:root {
    --bg-color: #fff;
    --text-color: #000;
    --bg-pattern-1: #e5e5f7;
    --bg-pattern-2: #444cf7;
    --link-color: #0b84ff;
    --border-color: #ccc;
    --label-color: #555;
    --article-bg: #fff;
    --input-bg: #fff;
    --code-bg: #fff;
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --bg-pattern-1: #2a2a2a;
    --bg-pattern-2: #5858ff;
    --link-color: #4da6ff;
    --border-color: #444;
    --label-color: #aaa;
    --article-bg: #242424;
    --input-bg: #2a2a2a;
    --code-bg: #2a2a2a;
}

html, body {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    padding: 0;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.content {
    line-height: 1.5;
    padding: 1rem;
    max-width: 700px;
    margin: 0 auto;
    z-index: 10;
}

div.background {
    position: fixed;
    width: 100vw;
    height: 100vh;
    background-color: var(--bg-pattern-1);
    opacity: 0.2;
    background-image: radial-gradient(var(--bg-pattern-2) 0.5px, var(--bg-pattern-1) 0.5px);
    background-size: 10px 10px;
    z-index: -1;
    transition: background-color 0.3s ease, background-image 0.3s ease;
}

h1, h2, h3, h4, h5, h6 {
    margin: 0 0 .5em;
    font-weight: bold;
    line-height: 1.2;
}

* + h1, *:not(h1) + h2 {
    margin-top: 2rem;
}

h1 {
    font-size: 1.5rem;
    text-align: center;
}

h2 {
    font-size: 1.25rem;
}

h3 {
    font-size: 1.125rem;
}

p {
    margin: 0 0 1em;
}

.lead {
    font-size: 1.25rem;
    font-weight: bold;
}

ul, ol {
    margin: 0 0 1em;
    padding-left: 1.25em;
}

nav {
    margin: 1rem auto;
    display: flex;
    gap: 0.5rem;
    align-items: center;
    width: fit-content;

    a {
        text-decoration: none;
        padding: 0.25rem 0.5rem;
        border: 1px solid transparent;
        border-radius: 10px;

        &:hover, &:focus, &:active {
            background: #0b84ff;
            color: #fff;
        }
    }
}

header {
    text-align: center;

    img {
        border-radius: 50%;
    }
}

footer {
    text-align: center;
}

a {
    color: var(--link-color);
    text-decoration: underline;
    transition: color 0.3s ease;
}

label {
    display: block;
    margin-bottom: .25em;
    font-size: .9rem;
    color: var(--label-color);
    transition: color 0.3s ease;
}

input, textarea, select, button {
    font: inherit;
    color: var(--text-color);
    padding: .5rem .6rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--input-bg);
    transition: background 0.3s ease, border-color 0.3s ease, color 0.3s ease;
}

textarea {
    resize: vertical;
    min-height: 6rem;
}

img, video {
    max-width: 100%;
    height: auto;
}

article {
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 15px;
    background: var(--article-bg);
    transition: background 0.3s ease, border-color 0.3s ease;

    h2 {
        text-align: center;
    }

    h3 {
        margin-top: 2rem;
    }

    & + & {
        margin-top: 2rem;
    }

    summary {
        text-align: center;
    }

    @media screen and (max-width: 900px) {
        padding: 1rem;
    }
}

pre {
    background: var(--code-bg);
    padding: 1rem;
    transition: background 0.3s ease;
}

/* Dark mode toggle button */
.theme-toggle-btn {
    position: fixed;
    top: 1rem;
    right: 1rem;
    background: transparent;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    z-index: 1000;
    opacity: 0.5;
    transition: opacity 0.3s ease, transform 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle-btn:hover {
    opacity: 1;
    transform: scale(1.1);
}

.theme-icon {
    display: block;
    color: var(--text-color);
    transition: color 0.3s ease;
}

.post-meta {
    text-align: center;
    color: var(--label-color);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.post-meta .separator {
    margin: 0 0.5rem;
}

.post-cover {
    display: block;
    width: 100%;
    border-radius: 6px;
    margin-bottom: 2rem;
}