body {
  display: flex;
  justify-content: center; /* Center horizontally */
  align-items: center;     /* Center vertically */
  height: 100vh;           /* Full height of viewport */
  margin: 0;               /* Remove default margin */
  background-color: #f2f2f2; /* Optional: light background */
  background-color: rgb(40, 40, 40);
}

#calculator {
  border: 1px solid rgb(187, 183, 183);
  border-radius: 15px;
  width: 270px;
  background-color: black;
  padding: 20px;          /* more inner spacing */
  padding-bottom: 40px;   /* extra bottom space */
}

#display {
  margin: 10px;
  width: 90%;
  height: 60px;
  font-size: 25px;
  text-align: right;
  border-radius: 10px;
}

.button-container {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  padding: 10px 0px;

}

.button {
  width: 60px;
  height: 60px;
  margin: 3px;
  background-color: rgb(121, 121, 121);
  color: white;
  border-radius: 15px;
  font-size: 20px;        /* larger text */
}

#button-zero{
    padding: 2px 45px;
}
.b-color{
    background-color: rgb(255, 191, 80);
}
#b-eq-color{
     background-color: rgb(255, 121, 80);
}
.b-sp-color{
    background-color: rgb(82, 82, 82);
}

.button:hover {
  background-color: rgb(180, 180, 180); /* lighter background */
  color: black;                         /* change text color */
  cursor: pointer;                      /* pointer cursor */
  transform: scale(1.05);               /* slight zoom effect */
  transition: 0.2s;                      /* smooth transition */
}

.b-color:hover {
  background-color: rgb(255, 211, 120);  /* lighter yellow */
}

#b-eq-color:hover {
  background-color: rgb(255, 141, 100);  /* lighter orange */
}

.b-sp-color:hover {
  background-color: rgb(102, 102, 102);  /* lighter dark gray */
}

/* Smallest screens */
@media screen and (max-width: 250px) {
  #calculator {
    width: 95%;
    padding: 10px;
  }

  #display {
    font-size: 20px;
    height: 45px;
  }

  .button {
    width: 45px;
    height: 45px;
    font-size: 16px;
  }

  #button-zero {
    padding: 2px 25px;
  }
}

/* Extra small but slightly bigger screens */
@media screen and (min-width: 250px) and (max-width: 305px) {
  #calculator {
    width: 90%;
    padding: 10px;
  }

  #display {
    font-size: 22px;
    height: 50px;
  }

  .button {
    width: 50px;
    height: 50px;
    font-size: 18px;
  }

  #button-zero {
    padding: 2px 35px;
  }
}
/* Larger screens (tablets, desktops) */
@media screen and (min-width: 768px) {
  #calculator {
    width: 320px;        /* slightly bigger calculator */
    padding: 25px;
  }

  #display {
    font-size: 28px;
    height: 70px;
  }

  .button {
    width: 70px;
    height: 70px;
    font-size: 22px;
  }

  #button-zero {
    padding: 2px 55px;
  }
}