:root {
    --blue: #66b2fe;
    --color-main: white;
    --color-bg-main: var(--blue);
}

/* 通用代码 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
a {
    text-decoration: none;
    color: inherit;
}
ul>li, ol>li {
    list-style-type: none;
}
body>* {
    min-width: 300px;
}

.box-center {
    margin: 0 auto;
}

.safe-width {
    width: 100%;
    max-width: 1200px;
    min-width: 320px;
}

@media screen and (max-width: 1200px) {
    .safe-width {
        padding: 0 10px;
    }
}

.article-header {
    padding: 30px 0 20px 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    line-height: 1;
    text-align: center;
}
.article-header>div:nth-child(1) {
    font-size: 14px;
}
.article-header>div:nth-child(2) {
    position: relative;
    margin-top: 10px;
    font-size: 24px;
    width: 100px;
}
.article-header>div:nth-child(2):before, .article-header>div:nth-child(2):after {
    content: '';
    position: absolute;
    top: 50%;
    margin-top: -1px;
    display: block;
    height: 2px;
    width: 50px;
    background-color: white;
}
.article-header>div:nth-child(2):before {
    left: -65px;
}
.article-header>div:nth-child(2):after {
    right: -65px;
}

#header {
    height: 100px;
    display: flex;
    align-items: center;
}
#header-logo>span {
    font-size: 30px;
}

#version-container {
    position: relative;
    min-height: 400px;
    background-color: var(--color-bg-main);
    color: var(--color-main);
}
#version {
    min-height: 100px;
    line-height: 2;
    font-size: 16px;
}
#version li::before {
    content: '';
    display: inline-block;
    height: 0;
    width: 0;
    border-left: 9px solid white;
    border-top: 6px solid transparent;
    border-bottom: 6px solid transparent;
    box-sizing: content-box;
}
#version li>span {
    margin-left: .5em;
}

@media screen and (min-width: 700px) {
    #version-container::before {
        content: '';
        display: block;
        position: absolute;
        bottom: 4px;
        right: 0;
        width: 310px;
        height: 297px;
        background-image: url("../image/web-history.png");
    }
}
@media screen and (min-width: 1200px) {
    #version-container::before {
        left: 50%;
        right: auto;
        margin-left: 207px;
    }
}


/* 页脚 */
#footer {
    margin-top: 60px;
    width: 100%;
    position: static;
    padding: 15px 0;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    color: gray;
}
#footer>span {
    padding: 5px 10px;
}