:root {
  --bg: #eef3f1;
  --surface: #ffffff;
  --text: #14232a;
  --muted: #55676d;
  --line: #c9d6d2;
  --accent: #0b6e6e;
  --accent-dark: #084f4f;
  --error: #b4432b;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.5;
}

main { max-width: 760px; margin: 0 auto; padding: 40px 20px 60px; }

h1 { margin: 0 0 4px; font-size: 2.2rem; letter-spacing: -0.02em; }
.sub { margin: 0 0 12px; color: var(--muted); max-width: 52ch; }

.status { display: inline-block; margin: 0 0 28px; padding: 2px 10px; border: 1px solid var(--line); border-radius: 99px; font-size: 0.85rem; color: var(--muted); background: var(--surface); }
.status.ok { color: #0a6b3a; border-color: #0a6b3a; }
.status.down { color: var(--error); border-color: var(--error); }

.panel { display: grid; grid-template-columns: 1fr; gap: 28px; background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 28px; }
@media (min-width: 700px) { .panel { grid-template-columns: 1fr 1fr; } }

label { display: block; margin: 0 0 4px; font-weight: 600; }
input { width: 100%; margin: 0 0 16px; padding: 10px 12px; font-size: 1rem; border: 1px solid var(--line); border-radius: 6px; background: #fff; color: var(--text); }
input:focus-visible, button:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }

button { width: 100%; padding: 12px; font-size: 1rem; font-weight: 600; color: #fff; background: var(--accent); border: 0; border-radius: 6px; cursor: pointer; }
button:hover { background: var(--accent-dark); }
button:disabled { opacity: 0.6; cursor: wait; }

.error { margin: 12px 0 0; color: var(--error); font-weight: 500; }

.result { border-left: 1px solid var(--line); padding-left: 28px; }
@media (max-width: 699px) { .result { border-left: 0; border-top: 1px solid var(--line); padding: 24px 0 0; } }

.bmi-value { margin: 0; font-size: 4rem; font-weight: 700; line-height: 1; letter-spacing: -0.03em; }
.bmi-value small { font-size: 1rem; font-weight: 400; color: var(--muted); letter-spacing: 0; }
.category { margin: 8px 0 24px; font-size: 1.2rem; font-weight: 600; color: var(--accent-dark); }

.gauge { position: relative; height: 14px; }
.bar {
  height: 100%; border-radius: 7px;
  background: linear-gradient(to right,
    #7fb0d6 0 14%,
    #5fae8a 14% 40%,
    #e2b04a 40% 60%,
    #cf6a4e 60% 100%);
}
.marker {
  position: absolute; top: -6px; width: 4px; height: 26px; margin-left: -2px;
  background: var(--text); border-radius: 2px; left: 0;
  transition: left 0.5s ease;
}
.ticks { display: flex; margin-top: 10px; font-size: 0.8rem; color: var(--muted); }
.ticks span:nth-child(1) { width: 14%; }
.ticks span:nth-child(2) { width: 26%; }
.ticks span:nth-child(3) { width: 20%; }
.ticks span:nth-child(4) { width: 40%; }

.note { margin: 20px 0 0; font-size: 0.85rem; color: var(--muted); }

@media (prefers-reduced-motion: reduce) { .marker { transition: none; } }