/* 단위 변환기 */
:root {
  --bg: #f8fafc;
  --card: #ffffff;
  --ink: #1e293b;
  --muted: #64748b;
  --line: #e2e8f0;
  --orange: #ea580c;
  --orange2: #c2410c;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,.07);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { background: var(--bg); color: var(--ink); font-family: 'Pretendard', 'Apple SD Gothic Neo', sans-serif; font-size: 14px; }

.wrap { max-width: 100%; padding: 0 0 60px; }

/* ── 헤더 ── */
.top { padding: 20px 0 16px; }
.brand { display: flex; align-items: center; gap: 14px; }
.logo {
  width: 48px; height: 48px; flex-shrink: 0;
  background: linear-gradient(135deg, #ea580c, #ca8a04);
  border-radius: 13px; display: flex; align-items: center; justify-content: center; font-size: 22px;
}
h1 { font-size: 22px; font-weight: 700; }
.sub { font-size: 13px; color: var(--muted); margin-top: 2px; }

/* ── 카테고리 탭 ── */
.cat-tabs { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 16px; }
.cat-btn {
  padding: 7px 14px; border-radius: 20px; border: 1.5px solid var(--line);
  background: var(--card); cursor: pointer; font-size: 13px; color: var(--muted);
  transition: all .12s;
}
.cat-btn.active { background: var(--orange); border-color: var(--orange); color: #fff; font-weight: 600; }
.cat-btn:hover:not(.active) { border-color: var(--orange); color: var(--orange); }

/* ── 변환 카드 ── */
.conv-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 24px; box-shadow: var(--shadow); margin-bottom: 12px;
}
.conv-card h2 { font-size: 15px; font-weight: 700; margin-bottom: 18px; color: var(--ink); }

.input-row { display: flex; gap: 10px; align-items: flex-end; margin-bottom: 20px; }
.input-group { flex: 1; }
.input-group label { display: block; font-size: 11px; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; margin-bottom: 5px; }
.input-group input {
  width: 100%; padding: 10px 12px; border: 1.5px solid var(--line); border-radius: 9px;
  font-size: 16px; font-weight: 600; outline: none; transition: border-color .12s;
}
.input-group input:focus { border-color: var(--orange); }
.select-group { flex: 1; }
.select-group label { display: block; font-size: 11px; font-weight: 700; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; margin-bottom: 5px; }
.select-group select {
  width: 100%; padding: 10px 12px; border: 1.5px solid var(--line); border-radius: 9px;
  font-size: 14px; background: var(--card); outline: none; cursor: pointer; transition: border-color .12s;
}
.select-group select:focus { border-color: var(--orange); }

.swap-btn {
  padding: 10px 12px; border-radius: 9px; border: 1.5px solid var(--line);
  background: var(--card); cursor: pointer; font-size: 18px; transition: all .12s; flex-shrink: 0;
  align-self: flex-end;
}
.swap-btn:hover { border-color: var(--orange); background: #fff7ed; }

/* ── 결과 ── */
.result-box {
  background: #fff7ed; border: 1.5px solid #fed7aa; border-radius: 10px;
  padding: 14px 18px;
}
.result-main { font-size: 24px; font-weight: 700; color: var(--orange); }
.result-formula { font-size: 12px; color: var(--muted); margin-top: 4px; }

/* ── 참고표 ── */
.ref-table { width: 100%; border-collapse: collapse; font-size: 13px; margin-top: 20px; }
.ref-table th { background: #fff7ed; padding: 8px 10px; text-align: left; font-weight: 700; color: var(--orange); border-bottom: 2px solid #fed7aa; }
.ref-table td { padding: 7px 10px; border-bottom: 1px solid var(--line); }
.ref-table tr:last-child td { border-bottom: none; }
.ref-table tr:hover td { background: #fafafa; }

/* ── 사용 안내 ── */
.guide-section {
  margin-top: 24px; background: rgba(246,248,255,.6);
  border: 1px solid var(--line); border-radius: var(--radius); padding: 24px;
}
.guide-section h2 { font-size: 15px; font-weight: 800; margin: 0 0 10px; color: var(--ink); }
.guide-section h2:not(:first-child) { margin-top: 18px; }
.guide-steps, .guide-features, .guide-usecase {
  margin: 0; padding-left: 18px; color: var(--muted); font-size: 13px; line-height: 1.8;
}
.guide-steps li, .guide-features li, .guide-usecase li { margin-bottom: 4px; }
.guide-steps strong, .guide-features strong { color: var(--ink); }
.guide-privacy {
  margin-top: 16px; background: #eff6ff; border: 1px solid rgba(37,99,235,.22);
  border-radius: 12px; padding: 12px 14px; font-size: 12px; color: #1e40af; line-height: 1.55;
}

@media (max-width: 540px) {
  .input-row { flex-wrap: wrap; }
  .swap-btn { align-self: center; }
}