:root {
  color-scheme: light;
  --bg: #f5f7fa;
  --panel: #ffffff;
  --ink: #1f2937;
  --muted: #5f6b7a;
  --line: #d8dee8;
  --accent: #1769aa;
  --accent-dark: #0f4f85;
  --danger: #a83232;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
input {
  font: inherit;
}

.shell {
  width: min(1180px, calc(100vw - 32px));
  margin: 0 auto;
  padding: 24px 0;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
  padding: 18px 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
}

h1,
h2,
p {
  margin: 0;
}

h1 {
  font-size: 24px;
  line-height: 1.2;
}

h2 {
  font-size: 16px;
  line-height: 1.25;
}

p {
  margin-top: 4px;
  color: var(--muted);
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.panel {
  display: grid;
  gap: 14px;
  padding: 18px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
}

label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 13px;
}

input {
  width: 100%;
  min-height: 40px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  color: var(--ink);
  background: #fff;
}

input:focus {
  outline: 2px solid rgba(23, 105, 170, 0.18);
  border-color: var(--accent);
}

button {
  min-height: 40px;
  padding: 8px 14px;
  border: 0;
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  cursor: pointer;
}

button:hover {
  background: var(--accent-dark);
}

.output-panel {
  grid-column: 1 / -1;
}

pre {
  min-height: 240px;
  margin: 0;
  padding: 14px;
  overflow: auto;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #101826;
  color: #e5edf7;
  font-size: 13px;
  line-height: 1.5;
}

.error {
  color: var(--danger);
}

@media (max-width: 820px) {
  .topbar {
    align-items: stretch;
    flex-direction: column;
  }

  .grid {
    grid-template-columns: 1fr;
  }
}