/* CSS Variables for theming */
:root {
    --bg-color: #fafafa;
    --text-color: #222222;
    --header-bg: #2c3e50;
    --header-text: #ffffff;
    --primary-color: #3498db;
    --secondary-color: #8e44ad;
    --accent-color: #e67e22;
    --border-color: #e0e0e0;
}

body.dark {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --header-bg: #1e272e;
    --header-text: #f5f5f5;
    --border-color: #333333;
}

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

html {
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.5;
    scroll-behavior: smooth;
    color: var(--text-color);
    background-color: var(--bg-color);
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header */
.site-header {
    background-color: var(--header-bg);
    color: var(--header-text);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.logo {
    font-size: 1.8rem;
    margin: 0;
}

/* Navigation */
nav {
    display: flex;
    align-items: center;
}
.nav-list {
    list-style: none;
    display: flex;
    gap: 1.5rem;
    margin: 0;
}
.nav-list a {
    color: var(--header-text);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}
.nav-list a.active,
.nav-list a:hover {
    text-decoration: underline;
    color: var(--accent-color);
}

/* Hamburger menu */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--header-text);
    font-size: 1.5rem;
    cursor: pointer;
    margin-right: 0.5rem;
}

/* Theme toggle button */
.theme-toggle {
    background: none;
    border: none;
    color: var(--header-text);
    font-size: 1.4rem;
    cursor: pointer;
    margin-left: 0.5rem;
    transition: transform 0.2s ease;
}
.theme-toggle:hover {
    transform: rotate(20deg);
}

/* Hero */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: #ffffff;
    padding: 4rem 0;
    text-align: center;
}
.hero h2 {
    font-size: 2.2rem;
    margin-bottom: 1rem;
}
.hero p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
}
.cta-button {
    display: inline-block;
    background-color: var(--accent-color);
    color: #fff;
    padding: 0.75rem 1.5rem;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.2s ease;
}
.cta-button:hover {
    background-color: #d35400;
}

/* Sections */
.section {
    padding: 3rem 0;
    border-bottom: 1px solid var(--border-color);
}
.section h2 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    color: var(--header-bg);
}
.section p {
    font-size: 1rem;
    color: var(--text-color);
}

/* Footer */
.site-footer {
    background-color: var(--header-bg);
    color: var(--header-text);
    text-align: center;
    padding: 1.5rem 0;
    font-size: 0.9rem;
}
.site-footer p {
    margin: 0.3rem 0;
}

/* Skip link */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: #000;
    color: #fff;
    padding: 0.5rem 1rem;
    z-index: 100;
    transition: top 0.3s;
}
.skip-link:focus {
    top: 0;
}

/* Focus outline for accessibility */
a:focus,
button:focus {
    outline: 2px solid var(--accent-color);
    outline-offset: 2px;
}

/* Responsive */
@media (max-width: 600px) {
    .nav-list {
        flex-direction: column;
        background-color: var(--header-bg);
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        display: none;
        padding: 1rem 0;
    }
    body.nav-open .nav-list {
        display: flex;
    }
    .menu-toggle {
        display: block;
    }
    .hero h2 {
        font-size: 1.8rem;
    }
    .hero p {
        font-size: 1rem;
    }
}