:root{
  --bg:#f5f4f0; --surface:#fbfbf9; --panel:#ffffff; --panel-soft:#f7f6f2;
  --ink:#1c1c1a; --ink-hover:#3a3935; --ink-2:#55534d; --sub:#7a776f; --muted:#8a877f;
  --line:#e3e1db; --line-2:#dcdad3; --line-3:#efeee9; --hover:#efeee9; --soft:#f3f2ee; --track:#ebe9e3;
  --accent:#d9480f; --accent-soft:#fdeee6;
  --font:"IBM Plex Sans KR",sans-serif; --mono:"JetBrains Mono",monospace;
}
*{box-sizing:border-box}
[hidden]{display:none !important}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font);-webkit-font-smoothing:antialiased}
button{font:inherit;color:inherit}
.mono{font-family:var(--mono)}
.mono-label{font-family:var(--mono);font-size:11px;letter-spacing:.12em;color:var(--muted)}
.note{font-size:12px;line-height:1.6;color:var(--muted);margin:0}
.app{min-height:100vh;display:flex;flex-direction:column}
.topbar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:16px 28px;border-bottom:1px solid var(--line);background:var(--surface);flex-wrap:wrap}
.brand{display:flex;align-items:baseline;gap:14px;min-width:0;flex-wrap:wrap}
.home{font-size:13px;color:var(--ink-2);text-decoration:none}
.home:hover{color:var(--ink)}
.brand-title{font-size:17px;font-weight:700;letter-spacing:-.01em}
.actions{display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.btn{height:36px;padding:0 14px;background:transparent;border:1px solid var(--line-2);border-radius:999px;font-size:13px;cursor:pointer;white-space:nowrap}
.btn:hover{background:var(--hover)}
.btn--solid{background:var(--ink);color:#fff;border:none;font-weight:500}
.btn--solid:hover{background:var(--ink-hover)}
.btn--accent{background:var(--accent);color:#fff;border:none;font-weight:500}
.btn--accent:hover{filter:brightness(1.07)}
.btn--ghost{background:#fff}
.text-input{height:40px;padding:0 12px;background:var(--surface);border:1px solid var(--line-2);border-radius:8px;font:inherit;font-size:14px;color:var(--ink)}
input[type=number]{-moz-appearance:textfield;appearance:textfield}
input[type=number]::-webkit-outer-spin-button,input[type=number]::-webkit-inner-spin-button{-webkit-appearance:none;margin:0}

/* 기준 크기 */
.base{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--ink-2)}
.base-field{position:relative;display:inline-flex;align-items:center}
.base-input{width:84px;height:36px;padding:0 30px 0 12px;background:#fff;border:1.5px solid var(--ink);border-radius:999px;font-family:var(--mono);font-size:15px;font-weight:700;color:var(--ink);text-align:right}
.base-input:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(217,72,15,.14)}
.base-u{position:absolute;right:12px;font-family:var(--mono);font-size:11px;color:var(--muted);pointer-events:none}
.base-field--sm .base-input{width:80px;height:34px;border-width:1px;border-color:var(--line-2);font-weight:500;font-size:14px}
.chips{display:flex;gap:4px}
.chip{height:30px;min-width:38px;padding:0 8px;border:1px solid var(--line-2);border-radius:999px;background:transparent;font-family:var(--mono);font-size:12px;cursor:pointer;color:var(--ink-2)}
.chip:hover{background:var(--hover)}
.chip.is-active{background:var(--ink);color:#fff;border-color:var(--ink)}

/* 레이아웃 */
.wrap{width:100%;max-width:1240px;margin:0 auto;padding:32px 28px 72px;display:grid;grid-template-columns:minmax(0,1fr) 340px;gap:24px;align-items:start}
.col-main{display:flex;flex-direction:column;gap:24px;min-width:0}
.card{position:relative;background:var(--panel);border:1px solid var(--line);border-radius:20px;padding:26px;display:flex;flex-direction:column;gap:18px;min-width:0}
.card-head h2{margin:6px 0 0;font-size:20px;font-weight:700;letter-spacing:-.01em}

/* 자 눈금 장식 */
.ruler{position:absolute;left:0;right:0;top:0;height:14px;border-radius:20px 20px 0 0;overflow:hidden;opacity:.55;
  background:
    repeating-linear-gradient(90deg,var(--ink) 0 1px,transparent 1px 80px) 0 0/100% 14px no-repeat,
    repeating-linear-gradient(90deg,var(--muted) 0 1px,transparent 1px 16px) 0 0/100% 8px no-repeat,
    repeating-linear-gradient(90deg,var(--line-2) 0 1px,transparent 1px 8px) 0 0/100% 5px no-repeat}
.conv{padding-top:34px}

/* 변환기 */
.conv-row{display:grid;grid-template-columns:minmax(0,1fr) auto minmax(0,1fr) auto minmax(0,1fr);gap:10px;align-items:stretch}
.eq{align-self:center;font-family:var(--mono);font-size:22px;color:var(--muted)}
.unit-box{position:relative;display:flex;flex-direction:column;gap:6px;padding:14px 14px 12px;border:1.5px solid var(--line);border-radius:16px;background:var(--surface);transition:border-color .15s,background .15s;min-width:0}
.unit-box:focus-within{border-color:var(--accent);background:#fff}
.unit-box.is-src{border-color:var(--ink)}
.unit-k{font-family:var(--mono);font-size:12px;letter-spacing:.1em;color:var(--muted);text-transform:uppercase}
.unit-in{width:100%;min-width:0;border:none;background:transparent;padding:0;font-family:var(--mono);font-size:clamp(26px,3.4vw,40px);font-weight:700;letter-spacing:-.03em;color:var(--ink)}
.unit-in:focus{outline:none}
.unit-copy{align-self:flex-start;height:26px;padding:0 10px;border:none;border-radius:999px;background:var(--soft);font-size:11px;color:var(--ink-2);cursor:pointer}
.unit-copy:hover{background:var(--ink);color:#fff}
.parent-row{display:flex;align-items:center;justify-content:space-between;gap:12px;flex-wrap:wrap}
.parent{display:flex;align-items:center;gap:10px;font-size:13px;color:var(--ink-2);flex-wrap:wrap}
.check{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--ink-2);cursor:pointer}
.check input{width:16px;height:16px;margin:0;accent-color:var(--accent)}

/* clamp */
.clamp-inputs{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.pair{margin:0;padding:12px 14px 14px;border:1px solid var(--line);border-radius:14px;display:grid;grid-template-columns:1fr 1fr;gap:8px;min-width:0}
.pair legend{padding:0 6px;margin-left:-6px;font-size:13px;font-weight:500;color:var(--ink)}
.mini{display:flex;flex-direction:column;gap:4px;font-size:12px;color:var(--muted);min-width:0}
.mini-f{position:relative;display:block}
.mini-f input{width:100%;height:40px;padding:0 28px 0 10px;background:var(--surface);border:1px solid var(--line-2);border-radius:10px;font-family:var(--mono);font-size:16px;font-weight:500;color:var(--ink);text-align:right}
.mini-f input:focus{outline:none;border-color:var(--accent);background:#fff;box-shadow:0 0 0 3px rgba(217,72,15,.12)}
.mini-f i{position:absolute;right:10px;top:50%;transform:translateY(-50%);font-style:normal;font-family:var(--mono);font-size:11px;color:var(--muted);pointer-events:none}

.formula{display:flex;flex-direction:column;gap:12px;padding:20px;background:var(--ink);color:#fff;border-radius:16px}
.formula-code{font-family:var(--mono);font-size:clamp(15px,2vw,22px);font-weight:500;line-height:1.5;word-break:break-word;color:#fff}
.formula-code .fn{color:#ffb38a}
.formula-code .v{color:#fff}
.formula-code .p{color:#8a877f}
.formula-actions{display:flex;gap:8px;flex-wrap:wrap}
.formula .btn--ghost{background:transparent;color:#efeee9;border-color:rgba(255,255,255,.22)}
.formula .btn--ghost:hover{background:rgba(255,255,255,.08)}
.formula-sub{margin:0;font-family:var(--mono);font-size:12px;color:#a8a59c;line-height:1.6;word-break:break-word}
.formula-sub button{background:none;border:none;padding:0;color:inherit;font:inherit;cursor:pointer;text-decoration:underline;text-decoration-color:rgba(255,255,255,.25);text-underline-offset:3px;text-align:left;word-break:break-word}
.formula-sub button:hover{color:#fff}
.formula-err{margin:0;font-size:13px;color:#ffb38a}
.formula.pulse{animation:pulse .3s ease}
@keyframes pulse{from{transform:scale(.99);opacity:.85}to{transform:none;opacity:1}}

.sim{display:flex;flex-direction:column;gap:12px}
.sim-head{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}
.sim-k{font-size:13px;font-weight:500}
.sim-v{font-size:13px;color:var(--muted)}
.sim-v b{color:var(--ink);font-size:16px}
.sim-v{display:inline-flex;align-items:center;gap:6px}
/* 뷰포트 폭 직접 입력칸 · 자주 쓰는 폭 버튼 */
.sim-v .tb-num{width:64px;height:32px;font-size:15px;font-weight:600;color:var(--ink);border-color:var(--line-2);background:var(--surface);border-radius:8px}
.sim-v .tb-num-wrap{font-size:13px;color:var(--muted);gap:4px}
.sim .tb-presets{margin-top:-4px;gap:6px}
.sim .tb-presets button{border-color:var(--line-2)}
@media (pointer:coarse){.sim-v .tb-num{height:36px;font-size:16px}}
#fsOut{color:var(--accent)}
input[type=range]{width:100%;accent-color:var(--accent);margin:0}
.chart{height:150px;border-radius:12px;background:var(--panel-soft);border:1px solid var(--line-3);overflow:hidden}
.chart svg{display:block;width:100%;height:100%}
.sample{border:1px dashed var(--line-2);border-radius:14px;padding:18px;min-height:110px;display:flex;align-items:center;overflow:hidden;background:repeating-linear-gradient(0deg,transparent 0 23px,var(--line-3) 23px 24px)}
.sample-t{margin:0;font-weight:700;letter-spacing:-.02em;line-height:1.2;outline:none;overflow-wrap:anywhere;min-width:0;width:100%}
.sample-t:focus{background:rgba(217,72,15,.05);border-radius:6px}

/* 표 */
.table-card{position:sticky;top:20px;gap:10px;padding:22px 18px}
.tbl{width:100%;table-layout:fixed;border-collapse:collapse;font-family:var(--mono);font-size:13px}
.tbl th{font-weight:500;font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);text-align:left;padding:6px 6px 8px;border-bottom:1px solid var(--line)}
.tbl td{padding:0;border-bottom:1px solid var(--line-3);vertical-align:middle}
.tbl tr.is-cur td{background:var(--accent-soft)}
.tbl tr.is-base .cell-px{font-weight:700}
.cell{display:block;width:100%;height:36px;padding:0 6px;border:none;background:transparent;font-family:var(--mono);font-size:13px;text-align:left;cursor:pointer;border-radius:6px;white-space:nowrap}
.cell:hover{background:var(--ink);color:#fff}
.cell-rem{color:var(--accent);font-weight:500}
.pv{padding:0 6px !important;overflow:hidden;white-space:nowrap;line-height:1;font-family:var(--font);font-weight:500;color:var(--ink-2)}
.tbl th:nth-child(1){width:26%}.tbl th:nth-child(2){width:36%}.th-pv{width:38%}

/* 토스트 */
.toast{position:fixed;left:50%;bottom:28px;transform:translate(-50%,20px);background:var(--ink);color:#fff;padding:10px 18px;border-radius:999px;font-size:13px;opacity:0;pointer-events:none;transition:opacity .2s,transform .2s;z-index:50;max-width:calc(100% - 32px);white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.toast.is-on{opacity:1;transform:translate(-50%,0)}
.toast b{font-family:var(--mono);font-weight:500}

@media (max-width:1020px){
  .wrap{grid-template-columns:minmax(0,1fr)}
  .table-card{position:static}
}
@media (max-width:720px){
  .conv-row{grid-template-columns:minmax(0,1fr)}
  .eq{display:none}
  .unit-box{flex-direction:row;flex-wrap:wrap;align-items:center;gap:4px 10px}
  .unit-k{width:100%}
  .unit-in{flex:1;font-size:30px}
  .unit-copy{align-self:center}
  .clamp-inputs{grid-template-columns:minmax(0,1fr)}
}
@media (max-width:640px){
  .topbar{padding:14px 16px}
  .wrap{padding:20px 16px 56px;gap:18px}
  .col-main{gap:18px}
  .card{padding:20px 16px;border-radius:16px}
  .conv{padding-top:28px}
  .formula{padding:16px}
  .chips{flex-wrap:wrap}
}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{transition:none !important;animation:none !important}
}

/* 다크 모드 (인쇄는 라이트 그대로) */
@media screen{
  :root[data-theme="dark"]{
    color-scheme:dark;
    --bg:#151312; --surface:#1b1918; --panel:#201e1c; --panel-soft:#252321;
    --ink:#eeebe7; --ink-hover:#ffffff; --ink-2:#cbc6c0; --sub:#a39d96; --muted:#8d8780;
    --line:#302d2a; --line-2:#3b3834; --line-3:#282624; --hover:#2b2926; --soft:#272523; --track:#373431;
    --accent:#ff8a50; --accent-soft:rgba(255,138,80,.14);
  }
  :root[data-theme="dark"] .btn--solid,:root[data-theme="dark"] .btn--accent,:root[data-theme="dark"] .chip.is-active,
  :root[data-theme="dark"] .unit-copy:hover,:root[data-theme="dark"] .cell:hover,:root[data-theme="dark"] .toast,
  :root[data-theme="dark"] .tb-presets button[aria-pressed="true"]{color:var(--bg)}
  :root[data-theme="dark"] .btn--ghost{background:var(--panel)}
  :root[data-theme="dark"] .base-input{background:var(--surface)}
  :root[data-theme="dark"] .base-input:focus{box-shadow:0 0 0 3px rgba(255,138,80,.2)}
  :root[data-theme="dark"] .unit-box:focus-within,:root[data-theme="dark"] .mini-f input:focus{background:var(--panel)}
  :root[data-theme="dark"] .mini-f input:focus{box-shadow:0 0 0 3px rgba(255,138,80,.18)}
  /* 공식 카드는 원래 어두운 코드 패널 → 배경보다 한 톤 깊게 + 테두리 */
  :root[data-theme="dark"] .formula{background:#0f0e0d;box-shadow:inset 0 0 0 1px var(--line-2)}
  :root[data-theme="dark"] .formula .btn--ghost{background:transparent}
  :root[data-theme="dark"] .formula .btn--ghost:hover{background:rgba(255,255,255,.08)}
  :root[data-theme="dark"] .sample-t:focus{background:rgba(255,138,80,.08)}
  /* 그래프(SVG): CSS가 presentation 속성보다 우선 */
  :root[data-theme="dark"] .chart text{fill:var(--muted)}
  :root[data-theme="dark"] .chart line[stroke="#e3e1db"],:root[data-theme="dark"] .chart line[stroke="#dcdad3"]{stroke:var(--line-2)}
  :root[data-theme="dark"] .chart polygon{fill:rgba(255,138,80,.07)}
  :root[data-theme="dark"] .chart polyline{stroke:var(--accent)}
  :root[data-theme="dark"] .chart line[stroke="#1c1c1a"]{stroke:var(--ink)}
  :root[data-theme="dark"] .chart circle{fill:var(--panel);stroke:var(--ink)}
}