/* ===== CSS Reset & Variables ===== */
:root {
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-card: #21262d;
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --accent: #58a6ff;
    --accent-hover: #79b8ff;
    --border: #30363d;
    --success: #3fb950;
    --tag-bg: #1f6feb;
    --tag-text: #ffffff;
    --shadow: rgba(0, 0, 0, 0.3);
    --transition: 0.2s ease;
}

[data-theme="light"] {
    --bg-primary: #f6f8fa;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --text-primary: #1f2328;
    --text-secondary: #656d76;
    --accent: #0969da;
    --accent-hover: #0550ae;
    --border: #d0d7de;
    --success: #1a7f37;
    --tag-bg: #0969da;
    --tag-text: #ffffff;
    --shadow: rgba(0, 0, 0, 0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background var(--transition), color var(--transition);
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* ===== Header ===== */
.header {
    text-align: center;
    padding: 40px 0;
    border-bottom: 1px solid var(--border);
    margin-bottom: 30px;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
}

.logo {
    font-size: 2rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo-icon {
    font-size: 2.5rem;
    color: var(--accent);
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-top: 10px;
}

.theme-toggle {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px 15px;
    cursor: pointer;
    font-size: 1.2rem;
    transition: all var(--transition);
}

.theme-toggle:hover {
    background: var(--bg-secondary);
    border-color: var(--accent);
}

/* ===== Stats Bar ===== */
.stats-bar {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 15px;
    margin-bottom: 30px;
}

.stat {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 15px 20px;
    text-align: center;
}

.stat-label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 5px;
}

.stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
}

/* ===== Loading ===== */
.loading {
    text-align: center;
    padding: 60px 20px;
}

.spinner {
    width: 50px;
    height: 50px;
    margin: 0 auto 20px;
    border: 4px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Activity Feed ===== */
.activity-feed {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.date-group {
    margin-bottom: 30px;
}

.date-header {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border);
}

/* ===== Activity Card ===== */
.activity-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin-bottom: 20px;
    transition: all var(--transition);
}

.activity-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px var(--shadow);
    border-color: var(--accent);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 15px;
    gap: 15px;
}

.card-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--accent);
}

.card-date {
    font-size: 0.85rem;
    color: var(--text-secondary);
    white-space: nowrap;
}

.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 15px;
}

.tag {
    background: var(--tag-bg);
    color: var(--tag-text);
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
}

.card-content {
    color: var(--text-primary);
    line-height: 1.7;
}

/* Markdown content styling */
.card-content h1 {
    font-size: 1.5rem;
    margin-top: 20px;
    margin-bottom: 15px;
    color: var(--text-primary);
}

.card-content h2 {
    font-size: 1.2rem;
    margin-top: 20px;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.card-content h3 {
    font-size: 1.1rem;
    margin-top: 15px;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.card-content p {
    margin-bottom: 12px;
}

.card-content ul {
    margin-left: 20px;
    margin-bottom: 15px;
}

.card-content ol {
    margin-left: 20px;
    margin-bottom: 15px;
}

.card-content li {
    margin-bottom: 6px;
}

.card-content code {
    background: var(--bg-secondary);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: 'SF Mono', Monaco, 'Cascadia Code', monospace;
    font-size: 0.9em;
}

.card-content pre {
    background: var(--bg-secondary);
    padding: 15px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 15px 0;
}

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

.card-content strong {
    font-weight: 600;
}

.card-content em {
    font-style: italic;
}

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

.card-content a:hover {
    text-decoration: underline;
}

.card-content blockquote {
    border-left: 3px solid var(--accent);
    padding-left: 15px;
    margin: 15px 0;
    color: var(--text-secondary);
}

.card-content hr {
    border: none;
    border-top: 1px solid var(--border);
    margin: 20px 0;
}

.session-link {
    display: inline-block;
    margin-top: 10px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.session-link:hover {
    color: var(--accent);
}

/* ===== Empty State ===== */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
}

.empty-state-icon {
    font-size: 4rem;
    margin-bottom: 15px;
}

.empty-state-title {
    font-size: 1.3rem;
    margin-bottom: 10px;
    color: var(--text-primary);
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: 40px 0 20px;
    margin-top: 60px;
    border-top: 1px solid var(--border);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

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

.footer a:hover {
    text-decoration: underline;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .logo {
        font-size: 1.5rem;
    }

    .logo-icon {
        font-size: 2rem;
    }

    .card-header {
        flex-direction: column;
    }

    .stats-bar {
        grid-template-columns: 1fr;
    }
}