:root{
  --bg:#f6f7fb;
  --card:#ffffff;
  --text:#111827;
  --muted:#6b7280;
  --line:#e5e7eb;
  --primary:#2563eb;
  --danger:#b91c1c;
  --shadow: 0 10px 25px rgba(17,24,39,.08);
  --radius:16px;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  color:var(--text);
  background:var(--bg);
}
.mono{font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;}

.app-header{
  padding:18px 18px 10px;
  max-width: 1200px;
  margin: 0 auto;
}
.app-header h1{margin:0 0 6px;font-size:20px}
.sub{margin:0;color:var(--muted);font-size:13px}

.layout{
  max-width:1200px;
  margin:0 auto;
  padding: 10px 18px 22px;
  display:grid;
  grid-template-columns: 1.2fr 1fr;
  gap:14px;
}
@media (max-width: 980px){
  .layout{grid-template-columns:1fr;}
}

.card{
  background:var(--card);
  border:1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding:14px;
}

.card-title-row{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:10px;
  flex-wrap:wrap;
}
.card h2{margin:0;font-size:16px}

.diagram-wrap{
  position:relative;
  margin-top:10px;
  border-radius: 14px;
  overflow:hidden;
  border:1px solid var(--line);
  background:#fff;
  /* Match the (almost square) source image so overlay math stays aligned */
  aspect-ratio: 2062 / 2053;
}
.diagram-bg{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
  object-fit: fill;
  pointer-events:none;
}
.diagram-canvas{
  position:absolute;
  inset:0;
  width:100%;
  height:100%;
}

.hint{margin-top:10px;color:var(--muted);font-size:12px}
.eq{margin-top:6px;color:var(--text);font-size:12px;min-height:16px}

.controls{display:flex;flex-direction:column;gap:12px}

.top-row{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap}

.grid{
  display:grid;
  grid-template-columns: 1fr 1fr;
  gap:10px;
}
@media (max-width: 520px){
  .grid{grid-template-columns:1fr;}
}
.field label{display:block;font-size:12px;color:var(--muted);margin-bottom:6px}
.field input{
  width:100%;
  padding:10px 12px;
  border-radius: 12px;
  border:1px solid var(--line);
  font-size:14px;
}

.model-row{
  display:flex;
  justify-content:center;
}
.model-img{
  max-width: 100%;
  height:auto;
  border-radius: 14px;
  border:1px solid var(--line);
  background:#fff;
}

.sliders{display:flex;flex-direction:column;gap:10px}
.slider{
  border:1px solid var(--line);
  border-radius: 14px;
  padding:10px;
}
.slider-head{display:flex;align-items:baseline;justify-content:space-between;margin-bottom:8px}
.slider-body{display:grid;grid-template-columns: 38px 1fr 38px;gap:8px;align-items:center}
.slider input[type=range]{width:100%}
.slider-foot{margin-top:6px;color:var(--muted);font-size:11px}

.fired{display:flex;align-items:center;gap:10px}
.fired .label{font-size:12px;color:var(--muted)}
.fired .value{font-weight:700;font-size:16px;min-width:56px;text-align:center}

.btn{
  border:1px solid var(--line);
  background:#f3f4f6;
  color:var(--text);
  border-radius: 12px;
  padding:10px 12px;
  font-size:14px;
  cursor:pointer;
}
.btn:active{transform: translateY(1px)}
.btn-row{display:flex;gap:8px;align-items:center}
.btn-row.wrap{flex-wrap:wrap}
.btn-row.end{justify-content:flex-end}
.btn-mini{padding:8px 10px;border-radius: 10px}

.btn-primary{background:var(--primary);border-color:transparent;color:white}
.btn-ghost{background:white}
.btn-danger{background:var(--danger);border-color:transparent;color:white}

hr{border:none;border-top:1px solid var(--line);margin:4px 0}

.endless-title{font-weight:700;margin-bottom:6px}

.speed{
  border:1px solid var(--line);
  border-radius: 14px;
  padding:10px;
}
.speed-head{display:flex;justify-content:space-between;align-items:baseline;margin-bottom:8px}
.speed-foot{display:flex;justify-content:space-between;color:var(--muted);margin-top:2px}
.small{font-size:11px}

.footer{color:var(--muted);font-size:12px;text-align:right;margin-top:2px}

/* --- Desktop: wider layout & fewer wraps (less vertical scrolling) --- */
@media (min-width: 1100px){
  .app-header{ max-width: 1500px; }
  .layout{
    max-width: 1500px;
    grid-template-columns: 1.35fr 1fr;
  }
  /* Put the 3 parameter sliders next to each other */
  .sliders{
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px;
  }
  /* Keep the endless buttons in one line on typical desktops */
  .endless .btn-row.wrap{
    flex-wrap: nowrap;
  }
  .endless .btn-row.wrap .btn{
    white-space: nowrap;
  }
}

/* Slightly roomier on very wide screens */
@media (min-width: 1400px){
  .layout{ grid-template-columns: 1.45fr 1fr; }
}