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

:root {
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-color: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --radius: 8px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
}

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

a:hover {
    text-decoration: underline;
}

/* ========== Header ========== */
.header {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-color);
}

.logo:hover {
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
    text-decoration: none;
}

/* ========== Main Container ========== */
.container {
    max-width: 900px;
    margin: 2rem auto;
    padding: 0 2rem;
}

/* ========== Page Header ========== */
.page-header {
    margin-bottom: 2rem;
}

.page-header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.page-header p {
    color: var(--text-secondary);
}

/* ========== Article Card ========== */
.article-card {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 1.5rem;
    margin-bottom: 1rem;
    cursor: pointer;
    transition: box-shadow 0.2s, transform 0.2s;
}

.article-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.article-card h2 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.article-card .meta {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
}

.article-card .excerpt {
    color: var(--text-secondary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-card .tags {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.75rem;
    flex-wrap: wrap;
}

.tag {
    background: #eff6ff;
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.75rem;
    font-weight: 500;
}

/* ========== Article Detail ========== */
.article-detail {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
}

.article-detail h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
    line-height: 1.3;
}

.article-detail .meta {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.article-content {
    font-size: 1rem;
    line-height: 1.8;
}

.article-content p {
    margin-bottom: 1rem;
}

.article-content h2,
.article-content h3 {
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.article-content code {
    background: #f1f5f9;
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-size: 0.9em;
}

.article-content pre {
    background: #1e293b;
    color: #e2e8f0;
    padding: 1rem;
    border-radius: var(--radius);
    overflow-x: auto;
    margin-bottom: 1rem;
}

.article-content pre code {
    background: none;
    padding: 0;
}

.back-link {
    display: inline-block;
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

.back-link:hover {
    color: var(--primary-color);
    text-decoration: none;
}

/* ========== Comments ========== */
.comments-section {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

.comments-section h3 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
}

.comment-form {
    background: var(--bg-color);
    padding: 1.5rem;
    border-radius: var(--radius);
    margin-bottom: 1.5rem;
}

.comment-form .form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin-bottom: 1rem;
}

.comment-form input,
.comment-form textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: inherit;
    transition: border-color 0.2s;
}

.comment-form input:focus,
.comment-form textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.comment-form textarea {
    min-height: 100px;
    resize: vertical;
}

.comment-item {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

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

.comment-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.comment-author {
    font-weight: 600;
}

.comment-date {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.comment-content {
    color: var(--text-secondary);
}

.no-comments {
    text-align: center;
    color: var(--text-secondary);
    padding: 2rem;
}

/* ========== Buttons ========== */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 500;
    font-size: 1rem;
    cursor: pointer;
    border: none;
    transition: background-color 0.2s, transform 0.1s;
}

.btn:active {
    transform: scale(0.98);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-hover);
    text-decoration: none;
}

.btn-secondary {
    background: var(--bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--border-color);
}

.btn-danger {
    background: #ef4444;
    color: white;
}

.btn-danger:hover {
    background: #dc2626;
}

/* ========== Admin Page ========== */
.admin-form {
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 2rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 1rem;
    font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group textarea {
    min-height: 300px;
    resize: vertical;
    font-family: 'Monaco', 'Consolas', monospace;
}

.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

/* ========== Article List in Admin ========== */
.admin-articles {
    margin-top: 2rem;
}

.admin-article-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--card-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-bottom: 0.5rem;
}

.admin-article-item h4 {
    margin-bottom: 0.25rem;
}

.admin-article-item .meta {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.admin-article-actions {
    display: flex;
    gap: 0.5rem;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* ========== Empty State ========== */
.empty-state {
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.empty-state h2 {
    margin-bottom: 0.5rem;
}

/* ========== Toast Notification ========== */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: #1e293b;
    color: white;
    padding: 1rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    transform: translateY(100px);
    opacity: 0;
    transition: transform 0.3s, opacity 0.3s;
    z-index: 1000;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast.success {
    background: #10b981;
}

.toast.error {
    background: #ef4444;
}

/* ========== User Area ========== */
.user-area {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.user-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--primary-color);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.875rem;
}

.user-avatar.small {
    width: 24px;
    height: 24px;
    font-size: 0.75rem;
}

.user-name {
    font-weight: 500;
}

/* ========== Modal ========== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 200;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.2s, visibility 0.2s;
}

.modal-overlay.show {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 2rem;
    max-width: 500px;
    width: 90%;
    transform: scale(0.95);
    transition: transform 0.2s;
}

.modal-overlay.show .modal {
    transform: scale(1);
}

.auth-tabs {
    display: flex;
    gap: 0;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.auth-tab {
    flex: 1;
    padding: 0.75rem;
    background: none;
    border: none;
    border-bottom: 2px solid transparent;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: color 0.2s, border-color 0.2s;
}

.auth-tab:hover {
    color: var(--text-color);
}

.auth-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.auth-form .form-group {
    margin-bottom: 1rem;
}

.modal h3 {
    margin-bottom: 1rem;
}

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 1.5rem;
}

/* ========== Comment Hints ========== */
.logged-in-hint,
.guest-hint {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    background: #f0f9ff;
    border-radius: var(--radius);
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.logged-in-hint {
    background: #f0fdf4;
}

.logged-in-hint .user-avatar {
    margin-right: 0.25rem;
}

/* ========== Responsive ========== */
@media (max-width: 640px) {
    .header {
        padding: 1rem;
    }

    .header-content {
        flex-wrap: wrap;
        justify-content: center;
        gap: 1rem;
    }

    .nav-links {
        order: 3;
        width: 100%;
        justify-content: center;
    }

    .container {
        padding: 0 1rem;
    }

    .article-detail {
        padding: 1.5rem;
    }

    .comment-form .form-row {
        grid-template-columns: 1fr;
    }

    .admin-article-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .user-name {
        display: none;
    }
}