form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
}

.input-row {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1rem;
  width: 100%;
  flex-wrap: nowrap;
}

.serial {
  font-size: 1rem;
  color: #fff;
  width: 1.2rem;
  flex-shrink: 0;
  text-align: right;
}

input.credits,
select.grade {
  padding: 0.6rem 1rem;
  font-size: 1rem;
  border-radius: 8px;
  border: none;
  outline: none;
  background-color: #fff;
  color: #0f172a;
  flex: 1;
  min-width: 100px;
}

select.grade {
  max-width: 80px;
  text-align-last: center;
  -moz-text-align-last: center;
}

#result {
  font-size: 1.2rem;
  font-weight: bold;
  color: #ffffff;
}

@media (max-width: 480px) {
  .input-row {
    gap: 0.5rem;
  }
  select.grade {
    max-width: 65px;
    font-size: 0.9rem;
  }
  input.credits {
    font-size: 0.9rem;
  }
  .serial {
    font-size: 0.9rem;
    width: auto;
  }
}