From cef354d41271e0935fe1adb068d11ef82bf76316 Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nolan@nolanlawson.com>
Date: Sun, 25 Feb 2018 23:01:15 -0800
Subject: [PATCH] fix box sizing calculations

---
 routes/_utils/autosize.js | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/routes/_utils/autosize.js b/routes/_utils/autosize.js
index b29befb3..84880454 100644
--- a/routes/_utils/autosize.js
+++ b/routes/_utils/autosize.js
@@ -15,9 +15,18 @@ function assign (ta) {
     return
   }
 
+  let heightOffset = null
   let cachedHeight = null
 
   function init () {
+    const style = window.getComputedStyle(ta, null)
+
+    if (style.boxSizing === 'content-box') {
+      heightOffset = -(parseFloat(style.paddingTop) + parseFloat(style.paddingBottom))
+    } else {
+      heightOffset = parseFloat(style.borderTopWidth) + parseFloat(style.borderBottomWidth)
+    }
+
     update()
   }
 
@@ -33,7 +42,7 @@ function assign (ta) {
 
     ta.style.height = ''
 
-    let endHeight = ta.scrollHeight
+    let endHeight = ta.scrollHeight + heightOffset
 
     if (ta.scrollHeight === 0) {
       // If the scrollHeight is 0, then the element probably has display:none or is detached from the DOM.