* { box-sizing: border-box; }
body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    background: linear-gradient(135deg, #e8f3fb, #f6f9fc);
    color: #1d2b36;
}
.card {
    max-width: 520px;
    margin: 24px;
    padding: 36px 40px;
    background: #fff;
    border-radius: 20px;
    box-shadow: 0 12px 40px rgba(29, 43, 54, 0.12);
}
.logo { display: block; margin-bottom: 16px; }
h1 { margin: 0 0 12px; font-size: 28px; }
p, li { line-height: 1.6; }
ul { padding-left: 20px; }
a { color: #1f78b4; }
code { background: #eef4f9; padding: 1px 6px; border-radius: 6px; }
.css-ok { color: #1a8a4a; }
.css-fail { display: none !important; }
.css-ok { display: inline !important; }