html {
  color-scheme: light dark;
}

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif, system;
}

main {
  border-radius: 0.6rem;
  padding: 1rem 2rem 2rem 2rem;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  width: max-content;
}

h1 {
  margin: 1rem 0;
  font-size: 2rem;
  text-align: center;
}

input {
  outline: transparent;
  border-radius: 0.6rem;
  padding: 0.8rem;
  text-align: end;
  color: var(--input-color);
}

@media (orientation: landscape) {
  #first_num,
  #second_num {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1.5rem;
  }

  input {
    font-size: large;
  }

  select {
    border-radius: 0.6rem;
    padding: 0.8rem 0.4rem 0.8rem 0.3rem;
    font-size: large;
    text-align: end;
  }
}
@media (orientation: portrait) {
  #first_num,
  #second_num {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.5rem;
  }

  select {
    border-radius: 0.6rem;
    padding: 0.4rem 0.4rem 0.4rem 0.3rem;
    text-align: end;
  }
}

@media (orientation: landscape) {
  #operations {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }
}
@media (orientation: portrait) {
  #operations {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 1rem;
  }
}

#operations span {
  display: flex;
  gap: 0.5rem;
}

#operations button {
  border: none;
  border-radius: 0.4rem;
  width: 3rem;
  height: 3rem;
  font-size: xx-large;
  transition: background-color 0.4s, transform 0.4s;
}
#operations button:active {
  transform: scale(0.95);
}

output {
  text-align: right;
  font-size: 1.2rem;
}
sub {
  font-size: small;
}
hr {
  border: none;
  height: 1px;
  width: 100%;
}