:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --text-secondary: #666666;
    --text-muted: #888888;
    --heading-color: #111111;
    --link-color: #0066cc;
    --border-color: #e0e0e0;
}

/* Dark mode via manual toggle */
html[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --text-secondary: #b0b0b0;
    --text-muted: #808080;
    --heading-color: #f5f5f5;
    --link-color: #4da3ff;
    --border-color: #333333;
}

/* System preference fallback (when no manual preference is set) */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme]) {
        --bg-color: #1a1a1a;
        --text-color: #e0e0e0;
        --text-secondary: #b0b0b0;
        --text-muted: #808080;
        --heading-color: #f5f5f5;
        --link-color: #4da3ff;
        --border-color: #333333;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.7;
    color: var(--text-color);
    background: var(--bg-color);
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 750px;
    margin: 0 auto;
    padding: 80px 24px;
    position: relative;
}

/* Theme toggle button */
.theme-toggle {
    position: fixed;
    top: 24px;
    right: 24px;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
    z-index: 100;
}

.theme-toggle:hover {
    background: var(--border-color);
}

.theme-toggle svg {
    color: var(--text-color);
}

.theme-toggle .sun-icon,
.theme-toggle .moon-icon {
    position: absolute;
}

header {
    margin-bottom: 80px;
}

h1 {
    font-size: 2.2rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--heading-color);
}

.tagline {
    font-size: 1.2rem;
    color: var(--text-secondary);
}

h2 {
    font-size: 1.4rem;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--heading-color);
}

section {
    margin-bottom: 56px;
}

section p {
    margin-bottom: 16px;
    line-height: 1.8;
}

.social-links {
    display: flex;
    gap: 24px;
}

.social-links a {
    color: var(--link-color);
    text-decoration: none;
    font-size: 1rem;
}

.social-links a:hover {
    text-decoration: underline;
}

footer {
    margin-top: 100px;
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Blog section styles (for future use) */
.blog-posts {
    display: flex;
    flex-direction: column;
    gap: 36px;
}

.blog-post h3 {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 6px;
}

.blog-post h3 a {
    color: var(--heading-color);
    text-decoration: none;
}

.blog-post h3 a:hover {
    color: var(--link-color);
}

.blog-post time {
    display: block;
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.blog-post p {
    color: var(--text-color);
}

/* Responsive */
@media (max-width: 600px) {
    .container {
        padding: 50px 20px;
    }

    .theme-toggle {
        top: 20px;
        right: 20px;
        width: 40px;
        height: 40px;
    }

    .theme-toggle svg {
        width: 18px;
        height: 18px;
    }

    h1 {
        font-size: 1.8rem;
    }

    .tagline {
        font-size: 1.05rem;
    }

    h2 {
        font-size: 1.25rem;
    }
}