:root {
    --color-primary: #2563eb;
    --color-primary-dark: #1e40af;
    --color-text: #1f2937;
    --color-text-muted: #6b7280;
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-border: #e5e7eb;
    --max-width: 1100px;
}

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

html {
    scroll-behavior: smooth;
}

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

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    color: var(--color-primary);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

/* --- Main layout --- */
main {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 56px 24px 32px;
}

/* --- Hero --- */
.hero {
    text-align: center;
    margin-bottom: 24px;
}

.hero-logo {
    width: clamp(220px, 30vw, 320px);
    height: auto;
    margin: 0 auto 24px;
}

.hero .lead {
    font-size: clamp(16px, 1.6vw, 19px);
    color: var(--color-text-muted);
    max-width: 720px;
    margin: 0 auto 32px;
}

.cta {
    display: inline-block;
    padding: 14px 36px;
    background: var(--color-primary);
    color: #ffffff;
    font-size: 17px;
    font-weight: 600;
    border-radius: 8px;
    transition: background 0.2s, transform 0.1s;
    box-shadow: 0 1px 3px rgba(37, 99, 235, 0.25);
}

.cta:hover {
    background: var(--color-primary-dark);
    text-decoration: none;
    transform: translateY(-1px);
}

/* --- Diagram --- */
.diagram {
    margin: 0 auto;
}

.diagram img {
    width: 100%;
    height: auto;
}

/* --- Footer --- */
footer {
    border-top: 1px solid var(--color-border);
    background: var(--color-bg-alt);
    padding: 28px 24px;
    margin-top: 48px;
}

footer .contact,
footer .copyright {
    max-width: var(--max-width);
    margin: 0 auto;
    text-align: center;
}

footer .contact {
    margin-bottom: 6px;
    font-size: 15px;
}

footer .copyright {
    font-size: 13px;
    color: var(--color-text-muted);
}

/* --- Responsive tweaks --- */
@media (max-width: 640px) {
    main {
        padding: 32px 20px 24px;
    }

    .hero {
        margin-bottom: 16px;
    }

    .hero-logo {
        width: 200px;
        margin-bottom: 16px;
    }

    footer {
        margin-top: 32px;
    }
}