@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap');

:root {
    --bg: #fafafa;
    --bg-secondary: #ffffff;
    --text: #1a1a2e;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border: #e8e8ec;
    --accent: #2563eb;
    --accent-bg: #f0f4ff;
    --card-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
    --card-shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.06);
    --radius: 10px;
    --radius-lg: 12px;
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    --bg: #0c0c10;
    --bg-secondary: #141418;
    --text: #e4e4e7;
    --text-secondary: #71717a;
    --text-muted: #52525b;
    --border: #232328;
    --accent: #3b82f6;
    --accent-bg: #161622;
    --card-shadow: 0 1px 2px rgba(0, 0, 0, 0.3);
    --card-shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.4);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    width: 100%;
    min-height: 100vh;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    transition: background var(--transition), color var(--transition);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.top-bar {
    position: fixed;
    top: 0;
    right: 0;
    padding: 24px 40px;
    z-index: 100;
}

.theme-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border: none;
    background: transparent;
    color: var(--text-muted);
    cursor: pointer;
    transition: color var(--transition);
}

.theme-toggle:hover {
    color: var(--text);
}

.theme-toggle .icon-moon {
    display: none;
}

[data-theme="dark"] .theme-toggle .icon-sun {
    display: none;
}

[data-theme="dark"] .theme-toggle .icon-moon {
    display: block;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 160px 40px 60px;
}

.hero {
    text-align: center;
    margin-bottom: 60px;
    animation: fadeIn 0.6s ease-out;
}

.tagline {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 400;
    letter-spacing: 0.01em;
    line-height: 1.7;
    transition: color var(--transition);
}

.hero-divider {
    width: 100%;
    height: 1px;
    background: var(--border);
    margin: 24px 0 0;
}

.columns {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    animation: fadeIn 0.6s ease-out 0.1s both;
}

.column {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all var(--transition);
}

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

.column-header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
}

.column-number {
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--text-muted);
    letter-spacing: 0;
}

.column-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text);
    letter-spacing: -0.01em;
}

.column-content {
    padding: 24px;
}

.column-desc {
    font-size: 0.825rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 20px;
}

.items {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.item {
    padding: 12px 14px;
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition);
    border: 1px solid transparent;
}

.item:hover {
    background: var(--accent-bg);
}

.item.active {
    background: var(--accent-bg);
    border-color: var(--border);
}

.item-title {
    font-weight: 500;
    color: var(--text);
    font-size: 0.825rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

.item-title::before {
    content: '';
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--accent);
    opacity: 0.4;
    flex-shrink: 0;
    transition: opacity var(--transition);
}

.item.active .item-title::before {
    opacity: 1;
}

.item-desc {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-top: 8px;
    display: none;
}

.item.active .item-desc {
    display: block;
    animation: slideDown 0.2s ease-out;
}

.footer {
    text-align: center;
    padding: 40px;
    border-top: 1px solid var(--border);
    font-size: 0.8rem;
    color: var(--text-muted);
}

.footer a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition);
}

.footer a:hover {
    color: var(--text);
}

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

.footer-divider {
    margin: 0 10px;
    opacity: 0.4;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 900px) {
    .columns {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .container {
        padding: 130px 24px 40px;
    }

    .hero {
        margin-bottom: 60px;
    }

    .top-bar {
        padding: 20px 24px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 110px 16px 32px;
    }

    .top-bar {
        padding: 16px 16px;
    }

    .column-content {
        padding: 20px;
    }

    .column-header {
        padding: 16px 20px;
    }
}

@media print {
    .top-bar, .theme-toggle {
        display: none !important;
    }

    body {
        background: white !important;
        color: black !important;
        font-size: 11pt;
    }

    .container {
        padding: 0;
        max-width: 100%;
    }

    .hero {
        margin-bottom: 24px;
    }

    .tagline {
        color: #444 !important;
    }

    .columns {
        grid-template-columns: repeat(3, 1fr);
        gap: 16px;
    }

    .column {
        border: 1px solid #ccc;
        box-shadow: none !important;
        break-inside: avoid;
    }

    .column-header {
        background: #f5f5f5 !important;
        border-bottom: 1px solid #ccc;
    }

    .column-number, .column-title {
        color: black !important;
    }

    .item {
        border: none;
        padding: 6px 0;
    }

    .item-title::before {
        display: none;
    }

    .item-desc {
        display: block !important;
        font-size: 0.8rem;
        color: #444 !important;
    }

    .footer {
        border-top: 1px solid #ccc;
        color: #666 !important;
    }

    .footer a {
        color: #333 !important;
    }
}