You can add css over your theme, you need go to blogger's back-end and select these options: Themes > Advanced > Add CSS.
I add these piece of code in my blog in order to get responsible widths, separate code, avoid overflow in images without deformations and something else:
body {
    min-width: 0px !important;
    padding: 0px;
}
.content-outer, .content-fauxcolumn-outer, .region-inner {
    min-width: 0px !important;
    max-width: 10000px !important;
}
th {
    background-color: #006600;
    color: #ffff99;
}
th, td {
    padding: 0.04em 0.3em;
}
code {
    background-color: white;
    padding: 0.2em 0.7em;
    margin: 0.5em;
    box-shadow: inset 0 0 0 1px rgba(0,0,0,.15);
    border-radius: 0 0 2px 2px;
    display: block;
}
.main-outer img {
    max-width: 99%;
    height: auto;
}
.post-body img, .post-body .tr-caption-container {
   background: none;
}You might use the special theme for mobile, you need select theme, press the nut and activate mobile theme.


 

