Can't remove white space (left and right sides) from Navbar

I am very new to HTML programming. I was creating my first navigation bar using blogger and I can't remove default white space (left and right sides) set by blogger. Here is my blog link. I did use browser inspect tool also but I can't find what is causing the problem. Here's my blogger link: https://nainghtooaung2.blogspot.com/

I did use position:relative; to adjust alignment.Although the codes move the navigation bar to left without any white space, it will create more white space on the right side. This means the code I use just move the position of the navigation bar, but didn't remove the white space.

When I tried to use position:fixed, It remove all the white space from navigation bar. But my navigation bar overlapped with other contents.

.site-nav {
position:relative;
left:0;
width:100%
)

.site-nav {
position:fixed;
left:0;
width:100%
)

Solution

Always add browser reset CSS code in the beginning of your style sheet:

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed, 
figure, figcaption, footer, header, hgroup, 
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 100%;
    font: inherit;
    vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure, 
footer, header, hgroup, menu, nav, section {
    display: block;
}
body {
    line-height: 1;
}
ol, ul {
    list-style: none;
}
blockquote, q {
    quotes: none;
}
blockquote:before, blockquote:after,
q:before, q:after {
    content: '';
    content: none;
}
table {
    border-collapse: collapse;
    border-spacing: 0;
}