/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px; /* Slightly taller for friendliness */
  min-width: 48px;
  padding: 0 var(--space-5);
  border-radius: var(--border-radius-full); /* Pill shaped buttons are friendlier */
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 16px;
  transition: transform var(--transition-fast), background-color var(--transition-fast), box-shadow var(--transition-fast);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn:active {
  transform: scale(0.96);
}

.btn:disabled {
  opacity: 0.5;
  pointer-events: none;
  transform: none;
  box-shadow: none !important;
}

.btn-primary {
  min-height: 56px;
  font-size: 18px;
  background-color: var(--color-accent);
  color: #FFFFFF;
  width: 100%;
  box-shadow: 0 8px 20px var(--color-accent-glow);
  border: none;
}

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  box-shadow: 0 10px 24px var(--color-accent-glow);
  transform: translateY(-2px);
}

.btn-primary:active {
  transform: scale(0.96) translateY(0);
}

.btn-secondary {
  background-color: var(--color-surface);
  color: var(--color-text-primary);
  width: 100%;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background-color: var(--color-surface-2);
}

.btn-ghost {
  color: var(--color-text-secondary);
}

.btn-ghost:hover {
  background-color: var(--color-surface-2);
}

.btn-icon {
  padding: 0;
  border-radius: var(--border-radius-full);
}

/* Cards */
.card {
  background-color: var(--color-surface);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--border-radius-md);
  padding: var(--space-4);
  border: 1px solid var(--color-border);
  box-shadow: var(--glass-shadow);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Person Chip */
.person-chip {
  width: 52px;
  height: 52px;
  border-radius: var(--border-radius-full);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 700;
  color: #FFF;
  flex-shrink: 0;
  transition: transform var(--transition-spring), box-shadow var(--transition-fast);
  position: relative;
  -webkit-tap-highlight-color: transparent;
  box-shadow: var(--shadow-sm);
  text-shadow: 0 1px 2px rgba(0,0,0,0.2);
}

.person-chip.selected {
  transform: scale(1.15) translateY(-4px);
  box-shadow: 0 8px 16px rgba(0,0,0,0.15), 0 0 0 3px var(--color-bg), 0 0 0 6px var(--color-accent);
}

.person-chip .remove-btn {
  position: absolute;
  top: -4px;
  right: -4px;
  background: var(--color-surface);
  color: var(--color-danger);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  font-size: 12px;
  font-weight: 800;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--color-border);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast);
}

.person-chip .remove-btn:active {
  transform: scale(0.8);
}

/* Receipt Item */
.receipt-item {
  min-height: 64px; /* A bit taller for airy feel */
  background-color: var(--color-surface);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-md);
  padding: var(--space-3) var(--space-4);
  margin-bottom: var(--space-3);
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: all var(--transition-fast);
  position: relative;
  overflow: hidden;
  box-shadow: var(--glass-shadow);
}

.receipt-item:active {
  transform: scale(0.98);
}

.receipt-item.selected {
  border-color: var(--color-accent);
  background-color: var(--color-accent-glow);
  box-shadow: 0 4px 12px var(--color-accent-glow);
  transform: scale(1.02);
}

.receipt-item.assigned {
  background-color: var(--color-surface-2);
  border-color: var(--color-success);
  opacity: 0.95;
}

.receipt-item .item-details {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.receipt-item .item-name {
  font-weight: 700;
  font-family: var(--font-display);
  font-size: 16px;
}

.receipt-item .item-price {
  font-weight: 800;
  font-size: 18px;
  color: var(--color-text-primary);
}

.receipt-item.assigned .item-price {
  color: var(--color-success);
}

.receipt-item .assigned-avatars {
  display: flex;
  gap: -10px; /* overlapping */
}

.receipt-item .assigned-avatars .person-chip {
  width: 28px;
  height: 28px;
  font-size: 11px;
  border: 2px solid var(--color-surface);
  box-shadow: none;
  transform: none !important;
}

/* Bottom Sheet */
.bottom-sheet-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(30, 41, 59, 0.4); /* Softer backdrop */
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 100;
  opacity: 0;
  transition: opacity var(--transition-normal);
  pointer-events: none;
}

.bottom-sheet-backdrop.visible {
  opacity: 1;
  pointer-events: auto;
}

.bottom-sheet {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100%;
  background: var(--color-surface-2); /* Slightly less translucent for bottom sheet */
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-top-left-radius: var(--border-radius-lg);
  border-top-right-radius: var(--border-radius-lg);
  border-top: 1px solid var(--color-border);
  padding: var(--space-4) var(--space-4) calc(var(--space-4) + var(--safe-bottom));
  z-index: 101;
  transform: translateY(100%);
  transition: transform var(--transition-spring);
  box-shadow: 0 -10px 40px rgba(31, 38, 135, 0.1);
}

.bottom-sheet.visible {
  transform: translateY(0);
}

.bottom-sheet .drag-handle {
  width: 48px;
  height: 6px;
  background: var(--color-border);
  border-radius: var(--border-radius-full);
  margin: 0 auto var(--space-5);
}

/* Inputs */
.input-field {
  background: var(--color-surface-2);
  border: 2px solid transparent; /* invisible border for jumping prevention */
  border-radius: var(--border-radius-sm);
  padding: var(--space-4);
  width: 100%;
  font-family: var(--font-body);
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: var(--space-3);
  transition: all var(--transition-fast);
}

.input-field:focus {
  background: var(--color-surface);
  border-color: var(--color-accent);
  box-shadow: 0 4px 12px var(--color-accent-glow);
}

/* Toast */
.toast {
  position: fixed;
  bottom: calc(var(--space-10) + var(--safe-bottom));
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--color-text-primary); /* Dark toast in light mode */
  color: var(--color-surface);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--border-radius-full);
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 15px;
  box-shadow: 0 8px 24px rgba(30, 41, 59, 0.2);
  z-index: 1000;
  opacity: 0;
  transition: transform var(--transition-spring), opacity var(--transition-normal);
  text-align: center;
  white-space: nowrap;
}

.toast.visible {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* Loading Overlay */
#loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--color-surface);
  backdrop-filter: blur(8px);
  z-index: 500;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
}

.spinner {
  width: 64px;
  height: 64px;
  border: 6px solid var(--color-surface-2);
  border-top-color: var(--color-accent);
  border-radius: 50%;
  animation: spin 1s cubic-bezier(0.68, -0.55, 0.265, 1.55) infinite;
  margin-bottom: var(--space-5);
}

#loading-message {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 20px;
  color: var(--color-text-primary);
  text-align: center;
}

.progress-bar-container {
  width: 70%;
  height: 8px;
  background: var(--color-border);
  border-radius: var(--border-radius-full);
  margin-top: var(--space-5);
  overflow: hidden;
  box-shadow: inset 0 1px 3px rgba(0,0,0,0.05);
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-accent), var(--color-success));
  width: 0%;
  border-radius: var(--border-radius-full);
  transition: width 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}