style.css

*,
*::after,
*::before {
  padding: 0px;
  margin: 0px;
  font-family: inherit;
}
body,
html {
  height: 100vh;
  font-family: sans-serif;
}
button {
  cursor: pointer;
  border: 0px;
}
input[type="text"] {
  background-color: transparent;
  text-align: end;
  width: 100%;
  color: #d2d2d2;
  border: 0px;
  font-size: 4rem;
}
#main {
  border: 2px solid #ededed;
  border-radius: 50px;
  width: 100%;
  max-width: 280px;
  background-color: #000000;
  padding: 2rem 1rem;
}
.calc_header {
  margin-top: 90px;
  padding: 12px;
}
.calc_footer > * + * {
  margin-top: 1rem;
}
.calc_footer > *:last-child {
  gap: 1rem;
}
.btn_group {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.3rem;
}
.btn {
  display: flex;
  justify-content: center;
  align-items: center;
  border-radius: 50%;
  width: 60px;
  height: 60px;
  color: #ffffff;
  font-size: 20px;
  transition: all 0.3s cubic-bezier(0.19, 1, 0.22, 1);
}
.btn .btn-grow {
  flex-grow: 1;
  border-radius: 40px;
}
.btn:hover {
  transform: translate(-2px, -3px);
}
.btn.active {
  background-color: #ffffff;
  color: #f69906;
}
.btn-grey {
  background-color: #9f9f9f;
  color: #000000;
}
.btn-grey:hover {
  background-color: #ededed;
}
.btn-dark-grey {
  background-color: #313131;
}
.btn-dark-grey:hover {
  background-color: #999999;
}
.btn-orange {
  background-color: #f69906;
}
.btn-orange:hover {
  background-color: orange;
}