:root {
  color-scheme: light;
  --ink: #14201a;
  --muted: #5b6b63;
  --paper: #f3f6f2;
  --panel: #ffffff;
  --line: #c9d5cc;
  --ok: #1f7a3f;
  --bad: #b42318;
  --wait: #9a6700;
  --err: #6941c6;
  --brand: #0f3d2e;
  font-family: "IBM Plex Sans", "Segoe UI", sans-serif;
  line-height: 1.5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background:
    radial-gradient(1200px 500px at 10% -10%, #d9ebe1 0%, transparent 55%),
    linear-gradient(180deg, #eef3ef 0%, var(--paper) 40%, #e7eee9 100%);
}

main {
  max-width: 34rem;
  margin: 0 auto;
  padding: 3.5rem 1.25rem 4rem;
}

.brand {
  margin: 0 0 0.75rem;
  font-size: clamp(2.4rem, 8vw, 3.4rem);
  font-weight: 700;
  letter-spacing: -0.04em;
  color: var(--brand);
  line-height: 1;
}

h1 {
  margin: 0 0 0.5rem;
  font-size: 1.15rem;
  font-weight: 600;
}

.lead {
  margin: 0 0 1.5rem;
  color: var(--muted);
}

.guide {
  margin: 0 0 1.5rem;
  padding: 0.9rem 1rem;
  border: 1px dashed var(--line);
  background: color-mix(in srgb, var(--panel) 80%, #e4f0e8);
}

.guide-title {
  margin: 0 0 0.4rem;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.guide ul {
  margin: 0;
  padding-left: 1.1rem;
}

.guide li + li {
  margin-top: 0.25rem;
}

label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

input {
  width: 100%;
  padding: 0.7rem 0.8rem;
  border: 1px solid var(--line);
  border-radius: 0.35rem;
  background: var(--panel);
  font: inherit;
}

input:focus {
  outline: 2px solid color-mix(in srgb, var(--brand) 45%, white);
  outline-offset: 1px;
}

[data-ex-status="pending"] {
  outline: 2px solid var(--wait);
}

[data-ex-status="success"] {
  outline: 2px solid var(--ok);
}

[data-ex-status="invalid"] {
  outline: 2px solid var(--bad);
}

[data-ex-status="error"] {
  outline: 2px solid var(--err);
}

.msg {
  margin-top: 0.75rem;
  min-height: 1.5rem;
  color: var(--muted);
  font-size: 0.95rem;
}

.msg[data-ex-status="pending"]::before {
  content: "checking…";
}

.msg[data-ex-status="success"]::before {
  content: "available";
  color: var(--ok);
}

.msg[data-ex-status="invalid"]::before {
  content: "already taken";
  color: var(--bad);
}

.msg[data-ex-status="error"]::before {
  content: "request failed";
  color: var(--err);
}

.msg[data-ex-status="error"][data-ex-error="http:400"]::before {
  content: "empty is not allowed";
}

.foot {
  margin-top: 2rem;
  color: var(--muted);
  font-size: 0.85rem;
}

code {
  font-family: "IBM Plex Mono", ui-monospace, monospace;
  font-size: 0.9em;
}

a {
  color: var(--brand);
}