:root {
    --bg-color: #ffffff;
    --text-color: #000000;
    --link-color: #0000ff;
    --note-color: #555555;
    --hr-color: #000000;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1a1a1a;
        --text-color: #eeeeee;
        --link-color: #add8e6;
        --note-color: #aaaaaa;
        --hr-color: #eeeeee;
    }
}

@font-face {
    font-family: 'Product Sans';
    src: url('fonts/product-sans-bold.woff2') format('woff2');
    font-weight: bold;
    font-style: normal;
}

@font-face {
    font-family: 'Product Sans';
    src: url('fonts/product-sans-bold-italic.woff2') format('woff2');
    font-weight: bold;
    font-style: italic;
}

@font-face {
    font-family: 'Product Sans';
    src: url('fonts/product-sans-italic.woff2') format('woff2');
    font-weight: normal;
    font-style: italic;
}

@font-face {
    font-family: 'Product Sans';
    src: url('fonts/product-sans-regular.woff2') format('woff2');
    font-weight: normal;
    font-style: normal;
}

html {
    background-color: var(--bg-color);
    scroll-behavior: smooth;
}

body {
    font-family: "Product Sans", serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    max-width: 960px;
    margin: 20px auto;
    padding: 0 20px;
    transition: background-color 0.3s, color 0.3s;
}

header {
    text-align: center;
}

header h1 {
    font-size: 24px;
    font-weight: bold;
    margin-bottom: 5px;
}

header p {
    font-size: 16px;
    margin-top: 0;
}

hr {
    border: 0;
    height: 1px;
    background-color: var(--hr-color);
}

main {
    font-size: 17px;
}

.container {
    display: flex;
    justify-content: space-between;
}

.column {
    width: 48%;
}

.column ul {
    list-style-type: square;
    padding-left: 20px;
}

.column li {
    margin-bottom: 15px;
}

a {
    color: var(--link-color);
    text-decoration: underline;
}

.description {
    display: block;
    font-size: 14px;
    color: var(--note-color);
    margin-top: 3px;
}

footer {
    font-size: 14px;
}

.footer-content {
    text-align: center;
    margin: 20px 0;
}