change post text alignment & post font size

The theme I am using has post text defaulted to align left. I would like the post alignment to be full (justify) by default. How do I change this?

Also, how can I change the default size of post font only. I don’t want to change anything else on the page.

Below is the style sheet code. Thanks in advance for any help.

/*
Theme Name: Natural Remedy Blog Theme
Description: Natural Remedy Blog Theme is a dark, simple and stylish WordPress Theme brought to you free by <a href="https://jump2top.com/themes/" target="_blank">Free Blog Themes and Blog Templates</a>.
Author: Free Blog Themes and Blog Templates
Author URI: https://jump2top.com/themes/
Version: 1.0
Tags: green, black, gray, 2-columns, right sidebar, widget ready, fluid width, seo friendly, with image

*/
* {
	padding: 0px;
	margin: 0px;
}
body {
	background: url(images/background.gif) repeat-x #191919;
	color: #ffffff;
	font-size: 9pt;
	font-family:Geneva, Arial, Helvetica, sans-serif;
}
#wrapper {
	background: url(images/background_wrap.jpg) no-repeat left top;
}
#wrap {
	margin-left: 280px;
	width:70%;
}
#header {
	height: 75px;
}
#title {
	float: left;
	padding: 0px 10px 0px 0px;
}
#pagenav {
	font-size: 11pt;
	font-weight: bold;
	padding-top: 30px;
}
#sidebar {
	float: right;
	width: 200px;
	padding: 10px 0px 20px 0px;
	color: #acacac;
}
#content {
	margin: 10px 230px 20px 0px;
}
.clear {
	clear:both;
}
#footer {
	padding: 20px 0px 10px 0px;
	color:#CCCCCC;
}
.widget {
	padding: 20px 10px 20px 10px;
	border-bottom: 1px solid #333333;
}
.postmetadata {
	color: #548200;
	padding: 10px 0px;
}
/* text */
#title h1 {
	font-size: 20pt;
	font-weight: normal;
	padding-top: 10px;
}
#title h1 a {
	color: #ffffff;
	text-decoration: none;
}
.description {
	color: #d7d7d7;
	font-size: 10pt;
	font-weight: normal;
}
#pagenav ul li {
	list-style: none;
	display: inline;
	margin-left:30px;
}
#pagenav li a {
	color: #555555;
	padding-right: 20px;
	text-decoration:none;
}
#pagenav li a:hover {
	color: #ffffff;
}

#footer a {
	color: #cccccc;
	text-decoration: none;
}
p, #content h1, h2, h3, ol, ul, .post {
	padding-bottom: 10px;
}
#content h1 {
	font-size: 16pt;
	color: #78ac2d;
	font-weight:normal;
}
#content h1 a {
	color: #78ac2d;
	text-decoration: none;

}
#content ul li, #content ol li {
	margin-left: 30px;
}
a {
	color: #548200;
}
#sidebar a {
	color: #acacac;
	text-decoration: none;
}
h2 {
	font-size: 12pt;
	color:#CCCCCC;
}
h2 a {
	color:#cccccc;
	text-decoration:none;
}
#sidebar h2, h3, h4 {
	font-size: 12pt;
}
h3, h4 {
	color: #78ac2d;
}
blockquote {
	margin: 10px;
	font-size: 10pt;
	font-style: italic;
}
.postmetadata a {
	color: #548200;
	text-decoration: none;
}
#sidebar ul li {
	list-style: none;
}
#sidebar ul li ul li {
	margin-left: 5px;
}
#sidebar ul li ul li ul li {
	margin-left: 5px;
}
ul li ul li {
	margin-left: 10px;
}
ul li ul li ul li {
	margin-left: 10px;
}
/* calendar */
#today, caption {
	font-weight: bold;
}
#today {
	color: #548200;
}
td, th {
	padding: 2px;
}
#calendar_wrap {
	padding-bottom: 10px;
}

/* form */
#author, #email, #url, #comment, .s {
	border: 1px solid #666666;
	padding: 5px;
	font-size: 8pt;
	background:transparent;
	color: #ffffff;
	font-family: Arial, Helvetica, sans-serif;
}
#author, #email, #url, #comment {
	padding: 5px;
}
.s {
	padding: 3px;
}
#submit, .searchsubmit {
	background-color: #548200;
	color: #ffffff;
	border: 1px solid #666666;
	font-size: 8pt;
	padding: 2px;
	margin-top: 3px;
	font-weight: bold;
	font-family: Arial, Helvetica, sans-serif;
}

#commentform a {
	color: #666666;
	text-decoration: none;
}
#comments {
	margin: 10px 0px;
}
.comment {
	padding: 10px;
}
#date {
	padding-bottom: 10px;
}
#date a {
	text-decoration: none;
}
.alt strong {
	font-size: 9pt;
}
.alt a {
	text-decoration: none;
}
.searchform {
	margin-bottom: 20px;
}
/* wp default */
.center {
	text-align:center;
}
.aligncenter {
	display: block;
	margin-left: auto;
	margin-right: auto;
}

.alignleft {
	float: left;
}

.alignright {
	float: right;
}
.wp-caption {
	border: 1px solid #ddd;
	text-align: center;
	background-color: #f3f3f3;
	padding-top: 4px;
	margin: 10px;
	-moz-border-radius: 3px;
	-khtml-border-radius: 3px;
	-webkit-border-radius: 3px;
	border-radius: 3px;
}

.wp-caption img {
	margin: 0;
	padding: 0;
	border: 0 none;
}

.wp-caption-dd {
	font-size: 11px;
	line-height: 17px;
	padding: 0 4px 5px;
	margin: 0;
}