style.css

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: 'Inconsolata', monospace;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background: #020100;
}
.container {
    border: 10px solid rgb(0, 240, 0);
    width: 450px;
    height: 450px;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    color: #fff;
    font-size: 32px;
    border-radius: 50%;
    background: rgb(0, 0, 0);
    box-shadow: 
            0 0 5px rgb(0, 240, 0),
            0 0 10px rgb(0, 240, 0),
            0 0 15px rgb(0, 240, 0);
}
.time {
    font-size: 2em;
    color: rgb(0, 240, 0);
}
.blink-colon {
    animation: blink 1s infinite linear;
}
@keyframes blink {
    0%, 100% {
        opacity: 1;
    }
    30% {
        opacity: 0.4;
    }
}
.data-container {
    margin-top: 6px;
    font-size: 24px;
    color: rgba(255, 255, 255, 0.8);
}