:root{--fg:#1a1a1a;--bg:#fff;--muted:#444;--line:#666;--soft:#f3f5f8;--accent:#1f3a5f;--focus:#c2410c}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;font:16px/1.65 -apple-system,BlinkMacSystemFont,"Apple SD Gothic Neo","Malgun Gothic",sans-serif;color:var(--fg);background:var(--bg);word-break:keep-all;overflow-wrap:break-word}
.wrap{max-width:860px;margin:0 auto;padding:0 16px}
a{color:var(--accent)}
a:focus-visible,button:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid var(--focus);outline-offset:2px}
.site-head{border-bottom:1px solid #d0d4da}
.brand{display:inline-flex;align-items:center;min-height:44px;font-weight:700;color:var(--fg);text-decoration:none}
h1{font-size:1.6rem;line-height:1.3;margin:14px 0 8px}
h2{font-size:1.2rem;line-height:1.4;margin:28px 0 8px}
h3{font-size:1rem;line-height:1.5;margin:16px 0 4px}
p,ul,ol{margin:0 0 12px}
li{margin-bottom:4px}
.answer{margin:0 0 16px}
.note{font-size:.9rem;color:var(--muted)}

.tool{margin:0 0 8px;padding:12px;border:2px solid var(--line);border-radius:8px;background:var(--soft)}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:44px;min-width:44px;padding:8px 14px;font:inherit;font-weight:700;color:#fff;background:var(--accent);border:2px solid var(--accent);border-radius:6px;cursor:pointer;touch-action:manipulation}
.btn.ghost{color:var(--accent);background:#fff}
.btn[aria-pressed="true"]{color:#fff;background:var(--accent);box-shadow:inset 0 0 0 2px #fff}
.btn[aria-pressed="true"]::before{content:"\2713  "}
.ctl{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 6px}
.vol{display:flex;align-items:center;gap:10px;min-height:44px;margin:0 0 4px}
.vol label{font-weight:700}
.vol input{flex:1;min-width:0;width:auto;min-height:44px;padding:0;border:0;background:transparent;accent-color:var(--accent)}
.vol output{min-width:2.4em;text-align:right;font-variant-numeric:tabular-nums}
#audio-status{margin:0 0 6px;padding:2px 8px;border-left:4px solid var(--line);background:#fff;font-weight:700;font-size:.9rem}
#audio-status[data-state="on"]{border-left-color:var(--accent)}
#audio-status[data-state="on"]::before{content:"\2713  "}
#audio-status[data-state="off"]::before{content:"\26A0  "}
.rangebar{display:flex;align-items:center;justify-content:space-between;gap:6px;margin:0 0 6px}
.sign{flex:1;margin:0;text-align:center;font-size:.85rem;color:var(--muted)}
.scrollbtn{padding:0 10px}

.piano{--w:44px;--bw:33px;--kh:140px;margin:0 -12px}
.piano:focus-visible{outline:3px solid var(--focus);outline-offset:-3px}
.strip{overflow-x:auto;overflow-y:hidden;-webkit-overflow-scrolling:touch;overscroll-behavior-x:contain}
.keys{position:relative;display:flex;width:calc(var(--w)*15);height:var(--kh)}
.key{font:inherit;margin:0;padding:0;border:1px solid #222;cursor:pointer;touch-action:none;user-select:none;-webkit-user-select:none;-webkit-touch-callout:none;-webkit-tap-highlight-color:transparent;display:flex;flex-direction:column;align-items:center;justify-content:flex-end;gap:2px}
.key.white{flex:0 0 var(--w);height:100%;color:#1a1a1a;background:#fff;border-radius:0 0 6px 6px;padding-bottom:6px}
.key.black{position:absolute;top:0;left:calc(var(--w)*var(--i) - var(--bw)/2);width:var(--bw);height:62%;z-index:1;color:#fff;background:#1a1a1a;border-radius:0 0 4px 4px;padding-bottom:4px}
.key .kb{font-size:.75rem;font-weight:700;line-height:1;min-width:1.4em;padding:2px 3px;border:1px solid currentColor;border-radius:3px}
.key .nn{font-size:.7rem;line-height:1.1}
.key.white .nn{font-size:.8rem;font-weight:700}
.key:focus-visible{outline:3px solid var(--focus);outline-offset:-3px;z-index:2}
.key[aria-pressed="true"]{transform:translateY(3px);box-shadow:inset 0 -6px 0 var(--focus),inset 0 0 0 2px var(--focus)}
.key.white[aria-pressed="true"]{background:#dbe4f0}
.key.black[aria-pressed="true"]{background:#3b4a66}
.key[aria-pressed="true"] .nn::before{content:"\25CF  "}

table{border-collapse:collapse;background:#fff}
caption{text-align:left;font-weight:700}
th,td{border:1px solid #c4c8ce;text-align:left}
.keymap{width:auto;margin:10px 0 0;font-size:.9rem}
.keymap caption{padding:2px 0 4px}
.keymap th,.keymap td{padding:2px 10px}
.keymap td:nth-child(1),.keymap td:nth-child(3){text-align:left}

.site-foot{margin-top:40px;border-top:1px solid #d0d4da;padding:8px 0 24px;font-size:.9rem;color:var(--muted)}
.site-foot ul{list-style:none;padding:0;margin:0 0 8px;display:flex;flex-wrap:wrap;gap:0 16px}
.site-foot li{margin:0}
.site-foot a{display:inline-flex;align-items:center;min-height:44px}

@media (max-width:639px){
  h1{margin:8px 0 4px}
  .answer{margin:0 0 8px;font-size:.92rem;line-height:1.5}
}
@media (min-width:640px){
  h1{font-size:2rem}
}
@media (max-width:699px){
  .tool{margin:0 -16px 8px;padding:8px 16px;border-width:2px 0;border-radius:0}
  .piano{margin:0 -16px}
}
@media (min-width:700px){
  .rangebar{display:none}
  .piano{margin:0 -12px}
}
@media (min-width:880px){
  .piano{--w:54px;--bw:38px;--kh:200px}
}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important;scroll-behavior:auto!important}}