Random border on drop-down menu

Hello,

I have been tweaking the font and color options on my drop-down menus and there is a random border in my curriculum materials menu on the right side. From what I know of coding, there is not actually a code in my css to have borders on my menus but it is there.

I apologize if this ends up being the wrong support forum to post this question in. If there is a correct one for this question, please let me know.

Here is my codes for reference:

.site {
width: 1050px;
}
#main {
padding: 0px 45px 0;
}

@media screen and (max-width: 1050px) {
.site {
width: 100%;
}

#main {
padding: 20px 30px;
}
}

#primary {
width: 650px;
}

@media screen and (min-width: 1200px) {
.widget-area {
width: 200px;
}
}
@media screen and (min-width: 1200px) {
.widget-area {
width: 200px;
}
}

/* Menu Padding Horizontal */

.main-navigation ul li a {
padding-right: 15px !important;
padding-left: 15px !important;
}

/*Menu Item color*/
#primary-menu > ul > li > a, #primary-menu > li > a {
color: black;
}

.main-navigation ul li:hover > a {
background: #ffffff;
}

.main-navigation .current-menu-item a{
background: #ffffff;
}

.main-navigation .current-menu-parent a{
background: #ffffff;
}

.main-navigation a{
font-family: Open Sans;
}

.main-navigation a {
text-transform: uppercase;
}

.sub-menu > li > a {
color: #000000 !important;
background: #ffffff !important;
}

.sub-menu > li:hover > a {
color: #000000 !important;
background: #ffffff !important;
}
—-End of code—-

Thanks in advance,

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