:root {
    --background: #f5f5f7;
    --surface: #ffffff;
    --text: #111111;
    --text-secondary: #6b6b6b;
    --border: #dddddf;
    --primary: #4b7dff;

    --radius: 18px;

    --shadow:
        0 2px 10px rgba(0, 0, 0, .05);

    --max-width: 900px;
}

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

html {
    font-size: 16px;
}

body {
    background: var(--background);
    color: var(--text);

    font-family:
        Inter,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;

    line-height: 1.7;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 48px 24px 64px;
}

.topbar {

    display: flex;
    justify-content: space-between;
    align-items: center;

    gap: 20px;

    margin-bottom: 48px;
}

h1 {

    font-size: 3rem;
    font-weight: 800;
}

.subtitle {

    font-size: 1.2rem;
    color: var(--text-secondary);

    margin-bottom: 40px;
}

.language-switch {

    display: flex;
    gap: 10px;
}

.language-switch button {

    border: 1px solid var(--border);
    background: white;

    padding: 10px 18px;

    border-radius: 999px;

    cursor: pointer;

    transition: .2s;
}

.language-switch button:hover {

    border-color: var(--primary);
}

.language-switch button.active {

    background: var(--primary);
    color: white;

    border-color: var(--primary);
}

.cards {

    display: grid;
    gap: 20px;
}

.card {

    display: block;

    text-decoration: none;

    color: inherit;

    background: var(--surface);

    border: 1px solid var(--border);

    border-radius: var(--radius);

    padding: 26px;

    transition:
        transform .15s,
        box-shadow .15s,
        border-color .15s;
}

.card:hover {

    transform: translateY(-2px);

    border-color: var(--primary);

    box-shadow: var(--shadow);
}

.card h2 {

    font-size: 1.3rem;

    margin-bottom: 10px;
}

.card p {

    color: var(--text-secondary);
}

footer {

    margin-top: 80px;

    text-align: center;

    color: var(--text-secondary);

    font-size: .95rem;
}

.hidden {

    display: none;
}

/* ---------- */

.document {

    background: white;

    border: 1px solid var(--border);

    border-radius: var(--radius);

    padding: 40px;

    box-shadow: var(--shadow);
}

.document h1 {

    font-size: 2.2rem;

    margin-bottom: 16px;
}

.document h2 {

    margin-top: 40px;

    margin-bottom: 12px;

    font-size: 1.35rem;
}

.document p {

    margin-bottom: 16px;
}

.document ul {

    padding-left: 24px;

    margin-bottom: 16px;
}

.document li {

    margin-bottom: 8px;
}

.document a {

    color: var(--primary);
}

.back {

    display: inline-block;

    margin-bottom: 28px;

    text-decoration: none;

    color: var(--primary);

    font-weight: 600;
}

/* ---------- */

@media (max-width: 640px) {

    .topbar {

        flex-direction: column;
        align-items: flex-start;
    }

    h1 {

        font-size: 2.5rem;
    }

    .document {

        padding: 24px;
    }

}