/* ==========================================================================
   Distance Calculator Design System
   Modern Glassmorphism + Dynamic Fluid Typography + Curated HSL Palette
   ========================================================================== */

:root {
  /* Color Palette - Dark Mode Default */
  --bg-primary: #0a0e17;
  --bg-secondary: #111827;
  --card-bg: rgba(17, 24, 39, 0.75);
  --card-border: rgba(255, 255, 255, 0.08);
  --card-border-hover: rgba(56, 189, 248, 0.3);
  --panel-bg: rgba(15, 23, 42, 0.65);
  --panel-border: rgba(255, 255, 255, 0.07);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --accent-cyan: #38bdf8;
  --accent-blue: #3b82f6;
  --accent-indigo: #6366f1;
  --accent-emerald: #10b981;
  --accent-gradient: linear-gradient(135deg, #38bdf8 0%, #6366f1 100%);
  --accent-glow: rgba(56, 189, 248, 0.25);

  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 8px 24px -4px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 20px 40px -8px rgba(0, 0, 0, 0.6);
  --shadow-glow: 0 0 35px -5px rgba(56, 189, 248, 0.3);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  --transition-fast: 0.15s ease;
  --transition-base: 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-bounce: 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-primary: #f1f5f9;
  --bg-secondary: #e2e8f0;
  --card-bg: rgba(255, 255, 255, 0.85);
  --card-border: rgba(0, 0, 0, 0.08);
  --card-border-hover: rgba(14, 165, 233, 0.4);
  --panel-bg: rgba(248, 250, 252, 0.8);
  --panel-border: rgba(0, 0, 0, 0.06);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;

  --accent-cyan: #0284c7;
  --accent-blue: #2563eb;
  --accent-indigo: #4f46e5;
  --accent-emerald: #059669;
  --accent-gradient: linear-gradient(135deg, #0284c7 0%, #4f46e5 100%);
  --accent-glow: rgba(2, 132, 199, 0.2);

  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 24px -4px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 20px 40px -8px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 35px -5px rgba(2, 132, 199, 0.2);
}

/* Base Reset & Core Setup */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
  transition: background-color var(--transition-base), color var(--transition-base);
}

/* Ambient Animated Glow Orbs */
.glow-orb {
  position: fixed;
  border-radius: 50%;
  filter: blur(100px);
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
  transition: opacity var(--transition-base);
}

.orb-1 {
  width: 500px;
  height: 500px;
  top: -150px;
  left: 20%;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.25) 0%, rgba(99, 102, 241, 0.05) 70%, transparent 100%);
  animation: floatOrb 18s ease-in-out infinite alternate;
}

.orb-2 {
  width: 450px;
  height: 450px;
  bottom: -100px;
  right: 15%;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.2) 0%, rgba(16, 185, 129, 0.05) 70%, transparent 100%);
  animation: floatOrb 22s ease-in-out infinite alternate-reverse;
}

@keyframes floatOrb {
  0% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(30px, -40px) scale(1.08); }
  100% { transform: translate(-20px, 30px) scale(0.95); }
}

/* Layout Container */
.page-wrapper {
  position: relative;
  z-index: 1;
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Header & Navigation */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0 2rem;
}

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

.logo-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 4px 14px rgba(56, 189, 248, 0.4);
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.brand-badge {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--accent-cyan);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 0.65rem;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-sm {
  padding: 0.45rem 0.85rem;
  font-size: 0.825rem;
}

.btn-secondary {
  background: var(--panel-bg);
  color: var(--text-primary);
  border-color: var(--card-border);
  backdrop-filter: blur(8px);
}

.btn-secondary:hover {
  background: var(--card-border-hover);
  border-color: var(--accent-cyan);
  transform: translateY(-1px);
}

.icon-btn {
  background: var(--panel-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  backdrop-filter: blur(8px);
}

.icon-btn:hover {
  color: var(--accent-cyan);
  border-color: var(--card-border-hover);
  transform: translateY(-1px);
}

/* Theme Icon Visibility */
.sun-icon { display: none; }
.moon-icon { display: block; }
[data-theme="light"] .sun-icon { display: block; }
[data-theme="light"] .moon-icon { display: none; }

/* Hero Section */
.hero-section {
  text-align: center;
  padding: 1rem 0 2rem;
}

.main-headline {
  font-size: clamp(1.85rem, 4vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 0.6rem;
}

.highlight-text {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.sub-headline {
  color: var(--text-secondary);
  font-size: 1rem;
  max-width: 520px;
  margin: 0 auto 1.25rem;
}

.url-badge-container {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.4rem 0.9rem;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-full);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
  font-size: 0.85rem;
}

.url-badge-label {
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.775rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.url-code {
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  font-weight: 600;
}

/* Calculator Card */
.calculator-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  backdrop-filter: blur(16px);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  margin-bottom: 2.5rem;
  transition: border-color var(--transition-fast);
}

/* Mode Switcher Tabs */
.tabs-wrapper {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  padding: 0.35rem;
  border-radius: var(--radius-md);
  margin-bottom: 1.5rem;
}

.tab-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-base);
}

.tab-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.15rem 0.45rem;
  border-radius: 4px;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-muted);
  transition: all var(--transition-base);
}

.tab-btn.active {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 16px rgba(56, 189, 248, 0.35);
}

.tab-btn.active .tab-tag {
  background: rgba(255, 255, 255, 0.25);
  color: #ffffff;
}

.tab-btn:not(.active):hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.04);
}

/* Converter Interactive Area */
.converter-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.calc-panel {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  transition: all var(--transition-fast);
}

.calc-panel:focus-within {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.15);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.65rem;
}

.panel-label {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.panel-hint {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.input-wrapper, .output-wrapper {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}

.distance-field {
  width: 100%;
  background: transparent;
  border: none;
  font-family: var(--font-mono);
  font-size: 2.1rem;
  font-weight: 700;
  color: var(--text-primary);
  outline: none;
  min-width: 0;
}

/* Remove spin buttons from number input */
.distance-field::-webkit-outer-spin-button,
.distance-field::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.distance-field[type=number] {
  -moz-appearance: textfield;
}

.result-number {
  font-family: var(--font-mono);
  font-size: 2.1rem;
  font-weight: 700;
  color: var(--accent-cyan);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.unit-symbol {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-muted);
}

/* Swap Action Button */
.swap-action-wrapper {
  display: flex;
  justify-content: center;
}

.swap-button {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  color: var(--accent-cyan);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-bounce);
  box-shadow: var(--shadow-sm);
}

.swap-button:hover {
  background: var(--accent-cyan);
  color: #0f172a;
  transform: rotate(180deg) scale(1.1);
  box-shadow: 0 0 20px rgba(56, 189, 248, 0.5);
}

.swap-button:active {
  transform: rotate(180deg) scale(0.95);
}

/* Copy Action Button inside Output */
.copy-action-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--panel-border);
  color: var(--text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.55rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.copy-action-btn:hover {
  color: var(--accent-cyan);
  border-color: var(--card-border-hover);
  background: rgba(56, 189, 248, 0.1);
}

/* Formula Breakdown Card */
.formula-breakdown-card {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  margin-bottom: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.formula-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.formula-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.775rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.precision-control {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.decimal-dropdown {
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--panel-border);
  color: var(--text-primary);
  border-radius: 6px;
  padding: 0.2rem 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  outline: none;
  cursor: pointer;
}

[data-theme="light"] .decimal-dropdown {
  background: #ffffff;
}

.formula-text {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.formula-text strong {
  color: var(--accent-cyan);
}

/* Presets Section */
.presets-section {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.presets-title {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.preset-chips-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.preset-chip {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.825rem;
  font-weight: 600;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.preset-chip:hover {
  border-color: var(--accent-cyan);
  color: var(--text-primary);
  transform: translateY(-2px);
  background: rgba(56, 189, 248, 0.08);
}

.preset-chip.active {
  background: rgba(56, 189, 248, 0.15);
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
}

/* Educational Info Section */
.info-section {
  margin-top: 1rem;
}

.info-heading {
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 1.25rem;
  text-align: center;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 2rem;
}

.info-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  backdrop-filter: blur(12px);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.card-icon {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: rgba(56, 189, 248, 0.15);
  color: var(--accent-cyan);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 0.25rem;
}

.info-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
}

.info-card p {
  font-size: 0.825rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.info-card code {
  font-family: var(--font-mono);
  background: rgba(255, 255, 255, 0.06);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  color: var(--accent-cyan);
  font-size: 0.775rem;
}

/* Quick Reference Table */
.table-container {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  backdrop-filter: blur(12px);
}

.table-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.table-responsive {
  overflow-x: auto;
}

.conversion-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
}

.conversion-table th {
  text-align: left;
  padding: 0.75rem 1rem;
  background: var(--panel-bg);
  color: var(--text-muted);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--card-border);
}

.conversion-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--panel-border);
  color: var(--text-secondary);
}

.conversion-table tr:hover td {
  background: rgba(56, 189, 248, 0.04);
  color: var(--text-primary);
}

.table-val {
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--text-primary);
}

.table-res {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--accent-cyan);
}

.table-calc-btn {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  color: var(--accent-cyan);
  border-radius: var(--radius-sm);
  padding: 0.25rem 0.6rem;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.table-calc-btn:hover {
  background: var(--accent-cyan);
  color: #0f172a;
}

/* Footer */
.footer {
  margin-top: auto;
  padding-top: 3rem;
  text-align: center;
  border-top: 1px solid var(--panel-border);
}

.footer-content p {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.footer-sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
}

/* Toast Message */
.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: #0f172a;
  border: 1px solid var(--accent-cyan);
  color: #f8fafc;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-md);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5), 0 0 15px rgba(56, 189, 248, 0.3);
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 100;
  opacity: 0;
  transform: translateY(20px);
  pointer-events: none;
  transition: all var(--transition-base);
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.toast svg {
  color: var(--accent-emerald);
}

/* Responsive Breakpoints */
@media (max-width: 768px) {
  .converter-grid {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .swap-button {
    margin: -0.25rem 0;
    transform: rotate(90deg);
  }

  .swap-button:hover {
    transform: rotate(270deg) scale(1.1);
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .calculator-card {
    padding: 1.25rem;
  }
}