:root {
  color-scheme: dark;
  --canvas: #111713;
  --surface: #1a241d;
  --surface-raised: #222e25;
  --border: #3b4e40;
  --text: #f1f3e8;
  --muted: #b4bfb1;
  --accent: #c8d95b;
  --accent-ink: #17200d;
  --danger: #ffb4a8;
  --focus: #f2d879;
  font-family: Inter, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-width: 320px;
  background: radial-gradient(circle at top right, #283726 0, transparent 33rem), var(--canvas);
  color: var(--text);
}

.app-shell { width: min(100% - 2rem, 900px); margin: 0 auto; padding: 3rem 0 2rem; }
.masthead { border-left: 4px solid var(--accent); padding-left: 1rem; margin-bottom: 2rem; }
.eyebrow { color: var(--accent); font-size: .75rem; font-weight: 800; letter-spacing: .12em; margin: 0 0 .45rem; text-transform: uppercase; }
h1, h2, p { margin-top: 0; }
h1 { font-size: clamp(2rem, 5vw, 3.2rem); letter-spacing: -.04em; line-height: 1; margin-bottom: .75rem; }
h2 { font-size: 1rem; margin-bottom: .4rem; }
.intro { color: var(--muted); margin-bottom: 0; max-width: 44rem; }

form, .result-panel { background: var(--surface); border: 1px solid var(--border); }
form { padding: clamp(1rem, 3vw, 2rem); }
.coordinate-grid { display: grid; gap: 1rem; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.field-card { background: var(--surface-raised); border: 1px solid var(--border); padding: 1rem; }
label { display: block; font-size: .9rem; font-weight: 750; margin-bottom: .5rem; }
.field-hint { color: var(--muted); font-size: .875rem; line-height: 1.45; }
.field-hint { margin-bottom: .75rem; }
code { color: var(--accent); font-family: "Cascadia Code", Consolas, monospace; }
input {
  width: 100%; min-height: 2.8rem; border: 1px solid #687d6b; border-radius: 0; background: #101712;
  color: var(--text); font: inherit; padding: .6rem .7rem;
}
input:focus-visible, button:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; }
input[aria-invalid="true"] { border-color: var(--danger); }
.error-message { color: var(--danger); font-size: .8rem; font-weight: 650; min-height: 1.15rem; margin: .45rem 0 0; }

.actions { display: flex; flex-wrap: wrap; gap: .75rem; margin-top: 1.5rem; }
.button { border: 1px solid var(--border); border-radius: 0; cursor: pointer; font: inherit; font-weight: 750; min-height: 2.8rem; padding: .65rem 1rem; }
.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.button:hover { filter: brightness(1.1); }

.result-panel { margin-top: 1rem; padding: clamp(1rem, 3vw, 2rem); }
.result-panel h2 { font-size: clamp(3rem, 10vw, 5.5rem); letter-spacing: -.06em; line-height: .9; margin: .35rem 0 .8rem; }
.range-unit { color: var(--accent); font-size: .45em; letter-spacing: 0; }

@media (max-width: 620px) {
  .app-shell { width: min(100% - 1rem, 900px); padding-top: 1.25rem; }
  .coordinate-grid { grid-template-columns: 1fr; }
  .actions { display: grid; grid-template-columns: 1fr; }
}