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

:root {
  --bg-primary: #f0f2f5;
  --bg-secondary: #fff;
  --bg-canvas: #e8ecf1;
  --bg-header: #1a1a2e;
  --bg-header-btn: #16213e;
  --bg-header-btn-hover: #0f3460;
  --bg-palette: #f8f9fb;
  --bg-palette-hover: #eef4fb;
  --border-color: #ddd;
  --border-palette: #e0e3e8;
  --text-primary: #333;
  --text-secondary: #666;
  --text-muted: #888;
  --text-dimmed: #aaa;
  --accent: #4a90d9;
  --accent-light: rgba(74,144,217,0.15);
  --dot-color: #ccc;
  --menu-hover: #f0f4ff;
  --conn-label-bg: #fff;
  --snap-line: rgba(255, 50, 50, 0.5);
  --conn-color: #666;
  --toolbar-bg: #f5f6f8;
  --toolbar-border: #e0e3e8;
  --toolbar-btn-hover: #e8eaef;
}

[data-theme="dark"] {
  --bg-primary: #1a1a2e;
  --bg-secondary: #16213e;
  --bg-canvas: #0f0f23;
  --bg-header: #0a0a1a;
  --bg-header-btn: #1a1a3e;
  --bg-header-btn-hover: #2a2a5e;
  --bg-palette: #1e1e3a;
  --bg-palette-hover: #2a2a4e;
  --border-color: #2a2a4e;
  --border-palette: #2e2e50;
  --text-primary: #e0e0e0;
  --text-secondary: #aaa;
  --text-muted: #888;
  --text-dimmed: #666;
  --accent: #5a9ee6;
  --accent-light: rgba(90,158,230,0.2);
  --dot-color: #2a2a4e;
  --menu-hover: #2a2a4e;
  --conn-label-bg: #1e1e3a;
  --conn-color: #a0aec0;
  --snap-line: rgba(255, 80, 80, 0.6);
  --toolbar-bg: #12122a;
  --toolbar-border: #2a2a4e;
  --toolbar-btn-hover: #2a2a4e;
}

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  background: var(--bg-primary);
  color: var(--text-primary);
}

header {
  background: var(--bg-header);
  color: #fff;
  padding: 8px 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
  z-index: 100;
  gap: 12px;
}

header h1 { font-size: 16px; font-weight: 600; letter-spacing: 0.5px; white-space: nowrap; }

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

.header-actions button,
.header-actions label {
  background: var(--bg-header-btn);
  color: #fff;
  border: 1px solid var(--bg-header-btn-hover);
  padding: 5px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  transition: background 0.2s;
  white-space: nowrap;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}
.header-actions button:hover,
.header-actions label:hover { background: var(--bg-header-btn-hover); }
.header-actions input[type="file"] { display: none; }

.toolbar {
  background: var(--toolbar-bg);
  border-bottom: 1px solid var(--toolbar-border);
  padding: 4px 12px;
  display: flex;
  align-items: center;
  gap: 2px;
  flex-shrink: 0;
  overflow-x: auto;
}

.toolbar-separator {
  width: 1px;
  height: 22px;
  background: var(--toolbar-border);
  margin: 0 6px;
}

.toolbar button {
  background: none;
  border: 1px solid transparent;
  border-radius: 4px;
  padding: 4px 8px;
  cursor: pointer;
  font-size: 12px;
  color: var(--text-secondary);
  transition: all 0.15s;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 3px;
}
.toolbar button:hover {
  background: var(--toolbar-btn-hover);
  border-color: var(--border-color);
  color: var(--text-primary);
}
.toolbar button.active {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
}
.toolbar button svg { width: 14px; height: 14px; }

.main-container {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.sidebar {
  width: 200px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  padding: 10px;
  overflow-y: auto;
  flex-shrink: 0;
}

.sidebar h2 {
  font-size: 11px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 8px;
  letter-spacing: 1px;
}

.sidebar-section { margin-bottom: 14px; }
.sidebar-section h3 {
  font-size: 11px;
  color: var(--text-dimmed);
  margin-bottom: 5px;
  padding-left: 4px;
}

.shape-palette {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
}

.palette-item {
  background: var(--bg-palette);
  border: 1px solid var(--border-palette);
  border-radius: 6px;
  padding: 8px 4px;
  text-align: center;
  cursor: grab;
  transition: all 0.15s;
  user-select: none;
}
.palette-item:hover {
  border-color: var(--accent);
  background: var(--bg-palette-hover);
  box-shadow: 0 2px 8px var(--accent-light);
}
.palette-item:active { cursor: grabbing; }
.palette-item svg { width: 44px; height: 32px; display: block; margin: 0 auto 3px; }
.palette-item span { font-size: 10px; color: var(--text-secondary); }

.canvas-wrapper {
  flex: 1;
  position: relative;
  overflow: hidden;
  background: var(--bg-canvas);
}

#canvas {
  position: absolute;
  top: 0; left: 0;
  width: 4000px;
  height: 4000px;
  background-image: radial-gradient(circle, var(--dot-color) 1px, transparent 1px);
  background-size: 20px 20px;
  cursor: default;
}

.snap-line {
  position: absolute;
  background: var(--snap-line);
  z-index: 999;
  pointer-events: none;
}
.snap-line.horizontal { height: 1px; left: 0; width: 100%; }
.snap-line.vertical   { width: 1px; top: 0; height: 100%; }

.node {
  position: absolute;
  min-width: 80px;
  min-height: 40px;
  cursor: move;
  user-select: none;
}

.node.selected .node-body { outline: 2px solid var(--accent); outline-offset: 2px; }

.node-body {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  padding: 8px 12px;
  font-size: 13px;
  text-align: center;
  word-break: break-word;
  position: relative;
}

.node-label {
  outline: none;
  min-width: 20px;
  cursor: text;
}

.connector-handle {
  position: absolute;
  width: 12px;
  height: 12px;
  background: var(--accent);
  border: 2px solid #fff;
  border-radius: 50%;
  cursor: crosshair;
  opacity: 0;
  transition: opacity 0.15s;
  z-index: 5;
}
.node:hover .connector-handle,
.node.selected .connector-handle { opacity: 1; }

.connector-handle.top    { top: -6px;   left: 50%; transform: translateX(-50%); }
.connector-handle.bottom { bottom: -6px; left: 50%; transform: translateX(-50%); }
.connector-handle.left   { left: -6px;  top: 50%; transform: translateY(-50%); }
.connector-handle.right  { right: -6px; top: 50%; transform: translateY(-50%); }

.delete-btn {
  position: absolute;
  top: -10px;
  right: -10px;
  width: 22px;
  height: 22px;
  background: #e74c3c;
  border: 2px solid #fff;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s, background 0.15s;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
}
.delete-btn:hover {
  background: #c0392b;
}
.node:hover .delete-btn,
.node.selected .delete-btn { opacity: 1; }

svg.connections {
  position: absolute;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 0;
}
svg.connections path,
svg.connections line.conn-line {
  pointer-events: stroke;
  cursor: pointer;
}
svg.connections .conn-label-group { pointer-events: all; cursor: pointer; }

.resize-handle {
  position: absolute;
  width: 10px;
  height: 10px;
  background: var(--accent);
  border: 1px solid #fff;
  border-radius: 2px;
  cursor: nwse-resize;
  opacity: 0;
  transition: opacity 0.15s;
  z-index: 5;
  right: -5px;
  bottom: -5px;
}
.node:hover .resize-handle,
.node.selected .resize-handle { opacity: 1; }

.context-menu {
  position: fixed;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
  padding: 4px 0;
  z-index: 1000;
  min-width: 180px;
  display: none;
}
.context-menu.show { display: block; }
.context-menu-item {
  padding: 7px 14px;
  font-size: 12px;
  cursor: pointer;
  transition: background 0.1s;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--text-primary);
}
.context-menu-item:hover { background: var(--menu-hover); }
.context-menu-item .shortcut {
  font-size: 11px;
  color: var(--text-dimmed);
  margin-left: 16px;
}
.context-menu-separator {
  height: 1px;
  background: var(--border-color);
  margin: 4px 0;
}

.properties-panel {
  width: 220px;
  background: var(--bg-secondary);
  border-left: 1px solid var(--border-color);
  padding: 12px;
  overflow-y: auto;
  flex-shrink: 0;
  display: none;
}
.properties-panel.show { display: block; }
.properties-panel h2 {
  font-size: 11px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 10px;
}
.prop-group { margin-bottom: 10px; }
.prop-group label {
  font-size: 11px;
  color: var(--text-secondary);
  display: block;
  margin-bottom: 3px;
}
.prop-group input[type="color"] {
  width: 100%;
  height: 28px;
  padding: 2px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background: var(--bg-palette);
  cursor: pointer;
}
.prop-group input[type="number"],
.prop-group input[type="text"],
.prop-group select {
  width: 100%;
  padding: 4px 6px;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  font-size: 12px;
  background: var(--bg-palette);
  color: var(--text-primary);
}

.zoom-controls {
  position: absolute;
  bottom: 12px;
  right: 12px;
  display: flex;
  gap: 4px;
  z-index: 50;
}
.zoom-controls button {
  width: 32px;
  height: 32px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 16px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s;
  color: var(--text-primary);
}
.zoom-controls button:hover { background: var(--toolbar-btn-hover); }

.status-bar {
  background: var(--toolbar-bg);
  border-top: 1px solid var(--toolbar-border);
  padding: 3px 12px;
  font-size: 11px;
  color: var(--text-muted);
  display: flex;
  justify-content: space-between;
  flex-shrink: 0;
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
}
.modal {
  background: var(--bg-secondary);
  border-radius: 12px;
  padding: 24px;
  min-width: 320px;
  max-width: 480px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.2);
}
.modal h3 { margin-bottom: 12px; font-size: 16px; }
.modal input[type="text"] {
  width: 100%;
  padding: 8px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 14px;
  margin-bottom: 12px;
  background: var(--bg-palette);
  color: var(--text-primary);
}
.modal-actions { display: flex; gap: 8px; justify-content: flex-end; }
.modal-actions button {
  padding: 6px 16px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  cursor: pointer;
  font-size: 13px;
  background: var(--bg-palette);
  color: var(--text-primary);
}
.modal-actions button.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.selection-box {
  position: absolute;
  border: 1px dashed var(--accent);
  background: rgba(74,144,217,0.08);
  pointer-events: none;
  z-index: 998;
}

/* Dark mode toggle switch */
.dark-toggle {
  cursor: pointer;
  display: flex;
  align-items: center;
  margin-left: 4px;
}
.dark-toggle-track {
  position: relative;
  width: 52px;
  height: 26px;
  background: #334155;
  border-radius: 13px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 5px;
  transition: background 0.3s;
}
[data-theme="dark"] .dark-toggle-track {
  background: #4a6fa5;
}
.dark-toggle-icon {
  font-size: 14px;
  line-height: 1;
  z-index: 1;
  user-select: none;
}
.dark-toggle-icon.sun { color: #fbbf24; }
.dark-toggle-icon.moon { color: #cbd5e1; }
.dark-toggle-thumb {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  background: #fff;
  border-radius: 50%;
  transition: transform 0.3s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.3);
}
[data-theme="dark"] .dark-toggle-thumb {
  transform: translateX(26px);
  background: #1e293b;
}