:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text-main: #1e293b;
  --text-muted: #64748b;
  --accent: #7c3aed;
  --danger: #ef4444;
  --success: #10b981;
  --warning: #f59e0b;
  --border: #e2e8f0;
}

body {
  background-color: var(--bg);
  color: var(--text-main);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
  margin: 0;
  padding: 0;
}

/* 容器限制最大宽度，防止大屏拉伸 */
.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* --- 页面路由切换 --- */
.screen {
  display: none;
  opacity: 0;
  transform: translateY(10px);
  transition: all 0.4s ease-in-out;
}

.screen.active {
  display: block;
  opacity: 1;
  transform: translateY(0);
  animation: fadeIn 0.4s ease-out forwards;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* --- Hero 区域 --- */
.hero {
  background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
  color: white;
  padding: 4rem 1.5rem;
  text-align: center;
  border-bottom: 4px solid var(--accent);
}

.hero h1 {
  font-size: 2.5rem;
  margin-top: 0;
  margin-bottom: 1rem;
}

.hero .brand-en {
  font-weight: 300;
  color: #94a3b8;
  font-size: 1.5rem;
}

.hero-copy {
  max-width: 600px;
  margin: 0 auto 2rem;
  color: #cbd5e1;
  font-size: 1.1rem;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

/* --- 按钮与交互 --- */
button {
  font-family: inherit;
  font-size: 1rem;
  transition: all 0.2s ease;
}

button.primary {
  background-color: var(--primary);
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 6px -1px rgba(37, 99, 235, 0.2);
}

button.primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-2px);
}

button.secondary {
  background-color: transparent;
  color: white;
  padding: 0.75rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  border: 2px solid white;
  cursor: pointer;
}

button.secondary:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

button.text-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.5rem 0;
  font-weight: 500;
}

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

.issue-button {
  margin-top: auto;
  background: var(--bg);
  color: var(--primary);
  border: 1px solid var(--border);
  padding: 0.75rem;
  border-radius: 6px;
  font-weight: 600;
  cursor: pointer;
}

.issue-button:hover {
  background: var(--primary);
  color: white;
}

/* --- 布局网格 --- */
main {
  padding: 3rem 0;
}

.section-head {
  text-align: center;
  margin-bottom: 2.5rem;
}

.section-head h2 {
  font-size: 1.75rem;
  margin-bottom: 0.5rem;
}

.section-head p {
  color: var(--text-muted);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  transition: all 0.3s ease;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  display: flex;
  flex-direction: column;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  border-color: var(--primary);
}

.card h3 {
  margin-top: 0;
  color: var(--text-main);
}

.card p {
  color: var(--text-muted);
  flex-grow: 1;
}

.example-card {
  cursor: pointer;
}

.card-hint {
  color: var(--primary);
  font-weight: 600;
  margin-top: 1rem;
}

/* --- 表单样式 --- */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.field.full {
  grid-column: 1 / -1;
}

.field label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-main);
}

.field select, .field textarea {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: inherit;
  font-size: 1rem;
  background-color: #fff;
  box-sizing: border-box;
  transition: border-color 0.2s;
}

.field select:focus, .field textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* --- 面板与结果展示 --- */
.panel {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 2rem;
  margin-bottom: 1.5rem;
  border: 1px solid var(--border);
  border-left: 5px solid var(--primary);
  box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
}

.warning-panel {
  border-left-color: var(--danger);
  background-color: #fff1f2;
}

.results-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.results-grid .panel.full {
  grid-column: 1 / -1;
}

.results-grid h3 {
  margin-top: 0;
  font-size: 1.1rem;
  color: var(--text-main);
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.5rem;
  margin-bottom: 1rem;
}

.results-grid ul, .results-grid ol {
  padding-left: 1.25rem;
  margin: 0;
}

.results-grid li {
  margin-bottom: 0.5rem;
}

/* Chips 标签 */
.chips {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.chip {
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.875rem;
  font-weight: 600;
}

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

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

/* --- 页脚 --- */
.app-footer {
  background: #1e293b;
  color: #cbd5e1;
  padding: 3rem 1.5rem;
  margin-top: 4rem;
  text-align: center;
}

.footer-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: white;
  margin-bottom: 1rem;
}

.footer-logo span {
  font-weight: 300;
  color: #94a3b8;
}

.footer-disclaimer {
  max-width: 800px;
  margin: 0 auto 2rem;
  font-size: 0.875rem;
  line-height: 1.8;
  color: #94a3b8;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  font-size: 0.875rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: #cbd5e1;
  text-decoration: none;
}

.footer-links a:hover {
  color: white;
}

/* --- 响应式设计 --- */
@media (max-width: 768px) {
  .hero h1 { font-size: 2rem; }
  .form-grid, .results-grid { grid-template-columns: 1fr; }
  .hero-actions { flex-direction: column; }
  button.secondary { border-color: rgba(255,255,255,0.3); color: white; background: rgba(255,255,255,0.1); }
}