:root {
    --ink: #1d2433;
    --muted: #5b6475;
    --line: #d8dde6;
    --panel: #f4f6f9;
    --accent: #0b6b4f;
    --danger: #b42318;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    color: var(--ink);
    background: #fff;
}

.topbar {
    display: flex;
    align-items: baseline;
    gap: 12px;
    padding: 14px 16px;
    background: var(--accent);
    color: #fff;
}

.topbar .brand { color: #fff; font-weight: 700; font-size: 20px; text-decoration: none; }
.topbar .tag { opacity: .8; font-size: 14px; }

.container { max-width: 760px; margin: 0 auto; padding: 16px; }

.panel { background: var(--panel); border: 1px solid var(--line); border-radius: 8px; padding: 16px; margin: 16px 0; }

label { display: block; font-weight: 600; margin: 12px 0 4px; }
.check { font-weight: 400; display: flex; gap: 8px; align-items: center; margin: 6px 0; }

input[type=text], select {
    width: 100%;
    padding: 10px;
    font: inherit;
    border: 1px solid var(--line);
    border-radius: 6px;
}

button, .button {
    display: inline-block;
    margin-top: 16px;
    padding: 12px 20px;
    font: inherit;
    font-weight: 600;
    color: #fff;
    background: var(--accent);
    border: 0;
    border-radius: 6px;
    cursor: pointer;
    text-decoration: none;
}

.muted { color: var(--muted); font-size: 14px; }
.error { color: var(--danger); }
.ok { color: var(--accent); }

details summary { cursor: pointer; font-weight: 600; }

pre {
    overflow-x: auto;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 6px;
    padding: 10px;
    font-size: 13px;
}

/* The challenge window: full screen (challengeWindowSize 05). */
.challenge-overlay {
    position: fixed;
    inset: 0;
    display: flex;
    flex-direction: column;
    background: rgba(20, 24, 33, .6);
    padding: 16px;
}

.challenge-overlay .frame-info {
    color: #fff;
    font: 12px/1.4 ui-monospace, Menlo, monospace;
    margin-bottom: 8px;
    word-break: break-all;
}

.challenge-overlay iframe {
    flex: 1;
    width: 100%;
    border: 0;
    border-radius: 8px;
    background: #fff;
}