title: Change line border color in geom_smooth
body: <p>How does one change the color of the line border in <code>geom_smooth()</code>?</p>
  <pre><code>library(ggplot2)
  mtcars$cyl &lt;- as.factor(mtcars$cyl)
  
  ggplot(mtcars, aes(x=wt, y=mpg, color=cyl, shape=cyl)) +
    geom_point() + 
    geom_smooth(method=lm)
  </code></pre>
  <p><a href="https://i.stack.imgur.com/E2cuU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/E2cuU.png" alt="enter image description here" /></a></p>
  <p>It should look something like this:</p>
  <p><a href="https://i.stack.imgur.com/pxzcY.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pxzcY.png" alt="enter image description here" /></a></p>
  <p>Thank you for your time!</p>