Eliminate/Reduce the gap between each post

Can you provide a link to your site? With that, we can see the CSS and I give you the exact snippet you’ll need to add.

There you go and thanks for your help.

Hi Lou,
Sorry, but I don’t recognise this as the theme that I built, so not sure how this works.

Looking at the CSS, you can try changing

.hentry {
    border-top: 1px solid #ddd;
    display: inline-block;
    margin: 1em 0 2em;
    width: 100%;
}

to

.hentry {
    border-top: 1px solid #ddd;
    display: inline-block;
    margin: 1em 0 0;
    width: 100%;
}

That will reduce it a bit, but I’m confused as to how you set this up.

Thanks Christine for your help. I changed the code you gave me to:

.hentry {
    border-top: 1px solid #ddd;
    display: inline-block;
    margin: 0 0 0;
    width: 100%;
}

and it looks better now.
This is your theme but I have it loads inside an iframe with the following modification:

h1.entry-title {
font-size: 24px !important;
font-size: 2.4rem;
font-weight: bold;
font-style: italic;
}
.nav-previous {
display: none;
}
.nav-next {
display: none;
}
.cat-links {
display: none;
}
#primary .entry-summary {
float: left;
width: 100%;
}
.page-title {
display: none;
}
.hentry {
    border-top: 1px solid #ddd;
    display: inline-block;
    margin: 0 0 0;
    width: 100%;
}

and some modifications to the head & footer php.