:root {
  /* Primary */
  --green-400: hsl(172, 67%, 45%);

  /* Neutral */
  --green-900: hsl(183, 100%, 15%);
  --grey-500: hsl(186, 14%, 43%);
  --grey-400: hsl(184, 14%, 56%);
  --grey-200: hsl(185, 41%, 84%);
  --grey-50: hsl(189, 47%, 97%);
  --white: hsl(0, 100%, 100%);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Space Mono", monospace;
  font-weight: 700;
  background-color: var(--grey-200);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  font-size: 24px;
}

header {
  margin: 50px 0 40px;
}

.calculator {
  background-color: var(--white);
  border-radius: 25px;
  width: 100%;
  max-width: 920px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 30px;
  padding: 32px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.05);
}

.calculator__input,
.calculator__results {
  padding: 15px;
}

.input-group {
  margin-bottom: 40px;
}

label {
  display: block;
  color: var(--grey-500);
  font-size: 16px;
  margin-bottom: 10px;
}

.label-wrapper {
  display: flex;
  justify-content: space-between;
  margin-bottom: 10px;
}

.error-text {
  color: #e17052;
  font-size: 16px;
  display: none;
}

.input-wrapper {
  position: relative;
}

.input-icon {
  position: absolute;
  left: 15px;
  top: 50%;
  transform: translateY(-50%);
}

input {
  width: 100%;
  background-color: var(--grey-50);
  border: 2px solid transparent;
  border-radius: 5px;
  padding: 5px 15px;
  text-align: right;
  font-family: "Space Mono", monospace;
  font-size: 24px;
  font-weight: 700;
  color: var(--green-900);
  outline: none;
}

input:focus {
  border-color: var(--green-400);
}

input::placeholder {
  color: var(--grey-400);
}

/* Remove arrows from number inputs */
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
input[type="number"] {
  --moz-appearance: textfield;
}

.tip-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 15px;
}

.tip-btn {
  background-color: var(--green-900);
  color: var(--white);
  border: none;
  font-family: "Space Mono", monospace;
  font-size: 24px;
  font-weight: 700;
  padding: 6px 0;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.2s;
}

.tip-btn:hover {
  background-color: var(--green-400);
  color: var(--green-900);
}

.tip-btn.active {
  background-color: var(--green-400);
  color: var(--green-900);
}

#custom-tip {
  padding-right: 15px;
  background-color: var(--grey-50);
}

.calculator__results {
  background-color: var(--green-900);
  border-radius: 15px;
  padding: 40px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.results-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 25px;
}

.results-text p {
  color: var(--white);
  font-size: 16px;
}

.results-text span {
  color: var(--grey-400);
  font-size: 13px;
}

.amount {
  color: var(--green-400);
  font-size: 48px;
}

.reset-btn {
  background-color: var(--green-400);
  color: var(--green-900);
  border: none;
  border-radius: 5px;
  font-family: "Space Mono", monospace;
  font-size: 20px;
  font-weight: 700;
  padding: 10px;
  text-transform: uppercase;
  cursor: pointer;
  transition: background-color 0.2s;
  margin-top: auto;
}

.reset-btn:hover {
  background-color: var(--grey-200);
}

.reset-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.attribution {
  font-size: 11px;
  text-align: center;
  margin-top: 50px;
}

.attribution a {
  color: var(--green-900);
}

/* For error state */
.error .input-wrapper input {
  border-color: #e17052;
}

.error .error-text {
  display: block;
}

/* Media queries for responsive design */
@media screen and (max-width: 920px) {
  .calculator {
    grid-template-columns: 1fr;
    margin: 0 24px;
  }
}

@media screen and (max-width: 600px) {
  body {
    font-size: 18px;
  }

  header {
    margin: 30px 0;
  }

  .calculator {
    padding: 24px;
    border-radius: 25px 25px 0 0;
  }

  .tip-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .amount {
    font-size: 32px;
  }

  .calculator__results {
    padding: 24px;
  }
}