:root{
  --bg:#f6f4ef; --panel:#fffdf8; --ink:#23201b; --muted:#6b6459;
  --line:#d9d2c4; --accent:#b3541e; --accent2:#2f6f5b; --accent3:#3a5a9b;
  --shadow:0 1px 2px rgba(0,0,0,.05),0 8px 24px rgba(0,0,0,.06);
  --radius:14px;
}
@media (prefers-color-scheme:dark){
  :root{--bg:#17161a;--panel:#201f25;--ink:#ece8e1;--muted:#a49d92;
    --line:#3a3742;--accent:#e08a4e;--accent2:#61c2a3;--accent3:#8aa9e8;
    --shadow:0 1px 2px rgba(0,0,0,.4),0 8px 24px rgba(0,0,0,.35);}
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--bg);color:var(--ink);
  font:16px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  -webkit-text-size-adjust:100%;
}
a{color:var(--accent3)}

/* ---------- layout ---------- */
.wrap{display:flex;min-height:100vh;align-items:flex-start}
aside{
  width:262px;flex:0 0 262px;position:sticky;top:0;height:100vh;overflow-y:auto;
  border-right:1px solid var(--line);background:var(--panel);padding:20px 14px 40px;
}
.brand{font-size:19px;font-weight:700;letter-spacing:-.02em;padding:0 8px 4px}
.brand small{display:block;font-weight:400;font-size:12.5px;color:var(--muted);letter-spacing:0}
nav{margin-top:18px}
nav .grp{font-size:11px;text-transform:uppercase;letter-spacing:.09em;color:var(--muted);margin:18px 8px 6px}
nav a{
  display:flex;gap:9px;align-items:baseline;padding:7px 10px;border-radius:9px;
  color:var(--ink);text-decoration:none;font-size:14.5px;
}
nav a .n{color:var(--muted);font-variant-numeric:tabular-nums;font-size:12.5px;min-width:20px}
nav a:hover{background:rgba(127,127,127,.1)}
nav a.on{background:var(--accent);color:#fff}
nav a.on .n{color:rgba(255,255,255,.75)}

main{flex:1;min-width:0;padding:34px 40px 120px;max-width:960px}
h1{font-size:31px;line-height:1.2;letter-spacing:-.02em;margin:0 0 6px}
h2{font-size:22px;margin:38px 0 10px;letter-spacing:-.01em;
   padding-bottom:6px;border-bottom:1px solid var(--line)}
h3{font-size:17px;margin:26px 0 8px}
p{margin:10px 0}
.lead{font-size:17.5px;color:var(--muted);margin-bottom:4px}
ul,ol{padding-left:22px;margin:10px 0}
li{margin:5px 0}
code{background:rgba(127,127,127,.14);padding:1px 5px;border-radius:5px;font-size:14px}

.page{display:none;animation:fade .25s ease}
.page.on{display:block}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

.note-box{
  border-left:3px solid var(--accent2);background:var(--panel);
  padding:12px 16px;border-radius:0 10px 10px 0;margin:16px 0;box-shadow:var(--shadow)
}
.note-box b{color:var(--accent2)}
.warn{border-left-color:var(--accent)}
.warn b{color:var(--accent)}

table{border-collapse:collapse;width:100%;margin:14px 0;font-size:14.5px;
      background:var(--panel);border-radius:10px;overflow:hidden;box-shadow:var(--shadow)}
th,td{padding:8px 11px;text-align:left;border-bottom:1px solid var(--line)}
th{background:rgba(127,127,127,.09);font-size:13px;letter-spacing:.02em}
tr:last-child td{border-bottom:none}
.tbl-scroll{overflow-x:auto}

/* ---------- staff blocks ---------- */
.stave{
  background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:12px 14px 10px;margin:18px 0;box-shadow:var(--shadow);
}
.stave-head{display:flex;align-items:center;gap:10px;margin-bottom:2px;flex-wrap:wrap}
.stave-title{font-size:13.5px;font-weight:600;color:var(--muted);letter-spacing:.01em}
.stave-scroll{overflow-x:auto;overflow-y:hidden}
.stave svg{display:block}
.hit{cursor:pointer}
.hit:hover .hd{fill:var(--accent)}
.hit:hover .stm,.hit:hover .flg{stroke:var(--accent);fill:var(--accent)}
.hit.playing .hd,.hit.playing .stm,.hit.playing .flg{fill:var(--accent2);stroke:var(--accent2)}
.lbl{font-size:11.5px;fill:var(--muted)}
.hit:hover .lbl{fill:var(--accent)}

button,.btn{
  font:inherit;font-size:13.5px;border:1px solid var(--line);background:var(--panel);
  color:var(--ink);padding:5px 12px;border-radius:20px;cursor:pointer;
}
button:hover{border-color:var(--accent);color:var(--accent)}
button.primary{background:var(--accent);border-color:var(--accent);color:#fff}
button.primary:hover{opacity:.88;color:#fff}
button:disabled{opacity:.45;cursor:default}
.hint{font-size:12.5px;color:var(--muted)}

/* ---------- piano ---------- */
.piano{position:relative;height:130px;margin:18px 0;user-select:none;
  overflow-x:auto;white-space:nowrap;padding-bottom:4px}
.piano .kbd{position:relative;display:inline-block;height:126px}
.wk{position:absolute;top:0;width:38px;height:126px;background:#fffdf8;border:1px solid #b9b1a2;
    border-radius:0 0 6px 6px;cursor:pointer;box-shadow:inset 0 -8px 10px -8px rgba(0,0,0,.35)}
.wk span{position:absolute;bottom:5px;left:0;right:0;text-align:center;font-size:10.5px;color:#8b8375}
.bk{position:absolute;top:0;width:24px;height:78px;background:#2a2721;border-radius:0 0 5px 5px;
    cursor:pointer;z-index:2;box-shadow:0 2px 4px rgba(0,0,0,.4)}
.wk.act{background:var(--accent);border-color:var(--accent)}
.wk.act span{color:#fff}
.bk.act{background:var(--accent2)}

/* ---------- quiz ---------- */
.quiz{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
      padding:18px 20px;margin:18px 0;box-shadow:var(--shadow)}
.opts{display:flex;flex-wrap:wrap;gap:8px;margin:12px 0 4px}
.opts button{min-width:64px}
.opts button.good{background:var(--accent2);border-color:var(--accent2);color:#fff}
.opts button.bad{background:#c0392b;border-color:#c0392b;color:#fff}
.score{font-size:13px;color:var(--muted);font-variant-numeric:tabular-nums}

.chips{display:flex;flex-wrap:wrap;gap:8px;margin:6px 0 4px}
.chip{font:inherit;font-size:14px;padding:7px 14px;border-radius:20px;
      border:1px solid var(--line);background:var(--panel);color:var(--ink);
      cursor:pointer;min-height:38px;white-space:nowrap}
.chip:hover{border-color:var(--accent);color:var(--accent)}
.chip.on,.chip.on:hover{background:var(--accent);border-color:var(--accent);color:#fff}
.chips-label{font-size:11px;text-transform:uppercase;letter-spacing:.09em;
             color:var(--muted);margin:14px 0 2px}
.chips-label:first-child{margin-top:0}

.rowbtns{display:flex;gap:8px;flex-wrap:wrap;margin:10px 0}
.pager{display:flex;justify-content:space-between;gap:12px;margin:56px 0 0;
       border-top:1px solid var(--line);padding-top:18px}

.burger{display:none}
.scrim{display:none}

/* ======================= МОБИЛЬНАЯ ВЁРСТКА ======================= */
@media (max-width:900px){
  html,body{overflow-x:hidden}
  body{font-size:16.5px;line-height:1.6;-webkit-tap-highlight-color:transparent}
  button,.wk,.bk,.hit,nav a{touch-action:manipulation}

  .wrap{display:block}

  /* --- шапка: липкая полоса с бургером --- */
  aside{
    position:sticky;top:0;z-index:40;width:auto;flex:none;height:auto;overflow:visible;
    border-right:none;border-bottom:1px solid var(--line);
    padding:9px 14px;display:flex;align-items:center;gap:12px;
    backdrop-filter:saturate(1.4) blur(8px);
  }
  .brand{font-size:16px;padding:0;flex:1;min-width:0;
         white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
  .brand small{font-size:11.5px}
  .burger{display:inline-flex;align-items:center;justify-content:center;
          min-width:46px;min-height:42px;font-size:19px;padding:0 12px;margin:0;flex:none}

  /* --- меню как выдвижная панель --- */
  nav{
    position:fixed;top:0;right:0;z-index:60;
    width:min(84vw,330px);height:100dvh;overflow-y:auto;
    background:var(--panel);border-left:1px solid var(--line);
    padding:14px 12px calc(28px + env(safe-area-inset-bottom));
    margin:0;box-shadow:-8px 0 30px rgba(0,0,0,.25);
    transform:translateX(0);transition:transform .24s ease;
    overscroll-behavior:contain;
  }
  nav.hide{transform:translateX(103%);box-shadow:none}
  nav a{padding:12px 12px;font-size:16px;border-radius:11px;min-height:46px;align-items:center}
  nav a .n{min-width:24px;font-size:13.5px}
  nav .grp{margin:16px 10px 6px;font-size:11.5px}
  .scrim{display:block;position:fixed;inset:0;z-index:50;background:rgba(0,0,0,.42);
         opacity:0;pointer-events:none;transition:opacity .24s ease}
  .scrim.on{opacity:1;pointer-events:auto}

  main{padding:18px 14px calc(70px + env(safe-area-inset-bottom));max-width:none}
  h1{font-size:24px;line-height:1.22}
  h2{font-size:19.5px;margin:30px 0 8px}
  h3{font-size:16.5px}
  .lead{font-size:16.5px}
  ul,ol{padding-left:20px}

  /* --- нотные станы --- */
  .stave{padding:10px 10px 8px;margin:14px -2px;border-radius:12px}
  .stave-head{gap:8px;margin-bottom:6px}
  .stave-head button{min-height:40px;padding:8px 16px;font-size:14.5px;flex:none}
  .stave-title{font-size:13px;flex:1 1 100%;order:3;margin-top:-2px}
  .stave-scroll{
    -webkit-overflow-scrolling:touch;overscroll-behavior-x:contain;
    scrollbar-width:thin;padding-bottom:2px;
  }
  /* подсказка «можно листать вбок» */
  .stave-scroll.scrollable{
    -webkit-mask-image:linear-gradient(90deg,#000 88%,transparent 100%);
    mask-image:linear-gradient(90deg,#000 88%,transparent 100%);
  }
  .stave-scroll.scrollable.at-end{-webkit-mask-image:none;mask-image:none}
  .hint{font-size:12px;line-height:1.45;margin-top:2px}
  .hit{ /* увеличенная зона нажатия по нотам */ }

  /* --- таблицы --- */
  .tbl-scroll{margin:0 -2px;-webkit-overflow-scrolling:touch}
  table{font-size:14px}
  th,td{padding:8px 9px}

  /* --- блоки и кнопки --- */
  .note-box{padding:11px 13px;margin:14px -2px;font-size:15.5px}
  .quiz{padding:14px 13px;margin:14px -2px}
  .opts{gap:9px}
  .opts button{flex:1 1 calc(50% - 9px);min-height:48px;font-size:15.5px;padding:9px 10px}
  .rowbtns button{min-height:44px;padding:8px 16px;font-size:14.5px}
  .chips{gap:7px}
  .chip{min-height:44px;font-size:15px;padding:8px 14px;flex:1 0 auto}
  .chips-label{font-size:11.5px}
  .score{width:100%;padding-top:2px}

  .pager{flex-direction:column;gap:10px;margin-top:38px}
  .pager button{width:100%;min-height:48px;font-size:15.5px}

  /* --- клавиатура --- */
  .piano{height:auto;margin:14px -2px;padding-bottom:6px;
         -webkit-overflow-scrolling:touch;overscroll-behavior-x:contain}
  .piano .kbd{height:112px}
  .wk{height:112px}
  .bk{height:70px}
  .wk span{font-size:10px;bottom:4px}
}

@media (max-width:400px){
  main{padding-left:11px;padding-right:11px}
  h1{font-size:22px}
  .opts button{flex:1 1 100%}
  .stave{margin-left:-5px;margin-right:-5px}
}

/* мышиные ховеры не должны липнуть на тач-экранах */
@media (hover:none){
  button:hover{border-color:var(--line);color:var(--ink)}
  button.primary:hover{color:#fff}
  .hit:hover .hd{fill:currentColor}
  .hit:hover .stm,.hit:hover .flg{stroke:currentColor;fill:currentColor}
  .hit:hover .lbl{fill:var(--muted)}
  nav a:hover{background:none}
  nav a.on:hover{background:var(--accent)}
}