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

:root {
  --color-primary: #007bff;
  --color-success: #28a745;
  --color-header: #4facfe;
  --color-bg: #f5f6fa;
  --color-border: #ddd;
  --font-main: 'Microsoft JhengHei', sans-serif;
}

body {
  font-family: var(--font-main);
  background: var(--color-bg);
  height: 100vh;
  display: flex;
  flex-direction: column;
}

.btn {
  padding: 8px 12px;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  font-size: 13px;
}

.btn-primary { background: var(--color-primary); color: #fff; }
.btn-secondary { background: #f0f0f0; }

mark.highlight {
  background: #ffe564;
  color: #000;
  padding: 0 2px;
  border-radius: 3px;
}

span.replace-preview {
  color: var(--color-primary);
  font-weight: 600;
}