/* eCircuitCalc — shared tutorial kit (reused by learning modules).
   Relies on base.css tokens/components (container, page-hero, breadcrumb,
   hero-meta, grad-text, btn, badge, field, reveal, back-top, toast). */

/* Reading progress */
.rprog{position:fixed;top:0;left:0;right:0;height:3px;z-index:120;pointer-events:none}
.rprog span{display:block;height:100%;width:0;background:var(--grad);transition:width .1s linear}

/* Sticky lesson nav */
.dsg-bar{position:sticky;top:var(--nav-h,64px);z-index:90;background:color-mix(in srgb,var(--bg) 84%,transparent);backdrop-filter:blur(12px);-webkit-backdrop-filter:blur(12px);border-bottom:1px solid var(--border)}
.dsg-chips{display:flex;gap:.4rem;overflow-x:auto;padding:.6rem 0 .75rem;scrollbar-width:thin;scrollbar-color:var(--border2) transparent}
.dsg-chips::-webkit-scrollbar{height:6px}
.dsg-chips::-webkit-scrollbar-thumb{background:var(--border2);border-radius:99px}
.dsg-chip{flex:none;font-size:.8rem;padding:.45rem .8rem;border-radius:999px;border:1px solid var(--border);color:var(--text2);background:var(--surface);white-space:nowrap;transition:transform .2s var(--ease),color .2s,border-color .2s}
.dsg-chip:hover{color:var(--accent);border-color:var(--accent);transform:translateY(-1px)}
.dsg-chip.active{color:#fff;background:var(--grad);border-color:transparent}

/* Prose */
.prose{width:min(1120px,92%);margin:0 auto;display:grid;gap:clamp(2.4rem,5vw,3.4rem);padding:1.5rem 0 2rem}
.prose section{scroll-margin-top:120px}
.prose h2{font-size:clamp(1.3rem,3vw,1.75rem);font-weight:800;letter-spacing:-.02em;margin-bottom:.4rem}
.prose h3{font-size:1.05rem;margin:1.4rem 0 .6rem}
.prose p{color:var(--text2);line-height:1.72;margin-bottom:.9rem}
.prose a{color:var(--accent);text-decoration:underline;text-underline-offset:3px}
.muted{color:var(--text2);font-size:.92rem}
.lvl-tag{font-family:var(--mono);font-size:.72rem;letter-spacing:.1em;text-transform:uppercase;color:var(--accent);margin-bottom:.8rem}
.objs{list-style:none;display:grid;gap:.4rem;margin:0 0 1.1rem}
.objs li{position:relative;padding-left:1.4rem;color:var(--text2)}
.objs li::before{content:"✓";position:absolute;left:0;color:var(--accent);font-weight:700}

/* Formula strip */
.formula{display:flex;flex-wrap:wrap;gap:.5rem;align-items:stretch;margin:1rem 0}
.formula .f{flex:1 1 130px;border:1px solid var(--border);border-radius:12px;background:var(--surface);padding:.8rem 1rem;font-family:var(--mono);font-size:1.05rem;color:var(--text);display:grid;place-items:center;text-align:center}
.formula .f b{color:var(--accent)}
.formula .f .lbl{display:block;font-family:var(--font);font-size:.72rem;color:var(--text2);margin-top:.3rem}

/* Callouts */
.callout{border:1px solid var(--border);border-left:3px solid var(--accent);background:var(--surface);border-radius:0 12px 12px 0;padding:1rem 1.2rem;margin:1.1rem 0}
.callout p{margin:0}
.callout .tag{display:inline-block;font-family:var(--mono);font-size:.62rem;letter-spacing:.12em;text-transform:uppercase;margin-bottom:.4rem;font-weight:600}
.callout.pitfall{border-left-color:#fbbf24}.callout.pitfall .tag{color:#fbbf24}
.callout.takeaway{border-left-color:var(--accent);background:color-mix(in srgb,var(--accent) 8%,var(--surface))}.callout.takeaway .tag{color:var(--accent)}

/* Worked example */
.worked{border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem 1.2rem;margin:1.2rem 0}
.worked .tag{display:inline-block;font-family:var(--mono);font-size:.62rem;letter-spacing:.12em;text-transform:uppercase;color:var(--accent);font-weight:600;margin-bottom:.5rem}
.worked ol{margin:0 0 0 1.2rem;color:var(--text2);line-height:1.65}
.worked li{margin-bottom:.4rem}
.worked li strong{color:var(--text)}

/* Tables */
.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:14px;background:var(--surface);margin:1.2rem 0}
table{width:100%;border-collapse:collapse}
.spec{min-width:440px}
.spec caption{caption-side:top;text-align:left;padding:.9rem 1.1rem .3rem;font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text2)}
.spec th,.spec td{padding:.7rem 1rem;text-align:left;border-bottom:1px solid var(--border);font-size:.92rem}
.spec th{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--text2);background:var(--surface2)}
.spec tbody tr:last-child td{border-bottom:0}
.spec td strong{color:var(--text)}

/* Figure / SVG */
.fig{padding:1.2rem;border-radius:16px;background:var(--bg2);border:1px solid var(--border);margin:1.2rem 0}
.fig-svg{width:100%;height:auto;max-width:680px;margin:0 auto;display:block}
.fig figcaption{margin-top:1rem;font-size:.9rem;color:var(--text2);line-height:1.6}

/* Calc shell (reusable) */
.calc{margin:1.2rem 0;border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem;display:grid;gap:.9rem}
.calc h3{margin:0}
.calc .muted{margin:0}
.calc-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:.8rem}
.calc-out{display:flex;align-items:baseline;gap:.9rem;flex-wrap:wrap}
.calc-out .big{font-family:var(--mono);font-size:1.5rem;font-weight:800;color:var(--accent)}
.calc-out .sub{font-size:.9rem;color:var(--text2)}
.calc-out .sub b{font-family:var(--mono);color:var(--text)}
.calc-note{margin:0;font-size:.85rem;color:var(--text2)}
.calc-note.warn{color:#fbbf24}

/* Reveal (knowledge checks & quiz answers) */
.qa{border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1rem 1.2rem;margin:1rem 0}
.qa-q{margin:0 0 .8rem}
.qa-badge{display:inline-block;font-family:var(--mono);font-size:.6rem;letter-spacing:.12em;text-transform:uppercase;color:var(--accent);border:1px solid var(--border2);border-radius:6px;padding:.15rem .5rem;margin-right:.5rem;vertical-align:middle}
.qa-body{margin-bottom:.9rem}
.qa-a{margin-bottom:.5rem}
.qa-ex{color:var(--text2);font-size:.9rem;margin:0;border-left:2px solid var(--border);padding-left:.8rem}
.qa-btn{font-size:.85rem;font-weight:600;padding:.5rem 1rem;border-radius:10px;border:1px solid var(--border2);background:var(--surface2);color:var(--accent);cursor:pointer;transition:.2s}
.qa-btn:hover{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 10%,var(--surface2))}
.qa-quiz{border-left:3px solid var(--accent)}
.qa-quiz .qa-badge{background:var(--accent);color:#fff;border-color:transparent}

/* Multiple-choice quiz (reusable) */
.quiz{border:1px solid var(--border);border-radius:14px;background:var(--surface);padding:1.1rem 1.2rem;margin:1rem 0}
.quiz-q{margin:0 0 .9rem}
.quiz-opts{display:grid;gap:.5rem;margin-bottom:.9rem}
.quiz-opt{text-align:left;font-size:.92rem;padding:.7rem .9rem;border-radius:10px;border:1px solid var(--border2);background:var(--surface2);color:var(--text);cursor:pointer;transition:.2s}
.quiz-opt:hover:not(:disabled){border-color:var(--accent);color:var(--accent)}
.quiz-opt[aria-pressed="true"]{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 14%,var(--surface2));color:var(--accent);font-weight:600}
.quiz-opt:disabled{cursor:default;opacity:.85}
.quiz-opt.correct{border-color:#4ade80;background:rgba(74,222,128,.14);color:#4ade80;font-weight:600;opacity:1}
.quiz-opt.wrong{border-color:#f87171;background:rgba(248,113,113,.14);color:#f87171;opacity:1}
.quiz-foot{display:flex;align-items:center;gap:.9rem;flex-wrap:wrap}
.quiz-check{font-size:.85rem;font-weight:600;padding:.55rem 1.1rem;border-radius:10px;background:var(--grad);color:#fff;cursor:pointer;transition:transform .2s}
.quiz-check:hover:not(:disabled){transform:translateY(-1px)}
.quiz-check:disabled{opacity:.5;cursor:default}
.quiz-feedback{margin:0;font-weight:600;font-size:.9rem}
.quiz-feedback.ok{color:#4ade80}
.quiz-feedback.no{color:#fbbf24}
.quiz-ex{margin-top:.8rem}

/* FAQ accordion — reliable expand/collapse */
.faq{display:grid;gap:.7rem;margin-top:.6rem}
.faq-item{background:var(--surface);border:1px solid var(--border);border-radius:12px;overflow:hidden;transition:border-color .3s}
.faq-item.open{border-color:var(--accent)}
.faq-q{width:100%;display:flex;justify-content:space-between;align-items:center;gap:1rem;padding:1rem 1.15rem;font-weight:600;font-size:.98rem;text-align:left;cursor:pointer}
.faq-x{position:relative;width:16px;height:16px;flex:none;transition:transform .3s var(--ease)}
.faq-x::before,.faq-x::after{content:"";position:absolute;background:var(--accent);border-radius:2px;top:50%;left:50%}
.faq-x::before{width:14px;height:2px;transform:translate(-50%,-50%)}
.faq-x::after{width:2px;height:14px;transform:translate(-50%,-50%)}
.faq-item.open .faq-x{transform:rotate(180deg)}
.faq-a{overflow:hidden;max-height:0;transition:max-height .3s var(--ease)}
.faq-item.open .faq-a{max-height:300px}
.faq-a p{padding:0 1.15rem 1.1rem;color:var(--text2);font-size:.93rem;margin:0}

/* completed-module button state */
#markComplete.is-complete{background:linear-gradient(135deg,#22c55e,#15803d);box-shadow:0 10px 28px -12px rgba(34,197,94,.5)}
#markComplete.is-complete:hover{transform:none}


/* Multiple-choice option list (used inside .qa for MCQ reveal quizzes) */
.qa-opts{counter-reset:qopt;list-style:none;margin:.1rem 0 .3rem;display:grid;gap:.45rem}
.qa-opts li{counter-increment:qopt;position:relative;padding-left:1.9rem;color:var(--text2);font-size:.92rem}
.qa-opts li::before{content:counter(qopt,upper-alpha) ".";position:absolute;left:0;top:0;font-family:var(--mono);font-weight:600;color:var(--text2)}


/* Ad slot (auto-hides when empty) */
.ad-slot{max-width:728px;margin:1.5rem auto;text-align:center;transition:max-height .5s var(--ease),opacity .4s,margin .5s;max-height:160px;overflow:hidden}
.ad-slot.ad-hidden{max-height:0;opacity:0;margin:0}
.ad-label{display:block;font-family:var(--mono);font-size:.6rem;letter-spacing:.2em;text-transform:uppercase;color:var(--text2);opacity:.6;margin-bottom:.4rem}
.ad-box{min-height:90px;border:1.5px dashed var(--border2);border-radius:12px;display:grid;place-items:center;color:var(--text2);font-size:.85rem;background:var(--surface)}

/* Focus + reduced motion + responsive */
.dsg-chip:focus-visible,.qa-btn:focus-visible,.quiz-check:focus-visible,.quiz-opt:focus-visible,.faq-q:focus-visible,.back-top:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
@media (prefers-reduced-motion:reduce){
  .rprog span{transition:none}
  .dsg-chip,.qa-btn,.quiz-check,.quiz-opt,.faq-q{transition:none}
}
@media (max-width:640px){
  .calc-grid{grid-template-columns:1fr 1fr}
  .calc-out .big{font-size:1.25rem}
  .calc h3,.quiz-q,.qa-q{font-size:1rem}
}