/* DISPLAY */
.sci-display {
  width: 100%;
  padding: 14px;
  font-size: 24px;
  background: #f8fafc;
  border: 1px solid #cbd5e1;
  margin-bottom: 12px;
  border-radius: 6px;
}

/* GRID */
.sci-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.btn {
  padding: 12px 10px;
  font-size: 17px;
  background: #e2e8f0;
  border-radius: 8px;
  border: 1px solid #cbd5e1;
  cursor: pointer;
  text-align: center;
}

.btn.op {
  background: #bfdbfe;
}

.btn.func {
  background: #fde68a;
}

.btn.sec {
  background: #fca5a5;
  font-weight: 600;
}

.btn.equals {
  background: #4ade80;
  color: #064e3b;
  grid-column: span 4;
}

.btn:hover {
  opacity: 0.9;
}

/* HISTORY */
.history-box {
  background: #f1f5f9;
  padding: 10px;
  border: 1px solid #94a3b8;
  border-radius: 6px;
  margin-bottom: 12px;
  max-height: 180px;
  overflow-y: auto;
}