:root{
  --bg:#0b0d10;
  --card:#11151b;
  --panel:#0f1319;
  --text:#e9eef6;
  --muted:#97a3b6;
  --border:#222a35;
}
*{box-sizing:border-box}
body{
  margin:0;
  font-family:system-ui,-apple-system,Segoe UI,Roboto,Arial,sans-serif;
  background:var(--bg);
  color:var(--text);
}
.shell{max-width:1100px;margin:0 auto;padding:18px}
.top{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px}
.title{font-weight:800;font-size:18px}
.sub{color:var(--muted);font-size:13px;margin-top:2px}
.link{color:var(--muted);text-decoration:none}
.link:hover{color:var(--text)}

.calc{
  display:grid;
  grid-template-columns: 1fr 320px;
  gap:12px;
}
.screen{
  grid-column:1 / 2;
  background:linear-gradient(180deg,#0a0d12, #0b0d10);
  border:1px solid var(--border);
  border-radius:14px;
  padding:14px;
  margin-bottom:12px;
}
.line{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace}
.small{color:var(--muted);font-size:12px;min-height:16px}
.expr{color:var(--muted);font-size:13px;min-height:18px;word-break:break-word}
.big{font-size:34px;font-weight:800;min-height:40px;word-break:break-word}

.grid{
  grid-column:1 / 2;
  display:grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap:10px;
}
.k{
  padding:12px 10px;
  border-radius:14px;
  border:1px solid var(--border);
  background:var(--card);
  color:var(--text);
  cursor:pointer;
  font-weight:700;
}
.k:hover{filter:brightness(1.08)}
.k.op{background:#121a26}
.k.alt{background:#0f141c;color:var(--muted)}
.k.eq{background:#1d2633}
.k.wide{grid-column: span 2}

.history{
  grid-column:2 / 3;
  background:var(--panel);
  border:1px solid var(--border);
  border-radius:14px;
  padding:12px;
  display:flex;
  flex-direction:column;
  min-height:520px;
}
.histHead{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px}
.mini{
  border-radius:10px;border:1px solid var(--border);
  background:var(--card);color:var(--text);
  padding:6px 10px;cursor:pointer;font-size:12px
}
.histBody{flex:1;overflow:auto;border-top:1px solid var(--border);padding-top:10px}
.item{padding:8px 0;border-bottom:1px dashed rgba(255,255,255,.08)}
.item .q{color:var(--muted);font-family:ui-monospace,monospace;font-size:12px}
.item .a{font-family:ui-monospace,monospace;font-size:14px;font-weight:800}
.hint{margin-top:10px;color:var(--muted);font-size:12px}

@media (max-width: 920px){
  .calc{grid-template-columns:1fr}
  .history{grid-column:1 / 2;min-height:260px}
}