/* CSS Design System for CryptoPerpCalc — Mobile-First Responsive UI */

:root {
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --bg-color: #0b0e14;
  --card-bg: #151922;
  --card-border: #232936;
  --text-main: #f0f4f8;
  --text-muted: #8b98a5;
  --primary-color: #f0b90b;
  --primary-hover: #d8a40a;
  --success-color: #0ecb81;
  --danger-color: #f6465d;
  --warning-color: #f39c12;
  --side-long: #0ecb81;
  --side-short: #f6465d;
  --sponsor-border: #2c3545;
  --sponsor-bg: #121620;
  --border-radius: 8px;
  --transition: all 0.2s ease-in-out;
}

*, *::before, *::after {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html, body {
  width: 100%;
  overflow-x: hidden;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Base mobile layout (360px default width - Mobile-First) */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Site Header */
.site-header {
  border-bottom: 1px solid var(--card-border);
  background-color: rgba(21, 25, 34, 0.95);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  min-height: 56px;
  padding-top: 0.5rem;
  padding-bottom: 0.5rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.brand-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  text-decoration: none;
}

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

.main-nav {
  display: flex;
  gap: 0.75rem;
  align-items: center;
}

.nav-link {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  padding: 0.5rem 0.75rem;
  min-height: 44px;
  min-width: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  border-radius: var(--border-radius);
}

.nav-link:hover, .nav-link.active {
  color: var(--text-main);
  background-color: rgba(255, 255, 255, 0.05);
}

/* Main Content & Hero */
.main-content {
  flex: 1;
  padding-top: 1.5rem;
  padding-bottom: 2rem;
}

.hero-section {
  text-align: center;
  margin-bottom: 1.5rem;
}

.hero-section h1 {
  font-size: 1.65rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  line-height: 1.25;
}

.hero-subtitle {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* Calculator Grid Layout — Mobile First (1 column at 360px) */
.calculator-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}

@media (min-width: 768px) {
  .hero-section h1 {
    font-size: 2.25rem;
  }
  .hero-subtitle {
    font-size: 1.1rem;
  }
  .main-content {
    padding-top: 2.5rem;
    padding-bottom: 2.5rem;
  }
  .calculator-grid {
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
  }
}

/* Cards & Form Controls */
.card {
  background-color: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--border-radius);
  padding: 1.25rem;
}

@media (min-width: 768px) {
  .card {
    padding: 1.75rem;
  }
}

.card h2 {
  font-size: 1.15rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--card-border);
  padding-bottom: 0.5rem;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label, .control-label {
  display: block;
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 0.375rem;
}

.form-control, select, input {
  width: 100%;
  padding: 0.75rem;
  min-height: 44px;
  background-color: var(--bg-color);
  border: 1px solid var(--card-border);
  border-radius: var(--border-radius);
  color: var(--text-main);
  font-size: 16px; /* Avoid iOS auto-zoom (>= 16px) */
  transition: var(--transition);
}

.form-control:focus, select:focus {
  outline: none;
  border-color: var(--primary-color);
}

:where(a, button, input, select):focus-visible {
  outline: 3px solid rgba(240, 185, 11, 0.55);
  outline-offset: 2px;
}

.field-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
  display: block;
}

/* Validation Alert Message */
.validation-alert {
  display: none;
  background-color: rgba(246, 70, 93, 0.15);
  border: 1px solid var(--danger-color);
  color: var(--text-main);
  padding: 0.75rem 1rem;
  border-radius: var(--border-radius);
  font-size: 0.875rem;
  margin-bottom: 1.25rem;
  line-height: 1.4;
}

.validation-alert.visible {
  display: block;
}

/* Input Mode & Position Side Selectors */
.mode-selector, .side-selector {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
}

.btn {
  padding: 0.75rem 1rem;
  min-height: 44px;
  min-width: 44px;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--border-radius);
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.btn-toggle {
  background-color: var(--bg-color);
  color: var(--text-muted);
  border: 1px solid var(--card-border);
  font-size: 0.9rem;
}

.btn-toggle.active {
  background-color: var(--card-border);
  color: var(--primary-color);
  border-color: var(--primary-color);
}

.btn-side {
  background-color: var(--bg-color);
  color: var(--text-muted);
  border: 1px solid var(--card-border);
}

.btn-side-long.active {
  background-color: var(--side-long);
  color: #07110d;
  border-color: var(--side-long);
}

.btn-side-short.active {
  background-color: var(--side-short);
  color: #120407;
  border-color: var(--side-short);
}

.btn-primary {
  background-color: var(--primary-color);
  color: #000;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

.btn-block {
  width: 100%;
}

/* Leverage Slider & Preset Buttons */
.slider-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.slider-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.slider-val-badge {
  background-color: var(--primary-color);
  color: #000;
  font-weight: 700;
  font-size: 0.85rem;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

.leverage-slider {
  width: 100%;
  height: 44px;
  accent-color: var(--primary-color);
  cursor: pointer;
  margin-top: 0.25rem;
}

.leverage-presets {
  display: flex;
  gap: 0.375rem;
  flex-wrap: wrap;
  margin-top: 0.375rem;
}

.btn-preset {
  flex: 1;
  min-width: 44px;
  min-height: 44px;
  background-color: var(--bg-color);
  color: var(--text-muted);
  border: 1px solid var(--card-border);
  border-radius: var(--border-radius);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.btn-preset:hover, .btn-preset.active {
  background-color: var(--card-border);
  color: var(--primary-color);
  border-color: var(--primary-color);
}

/* Calculation Results Grid */
.results-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.75rem;
}

@media (min-width: 480px) {
  .results-grid {
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
  }
}

.result-card {
  background-color: var(--bg-color);
  border: 1px solid var(--card-border);
  border-radius: var(--border-radius);
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.result-card.highlight {
  border-color: var(--danger-color);
  background-color: rgba(246, 70, 93, 0.05);
}

.result-label {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.result-value {
  font-size: 1.25rem;
  font-weight: 700;
}

.danger-text {
  color: var(--danger-color);
}

.success-text {
  color: var(--success-color);
}

/* Liquidation Notice Box */
.liq-warning-notice {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  background-color: rgba(243, 156, 18, 0.08);
  border-left: 3px solid var(--warning-color);
  border-radius: 4px;
  font-size: 0.8rem;
  color: #e0d0b0;
  line-height: 1.45;
}

/* Monetization & CTAs */
.monetization-section {
  margin-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.primary-cta-container {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.btn-cta-primary {
  width: 100%;
  min-height: 48px;
  background-color: var(--primary-color);
  color: #000;
  font-weight: 700;
  font-size: 1rem;
  text-decoration: none;
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
  border: none;
}

.btn-cta-primary:hover {
  background-color: var(--primary-hover);
  color: #000;
}

.affiliate-disclosure {
  font-size: 0.75rem;
  color: var(--text-muted);
  line-height: 1.35;
  margin-top: 0.25rem;
}

/* Other Exchanges Collapsible / Secondary Section */
.secondary-exchanges-section {
  border-top: 1px solid var(--card-border);
  padding-top: 1rem;
  margin-top: 0.5rem;
}

.secondary-exchanges-title {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.secondary-links-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.5rem;
}

@media (min-width: 480px) {
  .secondary-links-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.referral-link {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: 0.6rem 0.85rem;
  background-color: var(--bg-color);
  border: 1px solid var(--card-border);
  border-radius: var(--border-radius);
  color: var(--text-main);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.85rem;
  transition: var(--transition);
}

.referral-link:hover {
  border-color: var(--primary-color);
  color: var(--primary-color);
}

/* FAQ Section */
.faq-section {
  margin-top: 2rem;
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.faq-item h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.375rem;
  color: var(--text-main);
}

.faq-item p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* 404 Page */
.not-found-main {
  padding-top: 4rem;
  padding-bottom: 4rem;
  text-align: center;
}

.not-found-card {
  max-width: 600px;
  margin: 0 auto;
}

.not-found-code {
  margin: 0 0 0.5rem;
  color: var(--primary-color);
  font-size: 3rem;
}

.not-found-copy {
  margin-bottom: 1.5rem;
  color: var(--text-muted);
}

.return-link {
  display: inline-flex;
  text-decoration: none;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--card-border);
  padding: 1.5rem 0;
  margin-top: auto;
  color: var(--text-muted);
  font-size: 0.875rem;
  text-align: center;
}

.footer-disclaimer {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}