/* ===== Reset & Base ===== */

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

:root {
    --bg: #191919;
    --bg-secondary: #222222;
    --text: #e8e8e8;
    --text-secondary: #999999;
    --border: #2e2e2e;
    --accent: #e8e8e8;
    --radius: 8px;
    --max-width: 720px;
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
        "Helvetica Neue", Arial, sans-serif;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    font-family: var(--font);
    font-size: 16px;
    line-height: 1.7;
    color: var(--text);
    background: var(--bg);
    -webkit-font-smoothing: antialiased;
}

/* ===== Layout ===== */

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* ===== Nav ===== */

.nav {
    position: sticky;
    top: 0;
    background: rgba(25, 25, 25, 0.92);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    z-index: 100;
}

.nav-inner {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 56px;
    gap: 24px;
}

.nav-logo {
    font-weight: 600;
    font-size: 15px;
    color: var(--text);
    text-decoration: none;
    white-space: nowrap;
    flex-shrink: 0;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 16px;
    flex-shrink: 1;
    min-width: 0;
    flex-wrap: nowrap;
    overflow-x: auto;
    -ms-overflow-style: none;
    scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
    display: none;
}

.nav-links a {
    font-size: 13px;
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s;
    white-space: nowrap;
}

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

/* ===== Nav toggle (mobile) ===== */

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 20px;
    height: 2px;
    background: var(--text);
    border-radius: 1px;
}

/* ===== Hero ===== */

.hero {
    padding: 80px 0 48px;
    border-bottom: 1px solid var(--border);
}

.hero h1 {
    font-size: 32px;
    font-weight: 700;
    letter-spacing: -0.5px;
    margin-bottom: 8px;
}

.hero-subtitle {
    font-size: 17px;
    color: var(--text-secondary);
    margin-bottom: 24px;
}

.hero-intro {
    font-size: 15px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ===== Sections ===== */

.section {
    padding: 48px 0;
    border-bottom: 1px solid var(--border);
}

.section:last-child {
    border-bottom: none;
}

.section h2 {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 16px;
    letter-spacing: -0.3px;
}

.section > p {
    color: var(--text-secondary);
    font-size: 15px;
    margin-bottom: 20px;
}

/* ===== Cards ===== */

.card {
    background: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    margin-bottom: 16px;
}

.card:last-child {
    margin-bottom: 0;
}

.card h3 {
    font-size: 14px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.card ul {
    list-style: none;
}

.card ul li {
    position: relative;
    padding-left: 18px;
    font-size: 15px;
    margin-bottom: 8px;
    color: var(--text);
}

.card ul li:last-child {
    margin-bottom: 0;
}

.card ul li::before {
    content: "";
    position: absolute;
    left: 0;
    top: 10px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--text-secondary);
}

/* ===== Checklist ===== */

.checklist {
    list-style: none;
}

.checklist li {
    padding-left: 0 !important;
    margin-bottom: 12px;
}

.checklist li::before {
    display: none !important;
}

.checklist label {
    display: flex;
    align-items: center;
    gap: 12px;
    cursor: pointer;
    font-size: 15px;
}

.checklist input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    min-width: 20px;
    border: 2px solid var(--border);
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.15s;
    position: relative;
    background: transparent;
}

.checklist input[type="checkbox"]:checked {
    background: var(--accent);
    border-color: var(--accent);
}

.checklist input[type="checkbox"]:checked::after {
    content: "";
    position: absolute;
    left: 5px;
    top: 2px;
    width: 5px;
    height: 9px;
    border: solid var(--bg);
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
}

.checklist input[type="checkbox"]:checked + span {
    color: var(--text-secondary);
    text-decoration: line-through;
}

/* ===== Footer ===== */

.footer {
    padding: 32px 0;
    border-top: 1px solid var(--border);
}

.footer p {
    font-size: 13px;
    color: var(--text-secondary);
    text-align: center;
}

/* ===== Mobile ===== */

@media (max-width: 640px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 56px;
        left: 0;
        right: 0;
        background: rgba(25, 25, 25, 0.98);
        backdrop-filter: blur(12px);
        -webkit-backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 16px 20px 24px;
        gap: 0;
        border-bottom: 1px solid var(--border);
        overflow-x: visible;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links li {
        border-bottom: 1px solid var(--border);
    }

    .nav-links li:last-child {
        border-bottom: none;
    }

    .nav-links a {
        display: block;
        padding: 12px 0;
        font-size: 15px;
    }

    .hero {
        padding: 56px 0 36px;
    }

    .hero h1 {
        font-size: 26px;
    }

    .section {
        padding: 36px 0;
    }

    .section h2 {
        font-size: 20px;
    }

    .card {
        padding: 20px;
    }
}