:root {
    --color-bg: #020617;
    --color-text: #f1f5f9;
    --color-border: #334155;
    --color-surface: #1e293b;
    --color-muted: #94a3b8;
}

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

body {
    font-family: 'Inter', Arial, Helvetica, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    /* WebKit/Blink only — intentional for Safari/Chrome text rendering */
    -webkit-font-smoothing: antialiased;
}

header {
    display: flex;
    flex-direction: column;
    align-items: center;
    max-width: 800px;
    margin: 3rem auto;
    padding: 0 1.5rem;
}

header img {
    width: 7rem;
    height: 7rem;
    margin-bottom: 1.5rem;
}

@media (min-width: 640px) {
    header img { width: 15rem; height: 15rem; }
}

h1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--color-text);
    text-align: center;
    margin-bottom: 0.375rem;
}

@media (min-width: 640px) {
    h1 { font-size: 4.5rem; margin-bottom: 3rem; }
}

main {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1.5rem 4rem;
}

h2 {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.375rem;
}

h4 {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--color-muted);
    margin-bottom: 0.375rem;
}

p {
    margin-bottom: 1.5rem;
    font-size: 1rem;
}

ul {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
    font-size: 1rem;
}

li {
    margin-bottom: 0.25rem;
}

.vo2-link {
    display: inline-block;
    margin-top: 2rem;
    padding: 0.6rem 1.4rem;
    background: var(--color-surface);
    color: var(--color-text);
    border-radius: 8px;
    text-decoration: none;
    font-weight: 600;
    border: 1px solid var(--color-border);
}

.vo2-link:hover { background: var(--color-border); }

.vo2-link:focus,
.vo2-link:focus-visible {
    outline: 2px solid var(--color-text);
    outline-offset: 3px;
}

/* Landing page */

.tagline {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.description {
    color: var(--color-muted);
    max-width: 52ch;
    margin-bottom: 2rem;
}

.link-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

footer {
    max-width: 800px;
    margin: 0 auto;
    padding: 1.5rem 1.5rem 3rem;
    color: var(--color-muted);
    font-size: 0.875rem;
    border-top: 1px solid var(--color-border);
}