css add padding around background code example

Example 1: css make background visible in text

.transparency{
    background-color: rgba(255, 255, 0, 0.3); /* <-- this line is modified */
    display: block;
    margin: 0 auto;
    width: 300px;
    height: 500px;
}
.content{
    color: #000;
    text-align: center;
}
img{
    /* Set rules to fill background */
    min-height: 100%;
    min-width: 1920px;
    /* Set up proportionate scaling */
    width: 100%;
    height: auto;
    /* Set up positioning */
    position: fixed;
    top: 0;
    left: 0;  
    z-index:-1; /* <-- this line is added */
}

Example 2: css make border rotate around element

.b-border{
    display: inline-block;
    position: relative;
    border: solid #333;
    border-width: 1px 1px 0px 1px;
    padding: 20px;
    margin-bottom: 100px;
}
.b-border.border-right{
  border-width: 1px 0 1px 1px;
}

.b-border.border-right:after{
    content: "";
    position: absolute;
    right: -30px;
    border-top: 1px solid #333;
     border-left: none medium;
    top: -1px;
    left: auto;
    width: 30px;
    height: 100%;
    background: linear-gradient(to top left, white calc(50% - 1px), #000 1px, white 50%);
}
.b-border:after{
    content: "";
    position: absolute;
    left: -1px;
    bottom: -15%;
    border-left: 1px solid #333;
    height: 15%;
    width: calc(100% + 1px);
    background: linear-gradient(to right bottom, white calc(50% - 1px), #000 1px, white 50%);
}