:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg-app: #f9fafb;
  --bg-panel: #ffffff;
  --bg-toolbar: #ffffff;
  --border: #e5e7eb;
  --text-main: #111827;
  --text-muted: #6b7280;
  --danger: #ef4444;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-app);
  height: 100vh;
  overflow: hidden;
  color: var(--text-main);
}

/* Layout */
.app-container {
  height: 100vh;
  display: flex;
  flex-direction: column;
}

.workspace {
  flex: 1;
  display: flex;
  overflow: hidden;
}

/* Toolbar */
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background: var(--bg-toolbar);
  border-bottom: 1px solid var(--border);
  gap: 16px;
}

.toolbar-left,
.toolbar-center,
.toolbar-right {
  display: flex;
  align-items: center;
  gap: 8px;
}

.title-input {
  font-size: 16px;
  font-weight: 600;
  border: none;
  background: transparent;
  padding: 4px 8px;
  border-radius: 4px;
  min-width: 200px;
}

.title-input:hover,
.title-input:focus {
  background: var(--bg-app);
  outline: none;
}

.separator {
  width: 1px;
  height: 24px;
  background: var(--border);
  margin: 0 4px;
}

/* Buttons */
.btn-primary,
.btn-secondary,
.btn-icon {
  padding: 6px 12px;
  border: none;
  border-radius: 6px;
  font-size: 14px;
  cursor: pointer;
  transition: background-color 0.15s;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-secondary {
  background: var(--bg-app);
  color: var(--text-main);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-icon {
  padding: 6px 10px;
  background: transparent;
  color: var(--text-main);
  font-size: 16px;
}

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

.btn-icon:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

#zoom-level {
  font-size: 12px;
  color: var(--text-muted);
  min-width: 40px;
  text-align: center;
}

/* Canvas */
.canvas-container {
  flex: 1;
  background: white;
  position: relative;
  overflow: hidden;
}

.uml-canvas {
  width: 100%;
  height: 100%;
  cursor: default;
}

/* Panel */
.panel {
  width: 300px;
  background: var(--bg-panel);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
}

.panel-tabs {
  display: flex;
  border-bottom: 1px solid var(--border);
}

.panel-tab {
  flex: 1;
  padding: 10px;
  border: none;
  background: transparent;
  font-size: 13px;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 2px solid transparent;
}

.panel-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
}

.panel-content {
  flex: 1;
  padding: 16px;
  overflow: auto;
}

.panel-content.hidden {
  display: none;
}

.panel-content .hint {
  color: var(--text-muted);
  font-size: 13px;
  text-align: center;
  margin-top: 40px;
}

#json-editor {
  width: 100%;
  height: 100%;
  font-family: 'SF Mono', Monaco, 'Courier New', monospace;
  font-size: 12px;
  border: none;
  resize: none;
  background: var(--bg-app);
  padding: 8px;
  border-radius: 4px;
}

/* SVG styles */
.class-view.selected rect:first-child {
  stroke: var(--primary);
  stroke-width: 2;
}

.relationship-view.selected path,
.relationship-view.selected line {
  stroke: var(--primary);
}

/* Responsive */
@media (max-width: 768px) {
  .panel {
    display: none;
  }
  
  .toolbar-left .title-input {
    min-width: 100px;
  }
}