:root {
    --background: #f8fafc;
    --surface: #ffffff;
    --text: #0f172a;
    --muted: #64748b;
    --border: #e2e8f0;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
}

* {
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    margin: 0;
    background: var(--background);
    color: var(--text);
    font-family:
        Inter,
        system-ui,
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        sans-serif;
    line-height: 1.6;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.hero {
    padding: 5rem 0 3rem;
    text-align: center;
}

.hero h1 {
    margin: 0;
    font-size: clamp(2.5rem, 6vw, 4rem);
    font-weight: 700;
}

.subtitle {
    margin-top: 1rem;
    color: var(--muted);
    font-size: 1.15rem;
}

.notes-grid {
    display: grid;
    gap: 1.5rem;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    padding-bottom: 4rem;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 18px;
    padding: 1.5rem;

    transition:
        transform 0.15s ease,
        box-shadow 0.15s ease;
}

.card:hover {
    transform: translateY(-2px);

    box-shadow:
        0 10px 30px rgba(15, 23, 42, 0.08);
}

.card h2 {
    margin-top: 0;
    margin-bottom: 0.75rem;
    font-size: 1.3rem;
}

.card p {
    color: var(--muted);
    margin-bottom: 1.5rem;
}

.button {
    display: inline-block;

    padding: 0.75rem 1rem;

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

    text-decoration: none;
    border-radius: 10px;

    font-weight: 600;

    transition: background 0.15s ease;
}

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

footer {
    border-top: 1px solid var(--border);
    padding: 2rem 0;
    text-align: center;
    color: var(--muted);
}

@media (max-width: 600px) {

    .hero {
        padding-top: 3rem;
    }

    .card {
        padding: 1.25rem;
    }
}