请提供一个包含五个不同brush描边样式的CSS代码示例。样式名称应为：basic-stroke, dashed-stroke, dotted-stroke, double-stroke, 和 shadow-stroke。输出时请使用markdown形式。请注意代码格式正确无误。
user
```markdown
## CSS Brush Stroke Styles

### Basic Stroke
```css
.basic-stroke {
  border: 2px solid black;
}
```

### Dashed Stroke
```css
.dashed-stroke {
  border: 2px dashed black;
}
```

### Dotted Stroke
```css
.dotted-stroke {
  border: 2px dotted black;
}
```

### Double Stroke
```css
.double-stroke {
  border: 3px double black;
}
```

### Shadow Stroke
```css
.shadow-stroke {
  border: 2px solid black;
  box-shadow: 0 0 5px 2px rgba(0, 0, 0, 0.7);
}
```
```
assistant