CSS issues related to DIV background_html/css_WEB-ITnose

CSS image URL

Today when I was working on a project, I found that the CSS code of the wrapping div of the
page is as follows
#wrapper
{
width:990px;
margin :0 auto;
padding:0
background:url(bgline.jpg) repeat-y;
}
I won’t upload the picture for convenience. It is a horizontal straight line as follows

--------------------------------------------- ------------------------(bgline.jpg)

In my understanding repeat-y is not supposed to put this image in vertical Does the direction keep repeating this photo? Isn't that the same effect? ?
----------------------------------------------- -----------------------
----------------------- -----------------------------------------------
--- -------------------------------------------------- ----------------
---------------------------------- -------------------------------------
--------- -------------------------------------------------- ----------
--------------------------------------------- --------------------------------

But the effect is that the wrapping div (id=wrapper ) represents the width of 990PX. I really can’t understand why the horizontal line turns into two vertical lines? ? ? Thank you very much for the answer~~

Reply to the discussion (solution)

y is the vertical axis, of course it is vertical. It should be repeat-x

y is the vertical axis, of course it is vertical, it should be repeat-x
But my picture is a straight line parallel to the X-axis, so REPEAT-Y should not Is that so?
----------------------------------------------- y-axis repeat
--- ----------------------------------    ↓
---------- --------------------------

y is the vertical axis, of course it is vertical, it should be repeat-x
But my picture is a straight line parallel to the X-axis, so shouldn’t REPEAT-Y be like this?
----------------------------------------------- y-axis repeat
--- ----------------------------------    ↓
---------- -----------------------------

repeat-y is repeated parallel to y, not along the y-axis

Floor 1 is right.

The horizontal axis is repeat-x; the vertical axis is repeat-y. You did not provide the background image, so it is difficult for everyone to help you. I guess there are some problems with your background image. The method is to follow This is the way to think