* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #667eea, #764ba2);
}

.title{

    color: #fff;
    background: #111;
    font-size: 1.8rem;
    font-weight: 600;
    padding: 12px 14px;
    border-bottom: 1px solid #333;
    text-align: center;
}

.calculator {
  width: 320px;
  background: #222;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.5);
}

#display {
  width: 100%;
  height: 70px;
  border: none;
  outline: none;
  background: #000;
  color: #fff;
  font-size: 2rem;
  text-align: right;
  padding: 10px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}

.btn {
  padding: 20px;
  font-size: 1.2rem;
  border: 1px solid #333;
  background: #444;
  color: white;
  cursor: pointer;
  transition: 0.2s;
}

.btn:hover {
  background: #666;
}

.operator {
  background: #f39c12;
}

.operator:hover {
  background: #e67e22;
}

.equal {
  grid-column: span 2;
  background: #27ae60;
}

.equal:hover {
  background: #2ecc71;
}* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: Arial, Helvetica, sans-serif;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #667eea, #764ba2);
}

.calculator {
  width: 320px;
  background: #222;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.5);
}

#display {
  width: 100%;
  height: 70px;
  border: none;
  outline: none;
  background: #000;
  color: #fff;
  font-size: 2rem;
  text-align: right;
  padding: 10px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
}

.btn {
  padding: 20px;
  font-size: 1.2rem;
  border: 1px solid #333;
  background: #444;
  color: white;
  cursor: pointer;
  transition: 0.2s;
}

.btn:hover {
  background: #666;
}

.operator {
  background: #f39c12;
}

.operator:hover {
  background: #e67e22;
}

.equal {
  grid-column: span 2;
  background: #27ae60;
}

.equal:hover {
  background: #2ecc71;
}