:root {
    --main-bg-color: #031321;;
    --bg-color:#f39821;
    --text-color: #694311;
/* 
    --bg-color:#2196f3;
    --text-color: #255784; */
}

body {
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background: var(--main-bg-color);
    font-family: 'Consolas';

}

a {
    position :relative;
    display: inline-block;
    padding: 15px 30px;
    color: var(--bg-color);
    text-transform: uppercase;
    letter-spacing: 4px;
    text-decoration: none;
    font-size: 24px;
    overflow: hidden;
    transition: 0.2s;
}

a:hover {    
    color: var(--text-color);
    background: var(--bg-color);
    box-shadow: 0 0 10px var(--bg-color), 0 0 40px var(--bg-color), 0 0 80px var(--bg-color);
    transition-delay: 1s;
}

a span {
    position: absolute;
    display: block;    
}

/* LINEA DE ARRIBA */
a span:nth-child(1) {
    top: 0;
    left: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg,transparent, var(--bg-color));
}
a:hover span:nth-child(1) {    
    left: 100%;
    transition: 1s;    
}

/* LINEA DE ABAJO */
a span:nth-child(3) {
    bottom: 0;
    right: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(270deg,transparent,var(--bg-color));
}
a:hover span:nth-child(3) {    
    right: 100%;
    transition: 1s; 
    transition-delay: 0.5s;
}

/* LINEA DE LA DERECHA */
a span:nth-child(2) {
    top: -100%;
    right: 0%;
    width: 2px;
    height: 100%;
    background: linear-gradient(180deg,transparent,var(--bg-color));
}
a:hover span:nth-child(2) {    
    top: 100%;
    transition: 1s; 
    transition-delay: 0.25s;
}

/* LINEA DE LA IZQUIERDA */
a span:nth-child(4) {
    bottom: -100%;
    left: 0%;
    width: 2px;
    height: 100%;
    background: linear-gradient(360deg,transparent,var(--bg-color));
}
a:hover span:nth-child(4) {    
    bottom: 100%;
    transition: 1s; 
    transition-delay: 0.75s;
}