/* 밝은 배경 + 코발트 블루 포인트 */
:root {
  --bg: #f6f8fc;
  --surface: #ffffff;
  --border: #e2e8f2;
  --ink: #1a2233;
  --ink-soft: #64708a;
  --cobalt: #0047ab;        /* 코발트 블루 */
  --cobalt-soft: #e8effa;
  --cobalt-deep: #003585;
  --warn: #b45309;
  --warn-soft: #fffaf0;
  --radius: 14px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 18px;
  padding: 24px 20px;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo",
               "Pretendard", "Malgun Gothic", system-ui, sans-serif;
  line-height: 1.6;
}

.card {
  width: 100%;
  max-width: 480px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: clamp(24px, 6vw, 36px);
  box-shadow: 0 1px 3px rgba(20, 40, 90, .06), 0 8px 24px rgba(20, 40, 90, .05);
}

h1 {
  margin: 0 0 6px;
  font-size: clamp(1.5rem, 5vw, 1.9rem);
  letter-spacing: -.02em;
  color: var(--cobalt);
}
.lede { margin: 0 0 22px; color: var(--ink-soft); font-size: .95rem; }

.input-row { display: flex; gap: 8px; }

input {
  flex: 1;
  min-width: 0;
  font: inherit;
  font-size: 1.05rem;
  padding: 12px 14px;
  border: 1.5px solid var(--border);
  border-radius: 10px;
  background: var(--bg);
  color: var(--ink);
}
input:focus {
  outline: none;
  border-color: var(--cobalt);
  background: var(--surface);
  box-shadow: 0 0 0 3px var(--cobalt-soft);
}
input.invalid { border-color: var(--warn); }

button {
  font: inherit; font-weight: 700;
  padding: 12px 20px;
  border: none; border-radius: 10px;
  background: var(--cobalt); color: #fff;
  cursor: pointer;
  white-space: nowrap;
}
button:hover { background: var(--cobalt-deep); }
button:focus-visible { outline: 3px solid var(--cobalt-soft); outline-offset: 2px; }

/* 안내 메시지 — 잘못 입력했을 때만 보인다 */
.message {
  margin: 12px 0 0;
  font-size: .9rem;
  color: var(--warn);
  background: var(--warn-soft);
  border: 1px solid #f5d9a8;
  border-radius: 8px;
  padding: 10px 12px;
}
.message:empty { display: none; }

/* 결과 */
.result {
  margin-top: 20px;
  padding: 20px;
  border-radius: 12px;
  background: var(--cobalt-soft);
  border: 1.5px solid #c3d6f5;
  text-align: center;
}
.verdict {
  margin: 0;
  font-size: clamp(1.3rem, 5vw, 1.6rem);
  font-weight: 750;
  color: var(--cobalt);
  letter-spacing: -.02em;
}
.reason { margin: 6px 0 0; font-size: .9rem; color: var(--ink-soft); }

details { margin-top: 14px; text-align: left; }
summary {
  cursor: pointer; font-size: .85rem; font-weight: 600; color: var(--cobalt);
}
.steps {
  margin-top: 8px; padding: 10px 12px;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
  font-size: .82rem; color: var(--ink-soft);
  font-variant-numeric: tabular-nums;
  max-height: 190px; overflow-y: auto;
}
.steps div { padding: 1px 0; }
.steps .hit { color: var(--warn); font-weight: 700; }

/* 예시 칩 */
.examples { margin-top: 22px; }
.hint { margin: 0 0 8px; font-size: .82rem; color: var(--ink-soft); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chips button {
  background: var(--surface);
  color: var(--ink-soft);
  border: 1.5px solid var(--border);
  font-size: .85rem; font-weight: 600;
  padding: 6px 12px; border-radius: 999px;
}
.chips button:hover { border-color: var(--cobalt); color: var(--cobalt); background: var(--surface); }

footer { font-size: .8rem; color: var(--ink-soft); }
footer p { margin: 0; }

.visually-hidden {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}