:root {
    --primary-color: #2c3e50;
    --accent-color: #3498db;
    --background-color: #f8f9fa;
    --text-color: #333;
    --border-color: #dee2e6;
    --sidebar-width: 280px;
}

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

body {
    font-family: 'Georgia', 'Times New Roman', serif;
    line-height: 1.7;
    color: var(--text-color);
    background-color: var(--background-color);
}

.container {
    display: flex;
    min-height: 100vh;
}

nav.sidebar {
    width: var(--sidebar-width);
    min-width: var(--sidebar-width);
    background: var(--primary-color);
    color: white;
    padding: 20px;
    position: fixed;
    top: 0;
    left: 0;
    height: 100vh;
    overflow-y: auto;
    z-index: 100;
}

.nav-header {
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid rgba(255,255,255,0.2);
}

.nav-header .home-link {
    display: block;
    color: rgba(255,255,255,0.7);
    text-decoration: none;
    font-size: 0.85rem;
    margin-bottom: 10px;
}

.nav-header .home-link:hover {
    color: white;
}

.nav-header h2 {
    font-size: 1.1rem;
    line-height: 1.4;
    font-weight: 600;
}

.nav-header h2 a {
    color: white;
    text-decoration: none;
}

.nav-list {
    list-style: none;
}

.nav-item {
    margin-bottom: 8px;
}

.nav-item a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    font-size: 0.9rem;
    display: block;
    padding: 6px 10px;
    border-radius: 4px;
    transition: all 0.2s;
    line-height: 1.4;
}

.nav-item a:hover {
    background: rgba(255,255,255,0.1);
    color: white;
}

.nav-item a.active {
    background: rgba(255,255,255,0.15);
    color: white;
}

main {
    margin-left: var(--sidebar-width);
    flex: 1;
    padding: 40px 60px;
    max-width: 900px;
}

article h1 {
    font-size: 1.9rem;
    margin-bottom: 30px;
    color: var(--primary-color);
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 15px;
}

article h2 {
    font-size: 1.5rem;
    margin: 40px 0 20px;
    color: var(--primary-color);
}

article h3 {
    font-size: 1.25rem;
    margin: 30px 0 15px;
    color: var(--primary-color);
}

article p {
    margin-bottom: 1.2em;
    text-align: justify;
}

a {
    color: var(--accent-color);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.abstract {
    background: #f0f7ff;
    border-left: 4px solid var(--accent-color);
    padding: 20px 25px;
    margin: 20px 0 30px;
    border-radius: 0 4px 4px 0;
}

.abstract h2 {
    margin-top: 0;
    font-size: 1.2rem;
}

.equation {
    margin: 1.5em 0;
    overflow-x: auto;
}

figure {
    margin: 2em 0;
    text-align: center;
}

figure img {
    max-width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    padding: 15px;
    background: white;
}

figcaption {
    margin-top: 12px;
    font-size: 0.95rem;
    color: #555;
    text-align: left;
    padding: 0 20px;
}

.citation {
    color: var(--accent-color);
}

.page-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 50px;
    padding-top: 25px;
    border-top: 1px solid var(--border-color);
}

.page-nav a {
    color: var(--accent-color);
    text-decoration: none;
    padding: 10px 18px;
    border: 1px solid var(--accent-color);
    border-radius: 4px;
    transition: all 0.2s;
    font-size: 0.95rem;
}

.page-nav a:hover {
    background: var(--accent-color);
    color: white;
    text-decoration: none;
}

.page-nav a.home {
    border: none;
    color: #666;
}

.page-nav a.home:hover {
    background: transparent;
    color: var(--accent-color);
}

.bib-entry {
    margin-bottom: 1.2rem;
    padding-left: 2rem;
    text-indent: -2rem;
    line-height: 1.6;
}

@media (max-width: 1200px) {
    nav.sidebar {
        width: 250px;
        min-width: 250px;
    }
    main {
        margin-left: 250px;
        padding: 30px 40px;
    }
}

@media (max-width: 900px) {
    .container {
        flex-direction: column;
    }
    nav.sidebar {
        position: relative;
        width: 100%;
        min-width: 100%;
        height: auto;
    }
    main {
        margin-left: 0;
        padding: 20px;
    }
}

@media print {
    nav.sidebar, .page-nav {
        display: none;
    }
    main {
        margin-left: 0;
        max-width: 100%;
    }
}

/* Comments section */
.comments-section {
    margin-top: 60px;
    padding-top: 30px;
    border-top: 2px solid #e0e0e0;
}
.comments-section h2 {
    font-size: 1.5rem;
    color: #2c3e50;
    margin-bottom: 20px;
}