:root {
    color-scheme: dark;
    --background: #10151b;
    --panel: #181f27;
    --inset: #12181f;
    --text: #eef2f5;
    --muted: #a0adbb;
    --line: #303c48;
    --accent: #b6e29d;
    --error: #ffb0a9;
    font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
body { margin: 0; background: var(--background); color: var(--text); line-height: 1.6; }
.shell { width: min(1080px, 100% - 64px); margin: 0 auto; }
a { color: inherit; }
.masthead { display: flex; justify-content: space-between; align-items: center; padding: 30px 0; border-bottom: 1px solid var(--line); }
.wordmark { font-weight: 700; text-decoration: none; letter-spacing: -.04em; font-size: 22px; }
.wordmark span { font-weight: 400; color: var(--muted); }
.environment { font-size: 12px; text-transform: uppercase; letter-spacing: .12em; color: var(--accent); }
.intro { padding: 68px 0 42px; }
.eyebrow { color: var(--accent); text-transform: uppercase; letter-spacing: .13em; font-size: 11px; font-weight: 650; margin: 0 0 16px; }
h1 { font-size: clamp(36px, 6vw, 62px); line-height: 1.08; letter-spacing: -.055em; font-weight: 550; margin: 0 0 24px; }
.lede { max-width: 540px; color: var(--muted); font-size: 16px; margin: 0; }
h2 { font-size: 19px; font-weight: 550; letter-spacing: -.025em; margin: 0; }
.request-panel { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 24px 28px; }
.panel-heading { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.tag { font: 12px ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; color: var(--accent); background: #23332a; padding: 5px 10px; border-radius: 4px; }
.request-details { display: grid; grid-template-columns: 1fr 1fr 1.5fr; gap: 24px; margin: 24px 0 18px; }
dt { color: var(--muted); font-size: 12px; margin-bottom: 5px; }
dd { margin: 0; font: 14px/1.5 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; overflow-wrap: anywhere; }
.fine-print { margin: 0; color: var(--muted); font-size: 12px; }
.echo-panel { margin-top: 24px; display: grid; grid-template-columns: 1.15fr 1fr; border: 1px solid var(--line); border-radius: 12px; overflow: hidden; }
.form-column { padding: 30px 28px; }
.form-column .eyebrow { margin-bottom: 10px; }
.description { color: var(--muted); font-size: 14px; margin: 12px 0 24px; }
label { display: block; font-weight: 550; font-size: 13px; margin-bottom: 8px; }
textarea { display: block; width: 100%; border: 1px solid #42505f; border-radius: 6px; background: var(--inset); color: var(--text); resize: vertical; min-height: 120px; padding: 12px; font: 14px/1.6 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }
textarea::placeholder { color: #8492a1; opacity: 1; }
textarea:focus-visible, button:focus-visible, a:focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
.field-help { color: var(--muted); font-size: 11px; margin: 10px 0 20px; }
button { display: flex; align-items: center; justify-content: space-between; gap: 28px; background: var(--accent); color: #17241a; font: 650 13px/1.5 ui-sans-serif, system-ui, sans-serif; border: 0; border-radius: 6px; padding: 12px 16px; cursor: pointer; }
button:hover { background: #c7edb2; }
button span { font-size: 19px; line-height: 1; }
.response-column { padding: 30px 28px; background: var(--inset); border-left: 1px solid var(--line); min-width: 0; }
.response-column .eyebrow { color: var(--muted); }
.response-status { font-size: 14px; margin: 24px 0 14px; }
.response-status span { display: block; color: var(--muted); font-size: 11px; margin-top: 6px; }
.response-help { font-size: 13px; color: var(--muted); max-width: 250px; }
.muted { color: var(--muted); }
.error { color: var(--error); }
.echo-output { font: 13px/1.7 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; white-space: pre-wrap; overflow-wrap: anywhere; margin: 0; }
footer { display: flex; justify-content: space-between; gap: 20px; padding: 30px 0 36px; color: var(--muted); font-size: 11px; }

@media (max-width: 700px) {
    .shell { width: calc(100% - 36px); }
    .masthead { padding: 22px 0; }
    .wordmark { font-size: 20px; }
    .environment { font-size: 10px; }
    .intro { padding: 44px 0 30px; }
    .request-panel, .form-column, .response-column { padding: 22px; }
    .request-details { grid-template-columns: 1fr; gap: 16px; }
    .echo-panel { grid-template-columns: 1fr; }
    .response-column { border-left: 0; border-top: 1px solid var(--line); min-height: 180px; }
    button { width: 100%; }
    footer { flex-direction: column; gap: 4px; }
}