/* Reset and base styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  background-color: hsl(185, 41%, 84%);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2rem 1rem;
}

/* Container and layout */
.container {
  width: 100%;
  max-width: 920px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.logo {
  margin-bottom: 1rem;
}

.calculator {
  background-color: hsl(0, 100%, 100%);
  border-radius: 1.5rem;
  padding: 2rem;
  width: 100%;
  max-width: 920px;
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  box-shadow: 0 32px 43px rgba(79, 166, 175, 0.2);
}

/* Input section */
.input-section {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.input-group label {
  color: hsl(186, 14%, 43%);
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.input-wrapper {
  position: relative;
}

.input-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
}

input[type="number"] {
  width: 100%;
  padding: 0.75rem 1rem 0.75rem 2.5rem;
  border: 2px solid transparent;
  border-radius: 0.5rem;
  background-color: hsl(189, 47%, 97%);
  color: hsl(183, 100%, 15%);
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  font-size: 1.5rem;
  text-align: right;
  outline: none;
  transition: border-color 0.3s ease;
}

input[type="number"]:focus {
  border-color: hsl(172, 67%, 45%);
}

input[type="number"]:invalid {
  border-color: #e17457;
}

input[type="number"]::placeholder {
  color: hsl(184, 14%, 56%);
}

/* Custom tip input */
#custom-tip {
  padding: 0.75rem 1rem;
  text-align: center;
}

#custom-tip::placeholder {
  color: hsl(184, 14%, 56%);
}

/* Tip buttons */
.tip-buttons {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.tip-btn {
  background-color: hsl(183, 100%, 15%);
  color: hsl(0, 100%, 100%);
  border: none;
  border-radius: 0.5rem;
  padding: 0.75rem;
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  font-size: 1.5rem;
  cursor: pointer;
  transition: all 0.3s ease;
}

.tip-btn:hover {
  background-color: hsl(172, 67%, 45%);
  color: hsl(183, 100%, 15%);
}

.tip-btn.active {
  background-color: hsl(172, 67%, 45%);
  color: hsl(183, 100%, 15%);
}

/* Results section */
.results-section {
  background-color: hsl(183, 100%, 15%);
  border-radius: 1rem;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.result-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.result-label {
  display: flex;
  flex-direction: column;
}

.result-title {
  color: hsl(0, 100%, 100%);
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.result-subtitle {
  color: hsl(184, 14%, 56%);
  font-size: 0.8rem;
}

.result-value {
  color: hsl(172, 67%, 45%);
  font-size: 2rem;
  font-weight: 700;
}

/* Reset button */
.reset-btn {
  background-color: hsl(172, 67%, 45%);
  color: hsl(183, 100%, 15%);
  border: none;
  border-radius: 0.5rem;
  padding: 0.75rem;
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  font-size: 1.25rem;
  cursor: pointer;
  transition: all 0.3s ease;
  margin-top: auto;
}

.reset-btn:hover:not(:disabled) {
  background-color: hsl(185, 41%, 84%);
}

.reset-btn:disabled {
  background-color: hsl(183, 78%, 24%);
  cursor: not-allowed;
  opacity: 0.3;
}

/* Error messages */
.error-message {
  color: #e17457;
  font-size: 0.875rem;
  margin-top: 0.25rem;
  min-height: 1.25rem;
}

/* Attribution */
.attribution {
  font-size: 11px;
  text-align: center;
  margin-top: 2rem;
  color: hsl(186, 14%, 43%);
}

.attribution a {
  color: hsl(228, 45%, 44%);
}

/* Desktop styles */
@media (min-width: 768px) {
  .calculator {
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    padding: 2.5rem;
  }
  
  .tip-buttons {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .results-section {
    padding: 2.5rem;
  }
  
  .result-value {
    font-size: 3rem;
  }
}