:root{color-scheme:dark;--bg:#090b10;--surface:#11151c;--raised:#171c25;--line:rgba(255,255,255,.1);--text:#f5f7fa;--muted:#9199a7;--cyan:#67e8f9;--violet:#a78bfa;--coral:#fb7185;--lime:#a3e635;--gold:#f5c96a}*{box-sizing:border-box}html,body{min-height:100%;margin:0}body{background:radial-gradient(circle at 12% 18%,rgba(103,232,249,.07),transparent 30%),radial-gradient(circle at 85% 12%,rgba(167,139,250,.08),transparent 28%),var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}button{font:inherit}.app{min-height:100vh}.site-header{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:20px clamp(20px,4vw,56px);border-bottom:1px solid var(--line)}.brand{display:inline-flex;align-items:center;gap:9px;color:var(--text);font-size:13px;font-weight:700;text-decoration:none}.brand-mark{width:10px;height:10px;background:linear-gradient(135deg,var(--cyan),var(--violet));border-radius:50%;box-shadow:0 0 14px rgba(103,232,249,.4)}.site-header>p,.eyebrow{margin:0;color:var(--muted);font-size:10px;font-weight:750;letter-spacing:.16em;text-transform:uppercase}.page-heading{display:flex;align-items:end;justify-content:space-between;gap:32px;padding:32px clamp(20px,4vw,56px) 26px}.page-heading h1{margin:7px 0 0;font-size:clamp(32px,4vw,54px);font-weight:620;letter-spacing:-.055em}.intro{max-width:560px;margin:0;color:var(--muted);font-size:14px;line-height:1.65}.lesson-tabs{display:flex;gap:4px;padding:0 clamp(20px,4vw,56px);border-bottom:1px solid var(--line);overflow-x:auto}.lesson-tab{padding:14px 17px;background:transparent;color:var(--muted);border:0;border-bottom:2px solid transparent;cursor:pointer;white-space:nowrap}.lesson-tab:hover{color:var(--text)}.lesson-tab.active{color:var(--cyan);border-bottom-color:var(--cyan)}.lesson-tab:focus-visible,.key-button:focus-visible,.compare-switch button:focus-visible,.progression-button:focus-visible,.play-button:focus-visible{outline:2px solid var(--cyan);outline-offset:2px}.workspace{display:grid;grid-template-columns:minmax(440px,.8fr) minmax(520px,1.2fr);min-height:660px}.circle-panel{display:flex;flex-direction:column;justify-content:center;align-items:center;gap:18px;padding:32px;border-right:1px solid var(--line)}.circle-copy{align-self:stretch;display:flex;justify-content:space-between;gap:20px}.circle-copy>p:last-child{max-width:270px;margin:0;color:var(--muted);font-size:11px;line-height:1.5;text-align:right}.circle{position:relative;width:min(44vw,500px);aspect-ratio:1;border-radius:50%}.circle-rings{position:absolute;inset:5%;border:1px solid var(--line);border-radius:50%;background:radial-gradient(circle,transparent 0 29%,rgba(255,255,255,.025) 29.2% 52%,transparent 52.2%),conic-gradient(from -15deg,rgba(255,255,255,.025),transparent 8.3%,rgba(255,255,255,.025) 8.4%,transparent 16.6%,rgba(255,255,255,.025) 16.7%,transparent 25%,rgba(255,255,255,.025) 25.1%,transparent 33.3%,rgba(255,255,255,.025) 33.4%,transparent 41.6%,rgba(255,255,255,.025) 41.7%,transparent 50%,rgba(255,255,255,.025) 50.1%,transparent 58.3%,rgba(255,255,255,.025) 58.4%,transparent 66.6%,rgba(255,255,255,.025) 66.7%,transparent 75%,rgba(255,255,255,.025) 75.1%,transparent 83.3%,rgba(255,255,255,.025) 83.4%,transparent 91.6%,rgba(255,255,255,.025) 91.7%)}.key-button{position:absolute;left:50%;top:50%;width:58px;height:58px;display:grid;place-items:center;padding:0;background:var(--surface);color:var(--text);border:1px solid var(--line);border-radius:50%;cursor:pointer;transform:translate(-50%,-50%) rotate(var(--angle)) translateY(var(--radius)) rotate(calc(-1 * var(--angle)));transition:background .18s,border-color .18s,transform .18s}.key-button.minor{width:48px;height:48px;color:var(--muted);font-size:11px}.key-button:hover{border-color:rgba(255,255,255,.3)}.key-button.home{background:rgba(103,232,249,.14);color:var(--cyan);border-color:var(--cyan);box-shadow:0 0 24px rgba(103,232,249,.16)}.key-button.neighbor{background:rgba(163,230,53,.09);color:var(--lime);border-color:rgba(163,230,53,.6)}.key-button.relative{background:rgba(167,139,250,.13);color:var(--violet);border-color:var(--violet)}.circle-center{position:absolute;inset:37%;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;border:1px solid var(--line);border-radius:50%;background:var(--surface);box-shadow:0 14px 35px rgba(0,0,0,.3)}.circle-center span{color:var(--muted);font-size:9px;font-weight:700;letter-spacing:.12em;text-transform:uppercase}.circle-center strong{font-size:clamp(28px,4vw,46px);letter-spacing:-.05em}.circle-center small{max-width:90px;color:var(--muted);font-size:9px;line-height:1.25}.circle-legend{display:flex;gap:16px;color:var(--muted);font-size:10px}.circle-legend span{display:flex;align-items:center;gap:6px}.dot{width:7px;height:7px;border-radius:50%;background:var(--cyan)}.dot.neighbor{background:var(--lime)}.dot.relative{background:var(--violet)}.lesson-panel{padding:clamp(32px,5vw,68px)}.lesson-view{display:none;max-width:850px;margin:auto}.lesson-view.active{display:block;animation:reveal .22s ease}@keyframes reveal{from{opacity:0;transform:translateY(5px)}}.lesson-lead{max-width:690px;margin-bottom:30px}.lesson-lead h2{margin:8px 0 12px;font-size:clamp(27px,3vw,42px);font-weight:610;letter-spacing:-.045em}.lesson-lead>p:last-child{margin:0;color:var(--muted);font-size:14px;line-height:1.65}.lesson-lead strong{color:var(--text)}.relationship-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}.relationship-card{min-height:205px;padding:20px;background:var(--surface);border:1px solid var(--line);border-top:2px solid var(--lime);border-radius:10px}.relationship-card.relative-card{border-top-color:var(--violet)}.relationship-card.clockwise{border-top-color:var(--coral)}.direction{color:var(--muted);font-size:9px;font-weight:750;letter-spacing:.12em;text-transform:uppercase}.relationship-card h3{margin:28px 0 11px;font-size:18px;letter-spacing:-.025em}.relationship-card p{min-height:42px;margin:0 0 18px;color:var(--muted);font-size:12px;line-height:1.5}.relationship-card small{color:var(--text);font-size:11px;line-height:1.4}.movement{display:flex;align-items:center;justify-content:center;gap:14px;margin-top:24px;padding:16px;background:var(--raised);border-radius:8px;color:var(--muted);font-size:11px}.movement b{color:var(--coral)}.movement strong{color:var(--cyan)}.chord-grid{display:grid;grid-template-columns:repeat(7,1fr);gap:7px}.chord-card{display:flex;min-height:125px;flex-direction:column;align-items:center;justify-content:center;background:var(--surface);border:1px solid var(--line);border-radius:8px}.chord-card.pillar{border-color:rgba(103,232,249,.5);background:rgba(103,232,249,.055)}.chord-card.relative-chord{border-color:rgba(167,139,250,.6)}.chord-card span{color:var(--muted);font-size:11px}.chord-card strong{margin:8px 0;font-size:22px}.chord-card small{color:var(--muted);font-size:9px;text-transform:uppercase}.lesson-note,.compare-explanation{margin:22px 0 0;padding:16px 18px;border-left:2px solid var(--violet);background:rgba(167,139,250,.06);color:var(--muted);font-size:12px;line-height:1.6}.lesson-note strong{color:var(--text)}.compare-switch{display:inline-flex;margin-bottom:24px}.compare-switch button{padding:11px 16px;background:var(--surface);color:var(--muted);border:1px solid var(--line);cursor:pointer}.compare-switch button:first-child{border-radius:7px 0 0 7px}.compare-switch button:last-child{margin-left:-1px;border-radius:0 7px 7px 0}.compare-switch button.active{position:relative;background:rgba(163,230,53,.09);color:var(--lime);border-color:rgba(163,230,53,.5)}.note-comparison{display:grid;grid-template-columns:1fr 1fr;gap:14px}.note-comparison>div{padding:18px;background:var(--surface);border:1px solid var(--line);border-radius:9px}.note-comparison>div>span{display:block;margin-bottom:15px;color:var(--muted);font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.1em}.note-row{display:flex;flex-wrap:wrap;gap:7px}.note{width:39px;height:39px;display:grid;place-items:center;border-radius:50%;background:var(--raised);font-size:12px}.note.shared{color:var(--cyan);border:1px solid rgba(103,232,249,.28)}.note.changed{color:var(--coral);border:1px solid rgba(251,113,133,.5)}.progression-list{display:grid;gap:8px}.progression-button{display:grid;grid-template-columns:110px 1fr auto;align-items:center;gap:18px;padding:16px 18px;text-align:left;background:var(--surface);color:var(--text);border:1px solid var(--line);border-radius:8px;cursor:pointer}.progression-button:hover{border-color:rgba(255,255,255,.25)}.progression-button.active{background:rgba(103,232,249,.06);border-color:rgba(103,232,249,.5)}.progression-button span{color:var(--muted);font-size:11px}.progression-button strong{font-size:17px}.progression-button small{color:var(--cyan)}.play-button{margin-top:18px;padding:13px 20px;background:var(--cyan);color:#071014;border:0;border-radius:7px;font-weight:750;cursor:pointer}.play-button.playing{background:var(--coral)}.progression-button.sounding{box-shadow:inset 3px 0 var(--cyan)}
@media(max-width:980px){.workspace{grid-template-columns:1fr}.circle-panel{border-right:0;border-bottom:1px solid var(--line)}.circle{width:min(88vw,500px)}}@media(max-width:680px){.page-heading{display:block}.intro{margin-top:16px}.circle-panel{padding:24px 14px}.circle-copy{padding:0 8px}.key-button{--radius:-43vw!important;width:48px;height:48px;font-size:12px}.key-button.minor{--radius:-30vw!important;width:40px;height:40px;font-size:9px}.lesson-panel{padding:34px 20px}.relationship-grid{grid-template-columns:1fr}.relationship-card{min-height:0}.relationship-card p{min-height:0}.movement{align-items:flex-start;flex-direction:column}.movement b{transform:rotate(90deg)}.chord-grid{grid-template-columns:repeat(4,1fr)}.note-comparison{grid-template-columns:1fr}.progression-button{grid-template-columns:80px 1fr}.progression-button small{grid-column:2}}@media(max-width:430px){.key-button{--radius:-41vw!important;width:43px;height:43px}.key-button.minor{--radius:-28vw!important;width:35px;height:35px}.circle-center small{display:none}}
@media(prefers-reduced-motion:reduce){.lesson-view{animation:none}.key-button{transition:none}}
.diatonic-layout{display:grid;grid-template-columns:minmax(300px,1fr) minmax(230px,.75fr);align-items:center;gap:28px}.diatonic-wheel{position:relative;width:min(100%,390px);aspect-ratio:1;margin:auto;border:1px solid var(--line);border-radius:50%;background:radial-gradient(circle,rgba(103,232,249,.05),transparent 48%),conic-gradient(from -25deg,rgba(255,255,255,.025),transparent 14.2%,rgba(255,255,255,.025) 14.3%,transparent 28.5%,rgba(255,255,255,.025) 28.6%,transparent 42.8%,rgba(255,255,255,.025) 42.9%,transparent 57.1%,rgba(255,255,255,.025) 57.2%,transparent 71.4%,rgba(255,255,255,.025) 71.5%,transparent 85.7%,rgba(255,255,255,.025) 85.8%)}.diatonic-wheel::after{content:"↻ harmonic motion";position:absolute;left:50%;bottom:7%;transform:translateX(-50%);color:var(--muted);font-size:8px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;white-space:nowrap}.diatonic-chord{position:absolute;left:50%;top:50%;width:68px;height:68px;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:0;background:var(--surface);color:var(--text);border:1px solid var(--line);border-radius:50%;cursor:pointer;transform:translate(-50%,-50%) rotate(var(--angle)) translateY(-155px) rotate(calc(-1 * var(--angle)));transition:border-color .18s,background .18s}.diatonic-chord span{color:var(--muted);font-size:9px}.diatonic-chord strong{font-size:15px}.diatonic-chord:hover{border-color:rgba(255,255,255,.35)}.diatonic-chord.active{background:rgba(103,232,249,.12);color:var(--cyan);border-color:var(--cyan);box-shadow:0 0 20px rgba(103,232,249,.12)}.diatonic-chord.diminished{border-style:dashed}.diatonic-chord.diminished strong{color:var(--coral)}.diatonic-center{position:absolute;inset:34%;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;background:var(--raised);border:1px solid var(--line);border-radius:50%}.diatonic-center span,.diatonic-center small{color:var(--muted);font-size:8px;text-transform:uppercase;letter-spacing:.09em}.diatonic-center strong{font-size:32px;letter-spacing:-.05em}.diatonic-center small{max-width:90px;line-height:1.35}.chord-explanation{padding:24px;background:var(--surface);border:1px solid var(--line);border-radius:10px}.chord-explanation h3{margin:8px 0 14px;font-size:28px;letter-spacing:-.04em}.chord-explanation>p:not(.eyebrow){min-height:78px;margin:0;color:var(--muted);font-size:12px;line-height:1.6}.resolution{margin:18px 0;padding:14px;background:var(--raised);border-radius:7px}.resolution span{display:block;margin-bottom:5px;color:var(--muted);font-size:8px;font-weight:700;letter-spacing:.12em;text-transform:uppercase}.resolution strong{font-size:16px}.listen-button{padding:11px 15px;background:transparent;color:var(--cyan);border:1px solid rgba(103,232,249,.45);border-radius:7px;cursor:pointer}.listen-button:hover{background:rgba(103,232,249,.07)}.diatonic-chord:focus-visible,.listen-button:focus-visible{outline:2px solid var(--cyan);outline-offset:2px}@media(max-width:680px){.diatonic-layout{grid-template-columns:1fr}.diatonic-wheel{width:min(90vw,390px)}.chord-explanation>p:not(.eyebrow){min-height:0}}@media(max-width:430px){.diatonic-chord{width:57px;height:57px;transform:translate(-50%,-50%) rotate(var(--angle)) translateY(-37vw) rotate(calc(-1 * var(--angle)))}.diatonic-chord strong{font-size:13px}}