:root {
  font-family: Inter,ui-sans-serif,system-ui,-apple-system,sans-serif;
  color: #eef5ef;
  background: #172521;
  font-synthesis: none;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  min-height: 100svh;
  background: radial-gradient(ellipse at 50% 30%,#2c4034 0,transparent
    65%),#172521;
}
main {
  max-width: 460px;
  margin: auto;
  padding: 48px 22px 32px;
}
.heading {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  font-size: 10px;
  letter-spacing: 3px;
  color: #bacabf;
}
.mark {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  border: 1px solid #768d79;
  border-radius: 8px;
  font-size: 20px;
  letter-spacing: 0;
}
h1 {
  text-align: center;
  font-size: 36px;
  font-weight: 500;
  letter-spacing: -1.4px;
  line-height: 1.18;
  margin: 28px 0 12px;
}
.intro {
  text-align: center;
  color: #a7baae;
  font-size: 14px;
  margin-bottom: 30px;
}
.calculator {
  background: #edf0e5;
  color: #23362b;
  border-radius: 24px;
  padding: 22px;
  box-shadow: 0 24px 65px #08130c55;
}
.display {
  padding: 8px 8px 15px;
}
label {
  display: block;
  font-size: 9px;
  letter-spacing: 2px;
  color: #66776a;
}
input {
  display: block;
  width: 100%;
  background: transparent;
  border: 0;
  border-bottom: 1px solid #cad2c4;
  padding: 12px 0 8px;
  font: inherit;
  font-size: 20px;
  text-align: right;
  color: #596c5d;
  outline: none;
  border-radius: 0;
}
input:focus {
  border-color: #638455;
}
output {
  display: block;
  overflow: auto;
  text-align: right;
  font-size: 45px;
  letter-spacing: -1.5px;
  margin-top: 12px;
  min-height: 55px;
}
#message {
  min-height: 17px;
  margin: 5px 0 0;
  color: #6e7e70;
  font-size: 11px;
  text-align: right;
}
#message.error {
  color: #a33226;
}
.keys {
  display: grid;
  grid-template-columns: repeat(4,1fr);
  gap: 9px;
}
button {
  border: 0;
  border-radius: 13px;
  background: #fffef7;
  color: #304333;
  min-height: 58px;
  font: inherit;
  font-size: 22px;
  cursor: pointer;
  transition: background .15s,transform .1s;
}
button:hover {
  background: #e2e9d9;
}
button:active {
  transform: scale(.95);
}
button:focus-visible {
  outline: 3px solid #6b8b54;
  outline-offset: 2px;
}
.utility {
  background: #dbe3d4;
  font-size: 18px;
}
.operator {
  background: #d4dfc4;
  color: #426030;
}
.equals {
  background: #33563a;
  color: #fff;
}
.equals:hover {
  background: #456b47;
}
.footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 12px;
  font-size: 10px;
  color: #73816f;
}
.footer button {
  min-height: 30px;
  width: 38px;
  font-size: 20px;
  background: transparent;
}
.note {
  text-align: center;
  color: #9cae9f;
  font-size: 12px;
  line-height: 2;
  margin-top: 20px;
}
.note small {
  font-size: 10px;
  color: #819789;
}
@media (max-width:380px) {
  main {
    padding: 28px 16px;
  }
  h1 {
    font-size: 30px;
  }
  .calculator {
    padding: 17px;
  }
  button {
    min-height: 53px;
  }
}