/* === DESIGN SYSTEM === */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #050508;
  --color-surface: rgba(255, 255, 255, 0.03);
  --color-surface-raised: rgba(255, 255, 255, 0.05);
  --color-surface-hover: rgba(255, 255, 255, 0.07);
  --color-border: rgba(255, 255, 255, 0.06);
  --color-border-strong: rgba(255, 255, 255, 0.1);
  --color-text: #f4f4f6;
  --color-text-secondary: rgba(255, 255, 255, 0.6);
  --color-text-muted: rgba(255, 255, 255, 0.35);
  --color-accent: #14b8a6;
  --color-accent-glow: rgba(20, 184, 166, 0.3);
  --color-accent-2: #06b6d4;
  --color-warning: #f59e0b;
  --color-warning-glow: rgba(245, 158, 11, 0.25);
  --color-success: #10b981;
  --color-danger: #ef4444;

  --radius-sm: 10px;
  --radius: 14px;
  --radius-lg: 20px;
  --radius-xl: 24px;

  --font-mono: "JetBrains Mono", "Fira Code", "Cascadia Code", monospace;
  --font-sans: "Inter", system-ui, -apple-system, sans-serif;

  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 400ms cubic-bezier(0.34, 1.56, 0.64, 1);

  --shadow-glow: 0 0 40px rgba(20, 184, 166, 0.08);
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 16px rgba(0, 0, 0, 0.3);
  --shadow-elevated: 0 1px 2px rgba(0, 0, 0, 0.5), 0 8px 32px rgba(0, 0, 0, 0.4);
}

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-size: 16px;
  color-scheme: dark;
}

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

/* === AMBIENT BACKGROUND === */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 10%, rgba(20, 184, 166, 0.06), transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 85%, rgba(6, 182, 212, 0.05), transparent 60%),
    radial-gradient(ellipse 50% 40% at 50% 50%, rgba(245, 158, 11, 0.03), transparent 60%);
  pointer-events: none;
  z-index: 0;
}

/* Subtle grain overlay */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.02'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
}

/* === CONTAINER === */
.container {
  max-width: 780px;
  margin: 0 auto;
  padding: clamp(1.5rem, 4vw, 3rem) clamp(1rem, 3vw, 2rem);
  position: relative;
  z-index: 1;
}

/* === HEADER === */
.header {
  text-align: center;
  margin-bottom: clamp(2rem, 5vw, 3.5rem);
}

.logo {
  width: 52px;
  height: 52px;
  margin: 0 auto 1.25rem;
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2));
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 26px;
  color: #fff;
  box-shadow: 0 0 30px var(--color-accent-glow), 0 0 60px rgba(20, 184, 166, 0.1);
  position: relative;
}

.logo::after {
  content: "";
  position: absolute;
  inset: -3px;
  border-radius: calc(var(--radius) + 3px);
  background: linear-gradient(135deg, var(--color-accent), var(--color-accent-2), var(--color-accent));
  opacity: 0.3;
  z-index: -1;
  filter: blur(8px);
}

h1 {
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.subtitle {
  color: var(--color-text-secondary);
  font-size: 0.925rem;
  max-width: 480px;
  margin: 0 auto;
  line-height: 1.5;
}

/* === CARD === */
.card {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border);
  overflow: hidden;
  margin-bottom: 1.25rem;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: var(--shadow-card);
  transition: border-color var(--transition-smooth);
}

.card:hover {
  border-color: var(--color-border-strong);
}

.card-header {
  padding: 1.5rem 1.75rem;
  border-bottom: 1px solid var(--color-border);
  background: var(--color-surface-raised);
}

.card-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
  letter-spacing: -0.01em;
}

.card-description {
  font-size: 0.825rem;
  color: var(--color-text-muted);
}

.card-body {
  padding: 1.5rem 1.75rem;
}

/* === TABS === */
.tab-group {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  background: var(--color-surface-hover);
  padding: 4px;
  border-radius: var(--radius);
  margin-bottom: 1.75rem;
}

.tab-btn {
  background: transparent;
  border: none;
  padding: 0.7rem 1rem;
  border-radius: calc(var(--radius) - 4px);
  font-weight: 600;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition-smooth);
  font-family: var(--font-sans);
  letter-spacing: -0.01em;
  position: relative;
}

.tab-btn.active {
  background: var(--color-surface);
  color: var(--color-accent);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.tab-btn:hover:not(.active) {
  color: var(--color-text-secondary);
}

/* === FORM GRID === */
.form-grid {
  display: grid;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

@media (min-width: 640px) {
  .form-grid.cols-2 {
    grid-template-columns: 1fr 1fr;
  }
}

.form-group {
  display: flex;
  flex-direction: column;
}

label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* === INPUT === */
.input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--color-surface-hover);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  transition: all var(--transition-smooth);
  overflow: hidden;
}

.input-wrapper:focus-within {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px var(--color-accent-glow);
  background: var(--color-surface-raised);
}

.input-prefix {
  padding: 0 0.85rem;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-accent);
  background: rgba(20, 184, 166, 0.08);
  border-right: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  align-self: stretch;
  letter-spacing: 0.03em;
  font-family: var(--font-mono);
}

input[type="number"] {
  flex: 1;
  border: none;
  background: transparent;
  padding: 0.85rem 1rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-text);
  font-family: var(--font-mono);
  outline: none;
  width: 100%;
  letter-spacing: -0.01em;
}

input[type="number"]:disabled {
  color: var(--color-text-muted);
  cursor: not-allowed;
  opacity: 0.5;
}

input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

input[type="number"] {
  -moz-appearance: textfield;
}

/* === CUSTOM TOGGLE SWITCH === */
.checkbox-group {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.75rem 0;
  flex-wrap: wrap;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  cursor: pointer;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  user-select: none;
  transition: color var(--transition-fast);
}

.checkbox-label:hover {
  color: var(--color-text);
}

/* Hide native checkbox */
.checkbox-label input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 40px;
  height: 24px;
  background: var(--color-surface-hover);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  cursor: pointer;
  position: relative;
  transition: all var(--transition-smooth);
  flex-shrink: 0;
}

.checkbox-label input[type="checkbox"]::after {
  content: "";
  position: absolute;
  top: 3px;
  left: 3px;
  width: 16px;
  height: 16px;
  background: var(--color-text-muted);
  border-radius: 50%;
  transition: all var(--transition-spring);
}

.checkbox-label input[type="checkbox"]:checked {
  background: rgba(20, 184, 166, 0.2);
  border-color: var(--color-accent);
}

.checkbox-label input[type="checkbox"]:checked::after {
  left: 19px;
  background: var(--color-accent);
  box-shadow: 0 0 8px var(--color-accent-glow);
}

/* === BUTTONS === */
.btn-group {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.btn {
  padding: 0.85rem 1.5rem;
  border: none;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.925rem;
  cursor: pointer;
  transition: all var(--transition-smooth);
  font-family: var(--font-sans);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  letter-spacing: -0.01em;
  position: relative;
  overflow: hidden;
}

.btn-secondary {
  background: var(--color-surface-hover);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: var(--color-surface-raised);
  color: var(--color-text);
  border-color: var(--color-border-strong);
  transform: translateY(-1px);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-accent), #0d9488);
  color: #fff;
  box-shadow: 0 2px 12px var(--color-accent-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(20, 184, 166, 0.4);
}

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

/* Ripple effect */
.btn::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at center, rgba(255, 255, 255, 0.15) 0%, transparent 70%);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.btn:active::before {
  opacity: 1;
}

/* === RESULTS === */
.result-card {
  background: var(--color-surface-raised);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  border: 1px solid var(--color-border);
  margin-bottom: 0;
}

.result-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.6rem 0;
  font-size: 0.925rem;
}

.result-label {
  color: var(--color-text-secondary);
  font-weight: 500;
  font-size: 0.875rem;
}

.result-value {
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  text-align: right;
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  transition: color var(--transition-smooth);
}

.result-divider {
  height: 1px;
  background: var(--color-border);
  margin: 0.6rem 0;
}

.result-total {
  background: linear-gradient(135deg, rgba(20, 184, 166, 0.08), rgba(6, 182, 212, 0.06));
  padding: 1rem 1.25rem;
  border-radius: var(--radius);
  margin-top: 0.75rem;
  border: 1px solid rgba(20, 184, 166, 0.15);
}

.result-total .result-label {
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--color-text);
}

.result-total .result-value {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--color-accent);
  text-shadow: 0 0 20px var(--color-accent-glow);
}

.highlight {
  color: var(--color-warning);
  font-weight: 800;
}

.note {
  font-size: 0.825rem;
  color: var(--color-text-muted);
  line-height: 1.5;
  margin-top: 0.75rem;
  padding: 0.75rem 1rem;
  background: rgba(255, 255, 255, 0.02);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--color-accent);
}

/* === UTILITY === */
.hidden {
  display: none !important;
}

.fade-in {
  animation: fadeSlideIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* === FOOTER === */
.footer {
  text-align: center;
  padding: 2rem 1rem;
  color: var(--color-text-muted);
  font-size: 0.8rem;
}

.noscript-note {
  margin-top: 1rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid rgba(245, 158, 11, 0.2);
  color: var(--color-text-secondary);
  font-size: 0.825rem;
}

/* === ADVANCED SETTINGS ANIMATION === */
#advancedSettings {
  animation: expandDown 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  overflow: hidden;
}

#advancedSettings.hidden {
  animation: none;
}

@keyframes expandDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
    max-height: 0;
  }
  to {
    opacity: 1;
    transform: translateY(0);
    max-height: 600px;
  }
}

/* === VALUE CHANGE PULSE === */
@keyframes valuePulse {
  0% { transform: scale(1); }
  50% { transform: scale(1.06); }
  100% { transform: scale(1); }
}

.value-updated {
  animation: valuePulse 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* === MOBILE === */
@media (max-width: 640px) {
  .btn-group {
    grid-template-columns: 1fr;
  }

  .checkbox-group {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }

  .card-header,
  .card-body {
    padding: 1.25rem 1rem;
  }

  .result-card {
    padding: 1rem;
  }

  .result-total .result-value {
    font-size: 1.2rem;
  }

  .form-grid.cols-2 {
    grid-template-columns: 1fr;
  }
}

/* === SCROLLBAR === */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-surface-hover);
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-border-strong);
}

/* === SELECTION === */
::selection {
  background: rgba(20, 184, 166, 0.2);
  color: var(--color-text);
}