:root {
    --color-purple: MediumPurple;
    --color-dark-blue: darkslateblue;
    --color-white: white;
    --color-light: #f0f0f0;
    --color-gainsboro: gainsboro;
    --color-gray: gray;
    --color-dark: #333333;
}

:root {
    --text-color: var(--color-dark);
    --background-color: var(--color-white);
}

@media (prefers-color-scheme: dark) {
    :root {
        --text-color: var(--color-light);
        --background-color: var(--color-dark);
    }
}

body {
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    font-family: "Microsoft Jhenghei","PingFang HK","STHeitiTC-Light",tahoma,arial,sans-serif;
    color: var(--text-color);
    background-color: var(--background-color);
}

a {
    color: var(--text-color);
}

.header {
    background-color: var(--color-dark-blue);
    color: var(--color-gainsboro);
    width: 100%;
    padding: 8px;
    box-sizing: border-box;
}

.header-container,
.header-lf,
.header-rt {
    display: flex;
    flex-direction: row;
    align-items: center;
    white-space: nowrap;
}

.header-lf{
    overflow-x: auto;
}

.header-container {
    justify-content: space-between;
}

.header-logo {
    font-size: 2rem;
    font-weight: bold;
    font-style: italic;
    margin-right: 16px;
}

.header-nav {
    display: flex;
    flex-direction: row;
}

.header-nav a {
    font-weight: bold;
    color: var(--color-gainsboro);
    margin-right: 8px;
}

.header-nav a:last-child {
    margin-right: 0;
}

.header-lang-select {
    position:relative;
    user-select: none;
}

.header-lang-select::before {
    content: "\1F310";
    font-weight: bold;
}

.header-rt:hover .all-lang {
    display: block;
}

.all-lang {
    position:absolute;
    top: calc(100% - 8px);
    right: 0;
    display: none;
    background-color: var(--background-color);
    border: 1px solid var(--color-gainsboro);
    margin-top: 8px;
    padding: 12px;
    white-space: nowrap;
    color: var(--text-color);
}

.all-lang-corner-border {
    width:0;
    height:0;
    border:4px solid transparent;
    border-bottom-color: var(--color-gainsboro);
    position: absolute;
    bottom: 100%;
    right:15%;
}

.all-lang-corner-in {
    width:0;
    height:0;
    border:3px solid transparent;
    border-bottom-color: #FFF;
    position: absolute;
    bottom: 100%;
    right:calc(15% + 1px);
}

.current-lang {
    font-weight: bold;
    cursor: pointer;
}

.lang-option {
    margin-bottom: 4px;
    cursor: pointer;
}

.lang-option:last-child {
    margin-bottom: 0;
}

.lang-option:hover,
.lang-option-active {
    color: var(--color-purple);
}

.lang-option-active {
    cursor: default;
}

.main-container {
    flex-grow: 1;
    align-items: flex-start;
    box-sizing: border-box;
    padding: 16px;
}

.footer {
    background-color: var(--color-dark-blue);
    color: var(--color-gainsboro);
    width: 100%;
}

.footer-container {
    flex-direction: row;
    box-sizing: border-box;
    padding: 4px;
    line-height: 1rem;
    text-align: center;
}

.header-container, .main-container, .footer-container {
    width: 100%;
    margin: 0 auto;
}

@media screen and (min-width: 576px) {
    .header-container, .main-container, .footer-container {
        width: 540px;
    }
}

@media screen and (min-width: 768px) {
    .header-container, .main-container, .footer-container {
        width: 720px;
    }
}

@media screen and (min-width: 992px) {
    .header-container, .main-container, .footer-container {
        width: 960px;
    }
}

@media screen and (min-width: 1200px) {
    .header-container, .main-container, .footer-container {
        width: 1140px;
    }
}
