/* Modern, Mobile-First, User-Friendly Styling */
:root {
  --primary: #d97706;
  --primary-hover: #b45309;
  --primary-light: #fef3c7;
  --bg-page: #f8fafc;
  --bg-card: #ffffff;
  --bg-input: #ffffff;
  --border: #e2e8f0;
  --border-focus: #d97706;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --text-sub: #475569;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-canvas: 0 20px 25px -5px rgb(0 0 0 / 0.2), 0 8px 10px -6px rgb(0 0 0 / 0.2);
  --radius-sm: 8px;
  --radius-md: 12px;
  --font-ui: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-sinhala: 'Noto Sans Sinhala', sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-page: #0b0f19;
    --bg-card: #131b2e;
    --bg-input: #0b0f19;
    --border: #1e293b;
    --border-focus: #f59e0b;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --text-sub: #cbd5e1;
    --primary-light: rgba(245, 158, 11, 0.15);
  }
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

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

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

/* App Container Layout */
.app-layout {
  flex: 1;
  display: grid;
  grid-template-columns: 380px 1fr;
  height: 100vh;
  overflow: hidden;
}

/* Controls Panel */
.panel.controls {
  background: var(--bg-card);
  border-right: 1px solid var(--border);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  overflow-y: auto;
  z-index: 10;
}

.sidebar-header {
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.sidebar-header h1 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: -0.01em;
}

.sidebar-header .subtitle {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 2px;
}

/* Form Controls */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-sub);
}

.form-control {
  font-family: var(--font-sinhala);
  font-size: 0.95rem;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--border);
  background: var(--bg-input);
  color: var(--text-main);
  outline: none;
  transition: all 0.2s ease;
  line-height: 1.5;
}

.form-control:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(217, 119, 6, 0.15);
}

textarea.form-control {
  resize: vertical;
  min-height: 80px;
}

.checkbox-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--text-sub);
  cursor: pointer;
  user-select: none;
  margin-top: 4px;
}

.checkbox-label input[type="checkbox"] {
  width: 17px;
  height: 17px;
  accent-color: var(--primary);
  cursor: pointer;
}

/* Multi-Donor Option Buttons */
.donor-options-container {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: 4px;
  margin-bottom: 8px;
  padding: 8px 10px;
  background: var(--bg-page);
  border: 1px dashed var(--border);
  border-radius: var(--radius-sm);
}

.donor-options-title {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.donor-options-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.donor-option-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 5px 10px;
  font-family: var(--font-sinhala), var(--font-ui);
  font-size: 0.82rem;
  color: var(--text-main);
  cursor: pointer;
  text-align: left;
  line-height: 1.35;
  transition: all 0.15s ease;
  user-select: none;
}

.donor-option-btn:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.donor-option-btn.active {
  border-color: var(--primary);
  background: var(--primary-light);
  color: var(--primary-hover);
  font-weight: 700;
  box-shadow: 0 1px 3px rgba(217, 119, 6, 0.15);
}

.date-input-wrap {
  display: flex;
  gap: 8px;
}

.date-control {
  flex: 1;
  font-family: var(--font-ui);
}

.btn-today {
  font-family: var(--font-ui);
  font-size: 0.82rem;
  font-weight: 600;
  padding: 0 12px;
  background: var(--bg-page);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-sub);
  cursor: pointer;
  transition: all 0.15s;
  white-space: nowrap;
}

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

/* Template Chips */
.template-chips {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.template-chip {
  background: var(--bg-page);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: all 0.2s ease;
  text-align: left;
}

.template-chip:hover {
  border-color: var(--primary);
}

.template-chip.active {
  border-color: var(--primary);
  background: var(--primary-light);
}

.chip-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

.dot-blue {
  background: #2563eb;
}

.dot-purple {
  background: #7c3aed;
}

.chip-name {
  font-family: var(--font-ui);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-main);
}

/* Action Buttons */
.action-buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-top: 4px;
}

.desktop-actions {
  display: flex;
}

.mobile-actions {
  display: none;
}

.btn {
  font-family: var(--font-ui);
  font-size: 0.92rem;
  font-weight: 600;
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: all 0.2s ease;
  user-select: none;
}

.btn-primary {
  background: var(--primary);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(217, 119, 6, 0.3);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
}

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

.btn-secondary {
  background: var(--bg-page);
  border: 1.5px solid var(--border);
  color: var(--text-sub);
}

.btn-secondary:hover {
  border-color: var(--text-muted);
  color: var(--text-main);
}

.btn-lg {
  padding: 14px 20px;
  font-size: 1rem;
}

/* Preview Column */
.panel.preview-area {
  background: #1e293b;
  background-image: 
    radial-gradient(#334155 1px, transparent 1px);
  background-size: 24px 24px;
  display: flex;
  flex-direction: column;
  height: 100%;
  overflow: hidden;
  position: relative;
}

.preview-header {
  background: rgba(15, 23, 42, 0.9);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  z-index: 20;
}

.preview-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: #f8fafc;
}

/* Canvas Viewport */
.canvas-viewport {
  flex: 1;
  overflow: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  -webkit-overflow-scrolling: touch;
}

.canvas-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
  transform-origin: center center;
  transition: transform 0.18s ease-out;
}

#certCanvas {
  display: block;
  max-width: 100%;
  max-height: calc(100vh - 100px);
  width: auto;
  height: auto;
  border-radius: 4px;
  box-shadow: var(--shadow-canvas);
  background: #ffffff;
}

/* Toast Message */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: #0f172a;
  color: #ffffff;
  padding: 12px 24px;
  border-radius: 9999px;
  font-size: 0.88rem;
  font-weight: 600;
  box-shadow: var(--shadow-lg);
  z-index: 9999;
  opacity: 0;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  pointer-events: none;
  white-space: nowrap;
}

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

/* Mobile Responsive Single-Scroll Layout (< 860px) */
@media (max-width: 860px) {
  body {
    overflow-y: auto;
    overflow-x: hidden;
  }

  .app-layout {
    display: flex;
    flex-direction: column;
    height: auto;
    min-height: 100vh;
    overflow: visible;
  }

  .panel.controls {
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 20px 16px;
    height: auto;
    overflow: visible;
  }

  .desktop-actions {
    display: none !important;
  }

  .panel.preview-area {
    display: flex;
    flex-direction: column;
    height: auto;
    overflow: visible;
  }

  .preview-header {
    padding: 12px 16px;
  }

  .canvas-viewport {
    padding: 20px 16px;
    height: auto;
    overflow: visible;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  #certCanvas {
    max-width: 100%;
    width: 100%;
    height: auto;
    max-height: none;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.4);
  }

  .mobile-actions {
    display: flex !important;
    padding: 16px;
    background: var(--bg-card);
    border-top: 1px solid var(--border);
    gap: 12px;
  }
}