:root {
  --color-primary: #2563EB;
  --color-secondary: #10B981;
  --color-accent: #F59E0B;
  --color-error: #EF4444;
  --color-bg-start: #1F2937;
  --color-bg-end: #111827;
  --color-text: #F9FAFB;
  --color-text-secondary: #9CA3AF;
  --spacing-unit: 8px;
  --border-radius: 12px;
  --transition-speed: 0.3s;
  --card-bg: rgba(255, 255, 255, 0.1);
}

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

body {
  font-family: 'Inter', 'Roboto', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  min-height: 100vh;
  background: linear-gradient(135deg, var(--color-bg-start) 0%, var(--color-bg-end) 100%);
  color: var(--color-text);
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: calc(var(--spacing-unit) * 3);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.converter-header {
  text-align: center;
  margin-bottom: calc(var(--spacing-unit) * 4);
  position: relative;
}

.page-logo {
  width: 180px;
  height: auto;
  margin-bottom: calc(var(--spacing-unit) * 2);
  opacity: 0.9;
  transition: opacity var(--transition-speed);
}

.page-logo:hover {
  opacity: 1;
}

.page-title {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: calc(var(--spacing-unit) * 1);
  text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.page-subtitle {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  font-weight: 400;
}

.loading {
  text-align: center;
  padding: calc(var(--spacing-unit) * 3);
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border-radius: var(--border-radius);
  margin-bottom: calc(var(--spacing-unit) * 3);
}

.loading.hidden {
  display: none;
}

.spinner {
  border: 4px solid rgba(255, 255, 255, 0.1);
  border-top: 4px solid var(--color-primary);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
  margin: 0 auto calc(var(--spacing-unit) * 2);
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.error-message {
  background: rgba(239, 68, 68, 0.1);
  border: 2px solid var(--color-error);
  color: var(--color-error);
  padding: calc(var(--spacing-unit) * 2);
  border-radius: var(--border-radius);
  margin-bottom: calc(var(--spacing-unit) * 3);
  text-align: center;
}

.error-message.hidden {
  display: none;
}

.input-section {
  margin-bottom: calc(var(--spacing-unit) * 4);
}

.input-section label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: calc(var(--spacing-unit) * 1);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  padding: 0 calc(var(--spacing-unit) * 2);
  transition: all var(--transition-speed);
}

.input-wrapper:focus-within {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2);
}

.currency-symbol {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-right: calc(var(--spacing-unit) * 1);
}

.entrada {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  color: var(--color-text);
  font-size: 1.25rem;
  font-weight: 500;
  padding: calc(var(--spacing-unit) * 2) 0;
  font-family: 'Roboto Mono', monospace;
}

.entrada::placeholder {
  color: var(--color-text-secondary);
  opacity: 0.5;
}

.helper-text {
  display: block;
  margin-top: calc(var(--spacing-unit) * 1);
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

.valor-atual {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  padding: calc(var(--spacing-unit) * 2);
  margin-bottom: calc(var(--spacing-unit) * 4);
  text-align: center;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
}

/* BRL Result Display */
.brl-result {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border: 2px solid var(--color-secondary);
  border-radius: var(--border-radius);
  padding: calc(var(--spacing-unit) * 3);
  margin-bottom: calc(var(--spacing-unit) * 4);
  text-align: center;
  animation: slideIn 0.3s ease-out;
}

.brl-result.hidden {
  display: none;
}

.brl-result-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: calc(var(--spacing-unit) * 1);
}

.brl-result-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-secondary);
  font-family: 'Roboto Mono', monospace;
}

@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.results-section {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: calc(var(--spacing-unit) * 3);
  margin-bottom: calc(var(--spacing-unit) * 4);
}

.currency-card {
  background: var(--card-bg);
  backdrop-filter: blur(10px);
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--border-radius);
  padding: calc(var(--spacing-unit) * 3);
  transition: all var(--transition-speed);
}

.currency-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
  border-color: var(--color-primary);
}

.card-header {
  display: flex;
  align-items: center;
  gap: calc(var(--spacing-unit) * 2);
  margin-bottom: calc(var(--spacing-unit) * 2);
}

.currency-icon {
  font-size: 2rem;
  color: var(--color-primary);
  width: 50px;
  height: 50px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(37, 99, 235, 0.1);
  border-radius: 50%;
}

.currency-card[data-currency="usd"] .currency-icon {
  color: #10B981;
  background: rgba(16, 185, 129, 0.1);
}

.currency-card[data-currency="eur"] .currency-icon {
  color: #2563EB;
  background: rgba(37, 99, 235, 0.1);
}

.currency-card[data-currency="btc"] .currency-icon {
  color: #F59E0B;
  background: rgba(245, 158, 11, 0.1);
}

.currency-card h2 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text);
  margin: 0;
}

.exchange-rate {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: calc(var(--spacing-unit) * 2);
  font-weight: 500;
}

.resultado {
  width: 100%;
  background: rgba(0, 0, 0, 0.3);
  border: 2px solid rgba(255, 255, 255, 0.1);
  border-radius: calc(var(--border-radius) * 0.75);
  padding: calc(var(--spacing-unit) * 2);
  color: var(--color-text);
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  font-family: 'Roboto Mono', monospace;
  outline: none;
  transition: all var(--transition-speed);
}

.resultado::placeholder {
  color: var(--color-text-secondary);
  opacity: 0.5;
  font-size: 0.875rem;
  font-weight: 400;
}

.resultado:focus {
  border-color: var(--color-primary);
}

.converter-footer {
  margin-top: auto;
  padding-top: calc(var(--spacing-unit) * 4);
  text-align: center;
}

.alura-logo {
  width: 50px;
  height: auto;
  opacity: 0.7;
  transition: opacity var(--transition-speed);
}

.alura-logo:hover {
  opacity: 1;
}

@media (max-width: 768px) {
  .container {
    padding: calc(var(--spacing-unit) * 2);
  }

  .page-title {
    font-size: 2rem;
  }

  .page-subtitle {
    font-size: 1rem;
  }

  .page-logo {
    width: 140px;
  }

  .results-section {
    grid-template-columns: 1fr;
    gap: calc(var(--spacing-unit) * 2);
  }

  .currency-card {
    padding: calc(var(--spacing-unit) * 2);
  }

  .entrada {
    font-size: 1.125rem;
  }

  .resultado {
    font-size: 1.25rem;
  }
}

@media (max-width: 480px) {
  .page-title {
    font-size: 1.75rem;
  }

  .card-header {
    flex-direction: column;
    text-align: center;
    gap: calc(var(--spacing-unit) * 1);
  }

  .currency-icon {
    font-size: 1.5rem;
    width: 40px;
    height: 40px;
  }
}

.currency-card {
  animation: fadeIn 0.5s ease-in-out;
}

.currency-card:nth-child(1) {
  animation-delay: 0.1s;
}

.currency-card:nth-child(2) {
  animation-delay: 0.2s;
}

.currency-card:nth-child(3) {
  animation-delay: 0.3s;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}