/* ===== RESET ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
}

/* ===== BODY ===== */
body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: radial-gradient(circle at top, #0a0a0a, #240046, #3c096c);
}

/* ===== CALCULATOR ===== */
.calculator {
  background: rgba(30, 30, 30, 0.9);
  border: 1px solid rgba(90, 0, 160, 0.6);
  border-radius: 16px;
  box-shadow: 0 0 15px rgba(90, 0, 160, 0.3);
  padding: 20px;
  width: 320px;
}

/* ===== DISPLAY ===== */
.display {
  width: 100%;
  height: 70px;
  background: #000;
  border: none;
  border-radius: 10px;
  color: #ffffff;
  font-size: 2rem;
  text-align: right;
  padding-right: 15px;
  box-shadow: inset 0 0 8px rgba(90, 0, 160, 0.4);
  margin-bottom: 20px;
}

/* ===== BUTTON GRID ===== */
.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 15px;
}

/* ===== BUTTONS ===== */
button {
  height: 60px;
  border-width:5px;
  border-radius: 10px;
  font-size: 1.2rem;
  font-weight: 600;
  cursor: pointer;
  background: #1a1a1a;
  color: #dcdcdc;
  transition: background 0.2s ease, box-shadow 0.2s ease;
}

/* Hover effect (subtle) */
button:hover {
  background: #2a2a2a;
  box-shadow: 0 0 10px rgba(140, 0, 255, 0.3);
   transform: scale(1.02);     /* light lift, very subtle */
}

/* Operator buttons */
.operator {
  color: #ff4b5c;
}

/* Equal button */
.equal {
  background: #1a1a1a;
  color: #fff;
  font-weight: bold;
  box-shadow: 0 0 10px rgba(123, 44, 191, 0.5);
}

.equal:hover {
  background: #413c3c;
}