/* ============================================================
 * Calculate · 单色技术制图风格
 * 白纸、黑线、灰阶；用线宽 / 虚线 / 剖面线区分对象，不用彩色。
 * 版式参考 Apple dimensional drawings（Enes Ozturk / MIT）
 * ============================================================ */

:root {
  --paper: #ffffff;
  --sheet: #ffffff;
  --ink: #111111;
  --ink2: #3d3d3d;
  --ink3: #767676;
  --ink4: #a6a6a6;
  --hair: #e2e2e2;
  --hair2: #eeeeee;
  --fill: #f5f5f5;
  --fill2: #ededed;
  --fill3: #e4e4e4;

  --sans: "Helvetica Neue", Arimo, Helvetica, Arial, "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, monospace;

  --r: 12px;
  --r-sm: 7px;

  --lh: 1.5;
  color-scheme: light;
}

* { box-sizing: border-box; }

html, body { background: var(--paper); }

body {
  margin: 0;
  color: var(--ink);
  font: 400 13px/var(--lh) var(--sans);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

button, input, select, textarea { font-family: inherit; color: inherit; }
button { cursor: pointer; }
code, kbd, samp { font-family: var(--mono); font-size: 0.94em; }

::selection { background: #111; color: #fff; }

/* ---------- 通用排版 ---------- */
.lbl {
  font-size: 9.5px;
  letter-spacing: 0.085em;
  text-transform: uppercase;
  color: var(--ink3);
  font-weight: 400;
  line-height: 1.2;
}
.val {
  font-size: 13px;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--ink);
}
.num { font-family: var(--mono); font-variant-numeric: tabular-nums; }
.muted { color: var(--ink3); }
.fineprint { font-size: 10.5px; color: var(--ink3); margin: 8px 0 0; letter-spacing: 0.02em; }
.fineprint code { color: var(--ink2); }

/* ============================================================
 * 图框 / 标题栏
 * ============================================================ */
.board {
  max-width: 1720px;
  margin: 0 auto;
  padding: 22px 22px 40px;
}

.titleblock {
  border: 1.2px solid var(--ink);
  border-radius: 16px;
  overflow: hidden;
  background: var(--sheet);
  display: grid;
  grid-template-columns: 2.6fr 1fr 1fr;
  margin-bottom: 18px;
}

.titleblock > * {
  border-right: 0.8px solid var(--ink);
  border-bottom: 0.8px solid var(--ink);
  padding: 9px 13px;
  min-width: 0;
}
.titleblock > *:nth-child(3),
.titleblock > *:nth-child(5) { border-right: 0; }

.tb-big {
  grid-row: span 2;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 9px;
}
.tb-big h1 {
  margin: 3px 0 0;
  font-size: clamp(24px, 3.1vw, 34px);
  font-weight: 400;
  letter-spacing: 0.10em;
  line-height: 1;
  text-transform: uppercase;
}
.tb-big .scope {
  font-size: 10.5px;
  color: var(--ink3);
  letter-spacing: 0.03em;
  line-height: 1.65;
  max-width: 46em;
}

.tb-notes {
  grid-column: 1 / -1;
  border-right: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 3px 26px;
  font-size: 10.5px;
  letter-spacing: 0.02em;
  color: var(--ink2);
  line-height: 1.7;
}
.tb-notes .nh { font-weight: 700; letter-spacing: 0.06em; color: var(--ink); }
.tb-notes .nh span { font-weight: 400; color: var(--ink3); margin-left: 6px; }
.tb-notes ol { margin: 3px 0 0; padding-left: 17px; }
.tb-notes li { margin: 0; }

.tb-figs {
  grid-column: 1 / -1;
  border-right: 0;
  border-bottom: 0;
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 0;
  padding: 0;
}
.tb-figs > div {
  border-left: 0.8px solid var(--ink);
  padding: 8px 13px;
  min-width: 0;
}
.tb-figs > div:first-child { border-left: 0; }
.tb-figs .val {
  font-size: 14.5px;
  letter-spacing: 0.04em;
  margin-top: 4px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.tb-figs .val small { font-size: 10.5px; color: var(--ink3); letter-spacing: 0.04em; margin-left: 3px; }

/* ============================================================
 * 工具条 / 标签页
 * ============================================================ */
.rail {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  padding: 9px 12px;
  margin-bottom: 14px;
  background: rgba(255, 255, 255, 0.94);
  backdrop-filter: saturate(180%) blur(8px);
  border: 1.2px solid var(--ink);
  border-radius: 12px;
}

.tb {
  height: 27px;
  min-width: 30px;
  padding: 0 9px;
  border: 1px solid var(--ink);
  border-radius: 6px;
  background: var(--sheet);
  color: var(--ink);
  font-size: 10.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  font-variant-numeric: tabular-nums;
  transition: background 0.12s ease, color 0.12s ease;
}
.tb:hover { background: var(--fill2); }
.tb:active { background: var(--ink); color: #fff; }
.tb.is-on { background: var(--ink); color: #fff; }
.tb:disabled { opacity: 0.28; cursor: not-allowed; }
.tb:disabled:hover { background: var(--sheet); color: var(--ink); }
.tb--wide { padding: 0 12px; }

.rail-sep {
  width: 1px;
  height: 18px;
  background: var(--hair);
  margin: 0 3px;
}

.tabs { display: flex; gap: 0; margin-left: auto; border: 1px solid var(--ink); border-radius: 6px; overflow: hidden; }
.tab {
  height: 27px;
  padding: 0 13px;
  border: 0;
  border-left: 1px solid var(--ink);
  background: var(--sheet);
  font-size: 10.5px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}
.tab:first-child { border-left: 0; }
.tab:hover { background: var(--fill2); }
.tab.is-active { background: var(--ink); color: #fff; }

/* ============================================================
 * 视图
 * ============================================================ */
.view { display: none; }
.view.is-active { display: block; animation: fade 0.18s ease both; }
@keyframes fade { from { opacity: 0; } to { opacity: 1; } }

.view-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
  padding: 4px 2px 14px;
  border-bottom: 1.2px solid var(--ink);
  margin-bottom: 16px;
}
.view-head h1 {
  margin: 0 0 6px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}
.view-head p { margin: 0; font-size: 11.5px; color: var(--ink2); letter-spacing: 0.02em; max-width: 62em; }

/* ============================================================
 * 工作区
 * ============================================================ */
.workspace {
  display: grid;
  grid-template-columns: 312px minmax(0, 1fr) 352px;
  gap: 12px;
  align-items: start;
}
.workspace.is-an-collapsed { grid-template-columns: 312px minmax(0, 1fr); }
.workspace.is-an-collapsed .analysis { display: none; }

.panel {
  border: 1.2px solid var(--ink);
  border-radius: var(--r);
  background: var(--sheet);
  overflow: hidden;
  min-width: 0;
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 11px;
  border-bottom: 0.8px solid var(--ink);
  background: var(--sheet);
}
.panel-head h2 {
  margin: 0;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  display: flex;
  align-items: baseline;
  gap: 7px;
}
.panel-head h2 em {
  font-style: normal;
  font-weight: 400;
  color: var(--ink3);
  letter-spacing: 0.06em;
  font-size: 9.5px;
}
.panel-tools { display: flex; gap: 5px; }

/* ---------- 左：代数区 ---------- */
.algebra { display: flex; flex-direction: column; }

.input-line {
  display: flex;
  align-items: center;
  gap: 0;
  border-bottom: 0.8px solid var(--hair);
  padding: 9px 10px;
  background: var(--fill);
}
.input-plus {
  font-family: var(--mono);
  font-size: 15px;
  color: var(--ink3);
  width: 16px;
  text-align: center;
  flex: none;
}
.input-line input {
  flex: 1 1 auto;
  min-width: 0;
  border: 1px solid var(--ink);
  border-radius: var(--r-sm) 0 0 var(--r-sm);
  background: var(--sheet);
  padding: 7px 8px;
  font-family: var(--mono);
  font-size: 12px;
  outline: none;
  margin-left: 4px;
}
.input-line input::placeholder { color: var(--ink4); font-family: var(--sans); font-size: 11.5px; }
.input-line input:focus { box-shadow: inset 0 0 0 1px var(--ink); }
.input-go {
  flex: none;
  width: 30px;
  height: 31px;
  border: 1px solid var(--ink);
  border-left: 0;
  border-radius: 0 var(--r-sm) var(--r-sm) 0;
  background: var(--ink);
  color: #fff;
  font-size: 13px;
  line-height: 1;
}
.input-go:hover { background: #000; }

.input-hint {
  margin: 0;
  padding: 7px 11px;
  font-size: 10.5px;
  color: var(--ink3);
  letter-spacing: 0.02em;
  border-bottom: 0.8px solid var(--hair);
  min-height: 30px;
}
.input-hint.is-error { color: var(--ink); background: repeating-linear-gradient(45deg, #f7f7f7 0 4px, #efefef 4px 8px); }

.obj-list { padding: 0; max-height: 42vh; overflow: auto; }

.obj {
  display: grid;
  grid-template-columns: 20px minmax(0, 1fr) auto;
  align-items: start;
  gap: 5px;
  padding: 8px 11px;
  border-bottom: 0.8px solid var(--hair2);
  cursor: pointer;
  transition: background 0.1s ease;
}
.obj:hover { background: var(--fill); }
.obj.is-active { background: var(--fill2); box-shadow: inset 2px 0 0 var(--ink); }

.obj-dot {
  width: 15px;
  height: 10px;
  margin-top: 3px;
  flex: none;
  border-radius: 1px;
}
/* 线型样本：与画布上的曲线一一对应 */
.obj-dot.k0 { height: 2px; margin-top: 6px; background: #000; }
.obj-dot.k1 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #2f2f2f 0 5px, transparent 5px 9px); }
.obj-dot.k2 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #575757 0 1.5px, transparent 1.5px 5px); }
.obj-dot.k3 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #7a7a7a 0 6px, transparent 6px 9px, #7a7a7a 9px 10.5px, transparent 10.5px 13px); }
.obj-dot.k4 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #1f1f1f 0 10px, transparent 10px 14px); }
.obj-dot.k5 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #454545 0 3px, transparent 3px 6px, #454545 6px 7px, transparent 7px 10px); }
.obj-dot.k6 { height: 2px; margin-top: 6px; background: repeating-linear-gradient(90deg, #6b6b6b 0 2px, transparent 2px 5px); }
.obj-dot--point { height: 9px; width: 9px; margin-left: 3px; margin-top: 3px; border-radius: 50%; border: 1.6px solid var(--ink); background: var(--sheet); }
.obj-dot--set { height: 9px; width: 9px; margin-left: 3px; margin-top: 3px; border-radius: 50%; border: 1.6px dashed var(--ink); background: var(--sheet); }

.obj-main { min-width: 0; }
.obj-line { display: flex; align-items: baseline; gap: 5px; flex-wrap: wrap; }
.obj-name {
  font-family: var(--mono);
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: 0.01em;
  padding: 0 2px;
  border-radius: 2px;
  outline: none;
}
.obj-name:hover { background: var(--fill3); }
.obj-name:focus { background: #fff; box-shadow: 0 0 0 1px var(--ink); }
.obj-expr {
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--ink2);
  overflow-wrap: anywhere;
  min-width: 0;
}
.obj-sub {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--ink3);
  margin-top: 3px;
  overflow-wrap: anywhere;
  letter-spacing: 0.01em;
}
.obj-actions { display: flex; gap: 2px; opacity: 0.45; transition: opacity 0.12s; }
.obj:hover .obj-actions, .obj.is-active .obj-actions { opacity: 1; }
.icon-act {
  width: 20px; height: 20px;
  display: grid; place-items: center;
  border: 1px solid transparent;
  border-radius: 4px;
  background: transparent;
  color: var(--ink2);
  font-size: 11px;
  line-height: 1;
  padding: 0;
}
.icon-act:hover { border-color: var(--ink); background: var(--sheet); }
.icon-act.is-off { color: var(--ink4); }
.icon-act.is-del:hover { background: var(--ink); color: #fff; }

.obj-empty {
  padding: 22px 14px;
  font-size: 11.5px;
  color: var(--ink3);
  line-height: 1.9;
  letter-spacing: 0.01em;
}
.obj-empty code { color: var(--ink); background: var(--fill2); padding: 1px 4px; border-radius: 3px; }

/* ---------- 批量数据 ---------- */
.data-box { border-top: 0.8px solid var(--hair); }
.data-box > summary {
  padding: 9px 11px;
  font-size: 10px;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink2);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 6px;
}
.data-box > summary::-webkit-details-marker { display: none; }
.data-box > summary::before {
  content: "+";
  font-family: var(--mono);
  color: var(--ink3);
  width: 10px;
}
.data-box[open] > summary::before { content: "−"; }
.data-box > summary:hover { background: var(--fill); }
.data-body { padding: 0 11px 12px; }
.data-body textarea {
  width: 100%;
  height: 88px;
  resize: vertical;
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  padding: 7px 8px;
  font-family: var(--mono);
  font-size: 11.5px;
  line-height: 1.7;
  background: var(--sheet);
  outline: none;
}
.data-body textarea:focus { box-shadow: inset 0 0 0 1px var(--ink); }
.data-actions { display: flex; gap: 6px; margin-top: 8px; flex-wrap: wrap; }
.data-actions select { flex: 1 1 120px; min-width: 0; }

select, input[type="number"], input[type="text"] {
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  background: var(--sheet);
  padding: 6px 8px;
  font-size: 11.5px;
  letter-spacing: 0.01em;
  outline: none;
}
select { appearance: none; padding-right: 24px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='9' height='6'%3E%3Cpath d='M1 1l3.5 3.5L8 1' stroke='%23111' stroke-width='1.2' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 8px center; }
select:focus, input:focus { box-shadow: inset 0 0 0 1px var(--ink); }
select option { background: #fff; }

.btn-primary {
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  background: var(--ink);
  color: #fff;
  padding: 6px 13px;
  font-size: 10.5px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}
.btn-primary:hover { background: #000; }
.btn-primary:disabled { opacity: 0.3; cursor: not-allowed; }

.mini-btn {
  height: 22px;
  padding: 0 8px;
  border: 1px solid var(--ink);
  border-radius: 5px;
  background: var(--sheet);
  font-size: 9.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink);
  line-height: 1;
}
.mini-btn:hover { background: var(--fill2); }
.mini-btn.is-on { background: var(--ink); color: #fff; }

/* ---------- 数学键盘 ---------- */
.keyboard {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 4px;
  padding: 10px;
  border-top: 0.8px solid var(--hair);
  background: var(--fill);
}
.key {
  height: 27px;
  border: 1px solid var(--ink);
  border-radius: 5px;
  background: var(--sheet);
  font-family: var(--mono);
  font-size: 11.5px;
  padding: 0;
  line-height: 1;
}
.key:hover { background: var(--fill2); }
.key:active { background: var(--ink); color: #fff; }
.key--fn { font-size: 10px; letter-spacing: 0.02em; }
.key--warn { font-size: 10px; }
.key--accent { background: var(--ink); color: #fff; font-size: 10px; }
.key--accent:hover { background: #000; }

/* ---------- 中：画布 ---------- */
.canvas-panel { display: flex; flex-direction: column; }
.canvas-wrap {
  position: relative;
  background: var(--sheet);
  padding: 0;
  line-height: 0;
  height: clamp(420px, 62vh, 760px);
  min-height: 320px;
}
.canvas-wrap canvas { display: block; width: 100%; height: 100%; touch-action: none; }

.canvas-badge {
  position: absolute;
  left: 10px;
  top: 10px;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.02em;
  color: var(--ink2);
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid var(--hair);
  border-radius: 4px;
  padding: 3px 7px;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s;
  line-height: 1.4;
}
.canvas-badge.is-on { opacity: 1; }

.view-chip {
  position: absolute;
  right: 10px;
  bottom: 10px;
  font-family: var(--mono);
  font-size: 9.5px;
  letter-spacing: 0.04em;
  color: var(--ink3);
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--hair);
  padding: 3px 6px;
  border-radius: 4px;
  pointer-events: none;
  line-height: 1.4;
}

.canvas-foot {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 7px 11px;
  border-top: 0.8px solid var(--ink);
  font-size: 9.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink3);
}

/* ---------- 右：分析 ---------- */
.analysis { display: flex; flex-direction: column; }
.an-body { padding: 0; max-height: calc(100vh - 190px); overflow: auto; }

.an-section { border-bottom: 0.8px solid var(--hair); padding: 11px 12px 12px; }
.an-section:last-child { border-bottom: 0; }
.an-title {
  font-size: 9.5px;
  letter-spacing: 0.09em;
  color: var(--ink);
  font-weight: 600;
  margin: 0 0 8px;
  display: flex;
  justify-content: space-between;
  gap: 8px;
  align-items: baseline;
}
.an-title .muted { color: var(--ink3); font-weight: 400; letter-spacing: 0.03em; }
.an-empty { font-size: 11px; color: var(--ink3); line-height: 1.8; }

.eq-card {
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  padding: 10px;
  background: var(--sheet);
}
.eq-main {
  font-family: var(--mono);
  font-size: 12.5px;
  line-height: 1.65;
  overflow-wrap: anywhere;
  letter-spacing: 0.01em;
}
.eq-card .lbl { margin-bottom: 5px; }

.metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  overflow: hidden;
  margin-top: 8px;
}
.metric {
  padding: 7px 8px;
  border-left: 0.8px solid var(--hair);
  min-width: 0;
}
.metric:first-child { border-left: 0; }
.metric span { display: block; font-size: 8.5px; letter-spacing: 0.05em; color: var(--ink3); }
.metric strong {
  display: block;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 500;
  margin-top: 3px;
  font-variant-numeric: tabular-nums;
  overflow: hidden;
  text-overflow: ellipsis;
}

.diags { display: flex; flex-direction: column; gap: 6px; }
.diag {
  border: 1px solid var(--hair);
  border-left: 3px solid var(--ink);
  border-radius: 4px;
  padding: 7px 9px;
  font-size: 11px;
  line-height: 1.65;
  background: var(--sheet);
}
.diag--warn { border-left-style: dashed; border-left-width: 3px; }
.diag--info { border-left: 3px solid var(--ink4); }
.diag--error { background: repeating-linear-gradient(45deg, #fafafa 0 5px, #f2f2f2 5px 10px); }
.diag strong {
  display: block;
  font-size: 10.5px;
  letter-spacing: 0.04em;
  margin-bottom: 2px;
  font-weight: 700;
}
.diag span { color: var(--ink2); display: block; }
.diag em { font-style: normal; color: var(--ink3); font-size: 10px; display: block; margin-top: 3px; }

.rank-item {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 8px;
  width: 100%;
  text-align: left;
  border: 1px solid var(--hair);
  border-radius: 4px;
  background: var(--sheet);
  padding: 5px 8px;
  margin-bottom: 4px;
  font-size: 11px;
}
.rank-item:hover { border-color: var(--ink); background: var(--fill); }
.rank-item.is-best { border-color: var(--ink); box-shadow: inset 0 0 0 0.5px var(--ink); }
.rank-item .rn { letter-spacing: 0.02em; }
.rank-item .rv { font-family: var(--mono); font-size: 10.5px; color: var(--ink2); font-variant-numeric: tabular-nums; }

.area-card { border: 1px solid var(--ink); border-radius: var(--r-sm); padding: 10px; }
.area-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 7px;
  font-size: 10.5px;
  color: var(--ink2);
  letter-spacing: 0.02em;
}
.area-row label { flex: none; min-width: 26px; font-size: 10px; letter-spacing: 0.02em; color: var(--ink3); }
.area-row select { flex: 1 1 auto; min-width: 0; }
.area-row input[type="number"] { width: 74px; flex: none; font-family: var(--mono); }
.area-row input[type="checkbox"] { width: 13px; height: 13px; accent-color: #111; margin: 0; }
.area-row .muted { font-family: var(--mono); font-size: 10.5px; }

.seg { display: flex; border: 1px solid var(--ink); border-radius: 5px; overflow: hidden; margin-bottom: 8px; }
.seg button {
  flex: 1 1 0;
  min-width: 0;
  border: 0;
  border-left: 1px solid var(--ink);
  background: var(--sheet);
  font-size: 9.5px;
  letter-spacing: 0.04em;
  padding: 4px 2px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.seg button:first-child { border-left: 0; }
.seg button:hover { background: var(--fill2); }
.seg button.is-active { background: var(--ink); color: #fff; }

.area-res {
  font-family: var(--mono);
  font-size: 11.5px;
  line-height: 1.9;
  border-top: 0.8px dashed var(--hair);
  padding-top: 7px;
  margin-top: 2px;
}
.area-line {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 10px;
  padding: 1px 0;
}
.area-line > span { color: var(--ink2); font-family: var(--sans); font-size: 10.5px; }
.area-line > b { font-family: var(--mono); font-variant-numeric: tabular-nums; white-space: nowrap; font-weight: 600; }
.area-line.is-main > b { font-size: 14px; }
.area-res b { font-weight: 600; }
.area-res .big { font-size: 15px; letter-spacing: 0.01em; }
.area-note { font-size: 10px; color: var(--ink3); margin: 6px 0 0; line-height: 1.65; letter-spacing: 0.01em; }

.r-table { width: 100%; border-collapse: collapse; font-size: 10.5px; font-variant-numeric: tabular-nums; }
.r-table th, .r-table td { border-bottom: 0.8px solid var(--hair2); padding: 4px 5px; text-align: right; }
.r-table th { font-size: 8.5px; letter-spacing: 0.07em; text-transform: uppercase; color: var(--ink3); font-weight: 400; border-bottom: 0.8px solid var(--hair); }
.r-table td:first-child, .r-table th:first-child { text-align: left; font-family: var(--mono); }
.r-table tr.is-outlier td { font-weight: 600; }

.custom-box { display: flex; flex-direction: column; gap: 6px; }
.custom-box input { font-family: var(--mono); }
.details { margin-top: 8px; }
.details summary { font-size: 10px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink3); cursor: pointer; }

.field-row { display: flex; gap: 6px; align-items: center; }
.field-row label { font-size: 10px; color: var(--ink3); letter-spacing: 0.05em; text-transform: uppercase; }

/* ============================================================
 * 例题视图
 * ============================================================ */
.ex-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }

.ex-card {
  border: 1.2px solid var(--ink);
  border-radius: var(--r);
  background: var(--sheet);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.ex-head {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr) auto;
  gap: 10px;
  align-items: start;
  padding: 10px 12px;
  border-bottom: 0.8px solid var(--ink);
}
.ex-no {
  border: 1px solid var(--ink);
  border-radius: 3px;
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  font-family: var(--mono);
  font-size: 11px;
}
.ex-head h3 {
  margin: 0;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.05em;
}
.ex-head .en {
  display: block;
  font-size: 9.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink3);
  margin-top: 3px;
  font-weight: 400;
}
.ex-src {
  font-size: 9px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--ink3);
  white-space: nowrap;
  border: 1px solid var(--hair);
  border-radius: 3px;
  padding: 2px 5px;
}
.ex-body { padding: 11px 12px 12px; display: flex; flex-direction: column; gap: 9px; flex: 1 1 auto; }
.ex-q { margin: 0; font-size: 11.5px; line-height: 1.8; color: var(--ink2); letter-spacing: 0.01em; }
.ex-q b { color: var(--ink); font-weight: 600; }

.ex-steps { border: 1px solid var(--hair); border-radius: var(--r-sm); overflow: hidden; }
.ex-step {
  display: grid;
  grid-template-columns: 18px minmax(0, 1fr);
  gap: 8px;
  padding: 6px 9px;
  border-bottom: 0.8px solid var(--hair2);
  font-size: 11px;
  line-height: 1.7;
}
.ex-step:last-child { border-bottom: 0; }
.ex-step .n { font-family: var(--mono); font-size: 9.5px; color: var(--ink3); padding-top: 1px; }
.ex-step .f { font-family: var(--mono); font-size: 11px; overflow-wrap: anywhere; display: block; }
.ex-step .c { color: var(--ink3); font-size: 10px; display: block; margin-top: 1px; }

.ex-ans {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  border: 1px solid var(--ink);
  border-radius: var(--r-sm);
  overflow: hidden;
}
.ex-ans > div {
  flex: 1 1 0;
  min-width: 88px;
  padding: 7px 9px;
  border-left: 0.8px solid var(--hair);
}
.ex-ans > div:first-child { border-left: 0; }
.ex-ans .lbl { margin-bottom: 3px; text-transform: none; letter-spacing: 0.04em; }
.ex-ans .val { font-family: var(--mono); font-size: 14px; }

.ex-actions { display: flex; gap: 6px; flex-wrap: wrap; margin-top: auto; padding-top: 2px; }

/* ============================================================
 * 物理工具
 * ============================================================ */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(420px, 1fr));
  gap: 12px;
}
.tool-card {
  border: 1.2px solid var(--ink);
  border-radius: var(--r);
  background: var(--sheet);
  padding: 0;
  overflow: hidden;
}
.tool-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding: 9px 12px;
  border-bottom: 0.8px solid var(--ink);
}
.tool-head h3 { margin: 0; font-size: 11.5px; font-weight: 700; letter-spacing: 0.06em; }
.tool-head .tool-formula {
  font-family: var(--mono);
  font-size: 9.5px;
  color: var(--ink3);
  letter-spacing: 0.01em;
  text-align: right;
  overflow-wrap: anywhere;
}
.tool-desc { margin: 0; padding: 8px 12px 0; font-size: 10.5px; color: var(--ink3); line-height: 1.65; }
.tool-fields { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 7px; padding: 10px 12px; }
.tool-fields .fld { display: flex; flex-direction: column; gap: 3px; min-width: 0; }
.tool-fields .fld label { font-size: 9.5px; letter-spacing: 0.02em; color: var(--ink3); }
.tool-fields .fld input, .tool-fields .fld select { width: 100%; font-family: var(--mono); font-size: 11.5px; }
.tool-fields .fld small { font-size: 9px; color: var(--ink4); }
.tool-output { border-top: 0.8px solid var(--hair); padding: 8px 12px; }
.out-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 10px;
  padding: 3px 0;
  border-bottom: 0.8px dotted var(--hair);
  font-size: 11px;
}
.out-row:last-child { border-bottom: 0; }
.out-label { color: var(--ink2); letter-spacing: 0.02em; }
.out-value { font-family: var(--mono); font-size: 12px; font-variant-numeric: tabular-nums; }
.out-unit { font-size: 9.5px; color: var(--ink3); margin-left: 3px; }
.out-row.is-main .out-value { font-size: 14px; font-weight: 600; }
.tool-note {
  font-size: 10px;
  color: var(--ink3);
  padding: 7px 12px;
  border-top: 0.8px solid var(--hair);
  line-height: 1.7;
  background: var(--fill);
}

.unit-cats { display: flex; flex-wrap: wrap; gap: 4px; padding: 10px 12px 0; }
.unit-cat {
  border: 1px solid var(--hair);
  border-radius: 999px;
  background: var(--sheet);
  padding: 3px 9px;
  font-size: 9.5px;
  letter-spacing: 0.04em;
}
.unit-cat:hover { border-color: var(--ink); }
.unit-cat.is-active { background: var(--ink); color: #fff; border-color: var(--ink); }

.unit-row { display: flex; gap: 6px; align-items: flex-end; padding: 10px 12px; }
.unit-row .unit { flex: 1 1 0; min-width: 0; display: flex; flex-direction: column; gap: 3px; }
.unit-row .unit label { font-size: 9.5px; letter-spacing: 0.02em; color: var(--ink3); }
.unit-row .unit input, .unit-row .unit select { width: 100%; font-family: var(--mono); }
.unit-swap {
  flex: none;
  width: 26px; height: 30px;
  border: 1px solid var(--ink);
  border-radius: 5px;
  background: var(--sheet);
  font-size: 11px;
  line-height: 1;
}
.unit-swap:hover { background: var(--fill2); }
.unit-result {
  font-family: var(--mono);
  font-size: 13px;
  padding: 0 12px 12px;
  line-height: 1.9;
  overflow-wrap: anywhere;
}
.unit-result small { display: block; font-family: var(--sans); font-size: 10px; color: var(--ink3); }

.chips { display: flex; flex-wrap: wrap; gap: 5px; }
.chip {
  border: 1px solid var(--hair);
  border-radius: 999px;
  padding: 2px 8px;
  font-size: 9.5px;
  letter-spacing: 0.04em;
  color: var(--ink2);
}

/* ============================================================
 * 公式卡 / 说明
 * ============================================================ */
.help-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(420px, 1fr)); gap: 12px; }
.help-card { padding: 0; }
.help-card h3 {
  margin: 0;
  padding: 9px 12px;
  border-bottom: 0.8px solid var(--ink);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  font-weight: 700;
}
.help-card ul { margin: 0; padding: 10px 12px 12px 26px; }
.help-card li { font-size: 11.5px; line-height: 1.85; color: var(--ink2); margin-bottom: 3px; }
.help-card li strong { color: var(--ink); }
.help-card code { background: var(--fill2); padding: 0 4px; border-radius: 3px; }

.f-table { width: 100%; border-collapse: collapse; font-size: 11px; }
.f-table th, .f-table td { border-bottom: 0.8px solid var(--hair2); padding: 5px 8px; text-align: left; }
.f-table th { font-size: 8.5px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink3); font-weight: 400; border-bottom: 0.8px solid var(--ink); }
.f-table td.mono, .f-table td:nth-child(2) { font-family: var(--mono); font-size: 11px; }
.f-table tr:hover td { background: var(--fill); }

.formula-list { padding: 10px 12px 12px; display: flex; flex-direction: column; gap: 6px; }
.formula {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 10px;
  align-items: baseline;
  border-bottom: 0.8px dotted var(--hair);
  padding-bottom: 5px;
}
.formula:last-child { border-bottom: 0; }
.formula .k { font-family: var(--mono); font-size: 10px; color: var(--ink3); letter-spacing: 0.02em; }
.formula .v { font-family: var(--mono); font-size: 12px; }
.formula .v small { font-family: var(--sans); color: var(--ink3); font-size: 10px; margin-left: 6px; }

/* ============================================================
 * 页脚
 * ============================================================ */
.site-foot {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-top: 18px;
  padding: 9px 2px 0;
  border-top: 1.2px solid var(--ink);
  font-size: 9.5px;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: var(--ink3);
}
.site-foot b { color: var(--ink); font-weight: 700; }

/* ============================================================
 * 响应式
 * ============================================================ */
@media (max-width: 1360px) {
  .workspace { grid-template-columns: 288px minmax(0, 1fr) 320px; }
}
@media (max-width: 1180px) {
  .workspace { grid-template-columns: 280px minmax(0, 1fr); }
  .analysis { grid-column: 1 / -1; }
  .an-body { max-height: none; }
  .ex-grid { grid-template-columns: 1fr; }
  .tb-figs { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .tb-figs > div:nth-child(5) { border-left: 0; }
}
@media (max-width: 860px) {
  .board { padding: 12px 10px 28px; }
  .titleblock { grid-template-columns: 1fr 1fr; }
  .tb-big { grid-column: 1 / -1; grid-row: auto; }
  .titleblock > *:nth-child(odd) { border-right: 0; }
  /* 手机上图纸信息不值一屏，收成 3 列并隐藏 NOTES */
  .tb-notes { display: none; }
  .tb-figs { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .tb-figs > div { border-left: 0.8px solid var(--hair); border-top: 0.8px solid var(--hair); }
  .tb-figs > div:nth-child(3n + 1) { border-left: 0; }
  .workspace { grid-template-columns: 1fr; }
  .rail { gap: 5px; padding: 8px; }
  .tabs { margin-left: 0; width: 100%; }
  .tab { flex: 1 1 0; padding: 0 6px; font-size: 9.5px; }
  .canvas-wrap { height: 58vh !important; }
  .tool-grid { grid-template-columns: 1fr; }
  .tool-fields { grid-template-columns: 1fr 1fr; }
  .obj-list { max-height: none; }
  .ex-head { grid-template-columns: 30px minmax(0, 1fr); }
  .ex-src { grid-column: 2; justify-self: start; }
}
@media (max-width: 520px) {
  .tb-figs { grid-template-columns: 1fr 1fr; }
  .tb-figs > div:nth-child(3n + 1) { border-left: 0.8px solid var(--hair); }
  .tb-figs > div:nth-child(2n + 1) { border-left: 0; }
  .tb-figs .val { font-size: 13px; }
  .tb-big h1 { font-size: 26px; }
  .tool-fields { grid-template-columns: 1fr; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

@media print {
  .rail, .site-foot { display: none; }
  .panel { break-inside: avoid; }
}