/* ==========================================================================
   Universal Unit Converter - High-Precision Engineering Converter Styles
   100% Valid CSS, Fully Modular, Ultra-Professional SaaS / Metrology Aesthetic
   ========================================================================== */

.converter-widget-container {
  max-width: 900px;
  margin: 0 auto 3.5rem auto;
}

/* ==========================================================================
   Converter Instrument Chassis
   ========================================================================== */

.converter-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-xl);
  position: relative;
  transition: all var(--transition-normal);
}

@media (max-width: 640px) {
  .converter-card {
    padding: 1.15rem 1rem;
    border-radius: var(--radius-lg);
  }
}

/* Top Instrument Header Status Bar */
.instrument-status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 1.25rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
  font-size: 0.8125rem;
}

.status-indicator-group {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.status-pulse-dot {
  width: 8px;
  height: 8px;
  border-radius: var(--radius-full);
  background-color: var(--status-success);
  box-shadow: 0 0 0 2px var(--status-success-light);
  display: inline-block;
  animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
  0% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.6); }
  70% { box-shadow: 0 0 0 6px rgba(16, 185, 129, 0); }
  100% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0); }
}

.engine-spec-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-xs);
  background-color: var(--bg-subtle);
  color: var(--text-muted);
  border: 1px solid var(--border-color);
}

/* Category Tabs (if embedded inside widget) */
.widget-category-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 0.75rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  scrollbar-width: none;
}

.widget-category-bar::-webkit-scrollbar {
  display: none;
}

.widget-cat-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 0.95rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
  background-color: var(--bg-subtle);
  border: 1px solid transparent;
  white-space: nowrap;
  flex-shrink: 0;
  min-height: 40px;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.widget-cat-btn:hover {
  background-color: var(--bg-subtle-hover);
  color: var(--text-primary);
}

.widget-cat-btn.active {
  background-color: var(--brand-primary);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}

/* ==========================================================================
   Dual Calculation Bays (Source & Target)
   ========================================================================== */

.converter-main-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 1.5rem;
}

@media (max-width: 768px) {
  .converter-main-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
}

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

.unit-label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.unit-input-group {
  display: flex;
  flex-direction: column;
  background-color: var(--bg-main);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
}

.unit-input-group:focus-within {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3.5px var(--brand-primary-light);
  background-color: var(--bg-surface);
}

.unit-number-input {
  width: 100%;
  border: none;
  background: transparent;
  padding: 1rem 1.25rem;
  font-size: 1.5rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
  outline: none;
}

.unit-number-input::placeholder {
  color: var(--text-muted);
  font-weight: 400;
}

.unit-result-input {
  background-color: var(--bg-subtle);
  color: var(--brand-primary);
}

/* Custom Select Unit Menu */
.unit-select {
  width: 100%;
  padding: 0.75rem 1.25rem;
  background-color: var(--bg-surface);
  border: none;
  border-top: 1px solid var(--border-color);
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2.5' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1.25rem center;
  padding-right: 2.75rem;
  transition: background-color var(--transition-fast);
}

.unit-select:hover {
  background-color: var(--bg-subtle);
}

/* Unit Swap Central Node */
.unit-swap-container, .swap-button-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 1.25rem;
}

@media (max-width: 768px) {
  .unit-swap-container, .swap-button-wrapper {
    padding-top: 0;
    margin: -0.25rem 0;
  }
}

.unit-swap-btn, .swap-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background-color: var(--bg-surface);
  border: 1.5px solid var(--border-color);
  color: var(--text-secondary);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.unit-swap-btn:hover, .swap-btn:hover {
  background-color: var(--brand-primary);
  color: #ffffff;
  border-color: var(--brand-primary);
  transform: rotate(180deg) scale(1.05);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.35);
}

/* ==========================================================================
   Quick Presets Interval Bar
   ========================================================================== */

.preset-values-bar {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
  padding: 0.5rem 0;
}

.preset-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-right: 0.25rem;
}

.preset-chip-btn {
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.preset-chip-btn:hover {
  background-color: var(--brand-primary-light);
  border-color: var(--brand-primary-border);
  color: var(--brand-primary);
}

.preset-chip-btn:active {
  transform: scale(0.95);
}

/* ==========================================================================
   Instrument Calibration Toolbar (Precision, Toggles, Copy)
   ========================================================================== */

.converter-toolbar, .converter-controls-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 1.25rem 0;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 1.5rem;
}

.toolbar-group, .controls-left-group {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.toolbar-label, .control-item {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.toolbar-select, .control-select {
  padding: 0.35rem 0.65rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  background-color: var(--bg-main);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-primary);
  outline: none;
  cursor: pointer;
  min-height: 36px;
}

/* Modern Toggle Switch Component */
.toggle-switch-label, .control-checkbox-label {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  user-select: none;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  min-height: 36px;
}

.toggle-checkbox {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.toggle-slider {
  position: relative;
  display: inline-block;
  width: 36px;
  height: 20px;
  background-color: var(--bg-subtle-hover);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  transition: all var(--transition-fast);
}

.toggle-slider::before {
  content: '';
  position: absolute;
  left: 2px;
  top: 2px;
  width: 14px;
  height: 14px;
  background-color: #ffffff;
  border-radius: var(--radius-full);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
  transition: transform var(--transition-fast);
}

.toggle-checkbox:checked + .toggle-slider {
  background-color: var(--brand-primary);
  border-color: var(--brand-primary);
}

.toggle-checkbox:checked + .toggle-slider::before {
  transform: translateX(16px);
}

/* Primary Action Buttons (Copy, Invert) */
.action-btn, .copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-md);
  font-size: 0.8125rem;
  font-weight: 700;
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  transition: all var(--transition-fast);
  cursor: pointer;
  min-height: 40px;
}

.action-btn:hover, .copy-btn:hover {
  background-color: var(--brand-primary);
  color: #ffffff;
  border-color: var(--brand-primary);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
}

.action-btn:active, .copy-btn:active {
  transform: scale(0.97);
}

.action-btn.copied, .copy-btn.copied {
  background-color: var(--status-success) !important;
  color: #ffffff !important;
  border-color: var(--status-success) !important;
}

/* Responsive Overrides for Mobile Viewports */
@media (max-width: 640px) {
  .converter-toolbar, .converter-controls-bar {
    flex-direction: column;
    align-items: stretch;
    gap: 0.85rem;
    padding: 1rem 0;
  }
  .toolbar-group, .controls-left-group {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    gap: 0.5rem;
  }
  .action-btn, .copy-btn {
    width: 100%;
    justify-content: center;
    min-height: 44px;
    font-size: 0.875rem;
  }
  .preset-values-bar {
    gap: 0.4rem;
  }
  .preset-chip-btn {
    padding: 0.35rem 0.65rem;
    min-height: 36px;
    min-width: 38px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 0.8125rem;
  }
  .unit-number-input {
    font-size: 1.35rem;
    padding: 0.85rem 1rem;
  }
  .unit-select {
    padding: 0.85rem 1rem;
    font-size: 0.9375rem;
    min-height: 48px;
  }
  .unit-swap-btn, .swap-btn {
    transform: rotate(90deg);
  }
  .unit-swap-btn:hover, .swap-btn:hover,
  .unit-swap-btn:active, .swap-btn:active {
    transform: rotate(270deg) scale(1.05);
  }
  .matrix-grid, .quick-matrix-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.5rem;
  }
  .matrix-card {
    padding: 0.65rem 0.75rem;
    min-height: 52px;
  }
  .matrix-preview-section, .quick-matrix-container {
    padding: 1.15rem 1rem;
  }
  .history-chip {
    min-height: 36px;
    padding: 0.4rem 0.75rem;
  }
}

@media (max-width: 400px) {
  .matrix-grid, .quick-matrix-grid {
    grid-template-columns: 1fr;
  }
  .toolbar-group {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* ==========================================================================
   Live Formula HUD & Step Breakdown
   ========================================================================== */

.converter-formula-card, .formula-banner {
  background: linear-gradient(135deg, var(--bg-subtle) 0%, var(--bg-surface) 100%);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.formula-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.formula-badge-label, .formula-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--brand-primary);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.formula-equation, .formula-text {
  font-family: var(--font-mono);
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.5;
  word-break: break-word;
}

.formula-highlight {
  color: var(--brand-primary);
}

/* Warning Badges */
.warning-pill, .validation-warning {
  display: none;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-xs);
  font-size: 0.75rem;
  font-weight: 700;
  background-color: var(--status-warning-light);
  color: var(--status-warning);
  border: 1px solid var(--status-warning);
}

.warning-pill.visible, .validation-warning.visible {
  display: inline-block;
}

/* ==========================================================================
   Quick Cross-Unit Reference Grid
   ========================================================================== */

.matrix-preview-section, .quick-matrix-container {
  margin-top: 2rem;
  background-color: var(--bg-main);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.matrix-preview-title, .quick-matrix-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.matrix-grid, .quick-matrix-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 0.65rem;
}

.matrix-card {
  padding: 0.75rem 1rem;
  background-color: var(--bg-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.matrix-card:hover {
  background-color: var(--brand-primary-light);
  border-color: var(--brand-primary-border);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.matrix-from {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
}

.matrix-to {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

/* ==========================================================================
   Session Calculation History Tray
   ========================================================================== */

.converter-history-section {
  margin-top: 1.75rem;
  padding-top: 1.25rem;
  border-top: 1px dashed var(--border-color);
}

.history-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.history-title {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.clear-history-btn {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-muted);
  text-decoration: underline;
  cursor: pointer;
  transition: color var(--transition-fast);
}

.clear-history-btn:hover {
  color: var(--status-error);
}

.history-list, .history-chips-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  min-height: 28px;
}

.history-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  box-shadow: var(--shadow-xs);
  transition: all var(--transition-fast);
}

.history-chip:hover {
  background-color: var(--brand-primary-light);
  border-color: var(--brand-primary);
  color: var(--brand-primary);
  transform: translateY(-1px);
}

.history-empty-text {
  font-size: 0.8125rem;
  color: var(--text-muted);
  font-style: italic;
}