.circle {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    position: absolute;
    transition: 0.7s;
    transform: translate(-50%, -50%);
}

/* The ring below */
.base {
    width: 64px;
    height: 64px;
    border: 6px solid;
    border-radius: 50%;
    position: absolute;
    transform: translate(-50%, -50%);
}

/* Use border to make a triangle */
.arrow-head {
    width: 0px;
    height: 0px;
    right: 0;
    top: 5px;
    position: absolute;
    border-left: 20px solid;
    border-top: 5px solid transparent;
    border-bottom: 5px solid transparent;
    transform: translateY(-50%);
}

.arrow-line {
    width: auto;
    height: 2px;
    left: 0px;
    right: 18px;
    top: 5px;
    position: absolute;
    transform: translateY(-50%);
}

.arrow {
    position: relative;
    height: 10px;
}

/* An edge is a arrow without head */
.edge {
    width: auto;
    height: 2px;
    left: 0;
    right: 0;
    top: 5px;
    position: absolute;
    transform: translateY(-50%);
}

/* Contains several arrows */
.arrow-stack {
    left: 35px;
    right: 35px;
    width: auto;
    position: absolute;
    align-content: center;
    transform: translateY(-50%);
}

.segment {
    position: absolute;
}

/* Two buttons, respectively red and blue */
.button {
    width: 100px;
    height: 40px;
    position: absolute;
    opacity: 0.7;
    display: flex;
    color: white;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    cursor: pointer;
}

#stage_name {
    height: 0;
    text-align: center;
    font-size: large;
    font-weight: bold;
    top: 40px;
}