@font-face {
font-family: 'PT Sans';
font-style: normal;
font-weight: 400;
font-display: swap;
src: url(/fonts/pt-sans-400-normal-cyrillic.woff2) format('woff2');
unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
font-family: 'PT Sans';
font-style: normal;
font-weight: 400;
font-display: swap;
src: url(/fonts/pt-sans-400-normal-latin.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
font-family: 'PT Sans';
font-style: normal;
font-weight: 700;
font-display: swap;
src: url(/fonts/pt-sans-700-normal-cyrillic.woff2) format('woff2');
unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
font-family: 'PT Sans';
font-style: normal;
font-weight: 700;
font-display: swap;
src: url(/fonts/pt-sans-700-normal-latin.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
font-family: 'PT Serif';
font-style: normal;
font-weight: 400;
font-display: swap;
src: url(/fonts/pt-serif-400-normal-cyrillic.woff2) format('woff2');
unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
font-family: 'PT Serif';
font-style: normal;
font-weight: 400;
font-display: swap;
src: url(/fonts/pt-serif-400-normal-latin.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
@font-face {
font-family: 'PT Serif';
font-style: normal;
font-weight: 700;
font-display: swap;
src: url(/fonts/pt-serif-700-normal-cyrillic.woff2) format('woff2');
unicode-range: U+0301, U+0400-045F, U+0490-0491, U+04B0-04B1, U+2116;
}
@font-face {
font-family: 'PT Serif';
font-style: normal;
font-weight: 700;
font-display: swap;
src: url(/fonts/pt-serif-700-normal-latin.woff2) format('woff2');
unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}
/* Молярная масса. Идея: вещество — это сложение клеток таблицы Менделеева. H₂SO₄ = [H]×2 + [S] + [O]×4 = 98,079.
Клетка элемента — главный графический знак сайта; страница элементов — сама таблица. Учебник, а не лаборатория:
PT Serif для формул и заголовков, PT Sans для текста; чёрная линия и один оранжевый акцент, как пометка на полях. */
:root{
--paper:#fff; --ink:#141619; --muted:#5c6168; --line:#e2e4e7; --tint:#f5f5f3; --acc:#d9480f; --acc-soft:#fbe4d8;
--wrap:1200px; --pad:clamp(16px,4vw,48px);
--serif:"PT Serif",Georgia,serif; --sans:"PT Sans",-apple-system,"Segoe UI",Arial,sans-serif;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font:400 18px/1.55 var(--sans);font-variant-numeric:tabular-nums lining-nums}
a{color:var(--ink);text-decoration:underline;text-decoration-color:var(--acc);text-decoration-thickness:1.5px;text-underline-offset:3px}
a:hover{color:var(--acc)}
:focus-visible{outline:3px solid var(--acc);outline-offset:2px}
.skip{position:absolute;left:-9999px;top:8px;background:var(--ink);color:#fff;padding:8px 12px;z-index:9}.skip:focus{left:8px}
sub{font-size:.7em;line-height:0}
.head,main,.foot{width:min(100% - 2 * var(--pad),var(--wrap));margin-left:auto;margin-right:auto}
.head{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:10px 28px;padding:18px 0;border-bottom:2px solid var(--ink)}
.brand{display:inline-flex;align-items:center;gap:12px;font:700 20px var(--serif);text-decoration:none}
.brand-cell{display:inline-grid;place-items:center;width:30px;height:30px;border:2px solid var(--ink);box-shadow:inset 0 -6px 0 var(--acc);font:700 16px var(--serif);padding-bottom:4px}
.nav{display:flex;flex-wrap:wrap;gap:4px 24px}
.nav a{text-decoration:none;font-size:17px;padding:4px 0;border-bottom:2px solid transparent}
.nav a:hover{border-color:var(--line)}
.nav a[aria-current]{border-color:var(--acc)}
main{padding-bottom:16px}
main:focus{outline:0}
.crumbs{font-size:15px;color:var(--muted);padding-top:14px}
.crumbs a{color:var(--muted);text-decoration-color:var(--line)}
h1{font:700 clamp(30px,4vw,48px)/1.1 var(--serif);letter-spacing:-.015em;margin:.5em 0 .45em;text-wrap:balance}
h2{font:700 clamp(23px,2.6vw,30px)/1.2 var(--serif);margin:1.9em 0 .55em}
p{margin:0 0 1em;max-width:40em;text-wrap:pretty}
.lead{font-size:clamp(18px,1.8vw,20px);line-height:1.55}
.src{font-size:15.5px;color:var(--muted)}
/* Клетка элемента */
.el{position:relative;display:inline-grid;grid-template-rows:auto 1fr auto;width:84px;height:92px;padding:6px 7px;border:2px solid var(--ink);background:#fff;text-align:center;vertical-align:middle}
.el-z{font-size:12.5px;text-align:left;line-height:1}
.el-s{font:700 34px/1.05 var(--serif);align-self:center}
.el-m{font-size:12.5px;line-height:1.1}
.el-big{width:150px;height:166px;padding:10px 12px;border-width:3px;box-shadow:8px 8px 0 var(--acc)}
.el-big .el-z{font-size:18px}.el-big .el-s{font-size:68px}.el-big .el-m{font-size:18px}
/* Сложение */
.calc{padding-bottom:clamp(20px,3vw,36px);border-bottom:1px solid var(--line)}
.field label{display:block;font-size:14.5px;font-weight:700;color:var(--muted);margin-bottom:6px}
.field input{font:700 clamp(30px,4vw,44px)/1 var(--serif);letter-spacing:.02em;width:100%;max-width:560px;padding:10px 14px;min-height:66px;border:2px solid var(--ink);background:#fff;color:var(--ink)}
.field input:focus-visible{outline:0;box-shadow:6px 6px 0 var(--acc)}
.hint{font-size:15.5px;color:var(--muted);margin:10px 0 0;min-height:1.6em;max-width:48em}
.hint.is-error{color:var(--acc);font-weight:700}
.answer{margin:26px 0 8px}
.answer.is-error{opacity:.25}
.answer.is-empty{opacity:.25}
.eq{display:flex;flex-wrap:wrap;align-items:center;gap:14px 12px}
.term{display:inline-flex;align-items:center;gap:6px}
.mul{font:700 22px var(--serif);white-space:nowrap}
.op{font:400 34px/1 var(--serif);color:var(--muted)}
.total{font:700 clamp(40px,5.4vw,64px)/1 var(--serif);letter-spacing:-.02em;color:var(--ink);white-space:nowrap}
.total small{font:400 .34em var(--sans);margin-left:.35em;color:var(--muted);letter-spacing:0}
.shares{display:flex;height:30px;margin-top:18px;max-width:900px;border:2px solid var(--ink)}
.shares i{display:flex;align-items:center;justify-content:center;font:700 13px var(--sans);font-style:normal;overflow:hidden;min-width:2px;border-right:2px solid #fff}
.shares i:last-child{border-right:0}
.sh0{background:var(--ink);color:#fff}.sh1{background:var(--acc);color:#fff}.sh2{background:#8b919a;color:#fff}.sh3{background:var(--acc-soft);color:var(--ink)}
@media(prefers-reduced-motion:no-preference){.shares i{animation:grow .5s cubic-bezier(.2,.7,.2,1) both}}
@keyframes grow{from{flex-basis:0;width:0!important}}
.parts{font-size:15.5px;color:var(--muted);margin:10px 0 0;min-height:1.5em}
.formula-big{font:700 clamp(46px,7vw,84px)/1 var(--serif);margin:.1em 0 .1em}
.elem-hero{display:grid;grid-template-columns:auto minmax(0,1fr);gap:24px clamp(28px,4vw,56px);align-items:center;padding:16px 0 30px;border-bottom:1px solid var(--line)}
.elem-hero h1{margin-top:0}
/* Таблица Менделеева */
.pt-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:1.4em 0 .6em;padding:4px 4px 10px}
.pt{display:grid;grid-template-columns:repeat(18,minmax(52px,1fr));grid-template-rows:repeat(7,auto) 14px repeat(2,auto);gap:3px;min-width:1000px}
.pt-cell{display:block;text-decoration:none;color:var(--ink)}
.pt-cell .el{width:100%;height:auto;aspect-ratio:1/1.1;padding:3px 4px;border-width:1.5px}
.pt-cell .el-z{font-size:10px}.pt-cell .el-s{font-size:clamp(16px,1.7vw,22px)}.pt-cell .el-m{font-size:9.5px}
.pt-cell:hover .el,.pt-cell:focus-visible .el{background:var(--acc);color:#fff;border-color:var(--acc)}
.pt-cell:focus-visible{outline:0}
.pt-gap{display:grid;place-items:center;border:1.5px dashed #b9bdc3;font-size:10px;color:var(--muted)}
.pt-gap::before{content:attr(data-l)}
/* Таблицы */
.scroll{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:0 0 1.4em}
table{border-collapse:collapse;width:100%;max-width:880px;font-size:17px}
table.narrow{max-width:600px}
thead th{font-size:14.5px;font-weight:700;color:var(--muted);text-align:left;padding:8px 16px 8px 0;border-bottom:2px solid var(--ink)}
td,tbody th{padding:8px 16px 8px 0;border-bottom:1px solid var(--line);text-align:left}
tbody th{font-weight:400}
.num,th.num{text-align:right;white-space:nowrap}
td:last-child,th:last-child{padding-right:0}
.strong{font-weight:700}
.f{font:400 19px var(--serif);white-space:nowrap}
.sym{font:700 19px var(--serif)}
tbody tr:hover th,tbody tr:hover td{background:var(--tint)}
.finder{display:flex;align-items:center;gap:12px;margin:.4em 0 .8em;max-width:480px}
.finder label{font-weight:700;white-space:nowrap}
.finder input{flex:1;min-width:0;font:inherit;padding:8px 12px;min-height:46px;border:2px solid var(--ink);background:#fff;color:var(--ink)}
.empty{padding:12px 16px;background:var(--tint);border-left:4px solid var(--acc)}
.chips{list-style:none;padding:0;margin:0 0 1em;display:flex;flex-wrap:wrap;gap:8px}
.chips a{display:inline-block;padding:6px 14px;border:2px solid var(--ink);text-decoration:none}
.chips a:hover{background:var(--ink);color:#fff}
ul:not(.chips){padding-left:1.2em;max-width:40em}
.foot{margin-top:64px;padding:24px 0 40px;border-top:2px solid var(--ink);font-size:15.5px;color:var(--muted)}
.foot nav{display:flex;flex-wrap:wrap;gap:4px 22px}
.foot nav a{color:var(--muted)}
.cookie{position:fixed;left:12px;right:12px;bottom:12px;max-width:560px;display:flex;gap:14px;align-items:center;background:#fff;color:var(--ink);padding:12px 14px 12px 18px;font-size:15px;border:2px solid var(--ink);box-shadow:6px 6px 0 var(--acc);z-index:5}
.cookie[hidden]{display:none}
.cookie p{margin:0}
.cookie button{flex:none;font:700 15px/1 var(--sans);min-height:40px;padding:0 16px;border:0;background:var(--ink);color:#fff;cursor:pointer}
@media(max-width:640px){
body{font-size:17px}
.head{display:block}
.nav{margin-top:8px}
.el{width:66px;height:74px;padding:4px 5px}
.el-s{font-size:26px}.el-z,.el-m{font-size:11px}
.op{font-size:24px}.mul{font-size:18px}
.elem-hero{grid-template-columns:minmax(0,1fr)}
.el-big{width:120px;height:132px}.el-big .el-s{font-size:52px}
.m-hide{display:none}
table{font-size:16px}
td,tbody th,thead th{padding-right:10px}
.finder{display:block}.finder label{display:block;margin-bottom:6px}
}