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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
    line-height: 1.7;
    color: #1a1a1a;
    background: #f0f4f8;
    display: flex;
    min-height: 100vh;
}

/* ── Sidebar ── */

.sidebar {
    width: 260px;
    background: #1e3a5f;
    color: #fff;
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
}

.sidebar-inner {
    padding: 2.5rem 1.5rem;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.logo {
    font-weight: 800;
    font-size: 1.5rem;
    color: #fff;
    text-decoration: none;
    letter-spacing: -0.02em;
}

.logo:hover {
    color: #90caf9;
}

.tagline {
    color: #90caf9;
    font-size: 0.85rem;
    margin-top: 0.25rem;
    margin-bottom: 2.5rem;
}

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

.sidebar nav li {
    margin-bottom: 0.25rem;
}

.sidebar nav a {
    display: block;
    padding: 0.5rem 0.75rem;
    color: #c5d9ed;
    text-decoration: none;
    font-size: 0.95rem;
    border-radius: 6px;
    transition: background 0.15s, color 0.15s;
}

.sidebar nav a:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
}

.sidebar nav a.active {
    background: #2a5a8f;
    color: #fff;
    font-weight: 600;
}

.sidebar-footer {
    margin-top: auto;
    color: #6a8db5;
    font-size: 0.8rem;
}

/* ── Main content ── */

main {
    margin-left: 260px;
    flex: 1;
    padding: 3rem 2rem 5rem;
    display: flex;
    justify-content: center;
}

article {
    max-width: 700px;
    width: 100%;
}

.post-meta {
    color: #5a7a9a;
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
    font-weight: 500;
}

h1 {
    font-size: 2.1rem;
    line-height: 1.3;
    margin-bottom: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: #0d2137;
}

h2 {
    font-size: 1.4rem;
    margin-top: 0.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
    color: #1e3a5f;
}

p {
    margin-bottom: 1rem;
    font-size: 1.05rem;
    color: #2c3e50;
}

hr {
    border: none;
    border-top: 2px solid #d0dce8;
    margin: 2.5rem 0;
}

ul {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

li {
    margin-bottom: 0.4rem;
    font-size: 1.05rem;
    color: #2c3e50;
}

a {
    color: #2a6cb6;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
    color: #1a4a80;
}

strong {
    color: #1a1a1a;
}

blockquote {
    border-left: 4px solid #2a6cb6;
    padding: 0.75rem 1.25rem;
    margin: 1.25rem 0;
    background: #e8f0fa;
    border-radius: 0 6px 6px 0;
    color: #1e3a5f;
    font-style: italic;
}

/* ── Mobile ── */

@media (max-width: 768px) {
    body {
        flex-direction: column;
    }

    .sidebar {
        position: relative;
        width: 100%;
        height: auto;
    }

    .sidebar-inner {
        padding: 1.5rem;
        flex-direction: row;
        flex-wrap: wrap;
        align-items: center;
        gap: 0.5rem 1.5rem;
    }

    .tagline {
        margin: 0;
    }

    .sidebar nav {
        width: 100%;
    }

    .sidebar nav ul {
        display: flex;
        gap: 0.25rem;
    }

    .sidebar-footer {
        display: none;
    }

    main {
        margin-left: 0;
        padding: 2rem 1.25rem 3rem;
    }

    h1 {
        font-size: 1.5rem;
    }
}