/* ============================================================
   SUIBE「AI+」社团 — "Build Notebook" theme
   A light engineering-graph-paper identity.
   Deliberately NOT the dark neon recruitment poster.
   ============================================================ */

/* ---------- fonts ---------- */
@font-face{font-family:"Space Grotesk";src:url("../fonts/space-grotesk-500.woff2") format("woff2");font-weight:500;font-display:swap}
@font-face{font-family:"Space Grotesk";src:url("../fonts/space-grotesk-700.woff2") format("woff2");font-weight:700;font-display:swap}
@font-face{font-family:"Plex Mono";src:url("../fonts/ibm-plex-mono-400.woff2") format("woff2");font-weight:400;font-display:swap}
@font-face{font-family:"Plex Mono";src:url("../fonts/ibm-plex-mono-500.woff2") format("woff2");font-weight:500;font-display:swap}

/* ---------- tokens ---------- */
:root{
  --paper:#F4F4EC;         /* warm off-white, cleaner than cream */
  --paper-2:#ECEDE2;       /* recessed panels */
  --card:#FBFBF6;          /* raised surfaces */
  --ink:#16191A;           /* primary text, near-black */
  --ink-soft:#585E54;      /* secondary text */
  --line:#DEDFD3;          /* graph grid + hairlines */
  --line-strong:#C9CBBB;
  --green:#0B7A4A;         /* deep emerald — the club DNA, de-neon'd */
  --green-deep:#075A37;
  --green-wash:#E4F0E5;    /* faint green fill */
  --spark:#D7ED45;         /* highlighter lime — used like a marker swipe */
  --shadow:#16191A;
  --shadow-soft:rgba(22,25,26,.13);
  --shadow-soft-hover:rgba(22,25,26,.17);
  --band-fg:rgba(244,244,236,.72);   /* muted text on ink bands */
  --band-soft:rgba(244,244,236,.55); /* hint text on ink bands */
  --band-accent:var(--spark);
  --on-green:#fff;

  --mono:"Plex Mono",ui-monospace,SFMono-Regular,Menlo,monospace;
  --display:"Space Grotesk","PingFang SC","Microsoft YaHei","Noto Sans SC",sans-serif;
  --cjk:"PingFang SC","Microsoft YaHei","Noto Sans SC","Hiragino Sans GB",sans-serif;
  --body:"Space Grotesk",var(--cjk);

  --wrap:74rem;
  --measure:60ch;
  --gutter:clamp(1.1rem,4vw,3rem);
  --unit:8px;                 /* graph square size */
}

/* ---------- reset ---------- */
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;
  font-family:var(--body);
  color:var(--ink);
  background:var(--paper);
  line-height:1.65;
  font-size:clamp(15px,1vw + 12px,17px);
  -webkit-font-smoothing:antialiased;
  /* the signature: faint graph paper drawn from the "+" grid */
  background-image:
    linear-gradient(var(--line) 1px,transparent 1px),
    linear-gradient(90deg,var(--line) 1px,transparent 1px);
  background-size:calc(var(--unit)*4) calc(var(--unit)*4);
  background-position:center top;
}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
h1,h2,h3,h4{margin:0;font-family:var(--display);font-weight:700;line-height:1.05;letter-spacing:-.01em}
p{margin:0}
:focus-visible{outline:2.5px solid var(--green);outline-offset:3px;border-radius:2px}

.container{width:100%;max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gutter)}

/* ============================================================
   header
   ============================================================ */
.site-header{
  position:sticky;top:0;z-index:60;
  background:color-mix(in srgb,var(--paper) 88%,transparent);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--line);
}
.site-header.scrolled{border-color:var(--line-strong);box-shadow:0 1px 0 var(--line)}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:66px}
.brand{display:flex;align-items:center;gap:.6rem}
.brand-logo{width:30px;height:30px;object-fit:contain;border-radius:7px}
.brand-name{font-family:var(--display);font-weight:700;font-size:1.05rem;line-height:1;letter-spacing:-.02em;display:flex;flex-direction:column;gap:3px}
.brand-name small{font-family:var(--mono);font-weight:400;font-size:.58rem;letter-spacing:.16em;color:var(--green);opacity:.9}

.nav{display:flex;align-items:center;gap:clamp(1rem,2.4vw,2rem)}
.nav > a:not(.btn){font-size:.92rem;color:var(--ink-soft);position:relative;padding:4px 0}
.nav > a:not(.btn):hover{color:var(--ink)}
.nav > a.active{color:var(--ink)}
.nav > a.active::after{content:"";position:absolute;left:0;right:0;bottom:-2px;height:2px;background:var(--green)}

.nav-toggle{display:none;background:none;border:1px solid var(--line-strong);border-radius:4px;color:var(--ink);width:42px;height:38px;align-items:center;justify-content:center;cursor:pointer}
.nav-toggle svg{width:22px;height:22px}

/* ---------- buttons ---------- */
.btn{
  --btn-bg:var(--green);--btn-fg:var(--on-green);
  display:inline-flex;align-items:center;gap:.5rem;
  font-family:var(--display);font-weight:700;font-size:.95rem;letter-spacing:-.01em;
  padding:.72em 1.15em;border-radius:3px;cursor:pointer;border:1.5px solid var(--btn-bg);
  background:var(--btn-bg);color:var(--btn-fg);
  transition:transform .12s ease,box-shadow .12s ease,background .15s ease;
  text-align:center;line-height:1.1;
}
.btn:hover{transform:translate(-2px,-2px);box-shadow:4px 4px 0 var(--shadow)}
.btn:active{transform:translate(0,0);box-shadow:1px 1px 0 var(--shadow)}
.btn-primary{--btn-bg:var(--green)}
.btn-ghost{--btn-bg:transparent;--btn-fg:var(--ink);border-color:var(--ink)}
.btn-ghost:hover{background:var(--spark);border-color:var(--ink)}
.btn-sm{font-size:.85rem;padding:.55em .85em}
/* kill the templated trailing arrow; use a mono plus that slides in */
.btn .arrow{font-family:var(--mono);font-weight:500;transition:transform .15s ease}
.btn:hover .arrow{transform:translateX(3px)}

/* ============================================================
   generic section rhythm
   ============================================================ */
.section{padding-block:clamp(3.4rem,8vw,6.2rem)}
.section--tight{padding-block:clamp(2rem,4vw,3rem)}
.section--band{background:var(--paper-2);border-block:1px solid var(--line)}

.section-head{max-width:52rem;margin-bottom:clamp(2rem,4vw,3rem)}
.index-num{
  display:inline-flex;align-items:center;gap:.5rem;
  font-family:var(--mono);font-size:.72rem;letter-spacing:.04em;color:var(--green-deep);
  margin-bottom:1rem;
}
.index-num::before{content:"+";color:var(--green);font-weight:500}
.h2{font-size:clamp(1.7rem,3.6vw,2.7rem);letter-spacing:-.025em}
.lede{margin-top:1rem;color:var(--ink-soft);font-size:clamp(1rem,1.4vw,1.12rem);max-width:var(--measure)}

/* the "mark" = highlighter swipe, not a colored word (avoids the 1-word-accent tell) */
.mark{background:linear-gradient(var(--spark),var(--spark)) left bottom / 100% .5em no-repeat;padding:0 .08em;border-radius:1px;color:var(--ink)}

/* ============================================================
   HERO (index) — the CSS "build canvas", replaces poster image
   ============================================================ */
.hero{position:relative;overflow:hidden;padding-block:clamp(3.5rem,9vw,7rem) clamp(3rem,7vw,5.5rem);border-bottom:1px solid var(--line)}
.hero-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);gap:clamp(2rem,5vw,4.5rem);align-items:center}

.prompt{
  font-family:var(--mono);font-size:clamp(.8rem,1.1vw,.95rem);color:var(--green-deep);
  display:inline-flex;align-items:center;gap:.1rem;margin-bottom:1.4rem;
  background:var(--card);border:1px solid var(--line-strong);border-radius:4px;padding:.4rem .7rem;
}
.prompt .dim{color:var(--ink-soft)}
.caret{display:inline-block;width:.55ch;height:1.05em;background:var(--green);margin-left:.15rem;transform:translateY(2px);animation:blink 1.05s steps(1) infinite}
@keyframes blink{50%{opacity:0}}

.hero h1{font-size:clamp(3.1rem,9vw,6rem);letter-spacing:-.04em;line-height:.94}
.hero h1 .cn{display:block}
.hero h1 .en{display:block;font-family:var(--mono);font-weight:500;font-size:clamp(.9rem,2vw,1.2rem);letter-spacing:.2em;color:var(--green);margin-top:1rem}
.hero-sub{margin-top:1.6rem;max-width:34rem;color:var(--ink-soft);font-size:clamp(1rem,1.4vw,1.15rem)}
.hero-sub strong{color:var(--ink)}
.hero-cta{display:flex;flex-wrap:wrap;gap:.8rem;margin-top:2rem}
.hero-note{margin-top:1.5rem;font-family:var(--mono);font-size:.76rem;color:var(--ink-soft);letter-spacing:.01em}

/* the build-canvas panel: a big "+" registration mark drawn in CSS */
.hero-visual{position:relative}
.poster-frame{
  position:relative;aspect-ratio:4/5;border:1.5px solid var(--ink);border-radius:6px;
  background:var(--card);
  background-image:
    linear-gradient(var(--line) 1px,transparent 1px),
    linear-gradient(90deg,var(--line) 1px,transparent 1px);
  background-size:calc(var(--unit)*3) calc(var(--unit)*3);
  box-shadow:6px 6px 0 var(--shadow);overflow:hidden;
  display:grid;place-items:center;
}
/* if a real poster/image is dropped in, let it fill the frame */
.poster-frame img{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
/* the giant plus crosshair */
.poster-frame::before{
  content:"";position:absolute;left:50%;top:50%;width:56%;height:56%;transform:translate(-50%,-50%);
  background:
    linear-gradient(var(--green),var(--green)) center/100% 3px no-repeat,
    linear-gradient(var(--green),var(--green)) center/3px 100% no-repeat;
}
.poster-frame::after{
  content:"AI+";position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);
  font-family:var(--display);font-weight:700;font-size:clamp(3rem,7vw,5rem);letter-spacing:-.04em;
  color:var(--ink);background:var(--card);padding:.1em .25em;
}
.hero-visual .corner{position:absolute;font-family:var(--mono);font-size:.66rem;color:var(--ink-soft);z-index:2}
.hero-visual .corner.tl{top:.7rem;left:.8rem}
.hero-visual .corner.br{bottom:.7rem;right:.8rem;color:var(--green-deep)}

.scroll-cue{position:absolute;left:var(--gutter);bottom:1.2rem;font-family:var(--mono);font-size:.66rem;letter-spacing:.3em;color:var(--ink-soft);writing-mode:vertical-rl;opacity:.7}
.hero-silhouette{display:none} /* drop the poster's silhouette — it's a poster device */

/* ============================================================
   toolbox
   ============================================================ */
.tools-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;background:var(--line);border:1px solid var(--line);border-radius:6px;overflow:hidden}
.tool-chip{display:flex;align-items:center;gap:.85rem;padding:1.15rem 1.1rem;background:var(--card);transition:background .15s ease}
.tool-chip:hover{background:var(--green-wash)}
.tool-icon{flex:0 0 auto;width:38px;height:38px;border-radius:8px;display:grid;place-items:center;background:var(--paper-2);border:1px solid var(--line);overflow:hidden}
.tool-icon img{width:24px;height:24px;object-fit:contain}
.tool-chip b{font-family:var(--display);font-size:1rem;display:block;letter-spacing:-.01em}
.tool-chip span{font-family:var(--mono);font-size:.64rem;letter-spacing:.08em;color:var(--ink-soft)}

/* ============================================================
   vision
   ============================================================ */
.vision{text-align:left}
.vision-line{font-family:var(--display);font-weight:700;font-size:clamp(1.9rem,5.5vw,4rem);letter-spacing:-.035em;line-height:1.05;max-width:20ch}
.vision-line .num{color:var(--green)}
.vision-arrow{display:inline-flex;align-items:center;gap:1rem;margin-top:2rem;font-family:var(--mono);font-size:clamp(.85rem,1.4vw,1.05rem);border:1px solid var(--line-strong);border-radius:40px;padding:.5rem 1.2rem;background:var(--card)}
.vision-arrow .glyph{color:var(--green);font-size:1.3em}
.vision-arrow span:last-child{color:var(--green-deep);font-weight:500}

/* ============================================================
   camp band (index promo)
   ============================================================ */
.camp-band{display:flex;align-items:center;justify-content:space-between;gap:2rem;flex-wrap:wrap;
  background:var(--ink);color:var(--paper);border-radius:8px;padding:clamp(1.6rem,3.5vw,2.4rem);position:relative;overflow:hidden}
.camp-band::before{content:"+";position:absolute;right:-1rem;bottom:-3rem;font-family:var(--display);font-weight:700;font-size:14rem;color:rgba(255,255,255,.05);line-height:1}
.camp-band h3{font-size:clamp(1.15rem,2.2vw,1.55rem);margin:.7rem 0;max-width:30ch;position:relative}
.camp-band p{color:var(--band-fg);max-width:44ch;position:relative}
.camp-tag{display:inline-flex;align-items:center;gap:.5rem;font-family:var(--mono);font-size:.72rem;letter-spacing:.06em;color:var(--band-accent)}
.camp-tag .dot{width:7px;height:7px;border-radius:50%;background:var(--spark);box-shadow:0 0 0 0 var(--spark);animation:pulse 2s infinite}
@keyframes pulse{0%{box-shadow:0 0 0 0 rgba(215,237,69,.5)}70%{box-shadow:0 0 0 8px rgba(215,237,69,0)}100%{box-shadow:0 0 0 0 rgba(215,237,69,0)}}
.camp-band .btn-primary{--btn-bg:var(--spark);--btn-fg:#16191A;border-color:var(--spark);position:relative}
.camp-band .btn-primary:hover{box-shadow:4px 4px 0 rgba(0,0,0,.4)}

/* ============================================================
   join band (index footer cta)
   ============================================================ */
.join-band{background:var(--paper-2);border-top:1px solid var(--line)}
.join-band h2{font-size:clamp(1.7rem,4vw,2.8rem);letter-spacing:-.03em;max-width:18ch}
.join-band .sub{margin-top:1rem;color:var(--ink-soft);max-width:var(--measure)}
.join-meta{display:flex;align-items:center;gap:1.4rem;flex-wrap:wrap;margin-top:2rem}
.qq-chip{display:flex;align-items:center;gap:.6rem;font-family:var(--mono);border:1px dashed var(--line-strong);border-radius:6px;padding:.6rem 1rem;background:var(--card)}
.qq-label{font-size:.68rem;color:var(--ink-soft);letter-spacing:.05em}
.qq-num{font-size:1.05rem;font-weight:500;color:var(--green-deep);letter-spacing:.04em}
.qq-qr img{width:88px;height:88px;border:1px solid var(--line-strong);border-radius:6px;background:#fff;padding:5px}

/* ============================================================
   To Be Continued
   ============================================================ */
/* light graph-paper stage so the black hand-drawn arrow reads (manga-style) */
.tbc{padding-block:clamp(4rem,9vw,7rem);background:var(--paper-2);position:relative;overflow:hidden;border-top:1px solid var(--line)}
.tbc-stage{display:flex;flex-direction:column;align-items:flex-end;gap:1.4rem;text-align:right}
/* clip window: arrow flies in from the right, JOJO "slam" */
.tbc-frame{width:100%;overflow:hidden;display:flex;justify-content:flex-end;padding-block:.5rem}
.tbc-asset{
  max-width:min(560px,86vw);height:auto;
  opacity:0;transform:translateX(160%) rotate(-9deg) scale(1.12);
  will-change:transform,opacity;
}
.tbc-asset.in{animation:tbcSlam .9s cubic-bezier(.16,.9,.3,1) forwards}
@keyframes tbcSlam{
  0%{opacity:0;transform:translateX(160%) rotate(-9deg) scale(1.12)}
  55%{opacity:1;transform:translateX(-5%) rotate(-5deg) scale(1)}
  74%{transform:translateX(3%) rotate(-5deg)}
  88%{transform:translateX(-1.5%) rotate(-5deg)}
  100%{opacity:1;transform:translateX(0) rotate(-5deg)}
}
/* one-shot flash line that sweeps as it lands — the "定格" beat */
.tbc-frame::after{
  content:"";position:absolute;inset:0;pointer-events:none;
  background:linear-gradient(105deg,transparent 40%,rgba(255,255,255,.55) 50%,transparent 60%);
  transform:translateX(-160%);opacity:0;
}
.tbc-stage.in .tbc-frame::after{animation:tbcFlash .6s ease .42s 1}
@keyframes tbcFlash{0%{opacity:0;transform:translateX(-160%)}30%{opacity:1}100%{opacity:0;transform:translateX(160%)}}
/* fallback text mark if the asset ever fails to load */
.tbc-fallback{font-family:var(--display);font-weight:700;font-style:italic;font-size:clamp(1.8rem,6vw,3.6rem);letter-spacing:-.03em;color:var(--ink)}
.tbc-caption{font-family:var(--mono);font-size:.82rem;color:var(--ink-soft)}
.tbc-caption em{color:var(--green-deep);font-style:normal;font-weight:500}

/* ============================================================
   footer
   ============================================================ */
.site-footer{border-top:1px solid var(--line);background:var(--paper)}
.footer-inner{display:flex;justify-content:space-between;align-items:center;gap:1rem;flex-wrap:wrap;padding-block:1.6rem;font-size:.82rem;color:var(--ink-soft)}
.footer-inner .mono{font-family:var(--mono);letter-spacing:.12em;color:var(--green-deep)}

/* ============================================================
   JOIN PAGE
   ============================================================ */
.page-hero{padding-block:clamp(3rem,7vw,5rem) clamp(2rem,4vw,3rem);border-bottom:1px solid var(--line)}
.page-hero h1{font-size:clamp(2.6rem,7vw,4.6rem);letter-spacing:-.04em;line-height:.98}
.page-hero h1 .en{display:block;font-family:var(--mono);font-weight:500;font-size:clamp(.8rem,1.6vw,1rem);letter-spacing:.22em;color:var(--green);margin-top:.9rem}
.page-hero .lede{margin-top:1.4rem}

/* you-are quiz list */
.quiz-list{list-style:none;margin:0;padding:0;display:grid;gap:1px;background:var(--line);border:1px solid var(--line);border-radius:6px;overflow:hidden}
.quiz-item{display:flex;gap:1rem;align-items:flex-start;padding:1.15rem 1.2rem;background:var(--card);transition:background .15s ease}
.quiz-item:hover{background:var(--green-wash)}
.quiz-check{flex:0 0 auto;width:26px;height:26px;border-radius:5px;background:var(--paper-2);border:1px solid var(--line-strong);display:grid;place-items:center;color:var(--green);transition:.15s ease}
.quiz-item:hover .quiz-check{background:var(--green);color:var(--on-green);border-color:var(--green)}
.quiz-check svg{width:16px;height:16px}
.quiz-item b{color:var(--ink)}
.quiz-item div{color:var(--ink-soft)}

/* we-offer rail */
.offer-rail{display:grid;grid-template-columns:repeat(4,1fr);gap:1.1rem}
.offer-item{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:1.4rem 1.25rem;position:relative;transition:border-color .15s ease}
.offer-item::before{content:"+";position:absolute;top:.7rem;right:.85rem;font-family:var(--mono);color:var(--green);opacity:.5}
.offer-item:hover{border-color:var(--green)}
.offer-item h3{font-size:1.15rem;margin-bottom:.5rem}
.offer-item p{color:var(--ink-soft);font-size:.92rem}

/* camp detail */
.camp-detail{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);gap:clamp(1.5rem,4vw,3rem);align-items:start}
.camp-copy h3{font-size:1.25rem;margin-bottom:1.1rem}
.check-list{list-style:none;margin:0;padding:0;display:grid;gap:1rem}
.check-list li{display:flex;gap:.8rem;align-items:flex-start}
.check-list .tick{flex:0 0 auto;width:24px;height:24px;border-radius:6px;background:var(--green-wash);color:var(--green-deep);display:grid;place-items:center;margin-top:1px}
.check-list .tick svg{width:15px;height:15px}
.camp-facts{display:grid;gap:1px;background:var(--line);border:1px solid var(--line);border-radius:8px;overflow:hidden}
.fact{background:var(--card);padding:1.2rem 1.25rem}
.fact-label{font-family:var(--mono);font-size:.7rem;letter-spacing:.06em;color:var(--green-deep);display:block;margin-bottom:.4rem}
.fact p{color:var(--ink-soft);font-size:.92rem}
.fact--highlight{background:var(--ink);color:var(--paper)}
.fact--highlight .fact-label{color:var(--band-accent)}
.fact--highlight p{color:var(--band-fg)}

/* tracks — parallel options, so plus-coordinates not a numbered sequence */
.tracks{display:grid;grid-template-columns:repeat(3,1fr);gap:1.1rem}
.track{background:var(--card);border:1px solid var(--line);border-radius:8px;padding:1.5rem 1.35rem;position:relative;transition:transform .12s ease,box-shadow .12s ease}
.track:hover{transform:translate(-2px,-2px);box-shadow:5px 5px 0 var(--shadow)}
.track-no{font-family:var(--mono);font-size:.7rem;letter-spacing:.05em;color:var(--green);display:block;margin-bottom:.8rem}
.track h3{font-size:1.2rem;margin-bottom:.55rem}
.track p{color:var(--ink-soft);font-size:.9rem}

/* signup */
.steps{display:grid;grid-template-columns:repeat(4,1fr);gap:1px;background:var(--line);border:1px solid var(--line);border-radius:8px;overflow:hidden;counter-reset:step}
.step{background:var(--card);padding:1.3rem 1.2rem;position:relative;counter-increment:step}
.step::before{content:counter(step,decimal-leading-zero);font-family:var(--mono);font-size:.72rem;color:var(--green);display:block;margin-bottom:.6rem}
.step h3{font-size:1.05rem;margin-bottom:.4rem}
.step p{color:var(--ink-soft);font-size:.88rem}
.step .qq{font-family:var(--mono);color:var(--green-deep);font-weight:500}

.signup-wrap{display:grid;grid-template-columns:minmax(0,1.3fr) minmax(0,.7fr);gap:clamp(1.5rem,3.5vw,2.6rem);align-items:start}
.form-card{background:var(--card);border:1.5px solid var(--ink);border-radius:8px;padding:clamp(1.4rem,3vw,2rem);box-shadow:5px 5px 0 var(--shadow)}
.form-row{display:grid;grid-template-columns:1fr 1fr;gap:1rem}
.field{margin-bottom:1.05rem;display:flex;flex-direction:column;gap:.4rem}
.field label{font-size:.85rem;font-weight:500;color:var(--ink)}
.field .req{color:var(--green)}
.field input,.field select,.field textarea{
  font-family:var(--body);font-size:.95rem;color:var(--ink);
  background:var(--paper);border:1px solid var(--line-strong);border-radius:5px;padding:.65rem .75rem;width:100%;
  transition:border-color .15s ease,box-shadow .15s ease;
}
.field textarea{min-height:84px;resize:vertical}
.field input:focus,.field select:focus,.field textarea:focus{outline:none;border-color:var(--green);box-shadow:0 0 0 3px var(--green-wash)}
.field input::placeholder,.field textarea::placeholder{color:#9AA093}
.form-card .btn{width:100%;justify-content:center;margin-top:.4rem}
.form-note{margin-top:.9rem;font-family:var(--mono);font-size:.7rem;color:var(--ink-soft);line-height:1.5}

.form-success{display:none;background:var(--card);border:1.5px solid var(--green);border-radius:8px;padding:clamp(1.6rem,3vw,2.2rem);text-align:center;box-shadow:5px 5px 0 var(--green)}
.form-success.show{display:block}
.form-success .ok-icon{width:52px;height:52px;border-radius:50%;background:var(--green);color:var(--on-green);display:grid;place-items:center;margin:0 auto 1rem}
.form-success .ok-icon svg{width:28px;height:28px}
.form-success h3{font-size:1.3rem;margin-bottom:.6rem}
.form-success p{color:var(--ink-soft)}
.form-success .qq{font-family:var(--mono);color:var(--green-deep);font-weight:500}

.signup-side{display:grid;gap:1rem}
.side-note{background:var(--paper-2);border:1px solid var(--line);border-left:3px solid var(--green);border-radius:0 6px 6px 0;padding:1.1rem 1.2rem}
.side-note h4{font-size:.98rem;margin-bottom:.45rem}
.side-note p{color:var(--ink-soft);font-size:.88rem}

/* qq block */
.qq-block{display:flex;align-items:center;justify-content:space-between;gap:2.5rem;flex-wrap:wrap;background:var(--ink);color:var(--paper);border-radius:10px;padding:clamp(1.8rem,4vw,2.8rem);position:relative;overflow:hidden}
.qq-block::before{content:"";position:absolute;inset:0;background-image:linear-gradient(rgba(255,255,255,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.04) 1px,transparent 1px);background-size:24px 24px}
.qq-block > *{position:relative}
.qq-block h3{font-size:clamp(1.3rem,2.5vw,1.8rem);margin-bottom:.7rem}
.qq-block .sub{color:var(--band-fg);max-width:40ch}
.qq-big{margin-top:1.4rem}
.qq-big .label{display:block;font-family:var(--mono);font-size:.72rem;letter-spacing:.08em;color:var(--spark);margin-bottom:.2rem}
.qq-big .num{font-family:var(--mono);font-weight:500;font-size:clamp(1.8rem,4vw,2.6rem);letter-spacing:.06em;color:var(--paper)}
.qq-block .hint{margin-top:.6rem;font-size:.8rem;color:var(--band-soft)}
.qq-qr-large img{width:150px;height:150px;background:#fff;border-radius:10px;padding:8px}

/* ============================================================
   MNIST 手写数字识别 (join page)
   ============================================================ */
.mnist-wrap{display:grid;grid-template-columns:minmax(0,320px) minmax(0,1fr);gap:clamp(1.5rem,3.5vw,2.6rem);align-items:start}
.mnist-board{background:#fff;border:1.5px solid var(--ink);border-radius:8px;box-shadow:5px 5px 0 var(--shadow);padding:10px}
#mnistCanvas{width:100%;height:auto;display:block;border:1px solid var(--line-strong);border-radius:4px;background:#fff;cursor:crosshair;touch-action:none}
.mnist-hint{display:block;font-family:var(--mono);font-size:.66rem;color:var(--ink-soft);padding:.7rem .2rem .15rem}
.mnist-side{display:flex;flex-direction:column;gap:1.1rem}
.mnist-actions{display:flex;flex-wrap:wrap;gap:.6rem}
.mnist-result{background:var(--card);border:1px solid var(--line-strong);border-radius:8px;padding:1rem 1.1rem}
.mnist-topline{display:flex;align-items:baseline;gap:.6rem;font-size:.95rem;color:var(--ink-soft)}
.mnist-digit{font-family:var(--display);font-weight:700;font-size:3rem;line-height:1;color:var(--green);letter-spacing:-.03em}
.mnist-conf{font-family:var(--mono);font-size:.75rem;color:var(--green-deep)}
.mnist-bars{list-style:none;margin:.9rem 0 0;padding:0;display:grid;gap:.35rem}
.mnist-bars li{display:grid;grid-template-columns:2.2ch 1fr 4ch;align-items:center;gap:.55rem;font-family:var(--mono);font-size:.72rem;color:var(--ink-soft)}
.mnist-bars .track{position:relative;display:block;height:9px;background:var(--paper-2);border:1px solid var(--line);border-radius:2px;overflow:hidden}
.mnist-bars .fill{position:absolute;left:0;top:0;bottom:0;display:block;background:var(--green);width:0;transition:width .45s cubic-bezier(.2,.7,.2,1)}
.mnist-bars .pct{text-align:right}
.mnist-bars li.top{color:var(--ink);font-weight:500}
.mnist-bars li.top .fill{background:var(--green-deep)}
.mnist-note{font-family:var(--mono);font-size:.68rem;color:var(--ink-soft);line-height:1.6;max-width:46ch}
.assistant-card{max-width:640px;margin-inline:auto}

/* ============================================================
   reveal-on-scroll (one restrained motion)
   ============================================================ */
.reveal{opacity:0;transform:translateY(14px);transition:opacity .5s ease,transform .5s ease;transition-delay:var(--d,0s)}
.reveal.in{opacity:1;transform:none}

/* ============================================================
   responsive
   ============================================================ */
@media (max-width:900px){
  .hero-grid{grid-template-columns:1fr}
  .hero-visual{max-width:340px}
  .tools-grid{grid-template-columns:repeat(2,1fr)}
  .offer-rail,.tracks,.steps{grid-template-columns:repeat(2,1fr)}
  .camp-detail,.signup-wrap{grid-template-columns:1fr}
  .mnist-wrap{grid-template-columns:1fr;max-width:340px}
  .scroll-cue{display:none}
}
@media (max-width:620px){
  .nav{position:fixed;inset:66px 0 auto 0;flex-direction:column;align-items:stretch;gap:0;
    background:var(--paper);border-bottom:1px solid var(--line-strong);padding:.5rem var(--gutter) 1rem;
    transform:translateY(-140%);transition:transform .25s ease;box-shadow:0 12px 24px rgba(0,0,0,.06)}
  .nav.open{transform:translateY(0)}
  .nav > a:not(.btn){padding:.85rem 0;border-bottom:1px solid var(--line)}
  .nav > a.active::after{display:none}
  .nav .btn{margin-top:.8rem}
  .nav-toggle{display:flex}
  .tools-grid,.offer-rail,.tracks,.steps,.form-row{grid-template-columns:1fr}
  .camp-band{flex-direction:column;align-items:flex-start}
  .tbc-stage{align-items:flex-start;text-align:left}
}

@media (prefers-reduced-motion:reduce){
  *{animation-duration:.001ms !important;animation-iteration-count:1 !important;transition-duration:.001ms !important}
  .reveal{opacity:1;transform:none}
  .caret{animation:none}
}

/* ============================================================
   招新小助手 chatbot demo (join page)
   ============================================================ */
.chat-card{
  display:flex;flex-direction:column;
  background:var(--card);border:1.5px solid var(--ink);border-radius:12px;
  box-shadow:5px 5px 0 var(--shadow);overflow:hidden;min-height:420px;
}
.chat-head{display:flex;align-items:center;gap:.7rem;padding:.85rem 1rem;background:var(--ink);color:var(--paper)}
.chat-avatar{flex:0 0 auto;width:34px;height:34px;border-radius:9px;background:var(--green);color:var(--on-green);
  font-family:var(--display);font-weight:700;font-size:1.2rem;display:grid;place-items:center;line-height:1}
.chat-who{display:flex;flex-direction:column;line-height:1.25}
.chat-who b{font-family:var(--display);font-size:.98rem}
.chat-status{font-family:var(--mono);font-size:.66rem;color:var(--band-fg);display:flex;align-items:center;gap:.35rem}
.chat-status i{width:6px;height:6px;border-radius:50%;background:var(--spark);box-shadow:0 0 0 0 var(--spark);animation:pulse 2s infinite}
.chat-badge{margin-left:auto;font-family:var(--mono);font-size:.6rem;letter-spacing:.1em;color:#16191A;
  background:var(--spark);padding:.2rem .45rem;border-radius:4px}

.chat-log{flex:1;overflow-y:auto;padding:1.1rem 1rem;display:flex;flex-direction:column;gap:.7rem;
  background-image:linear-gradient(var(--line) 1px,transparent 1px),linear-gradient(90deg,var(--line) 1px,transparent 1px);
  background-size:24px 24px;background-color:var(--paper);max-height:400px;scroll-behavior:smooth}
.msg{max-width:82%;padding:.6rem .8rem;border-radius:12px;font-size:.92rem;line-height:1.55;white-space:pre-wrap;word-break:break-word;animation:msgIn .28s ease}
@keyframes msgIn{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
.msg.bot{align-self:flex-start;background:var(--card);border:1px solid var(--line-strong);border-bottom-left-radius:3px;color:var(--ink)}
.msg.user{align-self:flex-end;background:var(--green);color:var(--on-green);border-bottom-right-radius:3px}
.msg a{color:var(--green-deep);text-decoration:underline;font-weight:500}
.msg.user a{color:var(--on-green)}
.msg .qq{font-family:var(--mono);font-weight:500}
/* typing indicator */
.msg.typing{display:inline-flex;gap:.28rem;align-items:center}
.msg.typing span{width:7px;height:7px;border-radius:50%;background:var(--ink-soft);opacity:.5;animation:typing 1s infinite}
.msg.typing span:nth-child(2){animation-delay:.15s}
.msg.typing span:nth-child(3){animation-delay:.3s}
@keyframes typing{0%,60%,100%{transform:translateY(0);opacity:.4}30%{transform:translateY(-4px);opacity:1}}

.chat-quick{display:flex;flex-wrap:wrap;gap:.45rem;padding:.7rem 1rem 0}
.chat-quick button{font-family:var(--body);font-size:.8rem;color:var(--green-deep);
  background:var(--green-wash);border:1px solid transparent;border-radius:20px;padding:.35rem .75rem;cursor:pointer;
  transition:background .15s ease,border-color .15s ease}
.chat-quick button:hover{background:#fff;border-color:var(--green)}

.chat-input{display:flex;gap:.55rem;padding:.8rem 1rem 1rem}
.chat-input input{flex:1;font-family:var(--body);font-size:.92rem;color:var(--ink);
  background:var(--paper);border:1px solid var(--line-strong);border-radius:22px;padding:.6rem .95rem;transition:border-color .15s,box-shadow .15s}
.chat-input input:focus{outline:none;border-color:var(--green);box-shadow:0 0 0 3px var(--green-wash)}
.chat-send{flex:0 0 auto;width:42px;height:42px;border-radius:50%;border:none;background:var(--green);color:var(--on-green);cursor:pointer;display:grid;place-items:center;transition:transform .12s,background .15s}
.chat-send:hover{transform:translateY(-2px);background:var(--green-deep)}
.chat-send svg{width:20px;height:20px}
.chat-note{padding:0 1rem 1rem;font-family:var(--mono);font-size:.68rem;color:var(--ink-soft);line-height:1.5}

/* ============================================================
   现场 · 照片墙 (index) — polaroids taped into the notebook
   ============================================================ */
.photo-sheet{display:grid;grid-template-columns:repeat(4,1fr);gap:clamp(1rem,2.6vw,1.9rem);padding-top:.4rem}
.photo{
  margin:0;background:#fff;padding:10px 10px 0;border:1px solid var(--line-strong);border-radius:2px;
  box-shadow:4px 6px 0 var(--shadow-soft);
  transform:rotate(var(--rot,0deg));
  transition:transform .2s cubic-bezier(.2,.7,.2,1),box-shadow .2s ease;
}
.photo:hover,.photo:focus-within{transform:rotate(0deg) translateY(-5px);box-shadow:7px 10px 0 var(--shadow-soft-hover);z-index:2}
.photo-img{aspect-ratio:4/3;overflow:hidden;background:var(--paper-2)}
.photo-img img{width:100%;height:100%;object-fit:cover;display:block}
.photo figcaption{font-family:var(--mono);font-size:.7rem;line-height:1.45;color:var(--ink-soft);padding:.7rem .25rem .85rem}
@media (max-width:900px){.photo-sheet{grid-template-columns:repeat(2,1fr)}}
@media (max-width:520px){.photo-sheet{grid-template-columns:1fr 1fr;gap:.9rem}.photo figcaption{font-size:.62rem}}

/* ============================================================
   黑夜模式
   ============================================================ */
.theme-toggle{
  display:flex;align-items:center;justify-content:center;
  width:38px;height:38px;border:1px solid var(--line-strong);border-radius:4px;
  background:none;color:var(--ink);cursor:pointer;
  transition:background .15s ease,color .15s ease,border-color .15s ease;
}
.theme-toggle:hover{background:var(--green-wash);color:var(--green-deep);border-color:var(--green)}
.theme-toggle svg{width:18px;height:18px}
.theme-toggle .icon-sun{display:none}
:root[data-theme="dark"] .theme-toggle .icon-moon{display:none}
:root[data-theme="dark"] .theme-toggle .icon-sun{display:block}

:root[data-theme="dark"]{
  --paper:#12171A;
  --paper-2:#0E1214;
  --card:#1A2124;
  --ink:#E8EEE9;
  --ink-soft:#A7B2AC;
  --line:#262E31;
  --line-strong:#3A4448;
  --green:#34C98F;
  --green-deep:#5FE3A8;
  --green-wash:rgba(52,201,143,.14);
  --shadow:rgba(0,0,0,.8);
  --shadow-soft:rgba(0,0,0,.45);
  --shadow-soft-hover:rgba(0,0,0,.62);
  --band-fg:rgba(22,25,26,.72);
  --band-soft:rgba(22,25,26,.55);
  --band-accent:var(--green-deep);
  --on-green:#052B1C;
}
/* 漫画收尾保持纸张色,黑线箭头才看得见 */
:root[data-theme="dark"] .tbc{background:#F4F4EC;color:#16191A}
:root[data-theme="dark"] .tbc-caption{color:#585E54}
:root[data-theme="dark"] .tbc-caption em{color:#075A37}
:root[data-theme="dark"] .tbc-fallback{color:#16191A}
:root[data-theme="dark"] .brand-logo{border:1px solid var(--line-strong)}