html,
body {
    padding: 0;
    margin: 0;
    color: #212529;
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", "Noto Sans", "Liberation Sans", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    font-size: 16px;
}

ul,
ol,
li {
    padding: 0;
    margin: 0;
    list-style: none;
}

h1,
h2,
h3,
h4 {
    padding: 0;
    margin: 0;
    font-weight: 500;
}

a {
    text-decoration: none;
    color: #343a40;
}

p {
    margin-bottom: 1rem;
    line-height: 30px;
}

hr {
    margin: 1rem 0;
    border: 0;
    border-top: 1px solid;
    opacity: .1;
}

* {
    box-sizing: border-box;
}

.a {
    padding: 1.5rem;
    padding-top: 3rem;
    padding-bottom: 3rem;
    width: 100%;
    margin: auto;
}

header {
    padding-bottom: 1rem !important;
    margin-bottom: 1.5rem !important;
    border-bottom: solid 1px #dee2e6;
}

header h3 {
    font-size: 1.5rem;
}

main {
    display: flex;
    justify-content: space-between;
    flex-direction: column;
}

.l h1 {
    font-size: 2.5rem;
}

.l h2 {
    font-size: 2rem;
}

.l ol {
    padding: 0;
    list-style: none;
    display: flex;
    margin-bottom: 1.5rem;
}

.l ol a {
    text-decoration: underline;
}

.l ol .at::before {
    content: "/";
    padding: 0 0.5rem;
}

.l ol .at {
    color: rgba(33, 37, 41, 0.75);
}

.pn {
    border-radius: 4px;
    border: solid 1px #e9ecef;
    background-color: #fcfcfd;
    padding: 1rem;
    margin-bottom: 2rem;
}

.pn ol {
    display: block;
    margin-bottom: 0;
}

.pn li {
    color: #6c757d;
    display: block;
    height: 32px;
    line-height: 32px;
}


.r {
    flex-shrink: 0;
    width: 100%;
}

.r>div {
    margin-bottom: 1rem;
}

.r h4 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.r ul {
    padding-left: 2rem;
}

.r ul li {
    height: 32px;
    overflow: hidden;
    line-height: 32px;
}

footer {
    padding-top: 1.5rem;
    border-top: solid 1px #dee2e6;
}


@media (min-width:576px) {
    main {
        display: flex;
        flex-direction: column;
    }

    .a {
        width: 100%;
    }

    .r {
        width: 100%;
    }
}

@media (min-width:992px) {
    main {
        display: flex;
        flex-direction: row;
    }

    .a {
        width: 970px;
    }

    .r {
        width: 290px;
    }
}

@media (min-width:1600px) {
    .a {
        width: 1600px;
    }

    .r {
        width: 528px;
    }
}