:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-muted: #f8fafc;
  --border: #dbe3ec;
  --border-strong: #cbd5e1;
  --text: #142132;
  --text-soft: #516173;
  --text-muted: #728194;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --accent: #0f9f6e;
  --accent-hover: #0b8a5f;
  --secondary: #edf2f7;
  --secondary-hover: #e2e8f0;
  --status-info-bg: #eef5ff;
  --status-info-border: #cfe0ff;
  --status-info-text: #24466f;
  --status-success-bg: #edf8f2;
  --status-success-border: #cae9d9;
  --status-success-text: #15583d;
  --status-error-bg: #fff2f1;
  --status-error-border: #f2d2cf;
  --status-error-text: #8f332a;
  --node-normal: #c8d3df;
  --node-glow: #efc14e;
  --node-path: #17a668;
  --node-mixed: #d98b1a;
  --edge: #d5dee8;
  --edge-path: #16a765;
  --focus: #0f172a;
  --shadow: 0 10px 24px rgba(15, 23, 42, 0.05);
  --radius-xl: 24px;
  --radius-lg: 18px;
  --radius-md: 14px;
  --space-1: 8px;
  --space-2: 12px;
  --space-3: 16px;
  --space-4: 20px;
  --space-5: 24px;
  --space-6: 32px;
  --max-width: 1180px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background:
    radial-gradient(circle at top, rgba(255, 255, 255, 0.92), transparent 30%),
    var(--bg);
  color: var(--text);
}

button,
input,
select {
  font: inherit;
}

.app-shell {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 18px 20px 24px;
}

.hero {
  margin-bottom: var(--space-3);
  text-align: center;
}

.hero h1 {
  margin: 0;
  font-size: clamp(1.95rem, 4vw, 2.7rem);
  line-height: 1.06;
  letter-spacing: -0.03em;
}

.hero-subtitle {
  max-width: 360px;
  margin: var(--space-2) auto 0;
  color: var(--text-soft);
  line-height: 1.5;
}

.layout {
  display: grid;
  grid-template-columns: minmax(300px, 340px) minmax(0, 1fr);
  gap: var(--space-4);
  align-items: start;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
}

.control-panel,
.stage-panel {
  padding: var(--space-5);
}

.panel-header {
  margin-bottom: var(--space-3);
}

.panel-header h2 {
  margin: 0;
  font-size: 1.15rem;
}

.field-group {
  margin-bottom: var(--space-3);
}

.field-label,
.result-label {
  display: block;
  margin-bottom: var(--space-2);
  font-weight: 700;
}

.input-control {
  width: 100%;
  padding: 13px 14px;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  background: #ffffff;
  color: var(--text);
  transition: border-color 0.18s ease, box-shadow 0.18s ease;
}

.input-control:focus {
  outline: none;
  border-color: rgba(37, 99, 235, 0.7);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.12);
}

.input-control[aria-invalid="true"] {
  border-color: #d14343;
  box-shadow: 0 0 0 4px rgba(209, 67, 67, 0.12);
}

.field-hint {
  margin: var(--space-2) 0 0;
  color: var(--text-muted);
  font-size: 0.92rem;
  line-height: 1.5;
}

.action-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-2);
}

.button {
  appearance: none;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  padding: 12px 14px;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.18s ease, border-color 0.18s ease, color 0.18s ease, transform 0.14s ease;
}

.button:hover:not(:disabled) {
  transform: translateY(-1px);
}

.button:active:not(:disabled) {
  transform: translateY(0);
}

.button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.button:focus-visible {
  outline: 3px solid rgba(37, 99, 235, 0.24);
  outline-offset: 2px;
}

.button-wide {
  grid-column: 1 / -1;
}

.button-primary {
  background: var(--primary);
  color: #ffffff;
}

.button-primary:hover:not(:disabled) {
  background: var(--primary-hover);
}

.button-accent {
  background: var(--accent);
  color: #ffffff;
}

.button-accent:hover:not(:disabled) {
  background: var(--accent-hover);
}

.button-secondary {
  background: var(--secondary);
  border-color: var(--border);
  color: var(--text);
}

.button-secondary:hover:not(:disabled) {
  background: var(--secondary-hover);
}

.helper-box {
  margin-top: var(--space-3);
  padding-top: var(--space-3);
  border-top: 1px solid var(--border);
}

.status-box {
  padding: 12px 13px;
  border-radius: var(--radius-md);
  border: 1px solid var(--status-info-border);
  background: var(--status-info-bg);
  color: var(--status-info-text);
  line-height: 1.45;
}

.status-box[data-state="success"] {
  background: var(--status-success-bg);
  border-color: var(--status-success-border);
  color: var(--status-success-text);
}

.status-box[data-state="error"] {
  background: var(--status-error-bg);
  border-color: var(--status-error-border);
  color: var(--status-error-text);
}

.legend-list {
  margin: var(--space-3) 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px var(--space-2);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-soft);
  font-size: 0.94rem;
}

.legend-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  flex: none;
}

.dot-normal {
  background: var(--node-normal);
  border: 2px solid rgba(255, 255, 255, 0.95);
}

.dot-glow {
  background: var(--node-glow);
  border: 2px dashed #8b5e00;
}

.dot-path {
  background: var(--node-path);
  border: 2px solid #0a6d46;
  box-shadow: 0 0 0 3px rgba(23, 166, 104, 0.16);
}

.dot-mixed {
  background: var(--node-mixed);
  border: 2px dashed #7a3f00;
  box-shadow: 0 0 0 3px rgba(217, 139, 26, 0.18);
}

.stat-row {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}

.stat-card,
.result-card,
.result-item {
  padding: var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface-muted);
}

.stat-label,
.result-label,
.result-item dt {
  color: var(--text-muted);
  font-size: 0.88rem;
}

.stat-card strong {
  display: block;
  margin-top: 6px;
  font-size: 1.03rem;
}

.maze-stage {
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  background: var(--surface-muted);
  min-height: 420px;
  padding: var(--space-3);
}

.maze-placeholder {
  display: grid;
  place-items: center;
  min-height: 392px;
  padding: var(--space-5);
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-lg);
  text-align: center;
  color: var(--text-soft);
  line-height: 1.7;
}

.placeholder-title {
  margin: 0 0 var(--space-2);
  font-weight: 700;
  color: var(--text);
}

.placeholder-flow {
  margin: 0;
}

.maze-scroll {
  display: none;
  overflow-x: auto;
  overflow-y: hidden;
  padding-bottom: 6px;
}

.maze-svg {
  display: block;
  max-width: none;
  height: auto;
}

.maze-edge {
  stroke: var(--edge);
  stroke-width: 1.8;
  stroke-linecap: round;
}

.maze-edge.path-edge {
  stroke: var(--edge-path);
  stroke-width: 4.2;
}

.maze-node {
  cursor: pointer;
  outline: none;
}

.maze-node .node-ring,
.maze-node .node-focus,
.maze-node .node-marker {
  fill: none;
  display: none;
}

.maze-node .node-core {
  fill: var(--node-normal);
  stroke: rgba(255, 255, 255, 0.96);
  stroke-width: 2.2;
  transition: fill 0.16s ease, stroke 0.16s ease;
}

.maze-node .node-hit {
  fill: transparent;
}

.maze-node.is-glow .node-core {
  fill: var(--node-glow);
  stroke: #8b5e00;
  stroke-dasharray: 2.2 1.8;
}

.maze-node.is-glow .node-marker {
  display: block;
  stroke: #8b5e00;
  stroke-width: 2;
  stroke-linecap: round;
}

.maze-node.is-path .node-ring {
  display: block;
  stroke: rgba(23, 166, 104, 0.24);
  stroke-width: 9;
}

.maze-node.is-path .node-core {
  fill: var(--node-path);
  stroke: #0a6d46;
  stroke-width: 2.8;
}

.maze-node.is-path.is-glow .node-ring {
  stroke: rgba(217, 139, 26, 0.22);
  stroke-width: 10;
}

.maze-node.is-path.is-glow .node-core {
  fill: var(--node-mixed);
  stroke: #7a3f00;
  stroke-dasharray: 2.6 1.8;
}

.maze-node.is-path.is-glow .node-marker {
  stroke: #7a3f00;
}

.maze-node.is-compact .node-core {
  stroke-width: 1.6;
}

.maze-node.is-compact .node-marker {
  stroke-width: 1.4;
}

.maze-node.is-compact.is-path .node-ring {
  stroke-width: 5.5;
}

.maze-node.is-compact.is-path.is-glow .node-ring {
  stroke-width: 6;
}

.maze-node.is-compact:focus-visible .node-focus {
  stroke-width: 3;
}

.maze-node:hover .node-core {
  stroke: var(--focus);
}

.maze-node:focus-visible .node-focus {
  display: block;
  stroke: rgba(15, 23, 42, 0.9);
  stroke-width: 4;
}

.result-panel {
  margin-top: var(--space-4);
  padding: var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  background: var(--surface-muted);
}

.section-title {
  margin: 0 0 var(--space-3);
  font-size: 1rem;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}

.result-card strong {
  display: block;
  margin-top: 8px;
  font-size: 1.38rem;
}

.result-list {
  margin: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-2);
}

.result-item {
  margin: 0;
}

.result-item-wide {
  grid-column: 1 / -1;
}

.result-item dt {
  margin: 0 0 8px;
}

.result-item dd {
  margin: 0;
  color: var(--text-soft);
  line-height: 1.5;
}

.path-value,
.algorithm-pre {
  font-family: "SF Mono", SFMono-Regular, ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.92rem;
  word-break: break-word;
}

.result-note {
  margin: var(--space-3) 0 0;
  color: var(--text-soft);
  line-height: 1.5;
}

.algorithm-details {
  margin-top: var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: #ffffff;
}

.algorithm-details summary {
  padding: 14px 16px;
  cursor: pointer;
  font-weight: 700;
  list-style: none;
}

.algorithm-details summary::-webkit-details-marker {
  display: none;
}

.algorithm-details summary::after {
  content: "展开";
  float: right;
  color: var(--text-muted);
  font-weight: 500;
}

.algorithm-details[open] summary::after {
  content: "收起";
}

.algorithm-body {
  padding: 0 16px 16px;
}

.algorithm-block + .algorithm-block {
  margin-top: var(--space-3);
}

.algorithm-block h4 {
  margin: 0 0 8px;
  font-size: 0.95rem;
}

.algorithm-note {
  margin: 0;
  color: var(--text-soft);
  line-height: 1.6;
}

.algorithm-pre {
  margin: 0;
  padding: 14px;
  border-radius: var(--radius-md);
  background: var(--surface-muted);
  border: 1px solid var(--border);
  overflow-x: auto;
  line-height: 1.6;
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 720px) {
  .app-shell {
    padding: 18px 14px 18px;
  }

  .control-panel,
  .stage-panel {
    padding: var(--space-4);
  }

  .action-row,
  .stat-row,
  .result-grid,
  .result-list,
  .legend-list {
    grid-template-columns: 1fr;
  }

  .maze-stage {
    min-height: 340px;
    padding: var(--space-2);
  }

  .maze-placeholder {
    min-height: 300px;
    padding: var(--space-4);
  }
}