/* CSS Custom Properties - Brand-aligned color palette */
:root {
  --primary-color: #2c2c2c;
  --secondary-color: #e67e22;
  --background-color: #ffffff;
  --card-background: #fafafa;
  --border-color: #e1e8ed;
  --success-color: #27ae60;
  --text-light: #7f8c8d;
  --shadow-light: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-medium: 0 4px 16px rgba(0, 0, 0, 0.12);
  --border-radius: 8px;
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

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

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  line-height: 1.6;
  color: var(--primary-color);
  background-color: var(--background-color);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.header {
  background: var(--background-color);
  border-bottom: 1px solid var(--border-color);
  padding: 40px 0;
  text-align: center;
}

.header__title {
  font-size: 2.5rem;
  font-weight: 700;
  margin: 0 0 10px 0;
  color: var(--primary-color);
}

.header__subtitle {
  font-size: 1.2rem;
  color: var(--text-light);
  margin: 0;
  font-weight: 400;
}

/* Main layout */
.main {
  padding: 60px 0;
}

.calculator {
  max-width: 900px;
  margin: 0 auto;
}

.calculator__intro {
  text-align: center;
  margin-bottom: 40px;
}

.calculator__intro p {
  font-size: 1.1rem;
  color: var(--text-light);
  max-width: 600px;
  margin: 0 auto;
}

/* Form layout */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.form-section {
  background: var(--card-background);
  padding: 30px;
  border-radius: var(--border-radius);
  border: 1px solid var(--border-color);
}

.form-section__title {
  font-size: 1.4rem;
  font-weight: 600;
  margin: 0 0 25px 0;
  color: var(--primary-color);
}

/* Input groups */
.input-group {
  margin-bottom: 20px;
}

.input-group__label {
  display: block;
  font-weight: 500;
  margin-bottom: 8px;
  color: var(--primary-color);
}

.input-group__input,
.input-group__select {
  width: 100%;
  padding: 12px 16px;
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  font-size: 1rem;
  font-family: var(--font-family);
  transition: border-color 0.2s ease;
}

.input-group__input:focus,
.input-group__select:focus {
  outline: none;
  border-color: var(--secondary-color);
  box-shadow: 0 0 0 3px rgba(230, 126, 34, 0.1);
}

.input-group__select {
  cursor: pointer;
  background-color: var(--background-color);
}

/* Input with toggle (weight) */
.input-with-toggle {
  display: flex;
  gap: 12px;
  align-items: stretch;
}

.input-with-toggle .input-group__input {
  flex: 1;
}

/* Height inputs */
.height-inputs {
  margin-bottom: 12px;
}

.height-imperial {
  display: flex;
  gap: 12px;
}

.height-imperial .input-group__input {
  flex: 1;
}

.height-metric .input-group__input {
  width: 100%;
}

/* Unit toggles */
.unit-toggle {
  display: flex;
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  overflow: hidden;
  background: var(--background-color);
}

.unit-toggle__button {
  padding: 12px 16px;
  border: none;
  background: var(--background-color);
  color: var(--text-light);
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.2s ease;
  flex: 1;
}

.unit-toggle__button:hover {
  background: var(--card-background);
}

.unit-toggle__button.active {
  background: var(--secondary-color);
  color: white;
}

/* Conversion display */
.input-group__conversion {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-top: 6px;
  font-style: italic;
}

/* Activity levels */
.activity-levels {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.activity-option {
  position: relative;
}

.activity-option__radio {
  position: absolute;
  opacity: 0;
  cursor: pointer;
}

.activity-option__label {
  display: block;
  padding: 16px 20px;
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: all 0.2s ease;
  background: var(--background-color);
}

.activity-option__label:hover {
  border-color: var(--secondary-color);
  background: var(--card-background);
}

.activity-option__radio:checked + .activity-option__label {
  border-color: var(--secondary-color);
  background: rgba(230, 126, 34, 0.05);
}

.activity-option.recommended .activity-option__label {
  border-color: var(--success-color);
  background: rgba(39, 174, 96, 0.05);
}

.activity-option.recommended .activity-option__radio:checked + .activity-option__label {
  border-color: var(--success-color);
  background: rgba(39, 174, 96, 0.1);
}

.activity-option__title {
  display: block;
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 4px;
}

.activity-option__desc {
  display: block;
  font-size: 0.9rem;
  color: var(--text-light);
  line-height: 1.4;
}

/* Calculator actions */
.calculator__actions {
  text-align: center;
  margin: 40px 0;
}

/* Button styles */
.btn {
  display: inline-block;
  padding: 16px 32px;
  border: none;
  border-radius: var(--border-radius);
  font-size: 1.1rem;
  font-weight: 600;
  font-family: var(--font-family);
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
}

.btn--primary {
  background: var(--secondary-color);
  color: white;
  box-shadow: var(--shadow-light);
}

.btn--primary:hover {
  background: #d35400;
  box-shadow: var(--shadow-medium);
  transform: translateY(-2px);
}

.btn--primary:active {
  transform: translateY(0);
}

/* Results section */
.results {
  background: var(--card-background);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: 40px;
  margin-top: 40px;
}

.results__title {
  text-align: center;
  font-size: 2rem;
  font-weight: 700;
  margin: 0 0 30px 0;
  color: var(--primary-color);
}

.results__values {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 30px;
  margin-bottom: 40px;
}

/* Result cards */
.result-card {
  text-align: center;
  padding: 30px 20px;
  background: var(--background-color);
  border: 2px solid var(--border-color);
  border-radius: var(--border-radius);
  transition: all 0.2s ease;
}

.result-card:hover {
  box-shadow: var(--shadow-light);
}

.result-card--primary {
  border-color: var(--secondary-color);
  background: rgba(230, 126, 34, 0.05);
}

.result-card__title {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 0 0 15px 0;
  color: var(--primary-color);
}

.result-card__value {
  font-size: 3rem;
  font-weight: 700;
  color: var(--secondary-color);
  margin: 0 0 5px 0;
  line-height: 1;
}

.result-card__unit {
  font-size: 0.9rem;
  color: var(--text-light);
  margin: 0 0 15px 0;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.result-card__desc {
  font-size: 0.9rem;
  color: var(--text-light);
  margin: 0;
  line-height: 1.4;
}

/* Results interpretation */
.results__interpretation {
  border-top: 1px solid var(--border-color);
  padding-top: 30px;
}

.results__interpretation h3 {
  font-size: 1.3rem;
  font-weight: 600;
  margin: 0 0 15px 0;
  color: var(--primary-color);
}

.results__interpretation p {
  margin: 0 0 15px 0;
  color: var(--text-light);
  line-height: 1.6;
}

.results__interpretation p:last-child {
  margin-bottom: 0;
}

/* Footer */
.footer {
  background: var(--card-background);
  border-top: 1px solid var(--border-color);
  padding: 40px 0;
  margin-top: 60px;
}

.disclaimer h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 0 0 15px 0;
  color: var(--primary-color);
}

.disclaimer p {
  font-size: 0.9rem;
  color: var(--text-light);
  line-height: 1.6;
  margin: 0;
  max-width: 800px;
}

/* Error handling */
.input-error {
  background: #fee;
  border: 1px solid #fcc;
  border-radius: var(--border-radius);
  padding: 15px;
  margin-bottom: 20px;
}

.input-error p {
  margin: 0 0 10px 0;
  color: #c33;
  font-size: 0.9rem;
}

.input-error p:last-child {
  margin-bottom: 0;
}

/* Responsive design */
@media (max-width: 768px) {
  .header__title {
    font-size: 2rem;
  }
  
  .header__subtitle {
    font-size: 1.1rem;
  }
  
  .form-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }
  
  .form-section {
    padding: 25px 20px;
  }
  
  .results__values {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  
  .result-card__value {
    font-size: 2.5rem;
  }
  
  .container {
    padding: 0 15px;
  }
  
  .main {
    padding: 40px 0;
  }
  
  .header {
    padding: 30px 0;
  }
}

@media (max-width: 480px) {
  .header__title {
    font-size: 1.8rem;
  }
  
  .form-section {
    padding: 20px 15px;
  }
  
  .height-imperial {
    flex-direction: column;
    gap: 8px;
  }
  
  .input-with-toggle {
    flex-direction: column;
    gap: 8px;
  }
  
  .result-card {
    padding: 25px 15px;
  }
  
  .result-card__value {
    font-size: 2.2rem;
  }
  
  .btn {
    width: 100%;
  }
}

/* Focus and accessibility */
.input-group__input:focus,
.input-group__select:focus,
.unit-toggle__button:focus,
.activity-option__radio:focus + .activity-option__label,
.btn:focus {
  outline: 2px solid var(--secondary-color);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --border-color: #666;
    --text-light: #444;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  * {
    transition: none !important;
  }
}