:root{
    --charge:#b86a6a;
    --ring:#4e9b74;
    --field:#4f7cac;
    --cone:#665d8a;
    --accent:#c89b3c;
  }
  header{margin-bottom:38px;}
  .eyebrow{
    font-family:'Space Mono',monospace;font-size:12px;letter-spacing:0.32em;
    text-transform:uppercase;color:var(--accent);margin-bottom:14px;
  }
  h1{
    font-family:'Merriweather',serif;font-weight:500;font-size:clamp(32px,5vw,52px);
    line-height:1.04;letter-spacing:-0.02em;max-width:18ch;
  }
  h1 em{font-style:italic;color:var(--cone);}
  .sub{
    color:var(--muted);font-size:18px;line-height:1.6;max-width:62ch;margin-top:18px;
  }

  .layout{display:grid;grid-template-columns:1.35fr 1fr;gap:28px;margin-top:42px;align-items:start;}
  @media(max-width:860px){.layout{grid-template-columns:1fr;}}

  .stage{
    background:var(--panel);border:1px solid var(--line);border-radius:20px;
    padding:14px;position:relative;overflow:hidden;
  }
  .stage::before{
    content:"";position:absolute;inset:0;
    background:none;
    pointer-events:none;
  }
  canvas{width:100%;height:480px;display:block;border-radius:12px;cursor:grab;}
  canvas:active{cursor:grabbing;}
  .hint{
    position:absolute;bottom:20px;left:0;right:0;text-align:center;
    font-family:'Space Mono',monospace;font-size:11px;letter-spacing:0.12em;
    color:var(--faint);text-transform:uppercase;pointer-events:none;
  }

  .side{display:flex;flex-direction:column;gap:18px;}

  .controls{
    background:var(--panel);border:1px solid var(--line);border-radius:18px;padding:24px;
  }
  .ctrl-row{display:flex;align-items:center;justify-content:space-between;margin-bottom:8px;}
  .ctrl-label{font-family:'Space Mono',monospace;font-size:12px;letter-spacing:0.1em;color:var(--muted);text-transform:uppercase;}
  .ctrl-val{font-family:'Space Mono',monospace;font-size:15px;color:var(--cone);}
  input[type=range]{
    -webkit-appearance:none;appearance:none;width:100%;height:4px;border-radius:4px;
    background:var(--panel-raised);outline:none;margin:6px 0 4px;
  }
  input[type=range]::-webkit-slider-thumb{
    -webkit-appearance:none;width:18px;height:18px;border-radius:50%;
    background:#fff;border:3px solid var(--cone);cursor:pointer;
  }
  input[type=range]::-moz-range-thumb{
    width:18px;height:18px;border-radius:50%;background:#fff;border:3px solid var(--cone);cursor:pointer;border-radius:50%;
  }
  .btns{display:flex;gap:10px;margin-top:20px;}
  button{
    flex:1;font-family:'DM Sans',sans-serif;font-size:12px;font-weight:700;letter-spacing:0.08em;
    text-transform:uppercase;color:var(--ink);background:transparent;
    border:1px solid var(--line);border-radius:10px;padding:11px 8px;cursor:pointer;
    transition:all .18s ease;
  }
  button:hover{border-color:var(--cone);background:rgba(102,93,138,0.10);}
  button.active{border-color:var(--ring);color:var(--ring);background:rgba(78,155,116,0.08);}

  .legend{display:flex;flex-direction:column;gap:12px;background:var(--panel);border:1px solid var(--line);border-radius:18px;padding:22px 24px;}
  .leg-item{display:flex;align-items:center;gap:12px;}
  .dot{width:13px;height:13px;border-radius:50%;flex-shrink:0;}
  .leg-text{font-size:15px;color:var(--ink);}
  .leg-text span{color:var(--muted);font-size:13px;display:block;margin-top:1px;}

  .concept{margin-top:48px;}
  .concept h2{
    font-family:'Merriweather',serif;font-weight:500;font-size:26px;margin-bottom:24px;
    letter-spacing:-0.01em;
  }
  .steps{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
  @media(max-width:780px){.steps{grid-template-columns:1fr;}}
  .step{
    background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:26px;
    position:relative;
  }
  .step-num{
    font-family:'Space Mono',monospace;font-size:13px;color:var(--accent);
    letter-spacing:0.1em;margin-bottom:14px;
  }
  .step h3{font-family:'Merriweather',serif;font-weight:500;font-size:19px;margin-bottom:10px;color:var(--cone);}
  .step p{color:var(--muted);font-size:15px;line-height:1.62;}
  .step .eq{
    font-family:'Space Mono',monospace;font-size:14px;color:var(--ink);
    background:rgba(255,255,255,0.04);border-radius:8px;padding:10px 12px;margin-top:14px;
    border:1px solid var(--line);
  }

  .result{
    margin-top:42px;background:var(--panel);border:1px solid var(--line);border-radius:18px;
    padding:32px;display:flex;align-items:center;gap:28px;flex-wrap:wrap;
  }
  .result .label{font-family:'Space Mono',monospace;font-size:12px;letter-spacing:0.18em;text-transform:uppercase;color:var(--field);margin-bottom:14px;}
  .result .formula{font-family:'Merriweather',serif;font-size:34px;font-weight:400;letter-spacing:-0.01em;}
  .result .formula sup,.result .formula sub{font-size:0.6em;}
  .result .note{color:var(--muted);font-size:15px;line-height:1.6;max-width:34ch;flex:1;min-width:240px;}
  .result .note b{color:var(--accent);font-weight:500;}