Editor.renderedLines' width is set to the maximum of either Editor.scrollView's width or the maximum rendered line width

spec/app/editor-spec.coffee

@@ -1239,8 +1239,9 @@ describe "Editor", ->
           expect(editor.renderedLines.find(".line:first").text()).toBe buffer.lineForRow(0)
           expect(editor.renderedLines.find(".line:last").text()).toBe buffer.lineForRow(6)
 
-      it "increases the width of the rendered lines element if the max line length changes", ->
+      it "increases the width of the rendered lines element to be either the width of the longest line or the width of the scrollView (whichever is longer)", ->
         widthBefore = editor.renderedLines.width()
+        expect(widthBefore).toBe editor.scrollView.width()
         buffer.change([[12,0], [12,0]], [1..50].join(''))
         expect(editor.renderedLines.width()).toBeGreaterThan widthBefore
 
@@ -1319,10 +1320,12 @@ describe "Editor", ->
 
           expect(editor.find('.line').length).toBe 7
 
-      it "decreases the width of the rendered screen lines if the max line length changes", ->
+      it "sets the rendered screen line's width to either the max line length or the scollView's width (whichever is greater)", ->
+        buffer.change([[12,0], [12,0]], [1..100].join(''))
+        expect(editor.renderedLines.width()).toBeGreaterThan editor.scrollView.width()
         widthBefore = editor.renderedLines.width()
-        buffer.delete([[6, 0], [6, Infinity]])
-        expect(editor.renderedLines.width()).toBeLessThan widthBefore
+        buffer.delete([[12, 0], [12, Infinity]])
+        expect(editor.renderedLines.width()).toBe editor.scrollView.width()
 
     describe "when folding leaves less then a screen worth of text (regression)", ->
       it "renders lines properly", ->

src/app/editor.coffee

@@ -650,7 +650,11 @@ class Editor extends View
     @renderedLines.css('padding-bottom', heightOfRenderedLines)
 
   adjustWidthOfRenderedLines: ->
-    @renderedLines.width(@charWidth * @maxScreenLineLength())
+    width = @charWidth * @maxScreenLineLength()
+    if width > @scrollView.width()
+      @renderedLines.width(width)
+    else
+      @renderedLines.width(@scrollView.width())
 
   handleScrollHeightChange: ->
     scrollHeight = @lineHeight * @screenLineCount()

static/editor.css

@@ -66,7 +66,6 @@
 .editor .lines {
   position: relative;
   display: table;
-  width: 100%;
   height: 100%;
 }