/* 有理数的加减法 —— 课件专属样式 */

/* ---------- 开场 ---------- */
.hero { padding: 30px 4px 4px; text-align: center; }
.eyebrow { display: inline-block; font-size: 13px; color: var(--ink-2); background: var(--surface-2); padding: 4px 12px; border-radius: 999px; }
.hero h1 { font-size: clamp(34px, 9vw, 52px); margin: 14px 0 6px; font-weight: 800; }
.hero h1 .n { font-family: var(--font); }
.hero .lead { font-size: 17px; }
.teaser { text-align: center; margin-top: 22px; }
.teaser-q { font-size: 17px; margin-bottom: 14px; }
.teaser-fb { min-height: 1.6em; margin-top: 12px; }
.teaser-fb .good { color: var(--ok); font-weight: 700; }
.teaser-fb .nope { color: var(--bad); font-weight: 700; }
.pill.right { border-color: var(--ok); background: var(--ok-soft); color: var(--ok); }
.pill.wrong { border-color: var(--bad); background: var(--bad-soft); color: var(--bad); }

/* ---------- 1. 数轴 ---------- */
.nl-wrap { width: 100%; margin: 4px 0 0; }
.nl-wrap svg { display: block; width: 100%; height: 170px; overflow: visible; }
.nl-axis { stroke: var(--ink); stroke-width: 2; }
.nl-tick { stroke: var(--ink); stroke-width: 1.5; }
.nl-tick.minor { stroke: var(--ink-3); stroke-width: 1; }
.nl-lbl { fill: var(--ink-2); font: 600 13px var(--font-num); text-anchor: middle; }
.nl-lbl.zero { fill: var(--ink); font-weight: 800; }
.nl-lbl.hit { font-size: 17px; font-weight: 800; }
.nl-arrow { stroke-width: 4; stroke-linecap: round; }
.nl-arrow.pos { stroke: var(--pos); }
.nl-arrow.neg { stroke: var(--neg); }
.nl-head.pos { fill: var(--pos); }
.nl-head.neg { fill: var(--neg); }
.nl-guide { stroke: var(--ink-3); stroke-width: 1.2; stroke-dasharray: 3 4; }
.nl-tag { font: 800 15px var(--font-num); text-anchor: middle; paint-order: stroke; stroke: var(--surface); stroke-width: 5px; stroke-linejoin: round; }
.nl-tag.pos { fill: var(--pos); }
.nl-tag.neg { fill: var(--neg); }
.nl-dot { fill: var(--surface); stroke-width: 3; }
.nl-frog { font-size: 28px; text-anchor: middle; dominant-baseline: auto; user-select: none; }

/* ---------- 棋子 ---------- */
.chip {
  display: inline-grid; place-items: center; aspect-ratio: 1; width: 100%; max-width: 38px;
  border-radius: 50%; color: #fff; font: 800 18px/1 var(--font-num);
  box-shadow: inset 0 -3px 0 rgba(0, 0, 0, .14);
}
.chip.pos { background: var(--pos); }
.chip.neg { background: var(--neg); }
.chip.inline { width: 1.5em; height: 1.5em; font-size: 15px; vertical-align: -.25em; }
.board { display: grid; gap: 10px; margin: 6px auto 0; max-width: 420px; }
.board-row { display: grid; grid-template-columns: repeat(9, 1fr); gap: 6px; justify-items: center; min-height: 34px; position: relative; }
.board-row .chip { animation: pop .3s cubic-bezier(.3, 1.6, .5, 1) both; }
.board-row .chip.pair { outline: 3px solid var(--hl); outline-offset: 2px; }
.board-row .chip.gone { animation: vanish .45s ease forwards; }
.board-row .chip.left { animation: glow 1.2s ease 2; }
.board-row .row-empty { grid-column: 1 / -1; font-size: 13px; color: var(--ink-3); align-self: center; }
@keyframes vanish { 0% { transform: scale(1); opacity: 1; } 40% { transform: scale(1.25); } 100% { transform: scale(0); opacity: 0; } }
@keyframes glow { 50% { transform: scale(1.15); } }

.msg { min-height: 1.7em; text-align: center; margin: 14px 0 0; }
.msg .big { font-size: 1.15em; }

/* ---------- 3. 法则 ---------- */
.rules { display: grid; gap: 10px; }
@media (min-width: 640px) { .rules { grid-template-columns: repeat(3, 1fr); } }
.rule {
  border: 2px solid var(--line); border-radius: 16px; padding: 12px 14px;
  transition: border-color .3s, background .3s, transform .3s;
}
.rule.active { border-color: var(--ink); background: var(--surface-2); transform: translateY(-2px); }
.rule-name { font-weight: 800; font-size: 16px; }
.rule p { font-size: 14.5px; color: var(--ink-2); margin: 4px 0 8px; }
.rule-eg { font-size: 15px; font-family: var(--font-num); white-space: nowrap; overflow-x: auto; }
.motto {
  margin: 16px 0 0; padding: 14px 16px; border-radius: 16px; background: var(--hl); color: #3b2f00;
  display: flex; gap: 12px; align-items: flex-start; font-weight: 600;
}
.motto-tag { flex: none; background: #3b2f00; color: var(--hl); font-size: 13px; padding: 2px 8px; border-radius: 6px; margin-top: 3px; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .motto { background: #3d3410; color: #ffe8a3; }
  :root:not([data-theme="light"]) .motto-tag { background: #ffe8a3; color: #3d3410; }
}

.solve { margin: 14px auto 6px; max-width: 520px; }
.solve .expr { text-align: center; font: 700 26px/1.4 var(--font-num); margin-bottom: 10px; }
.steps { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.steps li { display: flex; gap: 10px; align-items: baseline; padding: 10px 12px; border-radius: 12px; background: var(--surface-2); }
.steps .k { flex: none; font-size: 12.5px; font-weight: 700; color: var(--bg); background: var(--ink); padding: 1px 8px; border-radius: 6px; }
.steps li.final { background: var(--ok-soft); font-size: 18px; justify-content: center; }
.steps li.final .k { background: var(--ok); color: #fff; }

/* ---------- 4. 减法 ---------- */
.thermo-box { display: flex; gap: 10px; align-items: center; }
.thermo { width: 130px; flex: none; height: auto; }
.thermo-side { flex: 1; min-width: 0; }
.controls.col { flex-direction: column; align-items: flex-start; }
.controls.col .ctl { flex-direction: row; gap: 10px; }
.controls.col .ctl > span { width: 4.2em; font-weight: 700; font-size: 14px; }
.thermo-text { margin-top: 12px; font-size: 15px; }
.thermo-text .eqline { font: 700 22px/1.4 var(--font-num); margin: 2px 0; }
.th-tick { stroke: var(--ink-3); stroke-width: 1; }
.th-tick.major { stroke: var(--ink-2); stroke-width: 1.5; }
.th-lbl { fill: var(--ink-2); font: 600 11px var(--font-num); text-anchor: end; dominant-baseline: middle; }
.th-tube { fill: var(--surface-2); stroke: var(--ink-3); stroke-width: 1.5; }
.th-mark { font: 800 12px var(--font-num); dominant-baseline: middle; }
@media (max-width: 400px) {
  .thermo { width: 104px; }
  .controls.col .ctl > span { width: auto; }
  .controls.col .ctl { flex-direction: column; align-items: flex-start; gap: 2px; }
}

.law {
  margin: 20px 0 6px; border-radius: 18px; padding: 16px; text-align: center;
  background: linear-gradient(135deg, var(--pos-soft), var(--neg-soft));
}
.law-title { font-size: 13px; font-weight: 700; color: var(--ink-2); letter-spacing: .1em; }
.law-body { font-size: 18px; margin: 4px 0; }
.law-formula { font: 800 28px/1.3 var(--font-num); }
.law-formula i { font-family: "Times New Roman", serif; }

.flip-row { display: flex; justify-content: center; align-items: flex-start; gap: 8px; margin: 16px 0 0; perspective: 600px; }
.fl-cell { display: flex; flex-direction: column; align-items: center; gap: 6px; }
.fl-cell small { font-size: 12.5px; color: var(--ink-2); white-space: nowrap; transition: color .3s; }
.fl-cell small.chg { color: var(--bad); font-weight: 700; }
.fl-cell small.keep { color: var(--ok); font-weight: 700; }
.fl-card {
  min-width: 56px; height: 60px; padding: 0 10px; border-radius: 14px; border: 2px solid var(--line);
  background: var(--surface); display: grid; place-items: center; font: 800 24px/1 var(--font-num);
}
.fl-card.fl-op { min-width: 46px; color: var(--ink); }
.fl-card.flip { animation: flip .5s ease; }
.fl-card.changed { border-color: var(--hl); background: color-mix(in srgb, var(--hl) 25%, var(--surface)); }
@keyframes flip { 0% { transform: rotateY(0); } 50% { transform: rotateY(90deg); } 100% { transform: rotateY(0); } }
.fl-res { justify-content: center; }
.fl-eqres { height: 60px; display: flex; align-items: center; font: 800 24px/1 var(--font-num); white-space: nowrap; }
@media (max-width: 400px) {
  .flip-row { gap: 5px; }
  .fl-card { min-width: 46px; height: 54px; font-size: 20px; padding: 0 6px; }
  .fl-card.fl-op { min-width: 36px; }
  .fl-eqres { height: 54px; font-size: 20px; }
}

.pool {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; align-content: center;
  min-height: 90px; padding: 14px; margin: 8px 0 0; border-radius: 16px; border: 2px dashed var(--line);
}
.pool .chip { width: 34px; max-width: none; }
.pool .chip.enter { animation: pop .35s cubic-bezier(.3, 1.6, .5, 1) both; }
.pool .chip.added { outline: 3px solid var(--hl); outline-offset: 2px; }
.pool .chip.marked { outline: 3px dashed var(--bad); outline-offset: 2px; }
.pool .chip.gone { animation: vanish .45s ease forwards; }
.pool .empty { color: var(--ink-3); font-size: 14px; }

/* ---------- 5. 混合运算 ---------- */
.work { margin: 16px auto 0; max-width: 560px; display: grid; gap: 8px; }
.work-line { padding: 10px 14px; border-radius: 14px; background: var(--surface-2); }
.work-line .expr { font: 700 22px/1.5 var(--font-num); overflow-x: auto; white-space: nowrap; }
.work-line .expr .eqs { color: var(--ink-3); margin-right: .3em; }
.work-line .cap { font-size: 13.5px; color: var(--ink-2); }
.work-line.last { background: var(--ok-soft); }
.work-line mark { padding: 0 .15em; }
.grp { border-radius: 8px; padding: 1px 2px; }
.grp.g-pos { background: var(--pos-soft); }
.grp.g-neg { background: var(--neg-soft); }
.grp.g-zero { background: var(--zero-soft); }
@media (max-width: 480px) { .work-line .expr { font-size: 19px; } }

.tips { display: grid; gap: 10px; margin-top: 18px; }
@media (min-width: 640px) { .tips { grid-template-columns: repeat(3, 1fr); } }
.tip { display: flex; gap: 10px; padding: 12px; border-radius: 14px; border: 1px solid var(--line); line-height: 1.55; }
.tip-ico { font-size: 22px; }

/* ---------- 6. 闯关 ---------- */
.levels { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; }
.level {
  text-align: left; border: 2px solid var(--line); background: var(--surface); border-radius: 18px;
  padding: 14px; cursor: pointer; display: grid; gap: 2px; touch-action: manipulation;
  transition: transform .12s, border-color .2s;
}
.level:active { transform: scale(.97); }
.level:hover { border-color: var(--ink-3); }
.level .lv-ico { font-size: 26px; }
.level .lv-name { font-weight: 800; font-size: 17px; }
.level .lv-desc { font-size: 13px; color: var(--ink-2); }
.level .lv-stars { font-size: 15px; letter-spacing: 2px; color: var(--line); }
.level .lv-stars b { color: #fab005; font-weight: 400; }

.qz-top { display: flex; align-items: center; justify-content: space-between; gap: 8px; }
.dots { display: flex; gap: 6px; }
.dots i { width: 12px; height: 12px; border-radius: 50%; background: var(--line); transition: background .3s, transform .3s; }
.dots i.cur { background: var(--ink); transform: scale(1.2); }
.dots i.ok { background: var(--ok); }
.dots i.bad { background: var(--bad); }
.qz-name { text-align: center; font-size: 13px; color: var(--ink-2); margin-top: 14px; }
.qz-q { text-align: center; font: 800 30px/1.4 var(--font-num); margin: 4px 0 10px; }
@media (max-width: 400px) { .qz-q { font-size: 25px; } }
.qz-ans {
  margin: 0 auto 12px; max-width: 260px; height: 58px; border-radius: 16px; border: 2px solid var(--ink);
  display: flex; align-items: center; justify-content: center; font: 800 28px/1 var(--font-num);
  background: var(--surface); transition: border-color .2s, background .2s;
}
.qz-ans .ph { color: var(--ink-3); font-size: 18px; font-weight: 500; font-family: var(--font); }
.qz-ans .caret { display: inline-block; width: 2px; height: 30px; background: var(--ink); margin-left: 2px; animation: blink 1s steps(1) infinite; }
.qz-ans.ok { border-color: var(--ok); background: var(--ok-soft); }
.qz-ans.bad { border-color: var(--bad); background: var(--bad-soft); }
@keyframes blink { 50% { opacity: 0; } }
.qz-fb:empty { display: none; }
.qz-fb { margin: 0 auto 12px; max-width: 520px; }
.fb-head { font-weight: 800; font-size: 18px; text-align: center; margin-bottom: 8px; }
.fb-head.ok { color: var(--ok); }
.fb-head.bad { color: var(--bad); }
.fb-diag { background: var(--bad-soft); border-radius: 12px; padding: 10px 12px; margin-bottom: 8px; font-size: 15px; }
.fb-note { text-align: center; font-size: 14px; color: var(--ink-2); }
.qz-fb .work-line .expr { font-size: 18px; }
.pad-hint { margin: 10px 0 0; }

.result { text-align: center; padding: 10px 0; }
.result .stars { font-size: 46px; letter-spacing: 6px; color: var(--line); }
.result .stars b { color: #fab005; font-weight: 400; display: inline-block; animation: pop .5s cubic-bezier(.3, 1.6, .5, 1) both; }
.result .stars b:nth-child(2) { animation-delay: .15s; }
.result .stars b:nth-child(3) { animation-delay: .3s; }
.result h3 { font-size: 22px; margin: 6px 0; }

/* ---------- 7. 小结 ---------- */
.summary { display: grid; gap: 10px; }
.sum-row { display: flex; gap: 12px; padding: 12px 14px; border-radius: 16px; background: var(--surface-2); }
.sum-row p { margin: 2px 0; }
.sum-k { flex: none; font-weight: 800; width: 2.6em; }
.sum-row.warn { background: var(--bad-soft); }

.insight-grid { display: grid; gap: 10px; }
@media (min-width: 560px) { .insight-grid { grid-template-columns: 1fr 1fr; } }
.insight { background: var(--surface); border-radius: 14px; padding: 12px 14px; }
.insight p { margin: 4px 0; }
.ins-tag { font-weight: 800; }

/* ---------- 补充 ---------- */
.nl-wrap svg { color: var(--ink); }
.res { display: inline-block; animation: pop .45s cubic-bezier(.3, 1.6, .5, 1); }
.q { color: var(--ink-3); }
.nowrap { white-space: nowrap; }