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

:root {
    --black: #000000;
    --white: #ffffff;
    --gray: #666666;
    --light-gray: #e0e0e0;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--white);
    color: var(--black);
    line-height: 1.6;
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 250px;
    background-color: var(--black);
    color: var(--white);
    position: fixed;
    height: 100vh;
    left: 0;
    top: 0;
    padding: 3rem 2rem;
}

.sidebar-content {
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.brand {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.02em;
}

.nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.nav-link {
    background: none;
    border: none;
    color: var(--gray);
    text-align: left;
    padding: 0.5rem 0;
    font-size: 1rem;
    cursor: pointer;
    transition: color 0.2s;
    text-decoration: none;
    display: block;
}

.nav-link:hover {
    color: var(--white);
}

.nav-link.active {
    color: var(--white);
}

/* Main Content */
.main {
    margin-left: 250px;
    flex: 1;
    padding: 3rem 4rem;
    max-width: 900px;
}

.main h2 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

.subtitle {
    color: var(--gray);
    font-size: 1.125rem;
    margin-bottom: 3rem;
}

/* Tab Content */
.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Articles List */
#articles-list {
    display: flex;
    flex-direction: column;
    gap: 3rem;
    margin-top: 2rem;
}

.article-item {
    border-bottom: 1px solid var(--light-gray);
    padding-bottom: 2rem;
}

.article-item:last-child {
    border-bottom: none;
}

.article-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}

.article-excerpt {
    color: var(--gray);
    margin-bottom: 0.75rem;
    line-height: 1.7;
}

.article-meta {
    display: flex;
    gap: 1.5rem;
    font-size: 0.875rem;
    color: var(--gray);
}

.article-author,
.article-date {
    display: inline-block;
}

/* Loading & Error States */
.loading,
.error,
.no-articles {
    text-align: center;
    padding: 3rem 0;
    color: var(--gray);
}

.error {
    color: var(--black);
}

.hidden {
    display: none !important;
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
        padding: 2rem 1.5rem;
    }

    .sidebar-content {
        flex-direction: row;
        justify-content: space-between;
        align-items: center;
        gap: 2rem;
    }

    .nav {
        flex-direction: row;
        gap: 1rem;
    }

    .main {
        margin-left: 0;
        padding: 2rem 1.5rem;
    }

    .main h2 {
        font-size: 1.75rem;
    }

    .article-title {
        font-size: 1.25rem;
    }
}