/* ============================================================
   BrainBit Teaching · C Programming (Programming Fundamentals)
   Interactive tutorial deck — "C Blueprint" visual system.
   White paper, navy ink, steel-blue accents. Code windows stay
   dark so they are the only shape the eye lands on.
   100% offline · no external requests.
   Navigation: → / Space / click = next · ← = prev · F = fullscreen
               O or Esc = slide overview · Home / End = first / last
   ============================================================ */

:root{
  --paper:#ffffff;
  --ink:#10203a;
  --muted:#5a6a80;
  --steel:#0f4c81;
  --blue:#1d4ed8;
  --amber:#c47a0a;
  --green:#15803d;
  --line:#d7dfea;
  --wash:#f5f8fc;
  --code-bg:#0d1524;

  --font-display:"Bahnschrift","Segoe UI Variable Display","Segoe UI Semibold","Segoe UI",system-ui,sans-serif;
  --font-body:"Segoe UI Variable Text","Segoe UI",system-ui,-apple-system,sans-serif;
  --font-mono:"Cascadia Code","Cascadia Mono","Consolas",ui-monospace,monospace;

  --r:10px;
}

*{box-sizing:border-box;margin:0;padding:0}
html,body{height:100%}
body{
  font-family:var(--font-body);
  background:var(--paper);
  color:var(--ink);
  overflow:hidden;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

/* ---------- Deck & slides ---------- */
#deck{position:fixed;inset:0}
.slide{
  position:absolute;inset:0;
  display:flex;flex-direction:column;
  /* "safe center" keeps short slides vertically centred but falls back to
     top-aligned when the content is taller than the viewport — without it,
     centring pushes the first lines above the top edge where they cannot
     be scrolled back into view. */
  justify-content:safe center;
  padding:4.6vh 7vw 8vh;
  background:var(--paper);
  color:var(--ink);
  opacity:0;visibility:hidden;
  transform:scale(.985);
  transition:opacity .45s ease, transform .45s ease, visibility .45s;
  overflow-x:hidden;
  /* Code listings are long. Dense slides scroll rather than clip. */
  overflow-y:auto;
  scrollbar-width:thin;
  scrollbar-color:var(--line) transparent;
}
.slide::-webkit-scrollbar{width:9px}
.slide::-webkit-scrollbar-track{background:transparent}
.slide::-webkit-scrollbar-thumb{background:var(--line);border-radius:9px}
.slide:not(.active){overflow:hidden}
.slide.active{opacity:1;visibility:visible;transform:none;z-index:2}
.slide.prev{transform:scale(1.015)}

/* Module divider — a big tinted numeral, a blue rule, nothing else */
.slide.module-divider{justify-content:center}
.section-no{font-family:var(--font-display);font-weight:700;
  font-size:clamp(4.5rem,13vw,11rem);line-height:.8;color:#e4ecf6}
.module-divider h2{border-left:5px solid var(--blue);padding-left:1rem}

/* Day opener — "Today we cover" */
.slide.day-open{justify-content:center}
.day-open h2{border-left:5px solid var(--blue);padding-left:1rem}
.daychip{display:inline-flex;align-items:center;gap:.5em;
  font-family:var(--font-mono);font-size:.78rem;font-weight:700;
  letter-spacing:.14em;text-transform:uppercase;
  padding:.4em .95em;border-radius:999px;
  background:var(--wash);border:1px solid var(--line);color:var(--steel)}
.day-goal{margin-top:1.6rem;border-top:1px dashed var(--line);
  padding-top:.9rem;font-size:.95rem;color:var(--muted)}
.day-goal b{color:var(--steel)}

/* ---------- Reveal animation ---------- */
.anim{opacity:0;transform:translateY(26px);
  transition:opacity .6s cubic-bezier(.2,.75,.2,1), transform .6s cubic-bezier(.2,.75,.2,1);
  transition-delay:var(--d,0s);}
.slide.active .anim{opacity:1;transform:none}
.anim.left{transform:translateX(-30px)}
.anim.scale{transform:scale(.9)}

/* ---------- Typography ---------- */
.kicker{
  font-family:var(--font-mono);font-size:clamp(.7rem,1.1vw,.95rem);
  letter-spacing:.32em;text-transform:uppercase;font-weight:600;
  display:inline-flex;align-items:center;gap:.7em;
}
.kicker::before{content:"";width:34px;height:2px;background:linear-gradient(90deg,var(--steel),var(--blue))}
h1{font-family:var(--font-display);font-weight:700;line-height:.98;letter-spacing:-.5px}
h2{font-family:var(--font-display);font-weight:700;line-height:1.02;letter-spacing:-.4px;
   font-size:clamp(1.9rem,4.4vw,3.7rem)}
h3{font-family:var(--font-display);font-weight:600;letter-spacing:-.2px}
p{line-height:1.55}
.lead{font-size:clamp(1.02rem,1.6vw,1.42rem);line-height:1.5;max-width:62ch}
.grad{background:linear-gradient(110deg,var(--blue),var(--steel) 60%);
  -webkit-background-clip:text;background-clip:text;color:transparent}
.grad2{background:linear-gradient(110deg,var(--steel),var(--blue) 50%,var(--amber));
  -webkit-background-clip:text;background-clip:text;color:transparent}

/* ---------- Chrome (top progress + bottom bar) ---------- */
#bar{position:fixed;top:0;left:0;height:5px;z-index:50;
  background:linear-gradient(90deg,var(--steel),var(--blue));
  width:0;transition:width .5s cubic-bezier(.2,.8,.2,1);
  box-shadow:0 0 14px rgba(29,78,216,.45)}
#chrome{position:fixed;left:0;right:0;bottom:0;z-index:50;
  display:flex;align-items:center;justify-content:space-between;
  padding:14px 26px;pointer-events:none;
  font-family:var(--font-mono);font-size:.78rem;letter-spacing:.12em;color:var(--muted)}
#brandmark{display:flex;align-items:center;gap:10px;opacity:.92;pointer-events:auto}
#brandmark .logo{width:24px;height:24px;border-radius:7px;
  background:#fff url(../../../../assets/logo-mark-64.png) center/contain no-repeat;
  box-shadow:0 0 0 1px rgba(0,0,0,.08)}
#brandmark b{font-family:var(--font-display);letter-spacing:.5px;font-weight:700;color:var(--ink)}
#nav{display:flex;align-items:center;gap:10px;pointer-events:auto}
.btn{pointer-events:auto;cursor:pointer;border:none;color:var(--ink);
  width:38px;height:38px;border-radius:11px;font-size:1rem;
  display:grid;place-items:center;
  background:var(--wash);backdrop-filter:blur(8px);
  border:1px solid var(--line);transition:.2s}
.btn:hover{background:#e8eef6;transform:translateY(-2px)}
#count{min-width:74px;text-align:center;opacity:.85}
#hint{position:fixed;bottom:64px;right:26px;z-index:50;font-family:var(--font-mono);
  font-size:.68rem;letter-spacing:.1em;opacity:.5;text-align:right;pointer-events:none;
  line-height:1.7;color:var(--muted)}

/* ---------- Reusable pieces ---------- */
.card{background:var(--wash);border:1px solid var(--line);
  border-radius:var(--r);padding:1.4rem 1.5rem;
  box-shadow:0 22px 50px -28px rgba(16,32,58,.22)}
.glass{background:var(--wash);border:1px solid var(--line);
  border-radius:var(--r);backdrop-filter:blur(10px)}
.chip{display:inline-flex;align-items:center;gap:.5em;font-family:var(--font-mono);
  font-size:.74rem;letter-spacing:.06em;padding:.42em .85em;border-radius:999px;
  border:1px solid currentColor;font-weight:600}
.pill{display:inline-flex;align-items:center;gap:.5em;padding:.4em .9em;border-radius:999px;
  font-size:.8rem;font-weight:600;font-family:var(--font-mono);letter-spacing:.05em}
.tag-stack{display:flex;flex-wrap:wrap;gap:.4rem}
.tag{font-family:var(--font-mono);font-size:.72rem;padding:.3em .65em;border-radius:8px;
  background:var(--wash);border:1px solid var(--line);color:var(--steel)}

.grid{display:grid;gap:1.1rem}

.stat{font-family:var(--font-display);font-weight:700;font-size:clamp(2.2rem,5vw,4rem);line-height:1}
.stat b{display:block;color:var(--steel)}
.stat span{display:block;margin-top:.45rem;font-family:var(--font-mono);
  font-size:.78rem;font-weight:600;letter-spacing:.14em;
  text-transform:uppercase;color:var(--muted)}
mark{background:linear-gradient(transparent 58%, rgba(196,122,10,.35) 58%);color:inherit;padding:0 .1em}

ul.clean{list-style:none;display:grid;gap:.6rem}
ul.clean li{display:flex;gap:.7rem;align-items:flex-start;line-height:1.45}
ul.clean li::before{content:"▸";color:var(--steel);font-weight:700;margin-top:.05em}

/* keycap */
kbd{font-family:var(--font-mono);font-size:.82em;padding:.12em .5em;border-radius:6px;
  background:var(--wash);border:1px solid var(--line);
  box-shadow:0 2px 0 var(--line);color:var(--ink)}

/* table */
.tbl{width:100%;border-collapse:collapse;font-size:clamp(.72rem,1.05vw,.95rem)}
.tbl th{font-family:var(--font-mono);font-size:.68rem;letter-spacing:.14em;text-transform:uppercase;
  text-align:left;padding:.55rem .7rem;color:var(--muted);border-bottom:2px solid var(--line)}
.tbl td{padding:.5rem .7rem;border-bottom:1px solid var(--line)}
.tbl tr:hover td{background:var(--wash)}
.tbl td.dayno{font-family:var(--font-mono);font-weight:700;color:var(--steel);width:3.5rem;text-align:center}

/* ============================================================
   CODE-CARD COMPONENTS (tutorial-specific)
   ============================================================ */
.lab{display:grid;gap:.9rem;grid-template-columns:1.15fr .85fr;align-items:start;max-width:1180px}
.lab.stack{grid-template-columns:1fr}
@media (max-width:900px){.lab{grid-template-columns:1fr}}

/* concept badge above a heading */
.concept{display:inline-flex;align-items:center;gap:.55em;font-family:var(--font-mono);
  font-size:.72rem;letter-spacing:.12em;text-transform:uppercase;font-weight:700;
  padding:.35em .8em;border-radius:999px;
  background:var(--wash);border:1px solid var(--line);color:var(--steel)}

/* code block */
.codewrap{border-radius:var(--r);overflow:hidden;border:1px solid #1e2b42;
  box-shadow:0 18px 38px -24px rgba(16,32,58,.55);background:var(--code-bg)}
.codewrap .top{display:flex;align-items:center;gap:.5rem;padding:.55rem .9rem;
  background:#131d31;border-bottom:1px solid #22314c}
.codewrap .top .dot3{display:flex;gap:6px}
.codewrap .top .dot3 i{width:11px;height:11px;border-radius:50%;display:inline-block}
.codewrap .top .dot3 i:nth-child(1){background:#fb7185}
.codewrap .top .dot3 i:nth-child(2){background:#f59e0b}
.codewrap .top .dot3 i:nth-child(3){background:#34d399}
.codewrap .top .fname{font-family:var(--font-mono);font-size:.72rem;color:#93a4bf;margin-left:.3rem}
pre.code{margin:0;padding:1rem 1.1rem;font-family:var(--font-mono);
  font-size:clamp(.74rem,1.02vw,.92rem);line-height:1.62;color:#e2e8f0;
  white-space:pre;overflow:auto;max-height:54vh;tab-size:4}
pre.code::-webkit-scrollbar{height:8px;width:8px}
pre.code::-webkit-scrollbar-thumb{background:rgba(15,76,129,.35);border-radius:8px}

/* syntax colors — tuned for the dark code window */
.c-kw{color:#7dd3fc;font-weight:600}      /* keywords: int, if, for, return … */
.c-bi{color:#fbbf24}                      /* types & standard-library names */
.c-st{color:#a3e635}                      /* strings & chars */
.c-nu{color:#f0abfc}                      /* numbers */
.c-cm{color:#64748b;font-style:italic}    /* comments */
.c-pp{color:#fb923c;font-weight:600}      /* preprocessor directives: #include, #define … */

/* output box */
.out{border-radius:var(--r);border:1px solid #14532d;overflow:hidden;background:#06180f}
.out.hidden{display:none}
.out .top{display:flex;align-items:center;gap:.5rem;padding:.5rem .9rem;
  background:#0c2e1c;border-bottom:1px solid #14532d;
  font-family:var(--font-mono);font-size:.7rem;letter-spacing:.14em;
  text-transform:uppercase;color:#6ee7b7}
.out pre{margin:0;padding:.85rem 1.1rem;font-family:var(--font-mono);
  font-size:clamp(.74rem,1.02vw,.9rem);line-height:1.6;color:#d1fae5;white-space:pre-wrap}
.out .usr{color:#fde68a}  /* what the user typed, in sample runs */

/* explainer note */
.note{font-size:.95rem;line-height:1.5}
.note b{color:var(--steel)}

/* "why it matters for your project" callout */
.why{display:flex;gap:.7rem;align-items:flex-start;border-radius:var(--r);padding:.8rem 1rem;
  background:#fdf6e7;border:1px solid #e8d9b5;font-size:.9rem;line-height:1.45}
.why .ic{font-size:1.1rem;line-height:1}
.why b{color:var(--amber)}

/* game banner */
.gamebar{display:inline-flex;align-items:center;gap:.6em;font-family:var(--font-mono);
  font-size:.74rem;letter-spacing:.1em;text-transform:uppercase;font-weight:700;
  padding:.4em .9em;border-radius:999px;color:#fff;
  background:linear-gradient(90deg,var(--steel),var(--blue))}

/* section divider number list */
ol.steps{counter-reset:s;list-style:none;display:grid;gap:.55rem}
ol.steps li{display:flex;gap:.7rem;align-items:flex-start;line-height:1.45;counter-increment:s}
ol.steps li::before{content:counter(s);flex:0 0 auto;width:1.5em;height:1.5em;border-radius:50%;
  display:grid;place-items:center;font-family:var(--font-mono);font-size:.78rem;font-weight:700;
  background:var(--wash);border:1px solid var(--line);color:var(--steel)}

/* ============================================================
   TIMED SECTION TEST (15 questions · 15-minute timer)
   ============================================================ */
.exam-slide{justify-content:flex-start;padding-top:3.2vh}
.exam{display:flex;flex-direction:column;gap:.85rem;width:100%;max-width:1220px;margin:0 auto}

.exam-head{display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap}
.exam-title{font-family:var(--font-display);font-weight:700;font-size:clamp(1.2rem,2.5vw,1.85rem)}
.exam-tools{display:flex;align-items:center;gap:.55rem}
.exam-timer{font-family:var(--font-mono);font-weight:700;font-size:clamp(1.1rem,2.2vw,1.6rem);
  padding:.28em .7em;border-radius:12px;letter-spacing:.06em;min-width:5.4em;text-align:center;
  background:var(--wash);border:1px solid var(--line);color:var(--steel)}
.exam-timer.warn{background:#fee2e2;border-color:#fca5a5;color:#b91c1c;animation:pulse 1s infinite}
.exam-timer.done{background:#fdf6e7;border-color:#e8d9b5;color:var(--amber);font-size:clamp(.9rem,1.8vw,1.2rem)}
@keyframes pulse{50%{opacity:.5}}

.exam-banner{font-size:.9rem;line-height:1.4;border-radius:12px;padding:.6rem .9rem;
  background:var(--wash);border:1px solid var(--line)}
.exam-banner.live{background:#e7f6ec;border-color:#a7d7b7;color:var(--green)}
.exam-banner.reveal{background:#fdf6e7;border-color:#e8d9b5;color:var(--amber)}

.exam-body{overflow:auto;max-height:63vh;padding-right:.4rem}
.exam-body::-webkit-scrollbar{width:9px}
.exam-body::-webkit-scrollbar-thumb{background:var(--line);border-radius:8px}
.exam-grid{display:grid;grid-template-columns:1fr 1fr;gap:.7rem}
@media (max-width:820px){.exam-grid{grid-template-columns:1fr}}

/* Quiz and practice cards — written light-first, so there is nothing to
   override for a light slide and nothing to forget. */
.qz{background:var(--wash);border:1px solid var(--line);border-radius:14px;padding:.75rem .85rem}
.qz-code{border-left:3px solid var(--blue)}
.qz-concept{border-left:3px solid var(--amber)}
.qz-q{font-size:.92rem;line-height:1.45;color:var(--ink)}
.qz-q code{font-family:var(--font-mono);font-size:.86em;background:#e8eef6;
  border:1px solid var(--line);border-radius:5px;padding:.05em .35em}
.qz-q pre{white-space:pre;overflow:auto;font-family:var(--font-mono);font-size:.78rem;
  margin:.5rem 0;padding:.6rem .7rem;border-radius:10px;
  background:var(--code-bg);border:1px solid #1e2b42;color:#e2e8f0}
.qz-n{font-family:var(--font-mono);color:var(--steel);font-weight:700;margin-right:.2em}
.qz-tag{font-family:var(--font-mono);font-size:.6rem;letter-spacing:.1em;text-transform:uppercase;
  font-weight:700;padding:.22em .6em;border-radius:999px;margin-right:.45em;vertical-align:middle}
.qz-tag.code{background:var(--wash);border:1px solid var(--line);color:var(--blue)}
.qz-tag.concept{background:#fdf6e7;border:1px solid #e8d9b5;color:var(--amber)}

.qz-input{display:block;width:100%;margin-top:.55rem;font-family:var(--font-mono);
  font-size:.82rem;line-height:1.5;color:var(--ink);background:#fff;
  border:1px solid var(--line);border-radius:9px;padding:.5rem .6rem;
  resize:vertical;white-space:pre;overflow:auto}
.qz-input::placeholder{color:var(--muted)}
.qz-input:focus{outline:none;border-color:var(--blue)}
.qz-ans{display:none;margin-top:.6rem;border-top:1px dashed var(--green);padding-top:.55rem}
.qz-ans.show{display:block;animation:fade .3s ease}
.qz-ans-h{font-family:var(--font-mono);font-size:.64rem;letter-spacing:.12em;
  text-transform:uppercase;color:var(--green);font-weight:700;margin-bottom:.35rem}
.qz-ans-t{font-size:.86rem;line-height:1.5;color:var(--ink)}
.qz-ans pre.code{max-height:none;padding:.6rem .8rem;font-size:.8rem;
  border:1px solid #1e2b42;border-radius:10px}
.exam-btn{cursor:pointer;font-family:var(--font-mono);font-size:.76rem;font-weight:600;
  padding:.55em .9em;border-radius:10px;color:var(--ink);
  background:var(--wash);border:1px solid var(--line);transition:.16s}
.exam-btn:hover{background:#e8eef6;transform:translateY(-1px)}
.exam-btn.ghost{background:transparent}
.exam .qz,.practice .qz{min-width:0}

/* ---- Practice sets (untimed sibling of the timed .exam) ---- */
.practice-slide{justify-content:flex-start;padding-top:3.2vh}
.practice{display:flex;flex-direction:column;gap:.85rem;width:100%;max-width:1220px;margin:0 auto}
.practice-head{display:flex;align-items:center;justify-content:space-between;gap:1rem;flex-wrap:wrap}
.practice-title{font-family:var(--font-display);font-weight:700;font-size:clamp(1.2rem,2.5vw,1.85rem)}
.practice-tools{display:flex;align-items:center;gap:.55rem;flex-wrap:wrap}
.practice-marks{font-family:var(--font-mono);font-weight:700;font-size:.8rem;letter-spacing:.06em;
  padding:.4em .8em;border-radius:12px;
  background:#fdf6e7;border:1px solid #e8d9b5;color:var(--amber)}
.practice-banner{font-size:.9rem;line-height:1.4;border-radius:12px;padding:.6rem .9rem;
  background:var(--wash);border:1px solid var(--line)}
.practice-body{overflow:auto;max-height:63vh;padding-right:.4rem}
.practice-body::-webkit-scrollbar{width:9px}
.practice-body::-webkit-scrollbar-thumb{background:var(--line);border-radius:8px}
.qz-marks{font-family:var(--font-mono);font-size:.72rem;font-weight:700;opacity:.7}
.qz-reveal{margin-top:.5rem}

/* ---------- Overview grid ---------- */
#overview{position:fixed;inset:0;z-index:80;display:none;
  background:rgba(255,255,255,.95);backdrop-filter:blur(14px);
  padding:5vh 5vw;overflow:auto}
#overview.open{display:block;animation:fade .3s ease}
@keyframes fade{from{opacity:0}to{opacity:1}}
#overview h3{font-size:1.4rem;margin-bottom:1.4rem;color:var(--ink)}
#ovGrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(190px,1fr));gap:14px}
.ov{cursor:pointer;border-radius:14px;padding:14px 14px 16px;min-height:92px;
  background:var(--wash);
  border:1px solid var(--line);transition:.18s;display:flex;flex-direction:column;gap:8px}
.ov:hover{transform:translateY(-4px);border-color:var(--steel);box-shadow:0 16px 30px -16px rgba(15,76,129,.35)}
.ov .n{font-family:var(--font-mono);font-size:.7rem;opacity:.7;color:var(--muted)}
.ov .t{font-family:var(--font-display);font-weight:600;font-size:.95rem;line-height:1.15}
.ov.cur{border-color:var(--blue);box-shadow:0 0 0 2px var(--blue) inset}

@media (max-width:760px){
  .slide{padding:6vh 7vw 11vh}
  .hide-sm{display:none!important}
}
@media print{
  /* Default: print the whole deck, one slide per page (unchanged). */
  .slide{position:relative;opacity:1!important;visibility:visible!important;
    page-break-after:always;height:100vh}

  /* Worksheet / answer-key mode: one practice set on paper, in ink. */
  .printing-worksheet #chrome,.printing-key #chrome,
  .printing-worksheet #bar,.printing-key #bar,
  .printing-worksheet #hint,.printing-key #hint,
  .printing-worksheet #overview,.printing-key #overview,
  .printing-worksheet .practice-tools,.printing-key .practice-tools,
  .printing-worksheet .practice-banner,.printing-key .practice-banner,
  .printing-worksheet .qz-reveal,.printing-key .qz-reveal{display:none!important}

  .printing-worksheet .slide,.printing-key .slide{display:none!important}
  .printing-worksheet .slide:has(.print-target),
  .printing-key .slide:has(.print-target){
    display:block!important;height:auto;page-break-after:auto;padding:0;overflow:visible}

  .printing-worksheet body,.printing-key body,
  .printing-worksheet .slide,.printing-key .slide{
    background:#fff!important;color:#000!important}
  .printing-worksheet .practice-body,.printing-key .practice-body{
    overflow:visible!important;max-height:none!important}
  .printing-worksheet .exam-grid,.printing-key .exam-grid{
    display:block!important}
  .printing-worksheet .qz,.printing-key .qz{
    background:none!important;border:1px solid #999!important;
    page-break-inside:avoid;margin-bottom:.5rem}
  .printing-worksheet .practice-title,.printing-key .practice-title{color:#000!important}

  /* Worksheet: questions only, with room to write. */
  .printing-worksheet .qz-ans{display:none!important}
  .printing-worksheet .qz-input{display:block!important;width:100%;
    border:none!important;border-bottom:1px solid #bbb!important;
    background:none!important;color:#000!important;resize:none}
  .printing-worksheet .qz-code .qz-input{height:11rem}
  .printing-worksheet .qz-concept .qz-input{height:5rem}

  /* Answer key: questions plus answers, compact. */
  .printing-key .qz-input{display:none!important}
  .printing-key .qz-ans{display:block!important;opacity:1!important;
    max-height:none!important;color:#000!important}
  .printing-key .qz-ans pre.code{background:#f4f4f4!important;color:#000!important;
    border:1px solid #ddd!important;white-space:pre-wrap}
  .printing-key .c-kw,.printing-key .c-bi,.printing-key .c-st,
  .printing-key .c-nu,.printing-key .c-cm,.printing-key .c-pp{color:#000!important}
  .printing-key .qz-ans-h{color:#000!important}
  .printing-key .qz-ans-t{color:#000!important}
}

/* ============================================================
   PREDICT-THEN-REVEAL
   The .out box ships hidden; deck.js injects a ▶ Run button that
   removes .hidden. Since C compiles rather than runs in the
   browser, the student predicts the output first, then checks.
   ============================================================ */
.runbtn{
  display:inline-flex;align-items:center;gap:.5em;cursor:pointer;
  font-family:var(--font-mono);font-size:.78rem;letter-spacing:.06em;
  padding:.55em 1.15em;border-radius:999px;
  background:var(--wash);border:1px solid var(--line);
  color:var(--steel);font-weight:700;transition:background .18s ease,transform .18s ease;
}
.runbtn:hover{background:#e8eef6;transform:translateY(-1px)}
.runbtn:active{transform:translateY(0)}
.runbtn[hidden]{display:none}