:root {
    color-scheme: light dark;
    --bg: #fafaf9;
    --surface: #ffffff;
    --text: #1c1917;
    --text-muted: #57534e;
    --accent: #2563eb;
    --border: #e7e5e4;
    --warn-bg: #fef3c7;
    --warn-fg: #78350f;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #0c0a09;
        --surface: #1c1917;
        --text: #fafaf9;
        --text-muted: #a8a29e;
        --accent: #60a5fa;
        --border: #292524;
        --warn-bg: #422006;
        --warn-fg: #fde68a;
    }
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: grid;
    place-items: center;
    padding: 1.5rem;
}

.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 2rem 2.25rem;
    max-width: 28rem;
    width: 100%;
    box-shadow: 0 1px 2px rgba(0,0,0,0.04);
}

h1 {
    margin: 0 0 0.5rem;
    font-size: 1.75rem;
    letter-spacing: -0.02em;
}

p.lede {
    color: var(--text-muted);
    margin-top: 0;
    line-height: 1.55;
}

.chip {
    display: inline-block;
    background: var(--accent);
    color: white;
    padding: 0.25rem 0.625rem;
    border-radius: 999px;
    font-size: 0.8125rem;
    margin: 0.5rem 0 1rem;
}

.signin-list {
    list-style: none;
    padding: 0;
    margin: 1.5rem 0 0;
    display: grid;
    gap: 0.625rem;
}

.signin-btn {
    display: block;
    text-align: center;
    padding: 0.75rem 1rem;
    background: var(--surface);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: border-color 100ms;
}

.signin-btn:hover {
    border-color: var(--accent);
}

.warn {
    background: var(--warn-bg);
    color: var(--warn-fg);
    padding: 0.875rem 1rem;
    border-radius: 8px;
    margin: 1.25rem 0 0;
    font-size: 0.9375rem;
    line-height: 1.5;
}

footer {
    margin-top: 2rem;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border);
    color: var(--text-muted);
    font-size: 0.8125rem;
    line-height: 1.5;
}

code {
    font-family: ui-monospace, "SF Mono", Menlo, monospace;
    font-size: 0.875em;
    background: var(--bg);
    padding: 0.0625rem 0.3125rem;
    border-radius: 4px;
}