/* Reset & Variables */
:root {
  --bg-page: #f9fafb;
  --bg-card: #ffffff;
  --bg-control: #ffffff;
  --color-text: #111827;
  --color-muted: #4b5563;
  --color-border: #e5e7eb;
  --color-border-hover: #d1d5db;
  --color-accent: #3b82f6;
  --color-accent-hover: #2563eb;
  --color-accent-light: #eff6ff;
  --color-accent-text: #1d4ed8;
  --color-success: #10b981;
  --color-success-light: #ecfdf5;
  --color-success-text: #047857;
  --color-error: #ef4444;
  --color-error-light: #fef2f2;
  --color-error-text: #b91c1c;

  --shadow-card: 0 10px 40px -10px rgba(0, 0, 0, 0.04), 0 2px 8px -1px rgba(0, 0, 0, 0.02);
  --shadow-input: 0 1px 2px rgba(0, 0, 0, 0.05);

  --font-family: 'Barlow', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --border-radius: 8px;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-page);
  color: var(--color-text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app-container {
  max-width: 840px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

/* Header */
.app-header {
  text-align: center;
  margin-bottom: 3rem;
}

.app-logo {
  font-size: 4.25rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
}

.app-logo a {
  color: var(--color-text);
  text-decoration: none;
  transition: opacity 0.2s ease;
}

.app-logo a:hover {
  opacity: 0.9;
}

.logo-accent {
  color: var(--color-accent);
}

.app-tagline {
  font-size: 1.125rem;
  color: var(--color-muted);
  font-weight: 400;
}

/* Calculator Card */
.calculator-card {
  background-color: var(--bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  padding: 2.5rem;
  margin-bottom: 2rem;
}

/* Controls Section */
.controls-section {
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 2rem;
  margin-bottom: 2.5rem;
}

/* Mode Button Toggle */
.mode-toggle-container {
  display: flex;
  width: max-content;
  margin: 0 auto 2rem auto;
  background-color: var(--bg-page);
  border: 1px solid var(--color-border);
  padding: 4px;
  border-radius: var(--border-radius);
}

.mode-btn {
  font-family: var(--font-family);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-muted);
  background: none;
  border: none;
  padding: 0.5rem 1.25rem;
  border-radius: calc(var(--border-radius) - 2px);
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.mode-btn:hover {
  color: var(--color-text);
}

.mode-btn.active {
  background-color: var(--bg-card);
  color: var(--color-text);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

/* Inputs Grid */
.inputs-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 1.5rem;
}

@media (max-width: 768px) {
  .inputs-grid {
    grid-template-columns: 1fr;
  }
}

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

.input-group label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.amount-input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.currency-symbol {
  position: absolute;
  left: 1rem;
  font-size: 1.125rem;
  font-weight: 500;
  color: var(--color-muted);
}

.amount-input-wrapper input {
  width: 100%;
  padding: 0.75rem 1rem 0.75rem 2rem;
  font-family: var(--font-family);
  font-size: 1.125rem;
  font-weight: 500;
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  outline: none;
  box-shadow: var(--shadow-input);
  transition: all 0.15s ease;
}

.amount-input-wrapper input:hover {
  border-color: var(--color-border-hover);
}

.amount-input-wrapper input:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-light);
}

/* Selectors Group */
.period-selectors {
  display: flex;
  gap: 0.5rem;
}

.period-selectors select {
  flex: 1;
  padding: 0.75rem 1rem;
  font-family: var(--font-family);
  font-size: 1rem;
  font-weight: 500;
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  outline: none;
  background-color: var(--bg-control);
  box-shadow: var(--shadow-input);
  cursor: pointer;
  transition: all 0.15s ease;
}

.period-selectors select:hover {
  border-color: var(--color-border-hover);
}

.period-selectors select:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-light);
}

.period-selectors select.hidden {
  display: none;
}

/* Results Section */
.results-section {
  margin-bottom: 3rem;
}

.error-banner {
  background-color: var(--color-error-light);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-error);
  color: var(--color-error-text);
  padding: 1rem;
  border-radius: var(--border-radius);
  margin-bottom: 1.5rem;
  font-weight: 500;
}

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

.results-hero {
  text-align: center;
  margin-bottom: 2.5rem;
}

.results-text {
  font-size: 1.125rem;
  color: var(--color-muted);
  margin-bottom: 0.5rem;
}

.results-text strong {
  color: var(--color-text);
  font-weight: 600;
}

.primary-result {
  font-size: 4rem;
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.04em;
  line-height: 1.1;
  transition: opacity 0.15s ease;
}

/* Metrics Grid */
.metrics-grid {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 1.5rem;
  margin-top: 1.5rem;
}

@media (max-width: 600px) {
  .metrics-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
}

.metric-card {
  background-color: var(--bg-page);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: 1.25rem;
  text-align: center;
}

.metric-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.5rem;
}

.metric-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-text);
}

/* Chart Section */
.chart-section {
  border-top: 1px solid var(--color-border);
  padding-top: 2.5rem;
  margin-bottom: 2.5rem;
}

.chart-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.chart-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text);
}

.chart-toggle-container {
  display: flex;
  background-color: var(--bg-page);
  border: 1px solid var(--color-border);
  padding: 3px;
  border-radius: var(--border-radius);
}

.chart-toggle {
  font-family: var(--font-family);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--color-muted);
  background: none;
  border: none;
  padding: 0.4rem 0.85rem;
  border-radius: calc(var(--border-radius) - 3px);
  cursor: pointer;
  transition: all 0.15s ease;
}

.chart-toggle:hover {
  color: var(--color-text);
}

.chart-toggle.active {
  background-color: var(--bg-card);
  color: var(--color-text);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.chart-wrapper {
  position: relative;
  width: 100%;
  height: 300px;
}

/* Actions Section */
.actions-section {
  border-top: 1px solid var(--color-border);
  padding-top: 2rem;
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

@media (max-width: 600px) {
  .actions-section {
    justify-content: center;
  }

  .action-btn {
    width: 100%;
  }
}

.action-btn {
  font-family: var(--font-family);
  font-size: 0.95rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius);
  cursor: pointer;
  outline: none;
  border: 1px solid var(--color-border);
  background-color: var(--bg-card);
  color: var(--color-text);
  transition: all 0.15s ease;
}

.action-btn:hover {
  border-color: var(--color-border-hover);
  background-color: var(--bg-page);
}

.action-btn:active {
  transform: translateY(1px);
}

.btn-icon {
  width: 1.125rem;
  height: 1.125rem;
}

/* Copy Link Success State Animation */
.action-btn.success-state {
  background-color: var(--color-success-light);
  border-color: var(--color-success);
  color: var(--color-success-text);
}

/* Skeleton loader / placeholders */
.skeleton-text {
  background: linear-gradient(90deg, #f3f4f6 25%, #e5e7eb 50%, #f3f4f6 75%);
  background-size: 200% 100%;
  animation: loading 1.5s infinite;
  display: inline-block;
  height: 1rem;
  width: 250px;
  border-radius: 4px;
}

@keyframes loading {
  0% {
    background-position: 200% 0;
  }

  100% {
    background-position: -200% 0;
  }
}

/* Footer styling */
.app-footer {
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-muted);
}

.app-footer p {
  margin-bottom: 0.25rem;
}

/* Ad Section */
.ad-section {
  border-top: 1px solid var(--color-border);
  padding-top: 2.5rem;
  margin-bottom: 2.5rem;
  display: flex;
  justify-content: center;
  align-items: center;
}

.ad-container {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  max-width: 728px;
  min-height: 90px;
  background-color: var(--bg-page);
  border: 1px dashed var(--color-border-hover);
  border-radius: var(--border-radius);
  color: var(--color-muted);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.15em;
}

/* Responsive Overrides */
@media (max-width: 768px) {
  .app-logo {
    font-size: 2.75rem;
  }
  .app-tagline {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  html, body {
    overflow-x: hidden; /* Prevent horizontal layout stretching */
  }
  
  .app-container {
    padding: 2rem 1rem;
  }
  
  .app-logo {
    font-size: 2.15rem;
  }
  
  .calculator-card {
    padding: 1.25rem;
  }
  
  .primary-result {
    font-size: 2.5rem;
  }
  
  .mode-btn {
    padding: 0.5rem 0.75rem;
    font-size: 0.85rem;
  }
  
  .inputs-grid {
    gap: 1rem;
  }
  
  .metrics-grid {
    gap: 0.75rem;
  }
  
  .metric-card {
    padding: 1rem;
  }
  
  .metric-value {
    font-size: 1.5rem;
  }
}