Kaan Webpage Homepage CSS Code

body {margin:0;}
/* everything related to style goes here */
        .header,.footer {background-color:darkgreen;}
        .navigation {width:100%; color:white;
        display:flex;
        align-items:center;
        font-family: "Gill Sans", "Gill Sans MT", "Myriad Pro", "DejaVu Sans Condensed", Helvetica, Arial, "sans-serif";}
        .nav_left {flex:1;}
        .nav_right {display:flex;
        flex:3;
        margin-right:auto;
        justify-content:space-around;
        align-items:center;
        font-family:'Gill Sans', 'Gill Sans MT', 'Myriad Pro', 'DejaVu Sans Condensed', Helvetica, Arial, 'sans-serif';
        }
        .navigation a {color:white;
        text-decoration:none;}
.content{width:100%;
        font-family:'Gill Sans', 'Gill Sans MT', 'Myriad Pro', 'DejaVu Sans Condensed', Helvetica, Arial, 'sans-serif';
        background-color:yellow;
        display:flex;
        align-content:space-around;
        justify-content:center;
        flex-wrap:wrap;
        flex-direction:row;
}
.col_left {flex:1;} /*how much space the left column takes up*/
.col_right {flex:3;} /*how much space the right column takes up*/
.col_left img {width:100%;}
.content_home{background-color: yellow;
width:100%;}
.content_home{a:hover;}
.bottom_box{display:flex;
justify-content: space-between;}
table, th, td { /*to create table borders*/
  border: 1px solid black;
  border-collapse: collapse;
}/*end of border*/
th, td {
  padding: 7px;
  text-align: center;
}

.top_box {
  position: relative;
}

.image {
  display: block;
  width: 100%;
  height: auto;
}

.overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  transition: .5s ease;
  background-color: black;
}

.top_box:hover.overlay {
  opacity: 1;
}

.text {
  color: white;
  font-size: 20px;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}