/* ═══════════════════════════════════════════════════════════
   2427 PERIODIC_TABLE — "교과서" 변형 (base: kit-editorial)
   세리프 헤드라인 · 1px 헤어라인 · 각진 모서리 · 그림자 없음
   단색 액센트(산화철 적갈색) — 속성 값은 이 한 색의 명도 단계로만 표현
   분류별 색은 사용자가 켤 때만(저채도 팔레트)
═══════════════════════════════════════════════════════════ */
:root {
  --bg: #f7f5f0;
  --surface: #ffffff;
  --surface-2: #efece4;
  --ink: #1d1c19;
  --ink-2: #4f4c45;
  --ink-3: #85817a;
  --line: #dcd8ce;
  --line-2: #c4bfb3;
  --accent: #9b3b22;
  --accent-ink: #ffffff;
  --focus: #1d1c19;
  --serif: 'Source Serif 4', 'Noto Serif KR', 'Noto Serif JP', Georgia, 'Times New Roman', serif;
  --sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Apple SD Gothic Neo', 'Malgun Gothic', 'Noto Sans KR', 'Hiragino Sans', 'PingFang SC', 'Microsoft YaHei', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --mono: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --r: 3px;
  --cell: 58px;
  /* 분류 팔레트(저채도, 옵션 전용) */
  --k-alkali: #e4d3c6; --k-alkaline: #e6dcc2; --k-transition: #d3d8de; --k-post: #d4dccf;
  --k-metalloid: #dcd6c8; --k-nonmetal: #cfdcd7; --k-halogen: #ddd3dd; --k-noble: #cfd8e3;
  --k-lanthanide: #e2d8cd; --k-actinide: #e0cfcf;
}
:root[data-theme="dark"] {
  --bg: #141412; --surface: #1b1b19; --surface-2: #23221f; --ink: #ecebe6; --ink-2: #bdbab2; --ink-3: #8a877f;
  --line: #2f2e2a; --line-2: #45433e; --accent: #d98a6f; --accent-ink: #1b1b19; --focus: #ecebe6;
  --k-alkali: #3d332c; --k-alkaline: #3c372a; --k-transition: #2e3338; --k-post: #2f362c;
  --k-metalloid: #36332b; --k-nonmetal: #2b3632; --k-halogen: #372f37; --k-noble: #2c333c;
  --k-lanthanide: #3a332c; --k-actinide: #3b2d2d;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #141412; --surface: #1b1b19; --surface-2: #23221f; --ink: #ecebe6; --ink-2: #bdbab2; --ink-3: #8a877f;
    --line: #2f2e2a; --line-2: #45433e; --accent: #d98a6f; --accent-ink: #1b1b19; --focus: #ecebe6;
    --k-alkali: #3d332c; --k-alkaline: #3c372a; --k-transition: #2e3338; --k-post: #2f362c;
    --k-metalloid: #36332b; --k-nonmetal: #2b3632; --k-halogen: #372f37; --k-noble: #2c333c;
    --k-lanthanide: #3a332c; --k-actinide: #3b2d2d;
  }
}

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.65 var(--sans); -webkit-font-smoothing: antialiased; }
a { color: inherit; }
h1, h2, h3 { font-family: var(--serif); font-weight: 600; line-height: 1.25; letter-spacing: -0.01em; }
.mono { font-family: var(--mono); }
.muted { color: var(--ink-3); }
.small { font-size: 13px; }
.sr-only { position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }
.skip { position: absolute; left: 8px; top: -48px; background: var(--ink); color: var(--bg); padding: 6px 10px; z-index: 99; }
.skip:focus { top: 8px; }
:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }

/* ── header ── */
.site-header { border-bottom: 1px solid var(--ink); background: var(--bg); position: sticky; top: 0; z-index: 40; }
.hd { max-width: 1240px; margin: 0 auto; padding: 0 16px; min-height: 58px; display: flex; align-items: center; gap: 18px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; flex-shrink: 0; }
.brand-mark { width: 34px; height: 34px; border: 1.5px solid var(--ink); display: grid; place-items: center; font: 600 15px/1 var(--serif); position: relative; padding-top: 6px; }
.brand-mark span { position: absolute; top: 2px; left: 3px; font: 500 8px/1 var(--mono); }
.brand-name { font: 600 18px/1 var(--serif); }
.nav { display: flex; gap: 2px; overflow-x: auto; scrollbar-width: none; flex: 1; }
.nav::-webkit-scrollbar { display: none; }
.nav a { text-decoration: none; font-size: 14px; color: var(--ink-2); padding: 6px 10px; white-space: nowrap; border-bottom: 2px solid transparent; }
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--accent); }
.hd-tools { display: flex; align-items: center; gap: 8px; margin-left: auto; }
.lang-select { font: 13px var(--sans); background: var(--surface); color: var(--ink); border: 1px solid var(--line-2); border-radius: var(--r); padding: 5px 6px; max-width: 110px; }
.icon-btn { width: 34px; height: 34px; display: grid; place-items: center; background: transparent; color: var(--ink); border: 1px solid var(--line-2); border-radius: var(--r); cursor: pointer; }
.icon-btn:hover { border-color: var(--ink); }
@media (max-width: 760px) {
  .hd { flex-wrap: wrap; gap: 8px 12px; padding-top: 8px; }
  .nav { order: 3; flex-basis: 100%; margin: 0 -6px; }
  .brand-name { font-size: 16px; }
}

main { display: block; }

/* ── footer ── */
.site-footer { border-top: 1px solid var(--line-2); margin-top: 56px; }
.ft { max-width: 1240px; margin: 0 auto; padding: 26px 16px 40px; font-size: 13px; color: var(--ink-3); }
.ft-links { display: flex; flex-wrap: wrap; gap: 6px 16px; margin-bottom: 10px; }
.ft-links a { color: var(--ink-2); text-decoration: none; }
.ft-links a:hover { text-decoration: underline; }
.ft-guides a { color: var(--ink-3); }
.ft-note, .ft-copy { margin: 6px 0 0; }

/* ── tool (index) ── */
.tool { max-width: 1240px; margin: 0 auto; padding: 16px 16px 0; }
.tool.narrow { max-width: 760px; }
.pt-bar { display: flex; flex-wrap: wrap; gap: 10px 14px; align-items: center; }
.search { display: flex; align-items: center; gap: 8px; border: 1px solid var(--line-2); background: var(--surface); border-radius: var(--r); padding: 0 10px; flex: 1 1 240px; max-width: 360px; color: var(--ink-3); }
.search:focus-within { border-color: var(--ink); }
.search input { border: 0; outline: 0; background: transparent; color: var(--ink); font: 15px var(--sans); padding: 9px 0; width: 100%; }
.view { display: flex; align-items: center; gap: 8px; font-size: 14px; color: var(--ink-2); }
.view select { font: 14px var(--sans); background: var(--surface); color: var(--ink); border: 1px solid var(--line-2); border-radius: var(--r); padding: 8px 8px; }
.catcolor { display: flex; align-items: center; gap: 6px; font-size: 14px; color: var(--ink-2); cursor: pointer; user-select: none; }
.catcolor input { accent-color: var(--accent); width: 16px; height: 16px; }
.pt-slider { display: flex; align-items: center; gap: 12px; margin-top: 12px; font-size: 14px; color: var(--ink-2); max-width: 720px; }
.pt-slider input[type=range] { flex: 1; accent-color: var(--accent); }
.pt-slider output { min-width: 150px; font-size: 13px; color: var(--ink); }
.pt-legend { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 12px; margin: 12px 0 10px; font-size: 12.5px; color: var(--ink-2); min-height: 22px; }
.lg-item { display: inline-flex; align-items: center; gap: 6px; background: none; border: 0; padding: 2px 0; color: inherit; font: inherit; cursor: pointer; }
.lg-item[aria-pressed="true"] { text-decoration: underline; text-underline-offset: 3px; }
.lg-sw { width: 14px; height: 14px; border: 1px solid var(--line-2); display: inline-block; }
.lg-scale { display: inline-flex; border: 1px solid var(--line-2); }
.lg-scale i { width: 26px; height: 12px; display: block; }
.lg-end { font-family: var(--mono); font-size: 11.5px; }

.pt-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; padding-bottom: 6px; }
.pt-grid { display: grid; grid-template-columns: repeat(18, minmax(var(--cell), 1fr)); grid-template-rows: repeat(7, auto) 14px repeat(2, auto); gap: 2px; min-width: calc(18 * var(--cell) + 34px); position: relative; }
@media (max-width: 760px) { :root { --cell: 46px; } }
.el { position: relative; display: flex; flex-direction: column; align-items: flex-start; justify-content: space-between; aspect-ratio: 1 / 1.08; padding: 3px 4px 4px; text-decoration: none; color: var(--ink); background: var(--surface); border: 1px solid var(--line); border-radius: 1px; overflow: hidden; cursor: pointer; transition: opacity .15s, background-color .15s; min-width: 0; }
.el:hover, .el.is-sel { border-color: var(--ink); z-index: 2; }
.el.is-sel { outline: 2px solid var(--ink); outline-offset: -1px; }
.el-z { font: 500 10px/1 var(--mono); color: var(--ink-2); }
.el-sym { font: 600 clamp(15px, 1.55vw, 21px)/1 var(--serif); align-self: center; margin-top: -2px; }
.el-nm { font-size: 9.5px; line-height: 1.1; color: var(--ink-2); max-width: 100%; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; align-self: center; }
.el-v { font: 500 9px/1 var(--mono); color: var(--ink-2); align-self: center; min-height: 9px; white-space: nowrap; }
@media (max-width: 760px) { .el-nm { display: none; } .el-sym { font-size: 16px; } .el-v { font-size: 8px; } }
.el.ph { cursor: default; justify-content: center; align-items: center; font: 500 10px var(--mono); color: var(--ink-3); background: transparent; border-style: dashed; }
.el.dim { opacity: .18; }
.el.off { opacity: .12; }
/* 속성 명도 단계(단색) */
.el[data-s="0"] { background: color-mix(in srgb, var(--accent) 5%, var(--surface)); }
.el[data-s="1"] { background: color-mix(in srgb, var(--accent) 14%, var(--surface)); }
.el[data-s="2"] { background: color-mix(in srgb, var(--accent) 25%, var(--surface)); }
.el[data-s="3"] { background: color-mix(in srgb, var(--accent) 38%, var(--surface)); }
.el[data-s="4"] { background: color-mix(in srgb, var(--accent) 54%, var(--surface)); }
.el[data-s="5"] { background: color-mix(in srgb, var(--accent) 72%, var(--surface)); }
.el[data-s="6"] { background: color-mix(in srgb, var(--accent) 92%, var(--surface)); }
.el[data-s="4"], .el[data-s="5"], .el[data-s="6"] { color: var(--accent-ink); }
.el[data-s="4"] .el-z, .el[data-s="5"] .el-z, .el[data-s="6"] .el-z,
.el[data-s="4"] .el-nm, .el[data-s="5"] .el-nm, .el[data-s="6"] .el-nm,
.el[data-s="4"] .el-v, .el[data-s="5"] .el-v, .el[data-s="6"] .el-v { color: var(--accent-ink); opacity: .85; }
.el[data-s="na"] { background: var(--surface-2); border-style: dashed; color: var(--ink-3); }
.el[data-s="tbd"] { background: var(--surface); color: var(--ink-3); border-style: dashed; }
/* 분류(단색 명도) — 기본 */
.pt-grid[data-view="cat"] .el.c-alkali { background: color-mix(in srgb, var(--ink) 16%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-alkaline { background: color-mix(in srgb, var(--ink) 11%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-transition { background: color-mix(in srgb, var(--ink) 6%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-post { background: color-mix(in srgb, var(--ink) 9%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-metalloid { background: color-mix(in srgb, var(--accent) 16%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-nonmetal { background: color-mix(in srgb, var(--accent) 8%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-halogen { background: color-mix(in srgb, var(--accent) 26%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-noble { background: var(--surface); }
.pt-grid[data-view="cat"] .el.c-lanthanide { background: color-mix(in srgb, var(--ink) 3%, var(--surface)); }
.pt-grid[data-view="cat"] .el.c-actinide { background: color-mix(in srgb, var(--ink) 13%, var(--surface)); border-style: dotted; }
/* 분류별 색(옵션) */
.pt-grid.catcolor[data-view="cat"] .el.c-alkali, .lg-sw.k-alkali { background: var(--k-alkali); }
.pt-grid.catcolor[data-view="cat"] .el.c-alkaline, .lg-sw.k-alkaline { background: var(--k-alkaline); }
.pt-grid.catcolor[data-view="cat"] .el.c-transition, .lg-sw.k-transition { background: var(--k-transition); }
.pt-grid.catcolor[data-view="cat"] .el.c-post, .lg-sw.k-post { background: var(--k-post); }
.pt-grid.catcolor[data-view="cat"] .el.c-metalloid, .lg-sw.k-metalloid { background: var(--k-metalloid); }
.pt-grid.catcolor[data-view="cat"] .el.c-nonmetal, .lg-sw.k-nonmetal { background: var(--k-nonmetal); }
.pt-grid.catcolor[data-view="cat"] .el.c-halogen, .lg-sw.k-halogen { background: var(--k-halogen); }
.pt-grid.catcolor[data-view="cat"] .el.c-noble, .lg-sw.k-noble { background: var(--k-noble); }
.pt-grid.catcolor[data-view="cat"] .el.c-lanthanide, .lg-sw.k-lanthanide { background: var(--k-lanthanide); }
.pt-grid.catcolor[data-view="cat"] .el.c-actinide, .lg-sw.k-actinide { background: var(--k-actinide); }
.lg-sw.m-alkali { background: color-mix(in srgb, var(--ink) 16%, var(--surface)); }
.lg-sw.m-alkaline { background: color-mix(in srgb, var(--ink) 11%, var(--surface)); }
.lg-sw.m-transition { background: color-mix(in srgb, var(--ink) 6%, var(--surface)); }
.lg-sw.m-post { background: color-mix(in srgb, var(--ink) 9%, var(--surface)); }
.lg-sw.m-metalloid { background: color-mix(in srgb, var(--accent) 16%, var(--surface)); }
.lg-sw.m-nonmetal { background: color-mix(in srgb, var(--accent) 8%, var(--surface)); }
.lg-sw.m-halogen { background: color-mix(in srgb, var(--accent) 26%, var(--surface)); }
.lg-sw.m-noble { background: var(--surface); }
.lg-sw.m-lanthanide { background: color-mix(in srgb, var(--ink) 3%, var(--surface)); }
.lg-sw.m-actinide { background: color-mix(in srgb, var(--ink) 13%, var(--surface)); border-style: dotted; }
/* 상태(온도) */
.el[data-st="solid"] { background: color-mix(in srgb, var(--ink) 12%, var(--surface)); }
.el[data-st="liquid"] { background: color-mix(in srgb, var(--accent) 34%, var(--surface)); }
.el[data-st="gas"] { background: var(--surface); border-style: dashed; border-color: var(--line-2); }
.el[data-st="unknown"] { background: var(--surface-2); border-style: dashed; color: var(--ink-3); }
.lg-sw.st-solid { background: color-mix(in srgb, var(--ink) 12%, var(--surface)); }
.lg-sw.st-liquid { background: color-mix(in srgb, var(--accent) 34%, var(--surface)); }
.lg-sw.st-gas { background: var(--surface); border-style: dashed; }
.lg-sw.st-unknown { background: var(--surface-2); border-style: dashed; }

/* inset preview (1~3행 3~12열 빈 공간) */
.pt-inset { grid-row: 1 / 4; grid-column: 3 / 13; display: flex; align-items: center; gap: 14px; padding: 4px 10px; min-width: 0; }
.inset-hint { margin: 0; color: var(--ink-3); font-size: 13px; font-style: italic; font-family: var(--serif); }
.in-tile { width: 92px; height: 100px; border: 1.5px solid var(--ink); background: var(--surface); flex-shrink: 0; display: flex; flex-direction: column; justify-content: space-between; padding: 5px 7px; }
.in-tile .t-z { font: 500 12px/1 var(--mono); }
.in-tile .t-sym { font: 600 38px/1 var(--serif); align-self: center; }
.in-tile .t-m { font: 500 10.5px/1 var(--mono); align-self: center; }
.in-info { min-width: 0; }
.in-info h2 { margin: 0 0 4px; font-size: 22px; }
.in-info p { margin: 0; font-size: 12.5px; color: var(--ink-2); line-height: 1.5; }
.in-info .in-v { font-family: var(--mono); color: var(--ink); }
@media (max-width: 760px) { .in-tile { width: 70px; height: 76px; } .in-tile .t-sym { font-size: 28px; } .in-info h2 { font-size: 17px; } .in-info p { font-size: 11px; } }

/* detail panel */
.pt-detail { margin-top: 18px; border-top: 2px solid var(--ink); padding-top: 16px; display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 24px; }
@media (max-width: 860px) { .pt-detail { grid-template-columns: 1fr; } }
.dt-head { grid-column: 1 / -1; display: flex; align-items: flex-end; gap: 14px; flex-wrap: wrap; }
.dt-head h2 { margin: 0; font-size: 30px; }
.dt-head .dt-sym { font-family: var(--mono); font-size: 16px; color: var(--ink-2); }
.dt-head .dt-cat { font-size: 14px; color: var(--ink-2); }
.dt-actions { margin-left: auto; display: flex; gap: 8px; }
.btn-line { display: inline-flex; align-items: center; gap: 6px; font-size: 14px; text-decoration: none; color: var(--ink); border: 1px solid var(--ink); border-radius: var(--r); padding: 7px 12px; background: transparent; cursor: pointer; font-family: var(--sans); }
.btn-line:hover { background: var(--ink); color: var(--bg); }
.btn-solid { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.btn-solid:hover { background: var(--ink); border-color: var(--ink); }
.pt-detail h3 { font-size: 15px; margin: 0 0 8px; font-family: var(--sans); font-weight: 700; letter-spacing: .02em; text-transform: uppercase; color: var(--ink-2); }

/* tables (props) */
table { border-collapse: collapse; width: 100%; }
.props th, .props td { text-align: left; padding: 7px 0; border-bottom: 1px solid var(--line); font-size: 14px; vertical-align: top; }
.props th { font-weight: 500; color: var(--ink-2); width: 44%; padding-right: 12px; }
.props td { font-family: var(--mono); font-size: 13.5px; }
.props td .muted { font-family: var(--sans); font-size: 12px; }
.cfg-dl { margin: 0 0 14px; display: grid; grid-template-columns: max-content 1fr; gap: 6px 14px; font-size: 14px; }
.cfg-dl dt { color: var(--ink-2); }
.cfg-dl dd { margin: 0; word-break: break-word; }
.orb { display: flex; flex-wrap: wrap; gap: 10px 14px; margin-bottom: 10px; }
.orb-sub { display: flex; flex-direction: column; align-items: center; gap: 3px; }
.orb-lbl { font: 500 12px var(--mono); color: var(--ink-2); }
.orb-boxes { display: flex; }
.ob { width: 24px; height: 26px; border: 1px solid var(--ink); margin-left: -1px; display: grid; place-items: center; font: 600 13px/1 var(--mono); letter-spacing: -2px; }
.ob:first-child { margin-left: 0; }

/* ── molar ── */
.tool-h1 { font-size: 30px; margin: 8px 0 16px; }
.mm-card { border: 1px solid var(--line-2); background: var(--surface); padding: 18px; margin-bottom: 16px; }
.mm-label { display: block; font-size: 13px; color: var(--ink-2); margin-bottom: 6px; }
.mm-input { width: 100%; font-size: 22px; padding: 10px 12px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--bg); color: var(--ink); }
.mm-input:focus { outline: 0; border-color: var(--ink); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; margin-top: 10px; }
.chips-lbl { font-size: 12.5px; color: var(--ink-3); margin-right: 4px; }
.chip { font: 13px var(--mono); padding: 4px 9px; border: 1px solid var(--line-2); background: transparent; color: var(--ink); border-radius: var(--r); cursor: pointer; }
.chip:hover { border-color: var(--ink); }
.mm-out { margin-top: 16px; }
.mm-total { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; border-top: 2px solid var(--ink); padding-top: 12px; }
.mm-total .v { font: 600 34px/1.1 var(--mono); }
.mm-total .u { font-size: 15px; color: var(--ink-2); }
.mm-total .lbl { font-size: 13px; color: var(--ink-2); width: 100%; }
.mm-err { color: var(--accent); font-size: 14px; margin: 0; }
.mm-table { margin-top: 12px; font-size: 14px; }
.mm-table th, .mm-table td { padding: 7px 6px; border-bottom: 1px solid var(--line); text-align: right; }
.mm-table th:first-child, .mm-table td:first-child { text-align: left; }
.mm-table th { font-weight: 500; color: var(--ink-2); font-size: 12.5px; }
.mm-table td { font-family: var(--mono); font-size: 13px; }
.mm-bar { display: block; height: 3px; background: var(--accent); margin-top: 3px; margin-left: auto; }
[dir="rtl"] .mm-bar { margin-left: 0; margin-right: auto; }
.mm-h2 { font-size: 19px; margin: 0 0 12px; }
.conv { display: flex; align-items: flex-end; gap: 10px; flex-wrap: wrap; }
.conv label { display: flex; flex-direction: column; gap: 4px; font-size: 13px; color: var(--ink-2); flex: 1 1 160px; }
.conv input { font-size: 17px; padding: 8px 10px; border: 1px solid var(--line-2); border-radius: var(--r); background: var(--bg); color: var(--ink); width: 100%; }
.conv-eq { font-size: 20px; padding-bottom: 8px; color: var(--ink-3); }
.conv-p { font-size: 13px; color: var(--ink-2); margin: 10px 0 0; }

/* ── content pages ── */
.crumbs { max-width: 900px; margin: 16px auto 0; padding: 0 16px; font-size: 13px; color: var(--ink-3); display: flex; flex-wrap: wrap; gap: 6px; }
.crumbs a { color: var(--ink-2); text-decoration: none; }
.crumbs a:hover { text-decoration: underline; }
.page { max-width: 900px; margin: 0 auto; padding: 8px 16px 0; }
.page.center { text-align: center; padding-top: 60px; }
.big-z { font-size: 64px; margin: 0; color: var(--accent); }
.page-head { border-bottom: 2px solid var(--ink); padding: 14px 0 16px; margin-bottom: 22px; }
.page-head h1 { font-size: clamp(28px, 4.2vw, 40px); margin: 0 0 8px; }
.eyebrow { font: 500 12px/1.4 var(--mono); letter-spacing: .06em; text-transform: uppercase; color: var(--accent); margin: 0 0 6px; }
.lead { font-size: 17px; color: var(--ink-2); margin: 0; }
.prose { font-size: 16.5px; line-height: 1.8; }
.prose h2 { font-size: 24px; margin: 34px 0 10px; }
.prose h3 { font-size: 19px; margin: 24px 0 8px; }
.prose p { margin: 0 0 14px; }
.prose ul, .prose ol { padding-left: 22px; margin: 0 0 14px; }
.prose li { margin: 4px 0; }
.prose code, .props code { font-family: var(--mono); font-size: .9em; background: var(--surface-2); padding: 1px 4px; }
.table-wrap { overflow-x: auto; margin: 0 0 16px; }
.prose table th, .prose table td { border-bottom: 1px solid var(--line); padding: 7px 8px; text-align: left; font-size: 14.5px; }
.prose table th { border-bottom: 1.5px solid var(--ink); font-weight: 600; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 0; border-top: 1px solid var(--line-2); border-left: 1px solid var(--line-2); }
.card { display: block; padding: 18px; text-decoration: none; border-right: 1px solid var(--line-2); border-bottom: 1px solid var(--line-2); background: var(--surface); }
.card:hover { background: var(--surface-2); }
.card-n { font-size: 12px; color: var(--accent); }
.card h2 { font-size: 19px; margin: 6px 0 6px; }
.card p { margin: 0; font-size: 14px; color: var(--ink-2); line-height: 1.55; }
.feats { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px 22px; }
.feat h3 { font-size: 17px; margin: 0 0 4px; }
.feat p { font-size: 15px; margin: 0; color: var(--ink-2); line-height: 1.6; }
.faq { border-bottom: 1px solid var(--line); padding: 10px 0; }
.faq summary { cursor: pointer; font-weight: 600; font-size: 16px; }
.faq p { margin: 8px 0 4px; color: var(--ink-2); }
.el-list th, .el-list td { padding: 7px 8px; border-bottom: 1px solid var(--line); text-align: left; font-size: 14.5px; white-space: nowrap; }
.el-list th { border-bottom: 1.5px solid var(--ink); font-weight: 600; font-size: 13px; color: var(--ink-2); }
.el-list .sym { font-weight: 600; }
.el-list a { text-decoration: none; border-bottom: 1px solid var(--line-2); }
.el-list a:hover { border-color: var(--ink); }
.source { font-size: 12.5px; color: var(--ink-3); border-top: 1px solid var(--line); padding-top: 12px; margin-top: 28px; }
.back { font-size: 14px; }
.back a { color: var(--ink-2); }

/* element page */
.el-head { display: flex; gap: 22px; align-items: flex-start; border-bottom: 2px solid var(--ink); padding: 14px 0 20px; margin-bottom: 22px; }
.el-tile { width: 128px; height: 140px; flex-shrink: 0; border: 2px solid var(--ink); background: var(--surface); display: flex; flex-direction: column; justify-content: space-between; padding: 7px 9px; }
.el-tile .t-z { font: 500 15px/1 var(--mono); }
.el-tile .t-sym { font: 600 56px/1 var(--serif); align-self: center; }
.el-tile .t-m { font: 500 13px/1 var(--mono); align-self: center; }
.el-title h1 { font-size: clamp(30px, 5vw, 46px); margin: 0 0 6px; }
.h1-sym { font-family: var(--mono); font-size: .45em; color: var(--ink-3); font-weight: 500; }
.el-alias { font-size: 13.5px; color: var(--ink-3); margin: 0 0 10px; }
.el-title .lead { margin-bottom: 14px; }
@media (max-width: 600px) { .el-head { flex-direction: column; gap: 14px; } .el-tile { width: 104px; height: 114px; } .el-tile .t-sym { font-size: 44px; } }
.el-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 28px; margin-bottom: 20px; }
@media (max-width: 760px) { .el-grid { grid-template-columns: 1fr; } }
.el-grid h2 { font-size: 20px; margin: 0 0 10px; }
.el-grid h3 { font-size: 13px; font-family: var(--sans); font-weight: 700; text-transform: uppercase; letter-spacing: .04em; color: var(--ink-2); margin: 16px 0 8px; }
.el-sec h2 { border-top: 1px solid var(--line-2); padding-top: 18px; }
.facts ul { list-style: none; padding: 0; }
.facts li { border-left: 3px solid var(--accent); padding: 2px 0 2px 12px; margin: 10px 0; }
.mini-pt { display: grid; grid-template-columns: repeat(18, 1fr); grid-template-rows: repeat(7, auto) 5px repeat(2, auto); gap: 1px; max-width: 420px; }
.mini-pt .el { aspect-ratio: 1; padding: 0; align-items: center; justify-content: center; font: 500 7px/1 var(--mono); color: var(--ink-3); border-color: var(--line); }
.mini-pt .el.ph { font-size: 5px; }
.mini-pt .el.is-cur { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 700; }
.rel-grid { display: flex; flex-wrap: wrap; gap: 6px; }
.rel { display: inline-flex; gap: 6px; align-items: baseline; text-decoration: none; border: 1px solid var(--line-2); padding: 5px 10px; font-size: 14px; background: var(--surface); }
.rel b { font-family: var(--serif); }
.rel:hover { border-color: var(--ink); }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin-top: 26px; }
.pager a { display: flex; flex-direction: column; gap: 3px; text-decoration: none; border: 1px solid var(--line-2); padding: 12px 14px; background: var(--surface); }
.pager a:hover { border-color: var(--ink); }
.pager a span { font-size: 12.5px; color: var(--ink-3); }
.pager a b { font-family: var(--serif); font-size: 16px; font-weight: 600; }
.pager .nx { text-align: right; }

/* ── ads (애드핏 규정: 래퍼에 radius·overflow 금지) ── */
.ad-wrap { max-width: 1240px; margin: 24px auto; padding: 0 16px; }
.ad-grid { display: flex; flex-direction: column; align-items: center; gap: 14px; width: 100%; max-width: 672px; margin-left: auto; margin-right: auto; }
.ad-grid[data-ad-layout="mixed"] { max-width: 760px; }
.ad-row { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; width: 100%; }
.ad-cell { min-height: 50px; }
html[data-ad-media="pc"] .ad-mo, html[data-ad-media="mo"] .ad-pc { display: none; }
@media (min-width: 720px) { .ad-mo { display: none; } }
@media (max-width: 719.98px) { .ad-pc { display: none; } }

.toast { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); background: var(--ink); color: var(--bg); padding: 8px 14px; font-size: 14px; border-radius: var(--r); opacity: 0; pointer-events: none; transition: opacity .2s; z-index: 60; }
.toast.on { opacity: 1; }
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }

/* RTL(ar): 주기율표·오비탈·화학식은 국제 표준 배치(좌→우)를 유지 */
[dir="rtl"] .pt-grid, [dir="rtl"] .mini-pt, [dir="rtl"] .orb, [dir="rtl"] .cfg-dl dd, [dir="rtl"] .mm-input,
[dir="rtl"] .el-tile, [dir="rtl"] .in-tile { direction: ltr; }
[dir="rtl"] .pt-inset { direction: rtl; }
[dir="rtl"] .props th { padding-right: 0; padding-left: 12px; text-align: right; }
[dir="rtl"] .props td, [dir="rtl"] .el-list th, [dir="rtl"] .el-list td { text-align: right; }
[dir="rtl"] .prose ul, [dir="rtl"] .prose ol { padding-left: 0; padding-right: 22px; }
[dir="rtl"] .facts li { border-left: 0; border-right: 3px solid var(--accent); padding: 2px 12px 2px 0; }
[dir="rtl"] .pager .nx { text-align: left; }
[dir="rtl"] .dt-actions { margin-left: 0; margin-right: auto; }
[dir="rtl"] .hd-tools { margin-left: 0; margin-right: auto; }
[dir="rtl"] .mono, [dir="rtl"] .in-v, [dir="rtl"] .props td { direction: ltr; unicode-bidi: isolate; }
[dir="rtl"] .props td { text-align: right; }
[dir="rtl"] .eyebrow { font-family: var(--sans); letter-spacing: 0; }