:root{
    --fill: #3498db;
    --empty: #e0e0e0;
    --bck: #f7f7fa;
}

* {
    box-sizing: border-box;
}
body {
    font-family: 'Nunito', sans-serif;
    background-color: var(--bck);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    overflow: hidden;
    margin: 0;
}

.container {
    text-align: center;
}

.progress-container {
    display: flex;
    justify-content: space-between;
    position: relative;
    margin: 0 0 30px 0;
    max-width: 100%;
    width: 300px;
}

.progress-container::before {
    content: '';
    background-color: var(--empty);
    position: absolute;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    height: 4px;
    width: 100%;
    z-index: -1;
}

.progress {
    background-color: var(--fill);
    position: absolute;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
    height: 4px;
    width: 0%;
    z-index: -1;
    transition: 0.4s ease;
}

.circle {
    background-color: #fff;
    color: #aaa;
    border: 3px solid var(--empty);
    border-radius: 50%;
    height: 30px;
    width: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: 0.4s ease;
}

.circle.active{
    border: 3px solid var(--fill);
}

.btn{
    background-color: var(--fill);
    color: var(--bck);
    border: none;
    border-radius: 7rem;
    cursor: pointer;
    font-family: inherit;
    padding: 8px 20px;
    margin: 5px;
    font-size: 15px;
}

.btn:active{
    transform: scale(0.99);
}

.btn:focus{
    outline: 0;
}

.btn:disabled{
    background-color: var(--empty);
    cursor: not-allowed;
    border: 1px solid #aaaaaa12;
}