/* ============================================================
   Data URI Toolkit — Styles
   Theme: Dark mode with accent colors
   Primary: #6366F1  Secondary: #94A3B8  Accent: #22D3EE
   Background: #0F172A  Border Radius: 12px
   Font: Inter / system  Animations: 200-300ms ease
   ============================================================ */

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

:root {
  --primary: #6366F1;
  --primary-hover: #818CF8;
  --primary-glow: rgba(99, 102, 241, 0.25);
  --secondary: #94A3B8;
  --accent: #22D3EE;
  --accent-hover: #67E8F9;
  --bg: #0F172A;
  --bg-surface: #1E293B;
  --bg-elevated: #273449;
  --border: rgba(148, 163, 184, 0.15);
  --border-focus: rgba(99, 102, 241, 0.5);
  --text: #F1F5F9;
  --text-muted: #94A3B8;
  --text-dim: #64748B;
  --success: #22C55E;
  --error: #EF4444;
  --radius: 12px;
  --radius-sm: 8px;
  --radius-xs: 6px;
  --transition: 250ms ease;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

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

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  line-height: 1.6;
}

/* Screen reader only */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --- Header --- */
.header {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.08) 0%, rgba(34, 211, 238, 0.05) 100%);
  border-bottom: 1px solid var(--border);
  padding: 1rem 1.5rem;
  backdrop-filter: blur(12px);
}

.header-inner {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.logo-icon {
  color: var(--primary);
  filter: drop-shadow(0 0 8px var(--primary-glow));
}

.logo h1 {
  font-size: 1.25rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.tagline {
  font-size: 0.85rem;
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* --- Main --- */
.main {
  flex: 1;
  padding: 1.5rem;
  max-width: 1400px;
  margin: 0 auto;
  width: 100%;
}

/* --- Split-View Layout --- */
.split-view {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  height: calc(100vh - 160px);
  min-height: 500px;
}

/* --- Panel --- */
.panel {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transition: border-color var(--transition);
}

.panel:hover {
  border-color: rgba(148, 163, 184, 0.25);
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.875rem 1.25rem;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.panel-header h2 {
  font-size: 0.9rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

/* --- Mode Toggle --- */
.mode-toggle {
  display: flex;
  background: var(--bg);
  border-radius: var(--radius-xs);
  padding: 3px;
  gap: 2px;
}

.mode-btn {
  font-family: var(--font);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 0.4rem 1rem;
  border: none;
  border-radius: 4px;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
}

.mode-btn:hover {
  color: var(--text);
}

.mode-btn.active {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 2px 8px var(--primary-glow);
}

/* --- Tab Panel --- */
.tab-panel {
  display: none;
  flex-direction: column;
  flex: 1;
  overflow: auto;
  padding: 1.25rem;
  gap: 1rem;
}

.tab-panel.active {
  display: flex;
}

/* --- Drop Zone --- */
.drop-zone {
  position: relative;
  border: 2px dashed rgba(99, 102, 241, 0.3);
  border-radius: var(--radius);
  padding: 2.5rem 1.5rem;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: rgba(99, 102, 241, 0.03);
}

.drop-zone:hover,
.drop-zone:focus-visible {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.07);
  box-shadow: 0 0 24px var(--primary-glow);
}

.drop-zone.dragover {
  border-color: var(--accent);
  background: rgba(34, 211, 238, 0.07);
  box-shadow: 0 0 32px rgba(34, 211, 238, 0.2);
  transform: scale(1.01);
}

.drop-zone-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  pointer-events: none;
}

.drop-icon {
  color: var(--primary);
  opacity: 0.7;
  transition: opacity var(--transition);
}

.drop-zone:hover .drop-icon {
  opacity: 1;
}

.drop-text {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text);
}

.drop-subtext {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.drop-supported {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
}

.file-input {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
}

/* --- File Info --- */
.file-info {
  background: var(--bg-elevated);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  animation: fadeIn 300ms ease;
}

.file-info-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
}

.file-info-label {
  color: var(--text-dim);
  min-width: 64px;
  font-weight: 500;
}

.file-info-value {
  color: var(--text);
  word-break: break-all;
}

/* --- Options Bar --- */
.options-bar {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.option-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--text-muted);
  transition: color var(--transition);
}

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

.option-checkbox {
  appearance: none;
  width: 18px;
  height: 18px;
  border: 2px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  position: relative;
  transition: all var(--transition);
  flex-shrink: 0;
}

.option-checkbox:checked {
  background: var(--primary);
  border-color: var(--primary);
}

.option-checkbox:checked::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 5px;
  width: 5px;
  height: 9px;
  border: solid #fff;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

.option-checkbox:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* --- Decode Panel --- */
.decode-textarea {
  font-family: 'Courier New', monospace;
  font-size: 0.85rem;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem;
  resize: vertical;
  min-height: 200px;
  flex: 1;
  transition: border-color var(--transition);
}

.decode-textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.decode-textarea::placeholder {
  color: var(--text-dim);
}

.action-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 600;
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
}

.decode-action-btn {
  background: linear-gradient(135deg, var(--primary), #8B5CF6);
  color: #fff;
  box-shadow: 0 4px 16px var(--primary-glow);
}

.decode-action-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 24px var(--primary-glow);
}

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

/* --- Output Panel --- */
.output-actions {
  display: flex;
  gap: 0.25rem;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: var(--radius-xs);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  transition: all var(--transition);
}

.icon-btn:hover:not(:disabled) {
  background: var(--bg-elevated);
  color: var(--text);
}

.icon-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* --- Preview Area --- */
.preview-area {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: auto;
  border-bottom: 1px solid var(--border);
  min-height: 180px;
  position: relative;
}

.preview-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
  color: var(--text-dim);
  text-align: center;
}

.preview-placeholder svg {
  opacity: 0.3;
}

.preview-placeholder p {
  font-size: 0.85rem;
}

.preview-content {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  overflow: auto;
}

.preview-content img,
.preview-content svg {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
  border-radius: var(--radius-sm);
}

.preview-content audio {
  width: 100%;
  max-width: 400px;
}

.preview-font-sample {
  font-size: 2rem;
  line-height: 1.4;
  text-align: center;
  color: var(--text);
  padding: 1rem;
}

.preview-text {
  font-family: 'Courier New', monospace;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: center;
  padding: 1rem;
}

/* --- Output Textarea --- */
.output-box {
  padding: 0.75rem 1.25rem 1.25rem;
  flex-shrink: 0;
}

.output-textarea {
  font-family: 'Courier New', monospace;
  font-size: 0.8rem;
  background: var(--bg);
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.875rem 1rem;
  width: 100%;
  height: 120px;
  resize: vertical;
  transition: border-color var(--transition);
}

.output-textarea:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--primary-glow);
}

.output-textarea::placeholder {
  color: var(--text-dim);
}

/* --- Toast --- */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--bg-elevated);
  color: var(--text);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  font-size: 0.85rem;
  font-weight: 500;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  opacity: 0;
  pointer-events: none;
  transition: all 300ms ease;
  z-index: 999;
}

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

/* --- Footer --- */
.footer {
  text-align: center;
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 0.8rem;
  flex-shrink: 0;
}

/* --- Utilities --- */
.hidden {
  display: none !important;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* --- Responsive --- */
@media (max-width: 900px) {
  .split-view {
    grid-template-columns: 1fr;
    height: auto;
  }

  .panel {
    min-height: 400px;
  }

  .header-inner {
    flex-direction: column;
    gap: 0.25rem;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .main {
    padding: 0.75rem;
  }

  .split-view {
    gap: 0.75rem;
  }

  .panel-header {
    padding: 0.75rem 1rem;
    flex-wrap: wrap;
    gap: 0.5rem;
  }

  .drop-zone {
    padding: 1.5rem 1rem;
  }
}