/* 李约瑟 · 滴定：一页化学实验记录。浅水绿的记录纸（横格），蓝黑墨水，玻璃器皿用细线；
   唯一的颜色是酚酞的品红——读得越深，整页的底色越往品红那边偏一点（--t 由脚本按阅读进度设置）。 */
.c-needham {
  --bg: #eef3f1; --paper: #fbfcfb; --ink: #18202c; --ink-2: #3c4553; --ink-3: #5f6977; --rule: rgba(24, 32, 44, .15);
  --acc: #b0155e; --acc-ink: #fff; --pink: #f2c3d8; --glass: #8aa6b1; --glass-2: rgba(138, 166, 177, .35);
  --head: "Noto Serif SC", "Songti SC", serif; --body: "Noto Serif SC", "Songti SC", serif; --sans: "Noto Sans SC", "PingFang SC", sans-serif;
  --num: "STIX Two Text", "Noto Serif SC", serif;
  --page: #eef3f1;
  --bar-bg: rgba(238, 243, 241, .93); --chip-bg: rgba(251, 252, 251, .92); --chip-ring: #fbfcfb;
}
body.c-needham { background-color: var(--page);
  background-image: linear-gradient(rgba(40, 110, 120, .075) 1px, transparent 1px); background-size: 100% 30px; }
/* 读得越深，底色越往品红那边偏（--t 由脚本按阅读进度设置；不支持 color-mix 的浏览器停在浅水绿） */
@supports (color: color-mix(in oklab, red, blue)) {
  .c-needham { --page: color-mix(in oklab, #eef3f1, #f8d9e7 calc(var(--t, 0) * 55%)); --bar-bg: color-mix(in oklab, var(--page) 92%, transparent); }
}
.c-needham .dlg { --dlg-bg: #e9efed; --dlg-paper: #fcfdfc; --dlg-me: #18202c; --dlg-me-ink: #f4f7f6; --dlg-acc: #a3134f; }
.c-needham .c3bar { border-bottom: 3px double rgba(24, 32, 44, .35); }
.c-needham .c3bar__prog { background: var(--acc); }
.nd-num { font-family: var(--num); font-variant-numeric: lining-nums tabular-nums; }
.c-needham .mk { font-family: var(--sans); font-size: 12px; letter-spacing: .14em; color: var(--ink-3); }
.nd-kk { margin: 0 0 8px; font-family: var(--sans); font-size: 12.5px; letter-spacing: .16em; color: var(--acc); }
.nd-out { margin: 10px 0 0; min-height: 3.3em; padding: 9px 12px; border-left: 3px solid var(--acc); background: rgba(176, 21, 94, .045); font-size: 14.5px; line-height: 1.75; }
.nd-cap { margin: 8px 0 0; font-family: var(--sans); font-size: 12.5px; line-height: 1.7; color: var(--ink-3); }
.c-needham [data-js][hidden] { display: none !important; }
.nd-btn, .nd-seg button { min-height: 42px; padding: 7px 14px; border: 1px solid var(--ink); background: var(--paper); color: var(--ink); font-family: var(--sans); font-size: 14px; line-height: 1.25; cursor: pointer; }
.nd-btn:hover, .nd-seg button:hover { border-color: var(--acc); }
.nd-btn--acc { background: var(--acc); border-color: var(--acc); color: var(--acc-ink); }
.nd-btn--acc:hover { background: #8e0f4a; }
.nd-seg { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 12px; }
.nd-seg button[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
.nd-seg button small { display: block; font-size: 11.5px; opacity: .8; }

/* ---------- 页边目录：一支细滴定管 ---------- */
.c-needham .c3toc { right: 26px; }
.c-needham .c3toc ol { position: relative; gap: 0; padding: 10px 0 8px; }
.c-needham .c3toc li { padding: 5px 0; }
.nd-tube { position: absolute; right: 18px; top: -6px; bottom: -14px; width: 12px; border: 1.5px solid var(--ink-3); border-top: 0; border-radius: 0 0 4px 4px; overflow: hidden; }
.nd-tube::after { content: ""; position: absolute; left: 50%; bottom: -10px; width: 2px; height: 10px; background: var(--ink-3); }
.nd-tube__l { position: absolute; left: 0; right: 0; bottom: 0; top: calc(var(--p, 0) * 100%); background: rgba(138, 166, 177, .42); border-top: 2px solid var(--glass); transition: top .25s; }
.c-needham .c3toc a { position: relative; gap: 10px; padding-right: 34px; font-family: var(--sans); font-size: 12.5px; color: var(--ink-2); min-height: 20px; }
.c-needham .c3toc a b { max-width: 0; overflow: hidden; font-family: var(--num); font-size: 13px; font-weight: 500; transition: max-width .3s; }
.c-needham .c3toc a:hover b, .c-needham .c3toc a:focus-visible b { max-width: 4em; }
.c-needham .c3toc a span { background: var(--paper); padding: 0 4px; }
.c-needham .c3toc a::after { position: absolute; right: 18px; top: 50%; width: 9px; height: 0; border: 0; border-top: 1.5px solid var(--ink-3); border-radius: 0; margin: 0; }
.c-needham .c3toc a[aria-current="true"] { color: var(--acc); }
.c-needham .c3toc a[aria-current="true"]::after { width: 16px; right: 14px; border-top: 2.5px solid var(--acc); background: none; }

/* ---------- 首屏 ---------- */
.c-needham .c3hero { padding-top: calc(var(--bar) + 26px); padding-bottom: 36px; }
.nd-hero { max-width: 1240px; margin: 0 auto; display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: clamp(28px, 4vw, 64px); align-items: start; }
.nd-hl { display: flex; flex-direction: column; gap: 16px; min-width: 0; }
.nd-tag { position: relative; margin: 0; padding: 22px 26px 18px; background: var(--paper); border: 1px solid var(--ink);
  box-shadow: inset 0 0 0 5px var(--paper), inset 0 0 0 6px rgba(24, 32, 44, .55), 0 10px 26px rgba(24, 32, 44, .08); }
.nd-tag::before { content: ""; position: absolute; left: 0; right: 0; top: 0; height: 7px; background: var(--acc); }
.nd-tag__top { margin: 4px 0 0; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 4px 16px; font-family: var(--sans); font-size: 12.5px; letter-spacing: .16em; color: var(--ink-3); }
.nd-tag h1 { margin: 6px 0 0; font-family: var(--head); font-weight: 900; font-size: clamp(60px, 7.2vw, 108px); line-height: 1.04; letter-spacing: .05em; }
.nd-tag__en { margin: 6px 0 12px; padding-bottom: 12px; border-bottom: 1px solid var(--ink); display: flex; flex-wrap: wrap; gap: 4px 14px; align-items: baseline;
  font-family: var(--num); font-style: italic; font-size: 23px; color: var(--ink-2); }
.nd-tag__en .nd-num { font-style: normal; font-size: 17px; color: var(--ink-3); }
.nd-tag__who { margin: 0 0 4px; font-size: 18px; font-weight: 600; line-height: 1.6; }
.nd-tag__now { margin: 0; font-size: 14.5px; color: var(--ink-2); }
.nd-wk { list-style: none; margin: 0; padding: 0 0 0 14px; border-left: 2px solid var(--acc); font-size: 14.5px; line-height: 1.8; }
.nd-wk span { margin-left: 6px; font-family: var(--num); font-size: 14.5px; color: var(--ink-3); }
.nd-rel { margin: 0; padding: 12px 14px 13px; background: var(--paper); border: 1px solid var(--rule); border-left: 3px solid var(--ink); }
.nd-rel .mk { margin: 0 0 4px; color: var(--acc); }
.nd-rel p { margin: 0; font-size: 14.5px; line-height: 1.8; }
.nd-go { margin: 2px 0 0; }
.c-needham .c3-btn { border-radius: 0; font-family: var(--sans); font-size: 14px; min-height: 42px; }
.c-needham .c3-btn--go { background: var(--acc); border-color: var(--acc); color: var(--acc-ink); }
.c-needham .c3-btn--deep { background: transparent; border-color: var(--ink); color: var(--ink); }

/* 滴定管 = 问题目录 */
.nd-rig { margin: 0; justify-self: start; }
.nd-rig__b { position: relative; width: max-content; }
.c-needham .nd-rig__img { display: block; width: auto; max-width: none; height: min(66vh, 640px); min-height: 480px; mix-blend-mode: multiply; }
.nd-rig__q { list-style: none; margin: 0; padding: 0; position: absolute; left: 81%; top: 0; bottom: 0; width: clamp(250px, 26vw, 330px); }
.nd-rig__q li { position: absolute; left: 0; right: 0; top: var(--y); transform: translateY(-50%); }
.nd-rig__q a { display: flex; align-items: center; gap: 8px; min-height: 30px; text-decoration: none; font-size: 14.5px; line-height: 1.35; }
.nd-rig__q a::before { content: ""; flex: none; width: 22px; border-top: 1px dotted var(--ink-3); }
.nd-rig__q b { flex: none; font-family: var(--num); font-weight: 600; font-size: 15px; color: var(--acc); }
.nd-rig__q a:hover span, .nd-rig__q a:focus-visible span { text-decoration: underline; text-decoration-color: var(--acc); text-underline-offset: 3px; }
.nd-rig__end { position: absolute; left: calc(64.4% + 74px); top: calc(100% + 34px); display: flex; flex-direction: column; min-height: 40px; justify-content: center; padding-left: 10px; text-decoration: none; font-family: var(--sans); font-size: 13px; white-space: nowrap; }
.nd-rig__end b { font-family: var(--head); font-size: 18px; color: var(--acc); }
.nd-flask { position: absolute; left: calc(64.4% - 62px); top: calc(100% + 2px); width: 124px; pointer-events: none; }
.nd-flask svg { display: block; width: 100%; height: auto; overflow: visible; }
.nd-flask__g { fill: none; stroke: var(--ink); stroke-width: 2; stroke-linejoin: round; }
.nd-flask__l { fill: rgba(138, 166, 177, .22); }
.nd-flask__s { fill: var(--acc); opacity: 0; }
.nd-flask__tile { fill: var(--paper); stroke: var(--rule); }
.nd-fall { position: absolute; left: 50%; top: -14px; width: 6px; height: 8px; margin-left: -3px; border-radius: 50% 50% 50% 50% / 60% 60% 40% 40%; background: var(--glass); opacity: 0; }
.js .nd-fall { animation: nd-fall 3.4s ease-in infinite; }
.js .nd-flask__s { animation: nd-swirl 3.4s ease-out infinite; }
@keyframes nd-fall { 0% { transform: translateY(0); opacity: 0; } 8% { opacity: .9; } 30% { transform: translateY(78px); opacity: .9; } 31%, 100% { transform: translateY(78px); opacity: 0; } }
@keyframes nd-swirl { 0%, 29% { opacity: 0; transform: scale(.4); } 33% { opacity: .55; transform: scale(1); } 70%, 100% { opacity: 0; transform: scale(1.3); } }
.nd-flask__s { transform-box: fill-box; transform-origin: center; }
.nd-rig figcaption { max-width: 34em; margin-top: 112px; font-family: var(--sans); font-size: 12.5px; line-height: 1.65; color: var(--ink-3); }

.nd-band { max-width: 1240px; margin: 34px auto 0; padding-top: 18px; border-top: 3px double rgba(24, 32, 44, .4); }
.nd-facts { margin: 0 0 22px; font-size: 14.5px; line-height: 1.85; color: var(--ink-2); columns: 2 380px; column-gap: 48px; }
.nd-band__g { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 32px; }
.nd-band .mk { color: var(--acc); }
.c-needham .c3-feats { margin: 0; padding: 0; list-style: none; counter-reset: f; }
.c-needham .c3-feats li { counter-increment: f; position: relative; padding: 5px 0 5px 30px; border-bottom: 1px solid var(--rule); font-size: 14.5px; line-height: 1.65; }
.c-needham .c3-feats li::before { content: counter(f); position: absolute; left: 0; top: 4px; width: 20px; height: 20px; border-radius: 50%; border: 1px solid var(--acc); color: var(--acc); font: 500 12px/18px var(--num); text-align: center; }
.c-needham .c3-books li, .c-needham .c3-links li { font-size: 14.5px; border-bottom-style: solid; border-bottom-color: var(--rule); }
.c-needham .c3-books small, .c-needham .c3-links small { font-family: var(--sans); font-size: 12px; }

/* ---------- 每一问：一滴 ---------- */
.c-needham .c3q { display: block; padding-top: calc(var(--bar) + 30px); }
.nd-q { max-width: 1240px; margin: 0 auto; display: grid; grid-template-columns: 58px minmax(0, 1fr); gap: 0 18px; }
.nd-rail { position: relative; display: flex; flex-direction: column; align-items: center; gap: 10px; padding-top: 6px; }
.nd-rail::before { content: ""; position: absolute; top: 46px; bottom: -40px; left: 50%; border-left: 1px dashed var(--glass); }
.nd-rail span { position: relative; writing-mode: vertical-rl; font-family: var(--sans); font-size: 13px; letter-spacing: .22em; color: var(--ink-3); background: var(--page); padding: 6px 0; }
.nd-dropi { position: relative; width: 22px; height: 30px; }
.nd-dropi__b { fill: #cfdcdf; stroke: var(--ink); stroke-width: 1.2; }
.nd-dropi__c { fill: var(--acc); opacity: var(--k, 0); }
.nd-q__g { display: grid; grid-template-columns: minmax(0, .9fr) minmax(0, 1.1fr); grid-template-rows: auto 1fr; grid-template-areas: "a art" "b art"; gap: 0 clamp(26px, 4vw, 56px); align-items: start; }
.nd-q__a { grid-area: a; }
.nd-q__b { grid-area: b; }
.nd-q__art { grid-area: art; }
.c-needham .c3q__when b { font-family: var(--num); font-weight: 600; font-size: 32px; color: var(--acc); }
.c-needham .c3q__when span { font-family: var(--sans); font-size: 13.5px; }
.c-needham .c3q__q { font-weight: 900; font-size: clamp(28px, 3.2vw, 42px); line-height: 1.28; letter-spacing: .02em; }
.c-needham .c3q__lede { font-size: 16.5px; line-height: 1.9; text-align: justify; }
.nd-lab { display: inline-grid; grid-template-columns: auto auto; align-items: baseline; gap: 0 12px; margin: 0 0 16px; padding: 9px 14px 8px; position: relative;
  background: var(--paper); border: 1px solid var(--ink); box-shadow: 3px 3px 0 rgba(24, 32, 44, .1); }
.nd-lab::before { content: ""; position: absolute; left: 0; right: 0; top: 0; height: 4px; background: var(--acc); }
.nd-lab__k { grid-column: 1 / -1; margin-top: 2px; font-family: var(--sans); font-size: 11px; letter-spacing: .2em; color: var(--ink-3); }
.nd-lab b { font-family: var(--head); font-weight: 700; font-size: 19px; }
.nd-lab i { font-family: var(--num); font-size: 15px; color: var(--ink-2); }
.nd-lab__s { grid-column: 1 / -1; font-family: var(--sans); font-size: 11.5px; color: var(--ink-3); }
.c-needham .c3-quote { margin: 20px 0; padding: 12px 0 12px 18px; border-left: 3px solid var(--acc); background: linear-gradient(90deg, rgba(176, 21, 94, .05), transparent 70%); }
.c-needham .c3-quote blockquote p { font-weight: 600; font-size: 18px; }
.c-needham .c3-orig { font-family: var(--num); font-size: 15px; }
.c-needham .c3-quote figcaption { font-family: var(--sans); font-size: 12px; }
.c-needham .c3-tags li { border-radius: 2px; border-color: var(--glass); background: rgba(255, 255, 255, .5); font-family: var(--sans); font-size: 12.5px; }
.c-needham .c3-works .mk, .c-needham .c3-talk .mk { color: var(--acc); }
.c-needham .talk { border-radius: 4px; border-color: var(--ink); background: var(--paper); }
.c-needham .c3-ask { border-radius: 2px; border-style: solid; border-color: var(--glass); }
.c-needham .c3-deeplink { text-decoration-color: var(--acc); text-underline-offset: 4px; }

/* 配图 */
.nd-fig { margin: 0; }
.nd-fig img { display: block; width: 100%; height: auto; mix-blend-mode: multiply; }
.nd-fig figcaption { margin-top: 8px; font-family: var(--sans); font-size: 12.5px; line-height: 1.65; color: var(--ink-3); }
.c-needham .nd-fig--tall img { max-height: 74vh; width: auto; max-width: 100%; }
.nd-fig--su { max-width: 430px; margin-top: 22px; }
.nd-data { width: 100%; margin-top: 18px; border-collapse: collapse; font-size: 14.5px; line-height: 1.55; border-top: 2px solid var(--ink); border-bottom: 2px solid var(--ink); background: rgba(251, 252, 251, .6); }
.nd-data caption { caption-side: top; text-align: left; padding: 0 0 6px; font-family: var(--sans); font-size: 12.5px; letter-spacing: .16em; color: var(--acc); }
.nd-data th { width: 9.5em; padding: 6px 10px; text-align: left; font-family: var(--num); font-weight: 500; color: var(--acc); white-space: nowrap; vertical-align: baseline; }
.nd-data td { padding: 6px 10px 6px 0; vertical-align: baseline; }
.nd-data tr + tr th, .nd-data tr + tr td { border-top: 1px solid var(--rule); }

/* 面板 */
.nd-shelf, .nd-esc, .nd-ti, .nd-rv, .nd-hv { padding: 14px 16px 16px; background: var(--paper); border: 1px solid var(--ink); }

/* 第三问：书架 */
.nd-shelf__box { position: relative; height: 196px; margin: 4px 0 0; border-bottom: 3px solid var(--ink); }
.nd-shelf__bk { list-style: none; margin: 0; padding: 0; position: absolute; left: 0; right: 0; bottom: 0; height: 150px; }
.nd-bk { position: absolute; bottom: 0; left: var(--xv); width: 3.4%; height: 150px; }
.nd-shelf[data-mode="year"] .nd-bk { left: var(--xy); width: 1.5%; }
.nd-bk { transition: left .9s cubic-bezier(.5, 0, .2, 1), width .9s; }
.nd-bk b, .nd-bk small { transition: opacity .4s; }
.nd-shelf[data-mode="year"] .nd-bk b, .nd-shelf[data-mode="year"] .nd-bk small { opacity: 0; }
.nd-bk button { display: flex; flex-direction: column; align-items: center; justify-content: space-between; width: 100%; height: 100%; padding: 8px 0 6px; margin: 0;
  border: 1px solid var(--ink); border-bottom: 0; border-radius: 2px 2px 0 0; background: #c8d4d8; color: var(--ink); cursor: pointer; font: inherit; }
.nd-bk--a button { background: var(--ink); color: #eef3f1; }
.nd-bk--b button { background: #586a7c; color: #f2f5f4; }
.nd-bk b { writing-mode: vertical-rl; font-family: var(--num); font-weight: 600; font-size: 13px; letter-spacing: .05em; }
.nd-bk small { writing-mode: vertical-rl; font-family: var(--num); font-size: 10.5px; opacity: .85; }
.nd-bk button:hover, .nd-bk button:focus-visible { transform: translateY(-8px); }
.nd-bk button { transition: transform .2s; }
.nd-bk button[aria-current="true"] { transform: translateY(-14px); box-shadow: 0 0 0 2px var(--acc); }
.nd-shelf__ax { position: absolute; left: 0; right: 0; top: 4px; height: 20px; opacity: 0; transition: opacity .6s; font-family: var(--num); font-size: 12px; color: var(--ink-3); }
.nd-shelf__ax span { position: absolute; top: 0; transform: translateX(-2px); }
.nd-shelf__ax em { position: absolute; top: 18px; height: 168px; padding-left: 5px; border-left: 1.5px dashed var(--acc); font-style: normal; font-family: var(--sans); font-size: 11.5px; color: var(--acc); white-space: nowrap; }
.nd-shelf[data-mode="year"] .nd-shelf__ax { opacity: 1; }
.nd-legend { display: flex; flex-wrap: wrap; gap: 4px 16px; margin: 10px 0 0; font-family: var(--sans); font-size: 12.5px; color: var(--ink-2); }
.nd-lg i { display: inline-block; width: 11px; height: 11px; margin-right: 5px; vertical-align: -1px; border: 1px solid var(--ink); }
.nd-lg--a i { background: var(--ink); } .nd-lg--b i { background: #586a7c; } .nd-lg--c i { background: #c8d4d8; }
.nd-step { display: flex; gap: 6px; margin-top: 10px; }
.nd-step button { min-height: 42px; padding: 6px 14px; border: 1px solid var(--ink); background: var(--paper); color: var(--ink); font-family: var(--sans); font-size: 13.5px; cursor: pointer; }

/* 第四问：宫墙之内 */
.nd-hv__g { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 16px; align-items: stretch; }
.nd-hv__gr, .nd-hv__cn { padding: 14px 16px; font-size: 15px; line-height: 1.8; }
.nd-hv__gr p, .nd-hv__cn p { margin: 0; }
.nd-hv__gr { border: 1px dashed var(--ink-3); }
.nd-hv__cn { position: relative; margin-top: 12px; border: 3px solid var(--ink); background: rgba(176, 21, 94, .05); }
.nd-hv__cn::before { content: ""; position: absolute; left: -3px; right: -3px; top: -13px; height: 10px;
  background: repeating-linear-gradient(90deg, var(--ink) 0 12px, transparent 12px 22px); }
.nd-hv__k { font-family: var(--head); font-weight: 900; font-size: 20px; margin-bottom: 6px !important; }
.nd-hv__cn .nd-hv__k { color: var(--acc); }
.nd-hv__rec { margin-top: 20px; padding-top: 14px; border-top: 1px solid var(--rule); }
.nd-hv__rec svg { display: block; width: 100%; height: auto; }
.nd-hv__ax { stroke: var(--ink-3); stroke-width: 1; }
.nd-hv__cnl { stroke: var(--acc); stroke-width: 6; stroke-linecap: round; }
.nd-hv__t { font-family: var(--num); font-size: 15px; fill: var(--ink-2); }
.nd-hv__l { font-family: var(--sans); font-size: 14px; fill: var(--ink); }
.nd-hv__m { fill: var(--paper); stroke: var(--acc); stroke-width: 3; }
.nd-hv__t--k { fill: var(--acc); font-weight: 600; }
.nd-hv__go { margin: 6px 0 0; font-size: 14px; line-height: 1.7; }
.nd-hv__go a { color: var(--ink); text-decoration-color: var(--acc); text-underline-offset: 3px; }

/* 第五问：受水壶的秤 */
.nd-esc svg { display: block; width: 100%; height: auto; overflow: hidden; }
.nd-esc__tank path { fill: rgba(138, 166, 177, .25); stroke: var(--ink); stroke-width: 1.6; }
.nd-esc__tank text, .nd-esc__lev text, .nd-esc__lock text { font-family: var(--sans); font-size: 15px; fill: var(--ink-2); }
.nd-esc__jet { fill: none; stroke: var(--glass); stroke-width: 4; stroke-linecap: round; opacity: 0; transition: opacity .2s; }
.nd-esc.is-pour .nd-esc__jet { opacity: 1; }
.nd-esc__rim { fill: none; stroke: var(--ink); stroke-width: 2; }
.nd-esc__rim--in { stroke-width: 1; }
.nd-esc__sp { fill: none; stroke: var(--ink-3); stroke-width: 1.1; }
.nd-esc__hub { fill: var(--paper); stroke: var(--ink); stroke-width: 2; }
.nd-bkt path { fill: var(--paper); stroke: var(--ink); stroke-width: 1.6; }
.nd-bkt__w { fill: rgba(110, 150, 165, .8); }
.nd-esc__lev { transform-box: view-box; transform-origin: 318px 206px; transition: transform .35s cubic-bezier(.4, 0, .2, 1); }
.nd-esc__bar { stroke: var(--ink); stroke-width: 4; stroke-linecap: round; }
.nd-esc__post, .nd-esc__str { fill: none; stroke: var(--ink-3); stroke-width: 2; }
.nd-esc__piv { fill: var(--paper); stroke: var(--ink); stroke-width: 2; }
.nd-esc__wt { fill: var(--ink); }
.nd-esc__pawl { fill: none; stroke: var(--acc); stroke-width: 3.5; stroke-linecap: round; transform-box: view-box; transform-origin: 206px 96px; transition: transform .3s; }
.nd-esc.is-trip .nd-esc__lev { transform: rotate(-8deg); }
.nd-esc.is-trip .nd-esc__pawl { transform: rotate(52deg); }
.nd-esc__lb text { font-family: var(--sans); font-size: 14px; fill: var(--ink-3); paint-order: stroke; stroke: var(--paper); stroke-width: 4px; stroke-linejoin: round; }
.nd-gauge__b { fill: none; stroke: var(--ink); stroke-width: 1.2; }
.nd-gauge__f { fill: var(--glass); }
.nd-gauge__t { stroke: var(--acc); stroke-width: 2.5; }
.nd-gauge__l { font-family: var(--sans); font-size: 13px; fill: var(--ink-3); }
.nd-esc__ctl { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 10px; margin-top: 8px; }
.nd-esc__ctl [data-fill] { touch-action: none; user-select: none; -webkit-user-select: none; }
.nd-btn[aria-pressed="true"] { background: var(--ink); color: var(--paper); }
.nd-esc__n { margin: 0 0 0 auto; font-family: var(--sans); font-size: 13px; color: var(--ink-2); }
.nd-esc__n b { margin: 0 6px; font-family: var(--num); font-size: 26px; font-weight: 600; color: var(--acc); }

/* 第六问：换一种指示剂 */
.nd-ti__ind button { text-align: left; }
.nd-ti__svg { display: block; width: 100%; height: auto; }
.nd-ti__stand { fill: none; stroke: var(--ink-3); stroke-width: 2.5; stroke-linecap: round; }
.nd-ti__bur { fill: rgba(255, 255, 255, .7); stroke: var(--ink); stroke-width: 1.5; }
.nd-ti__bl { fill: rgba(138, 166, 177, .35); }
.nd-ti__tick { stroke: var(--ink-3); stroke-width: 1; }
.nd-ti__fl { fill: rgba(255, 255, 255, .6); stroke: var(--ink); stroke-width: 1.8; stroke-linejoin: round; }
.nd-ti__liq { fill: #e6eef0; }
.nd-ti__liq--c { fill: var(--acc); opacity: var(--c, 0); transition: opacity .9s; }
.nd-ti__set--cn { --c: var(--ccn, 0); }
.nd-ti__set--eu { --c: var(--ceu, 0); }
.nd-ti__lab { font-family: var(--head); font-weight: 900; font-size: 22px; fill: var(--ink); }
.nd-ti__drop { fill: var(--glass); opacity: 0; }
.nd-ti__set.is-drip .nd-ti__drop { animation: nd-tdrop .7s ease-in; }
@keyframes nd-tdrop { 0% { opacity: .9; transform: translateY(0); } 90% { opacity: .9; transform: translateY(62px); } 100% { opacity: 0; transform: translateY(66px); } }
.nd-ti__chips { list-style: none; margin: 8px 0 0; padding: 0; display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 4px; counter-reset: c; }
.nd-ti__chips li { counter-increment: c; padding: 6px 6px 7px; border: 1px solid var(--rule); background: rgba(255, 255, 255, .5); font-size: 12.5px; line-height: 1.35; color: var(--ink-3); transition: background .4s, color .4s, border-color .4s; }
.nd-ti__chips li b { display: block; font-family: var(--num); font-weight: 600; font-size: 13.5px; }
.nd-ti__chips li span { font-family: var(--sans); }
.nd-ti__chips li[data-k="eu"] { border-style: dashed; }
.nd-ti__chips li.is-done { color: var(--ink); border-color: var(--ink); background: var(--paper); }
.nd-ti__chips li.is-now { border-color: var(--acc); box-shadow: inset 0 -3px 0 var(--acc); }
.nd-ti__ctl { display: flex; gap: 8px; margin-top: 10px; }

/* 第七问：一条线，还是条条大河 */
.nd-rv svg { display: block; width: 100%; height: auto; }
.nd-rv text { font-family: var(--head); font-weight: 700; font-size: 17px; fill: var(--ink); }
.nd-rv__main { fill: none; stroke: var(--ink); stroke-width: 5; stroke-linecap: round; }
.nd-rv__line circle { fill: var(--ink); }
.nd-rv__iso circle { fill: var(--paper); stroke: var(--ink-3); stroke-width: 1.5; }
.nd-rv__iso text { fill: var(--ink-3); font-weight: 400; font-size: 15px; }
.nd-rv text.nd-rv__q { font-family: var(--sans); font-weight: 400; font-size: 14px; fill: var(--acc); }
.nd-rv text.nd-rv__end { font-size: 18px; }
.nd-rv__sea { fill: #dccbd4; }
.nd-rv text.nd-rv__seat { font-size: 16px; fill: var(--ink); }
.nd-rv__r { fill: none; stroke: #7f9fac; stroke-width: 7; stroke-linecap: round; stroke-dasharray: 600; stroke-dashoffset: 0; }
.nd-rv__line, .nd-rv__river { transition: opacity .6s; }
.nd-rv[data-rivers-mode="line"] .nd-rv__river { opacity: 0; }
.nd-rv[data-rivers-mode="river"] .nd-rv__line { opacity: 0; }
.nd-rv[data-rivers-mode="river"] .nd-rv__r { animation: nd-flow 1.6s ease-out both; }
.nd-rv[data-rivers-mode="river"] .nd-rv__r:nth-of-type(2) { animation-delay: .15s; }
.nd-rv[data-rivers-mode="river"] .nd-rv__r:nth-of-type(3) { animation-delay: .3s; }
.nd-rv[data-rivers-mode="river"] .nd-rv__r:nth-of-type(4) { animation-delay: .45s; }
@keyframes nd-flow { from { stroke-dashoffset: 600; } to { stroke-dashoffset: 0; } }
.nd-ti__nojs { display: none; }
.no-js .nd-ti__nojs { display: block; margin: 12px 0 0; font-size: 14px; line-height: 1.7; }
.no-js .nd-ti__nojs dt { margin-top: 8px; font-weight: 700; }
.no-js .nd-ti__nojs dd { margin: 2px 0 0 1em; }

/* 结尾：终点 */
.c-needham .c3end { padding-top: calc(var(--bar) + 30px); }
.nd-end { max-width: 1100px; margin: 0 auto; }
.nd-end__h { display: flex; align-items: flex-end; gap: 22px; margin-bottom: 22px; }
.nd-end__fl { flex: none; width: 112px; }
.nd-end__fl svg { display: block; width: 100%; height: auto; }
.nd-end__liq { fill: var(--acc); opacity: .85; }
.nd-end__h h2 { margin: 0; }
.nd-end__lede { margin: 6px 0 0; font-size: 17px; color: var(--ink-2); }
.c-needham .c3end h2 { font-family: var(--head); font-weight: 900; }
.c-needham .c3-lin li { border-radius: 2px; background: var(--paper); border-color: var(--rule); border-top: 3px solid var(--acc); }
.c-needham .c3end h3 { font-family: var(--head); }

/* ---------- 窄屏 ---------- */
@media (max-width: 1100px), (pointer: coarse) {
  /* 首屏：滴定管缩小放左边，问题列成普通的表 */
  .nd-rig { justify-self: stretch; }
  .nd-rig__b { width: auto; display: grid; grid-template-columns: 130px minmax(0, 1fr); gap: 4px 14px; align-items: start; }
  .c-needham .nd-rig__img { height: 310px; min-height: 0; }
  .nd-rig__q { position: static; width: auto; }
  .nd-rig__q li { position: static; transform: none; border-bottom: 1px solid var(--rule); }
  .nd-rig__q a { min-height: 40px; padding: 4px 0; font-size: 14px; }
  .nd-rig__q a::before { display: none; }
  .nd-rig__end { position: static; grid-column: 2; flex-direction: row; gap: 8px; align-items: baseline; padding-left: 0; }
  .nd-flask { display: none; }
  .nd-rig figcaption { margin-top: 12px; }
}
@media (max-width: 1300px) and (min-width: 861px) {
  .c-needham .c3hero, .c-needham .c3q, .c-needham .c3end { padding-right: 82px; }
}
@media (max-width: 1100px) {
  .nd-q__g { grid-template-columns: minmax(0, 1fr); grid-template-areas: "a" "art" "b"; }
  .nd-q__art { margin: 4px 0 22px; }
  .nd-band__g { grid-template-columns: minmax(0, 1fr); gap: 20px; }
}
@media (max-width: 900px) {
  .nd-hero { grid-template-columns: minmax(0, 1fr); }
  .nd-rig { justify-self: stretch; }
}
@media (max-width: 760px) {
  .nd-q { grid-template-columns: minmax(0, 1fr); }
  .nd-rail { flex-direction: row; justify-content: flex-start; padding: 0 0 8px; margin-bottom: 4px; }
  .nd-rail::before { display: none; }
  .nd-rail span { writing-mode: horizontal-tb; letter-spacing: .14em; padding: 0; }
  .nd-hv__g { grid-template-columns: minmax(0, 1fr); }
  .nd-ti__chips { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .nd-facts { columns: 1; }
}
@media (max-width: 560px) {
  .c-needham .c3hero { padding-top: calc(var(--bar) + 16px); }
  .nd-tag { padding: 18px 16px 14px; }
  .nd-rig__b { grid-template-columns: 108px minmax(0, 1fr); gap: 4px 10px; }
  .c-needham .nd-rig__img { height: 250px; }
  .c-needham .c3q__lede { text-align: left; }
  .nd-shelf__box { height: 170px; }
  .nd-shelf__bk, .nd-bk { height: 124px; }
  .nd-bk b { font-size: 11px; }
  .nd-bk small { display: none; }
  .nd-shelf__ax span:nth-child(even) { display: none; }
  .nd-ti__ind button { flex: 1 1 140px; }
  .nd-esc__n { margin-left: 0; width: 100%; }
}
.nd-ti__end { display: block; margin-top: 8px; padding-top: 8px; border-top: 1px solid rgba(176, 21, 94, .25); font-weight: 600; }
.nd-btn:disabled { opacity: .55; cursor: default; }