body {
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    margin: 0;
    padding: 0;
    background: #0f172a;
    color: #f8fafc;
}
header, section, footer, main.card {
    max-width: 720px;
    margin: 24px auto;
    padding: 24px;
    background: rgba(15, 23, 42, 0.85);
    border-radius: 12px;
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.3);
}
h1, h2 {
    margin-top: 0;
}
.button, button {
    display: inline-block;
    background: #22d3ee;
    color: #0f172a;
    padding: 10px 18px;
    border-radius: 999px;
    text-decoration: none;
    font-weight: 600;
    border: none;
    cursor: pointer;
}
button.secondary {
    background: transparent;
    color: #e2e8f0;
    border: 1px solid rgba(226, 232, 240, 0.4);
}
input {
    width: 100%;
    padding: 8px;
    margin-top: 4px;
    border-radius: 6px;
    border: 1px solid rgba(226, 232, 240, 0.3);
}
label {
    display: block;
    margin-bottom: 12px;
}
ul {
    list-style: none;
    padding: 0;
}
ul li {
    margin-bottom: 8px;
}
.error {
    color: #f87171;
}
footer {
    text-align: center;
    font-size: 0.9rem;
    opacity: 0.7;
}