px 20px;border:1px solid var(--site-line);border-radius:14px;background:var(--site-surface)}
.showcase-copy strong{display:block;font-size:15px;line-height:1.35}.showcase-copy p{font-size:12px;color:var(--site-muted);margin-top:5px;max-width:490px}
.showcase-buttons{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:7px;align-content:center}.showcase-buttons button{font-size:12px;line-height:1.35;padding:7px 9px;min-height:48px;white-space:normal}.showcase-buttons button[aria-pressed=true]{background:var(--site-accent);color:var(--site-on);border-color:var(--site-accent)}
.showcase-status{grid-column:1/-1;min-height:20px;font-size:12px;color:var(--site-muted)}
.ring-lines .polygon{stroke-width:2.4;fill:var(--site-soft);filter:drop-shadow(0 0 5px var(--site-soft))}
.ring-playhead{position:absolute;inset:0;width:100%;height:100%;z-index:5;pointer-events:none;overflow:visible}
.ring-cursor-spoke{stroke:var(--site-accent);stroke-width:2.5;stroke-linecap:round;opacity:.75}
.ring-cursor-halo{fill:var(--site-accent);opacity:.22;transform-box:fill-box;transform-origin:center;animation:ring-attack .28s ease-out both}
.ring-cursor-progress{fill:none;stroke:var(--site-accent);stroke-width:2.2;transform:rotate(-90deg);transform-box:fill-box;transform-origin:center}
.ring-cursor-core{fill:#fff;stroke:var(--site-accent);stroke-width:2.5;filter:drop-shadow(0 0 6px var(--site-accent))}
.ring-note.playing{background:var(--site-soft);color:var(--site-accent);border-color:var(--site-accent);outline:2px solid var(--site-accent);outline-offset:2px;text-shadow:0 0 9px var(--site-accent)}
.ring-note.tonic.playing{background:var(--site-ink);color:var(--site-canvas);border-color:var(--site-ink);outline-color:var(--site-accent)}
@keyframes ring-attack{from{opacity:.45;transform:scale(.72)}to{opacity:.22;transform:scale(1)}}
@media(max-width:1050px){.showcase-strip{grid-template-columns:1fr}.showcase-buttons{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media(max-width:760px){.showcase-strip{padding:15px;margin:14px 0 18px}.showcase-buttons button{min-height:48px;font-size:12px}.ring-cursor-core{stroke-width:3}}
@media(prefers-reduced-motion:reduce){.ring-cursor-halo{animation:none}.ring-cursor-progress{display:none}}

.score-note-select{display:none}
.score-presentation.compact~.note-readout .score-note-select:not([hidden]){display:block;flex:0 0 104px;width:104px;min-height:44px;padding:4px 8px;border:1px solid var(--site-line);border-radius:9px;background:var(--site-raised);color:var(--site-ink);font-size:12px}