* { box-sizing: border-box; }

body {
  margin: 24px;
  padding: 24px;
  background: linear-gradient(160deg, #0e172e, #131d32 60%);
  color: #e5e7eb;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Arial;
}

h1 { margin: 0 0 6px; font-weight: 700; }
.subtitle {  margin-bottom: 20px; font-size: 14px; }

.app {
  display: grid;
  gap: 20px;
  grid-template-columns: 920px 1fr;
  align-items: start;
}

.card {
  background: rgba(17,24,39,.7);
  border: 1px solid rgba(255,255,255,.06);
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 10px 30px rgba(0,0,0,.25);
}

.challenge { display: flex; justify-content: space-between; }
.target { font-size: 14px; }
.target strong { font-size: 24px; color: var #3bc9d6; }

.palette {
  display: grid;
  gap: 10px;
  grid-template-columns: repeat(4, minmax(0, 1fr));
}


.token {
  user-select: none;
  text-align: center;
  padding: 10px;
  border-radius: 12px;
  font-weight: 600;
  background: linear-gradient(180deg, #1f2937, #0b1324);
  border: 1px solid rgba(255,255,255,.08);
  cursor: grab;
}
.token.num { color: #fef3c7; }
.token.op  { color: #c7d2fe; }
.token.ctrl{ color: #bbf7d0; }
.token.pow { color: #fca5a5; }
.token.dropped { background: #0f172a; cursor: default; }

.expression-zone {
  min-height: 84px;
  border-radius: 14px;
  border: 2px dashed rgba(255,255,255,.15);
  background: rgba(2,6,23,.4);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 12px;
}

.toolbar { display: flex; gap: 8px; justify-content: flex-end; }
button { padding: 10px 14px; border-radius: 12px; font-weight: 600; cursor: pointer; }
button.primary { background: lightblue; color: white; }
button.ghost   { background: transparent; color: #cbd5e1; border: 1px solid rgba(255,255,255,.12); }
button.warn    { background: #5f0d5d; color: white; }

.status {
  font-size: 14px;
  padding: 10px;
  border-radius: 12px;
  margin-top: 8px;
  border: 1px solid rgba(255,255,255,.08);
}
.status.good { border-color: lightblue; }
.status.bad  { border-color:#5f0d5d;  }

.preview {
  font-family: monospace;
  opacity: .8;
}