:root {
  --app-bg: #f8f9fa;
  --app-panel: #ffffff;
  --app-border: #e5e7eb;
  --app-border-focus: #3b82f6;
  --app-text: #111827;
  --app-text-muted: #6b7280;
  --app-accent: #3b82f6;
  --app-accent-hover: #2563eb;
  --app-success: #10b981;
  --app-success-bg: #d1fae5;
  --app-warning: #f59e0b;
  --app-warning-bg: #fef3c7;
  --app-error: #ef4444;
  --app-error-bg: #fee2e2;
  --app-shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --app-shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
  --app-shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);

  --font-ui: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --radius: 8px;
  --radius-sm: 6px;

  --split-left: 52%;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--app-text);
  background: var(--app-bg);
  display: flex;
  flex-direction: column;
}

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


.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 20px 24px;
  background: var(--app-panel);
  border-bottom: 1px solid var(--app-border);
  flex-shrink: 0;
}

.app-title h1 {
  margin: 0;
  font-size: 20px;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.app-subtitle {
  font-size: 13px;
  color: var(--app-text-muted);
  margin-top: 4px;
  font-weight: 400;
}

.app-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

button, select, .btn {
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 500;
}

button, .btn {
  appearance: none;
  border: 1px solid var(--app-border);
  background: var(--app-panel);
  color: var(--app-text);
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  user-select: none;
  transition: all 0.15s ease;
}

button:hover, .btn:hover {
  background: var(--app-bg);
  border-color: var(--app-text-muted);
}

button:active, .btn:active {
  transform: translateY(1px);
}

.btn-secondary {
  background: var(--app-bg);
  color: var(--app-text-muted);
}

.btn-secondary:hover {
  background: #e5e7eb;
  color: var(--app-text);
}

select {
  border: 1px solid var(--app-border);
  background: var(--app-panel);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

select:hover {
  border-color: var(--app-text-muted);
}

button:focus-visible, select:focus-visible, .gutter:focus-visible, textarea:focus-visible {
  outline: 2px solid var(--app-border-focus);
  outline-offset: 2px;
}

.split {
  flex: 1;
  margin: 0 16px 16px 16px;
  display: grid;
  grid-template-columns: var(--split-left) 8px 1fr;
  gap: 12px;
  min-height: 0;
  overflow: hidden;
}

.panel {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  border: 1px solid var(--app-border);
  background: var(--app-panel);
  border-radius: var(--radius);
  box-shadow: var(--app-shadow-sm);
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  background: var(--app-bg);
  border-bottom: 1px solid var(--app-border);
}

.panel-title {
  font-weight: 600;
  font-size: 14px;
  color: var(--app-text);
}

.panel-tools {
  display: flex;
  align-items: center;
  gap: 10px;
}

.tool {
  display: flex;
  align-items: center;
  gap: 6px;
}

.tool-label {
  font-size: 13px;
  color: var(--app-text-muted);
  font-weight: 500;
}

textarea {
  width: 100%;
  height: 100%;
  min-height: 200px;
  border: 0;
  background: var(--app-panel);
  padding: 16px;
  resize: none;
  font-family: var(--font-ui);
  font-size: 13px;
  line-height: 1.5;
  color: var(--app-text);
}

textarea:focus {
  outline: none;
  background: #fefefe;
}

.hint {
  padding: 10px 16px;
  font-size: 13px;
  color: var(--app-text-muted);
  border-top: 1px solid var(--app-border);
  background: var(--app-bg);
}

.gutter {
  border-radius: var(--radius-sm);
  background: var(--app-border);
  cursor: col-resize;
  transition: background 0.15s ease;
  position: relative;
}

.gutter::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 3px;
  height: 32px;
  background: var(--app-text-muted);
  border-radius: 2px;
  opacity: 0.3;
}

.gutter:hover {
  background: var(--app-text-muted);
}

.gutter:hover::before {
  opacity: 0.6;
}

.status {
  margin: 16px;
  padding: 16px;
  border-radius: var(--radius);
  border: 1px solid var(--app-border);
  background: var(--app-bg);
}

.status .headline {
  font-weight: 600;
  font-size: 15px;
  letter-spacing: -0.01em;
}

.status .meta {
  margin-top: 6px;
  color: var(--app-text-muted);
  font-size: 13px;
}

.chips {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  font-size: 13px;
  border-radius: 999px;
  border: 1px solid var(--app-border);
  background: var(--app-panel);
  font-weight: 500;
}

.diagnostics {
  margin: 0 16px 16px 16px;
  padding: 0;
  overflow: auto;
  border: 1px solid var(--app-border);
  background: var(--app-panel);
  border-radius: var(--radius);
}

.diag {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--app-border);
}

.diag:last-child {
  border-bottom: 0;
}

.badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 22px;
  padding: 0 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.badge.error { 
  background: var(--app-error-bg); 
  color: var(--app-error);
  border: 1px solid var(--app-error);
}
.badge.warning { 
  background: var(--app-warning-bg); 
  color: var(--app-warning);
  border: 1px solid var(--app-warning);
}
.badge.info { 
  background: var(--app-success-bg); 
  color: var(--app-success);
  border: 1px solid var(--app-success);
}

.diag-main {
  min-width: 0;
}

.diag-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--app-text);
}

.diag-sub {
  margin-top: 4px;
  font-size: 13px;
  color: var(--app-text-muted);
  white-space: pre-wrap;
  word-break: break-word;
  line-height: 1.5;
}

.diag-loc {
  font-size: 13px;
  color: var(--app-text-muted);
}

@media (max-width: 920px) {
  .split {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
    height: auto;
  }

  .gutter {
    display: none;
  }

  textarea {
    min-height: 260px;
  }
}