* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background-color: rgba(248, 244, 244, 0.893);
  font-family: Arial, sans-serif;
}

.navbar {
  width: 100%;
  padding: 15px 30px;
  background-color: rgb(40, 38, 38);
  color: white;
  position: fixed;
  top: 0;
  left: 0;
  display: flex;
  align-items: center;
  z-index: 10;
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
}


.app-container {
  margin-top: 90px;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

#calculator {
  background-color: rgb(40, 38, 38);
  border-radius: 15px;
  width: 100%;
  max-width: 360px;
  overflow: hidden;
}

#display {
  width: 100%;
  padding: 20px;
  border: none;
  background-color: gray;
  text-align: right;
  font-size: 3rem;
  color: white;
}


#keys {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 20px;
}


button {
  width: 100%;
  aspect-ratio: 1 / 1;
  background-color: rgb(83, 78, 78);
  color: white;
  border: none;
  border-radius: 50%;
  font-size: 2rem;
  font-weight: bold;
  cursor: pointer;
}

button:hover {
  background-color: hsl(0, 0%, 40%);
}

button:active {
  background-color: hsl(0, 0%, 50%);
}


.operator-btn {
  background-color: rgb(222, 149, 15);
}

.operator-btn:hover {
  background-color: rgb(255, 170, 0);
}

.operator-btn:active {
  background-color: rgb(235, 206, 149);
}


@media (max-width: 480px) {
  #display {
    font-size: 2.2rem;
    padding: 15px;
  }

  button {
    font-size: 1.6rem;
  }

  .navbar {
    padding: 12px 20px;
  }

  .logo {
    font-size: 1.2rem;
  }
}