*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
@media (prefers-reduced-motion:no-preference){html{scroll-behavior:smooth}}
body,h1,h2,h3,h4,h5,p,ul,ol,dl,dt,dd,figure,blockquote{margin:0}
ul,ol{list-style:none;padding:0}
img,svg{display:block;max-width:100%;height:auto}
button{font:inherit;color:inherit;background:none;border:0;padding:0}
a{color:inherit;text-decoration:none}
table{border-collapse:collapse;width:100%}

:root{
  --paper:#F7F1E3;
  --paper-raised:#FDFBF6;
  --lake:#1E6F8C;
  --lake-deep:#155368;
  --teal:#1C9A8B;
  --teal-deep:#137065;
  --ink:#17313A;
  --ink-deep:#0F232A;
  --ink-soft:#4C6570;
  --coral:#E5674D;
  --coral-deep:#B83B27;
  --violet:#5B4BC4;
  --mist:#CFE7E3;
  --line:#D9C9A8;
  --ink-line:rgba(23,49,58,.14);
  --on-ink:rgba(253,251,246,.8);
  --on-ink-dim:rgba(207,231,227,.7);
  --font-display:"Noto Sans SC","Source Han Sans SC","PingFang SC","Microsoft YaHei",sans-serif;
  --font-body:"Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --font-serif:"Noto Serif SC","Songti SC",STSong,serif;
  --font-mono:"IBM Plex Mono",SFMono-Regular,Consolas,"Courier New",monospace;
  --radius:2px;
  --shadow-paper:5px 5px 0 rgba(217,201,168,.55);
  --shadow-lift:7px 9px 0 rgba(30,111,140,.18);
  --shell:1240px;
  --gutter:clamp(16px,4vw,48px);
}

body{
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.7;
  color:var(--ink);
  background:var(--paper);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
h1,h2,h3,h4,h5{font-family:var(--font-display);font-weight:800;line-height:1.18;letter-spacing:-.02em;color:var(--ink)}
strong{font-weight:700}
::selection{background:var(--mist);color:var(--ink)}
:focus-visible{outline:2px solid var(--coral);outline-offset:3px}

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

.skip-link{
  position:absolute;left:1rem;top:-120px;z-index:200;
  padding:.7rem 1.1rem;background:var(--ink);color:var(--paper-raised);
  font-weight:700;font-size:.9rem;border:2px solid var(--coral);border-radius:var(--radius);
  transition:top .2s ease;
}
.skip-link:focus{top:.6rem}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:60;
  background:var(--paper-raised);
  border-bottom:1px solid var(--line);
  box-shadow:0 1px 0 rgba(217,201,168,.85);
}
.site-header__progress{
  position:absolute;left:0;right:0;top:0;height:3px;
  background:rgba(23,49,58,.12);z-index:2;
}
.site-header__progress-bar{
  display:block;height:100%;width:0;
  background:linear-gradient(90deg,var(--teal),var(--lake) 55%,var(--coral));
  transition:width .12s linear;
}
.site-header__utility{background:var(--ink);color:var(--on-ink)}
.site-header__utility-inner{
  display:flex;align-items:center;gap:clamp(10px,2vw,26px);
  min-height:38px;padding-block:.4rem;flex-wrap:wrap;
}
.site-header__utility-label{
  font-family:var(--font-mono);font-size:.66rem;letter-spacing:.2em;
  text-transform:uppercase;color:var(--mist);white-space:nowrap;
}
.utility-nav{display:block}
.utility-nav__list{display:flex;align-items:center;gap:clamp(10px,1.8vw,24px);flex-wrap:wrap}
.utility-nav__item{display:flex;align-items:center}
.utility-nav__link{
  position:relative;font-size:.78rem;color:var(--on-ink);padding-block:.15rem;
  letter-spacing:.02em;
}
.utility-nav__link::after{
  content:"";position:absolute;left:0;bottom:0;height:1px;width:0;
  background:var(--teal);transition:width .2s ease;
}
.utility-nav__link:hover{color:var(--paper-raised)}
.utility-nav__link:hover::after{width:100%}
.utility-cta{
  margin-left:auto;display:inline-flex;align-items:center;
  padding:.32rem .85rem;background:var(--coral);color:var(--ink);
  font-family:var(--font-display);font-weight:800;font-size:.76rem;letter-spacing:.02em;
  border-radius:var(--radius);white-space:nowrap;
  transition:background-color .18s ease,transform .18s ease;
}
.utility-cta:hover{background:#F0846C;transform:translateY(-1px)}

.site-header__main{background:var(--paper-raised)}
.site-header__main-inner{
  display:flex;align-items:center;flex-wrap:wrap;
  gap:clamp(14px,3vw,40px);padding-block:clamp(10px,1.3vw,18px);
}
.brand{display:flex;flex-direction:column;gap:.2rem;min-width:0}
.brand__mark{
  font-family:var(--font-display);font-weight:900;
  font-size:clamp(1.5rem,2.4vw,2rem);line-height:1;letter-spacing:.1em;
  color:var(--ink);border-left:4px solid var(--coral);padding-left:.45rem;
}
.brand__tagline{
  font-family:var(--font-serif);font-size:.72rem;letter-spacing:.14em;
  color:var(--ink-soft);
}
.nav-toggle{
  display:none;margin-left:auto;align-items:center;gap:.5rem;
  padding:.5rem .7rem;border:1px solid var(--line);background:var(--paper);
  font-family:var(--font-mono);font-size:.74rem;letter-spacing:.08em;color:var(--ink);
  border-radius:var(--radius);cursor:pointer;
  transition:border-color .18s ease,background-color .18s ease;
}
.nav-toggle:hover{border-color:var(--ink);background:var(--mist)}
.nav-toggle__bars{display:inline-flex;flex-direction:column;justify-content:center;gap:3px;width:16px}
.nav-toggle__bars span{display:block;height:2px;width:100%;background:var(--ink);transition:transform .2s ease,opacity .2s ease}
.nav-toggle__text{font-weight:700}
.primary-nav{margin-left:auto}
.primary-nav__list{display:flex;align-items:center;gap:clamp(6px,1.7vw,26px);flex-wrap:wrap}
.primary-nav__item{display:flex}
.primary-nav__link{
  position:relative;display:inline-flex;align-items:baseline;gap:.4rem;
  padding:.45rem .1rem;font-family:var(--font-display);font-weight:700;
  font-size:.95rem;color:var(--ink);white-space:nowrap;
}
.primary-nav__link::after{
  content:"";position:absolute;left:0;bottom:0;height:2px;width:0;
  background:var(--coral);transition:width .22s ease;
}
.primary-nav__link:hover::after,
.primary-nav__link:focus-visible::after{width:100%}
.primary-nav__num{
  font-family:var(--font-mono);font-size:.64rem;font-weight:500;
  color:var(--violet);letter-spacing:.04em;transform:translateY(-.3em);
}
.primary-nav__link[aria-current="page"]{color:var(--lake)}
.primary-nav__link[aria-current="page"]::after{width:100%;background:var(--lake)}
.primary-nav__meta{
  display:none;font-family:var(--font-mono);font-size:.7rem;
  letter-spacing:.1em;color:var(--ink-soft);
}

/* ---------- footer ---------- */
.site-footer{background:var(--ink);color:var(--on-ink)}
.site-footer__top{
  display:grid;gap:clamp(28px,4vw,56px);
  grid-template-columns:minmax(0,1.15fr) minmax(0,1.5fr) minmax(0,1fr);
  padding-block:clamp(36px,5vw,64px);
  border-top:4px solid var(--teal);
}
.site-footer__brand{min-width:0}
.site-footer .brand__mark{color:var(--paper-raised);border-left-color:var(--coral)}
.site-footer .brand__tagline{color:var(--on-ink-dim)}
.site-footer__summary{
  margin-top:1.1rem;max-width:34ch;font-size:.94rem;line-height:1.75;
  color:var(--on-ink);
}
.site-footer__cta{margin-top:1.3rem}
.footer-nav{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:clamp(18px,3vw,40px)}
.footer-nav__col{min-width:0}
.footer-nav__title{
  font-family:var(--font-mono);font-size:.68rem;font-weight:500;
  letter-spacing:.2em;text-transform:uppercase;color:var(--mist);
  margin-bottom:.9rem;
}
.footer-nav__list{display:grid;gap:.55rem}
.footer-nav__item{display:block}
.footer-nav__link{
  position:relative;display:inline-block;font-size:.92rem;color:var(--on-ink);
  padding-block:.1rem;
}
.footer-nav__link::after{
  content:"";position:absolute;left:0;bottom:0;height:1px;width:0;
  background:var(--coral);transition:width .2s ease;
}
.footer-nav__link:hover{color:var(--paper-raised)}
.footer-nav__link:hover::after{width:100%}
.site-footer__contact{min-width:0}
.contact-list{display:grid;gap:.7rem;font-size:.85rem}
.contact-list__row{display:grid;grid-template-columns:auto minmax(0,1fr);gap:.65rem;align-items:baseline}
.contact-list__term{
  font-family:var(--font-mono);font-size:.66rem;letter-spacing:.14em;
  color:var(--on-ink-dim);white-space:nowrap;
}
.contact-list__value{color:var(--paper-raised);word-break:break-word;line-height:1.6}
.site-footer__note{
  margin-top:1.1rem;padding-left:.8rem;border-left:2px solid var(--teal);
  font-size:.75rem;line-height:1.7;color:var(--on-ink-dim);
}
.site-footer__legal{background:var(--ink-deep);border-top:1px solid rgba(207,231,227,.16)}
.site-footer__legal-inner{
  display:flex;flex-wrap:wrap;align-items:center;gap:.6rem 1.5rem;
  padding-block:1.1rem;font-size:.75rem;color:var(--on-ink-dim);
}
.site-footer__copy{font-family:var(--font-mono);letter-spacing:.04em}
.legal-links{display:flex;flex-wrap:wrap;gap:.4rem 1.2rem;margin-left:auto}
.legal-links a{position:relative;color:var(--on-ink);padding-block:.1rem}
.legal-links a::after{
  content:"";position:absolute;left:0;bottom:0;height:1px;width:0;
  background:var(--coral);transition:width .2s ease;
}
.legal-links a:hover::after{width:100%}
.site-footer__icp{font-family:var(--font-mono);letter-spacing:.02em}

/* ---------- shared sections & grid ---------- */
.section{padding-block:clamp(44px,6.5vw,92px)}
.section--paper{background:var(--paper-raised)}
.section--mist{background:var(--mist)}
.section__head{display:grid;gap:.8rem;max-width:62ch;margin-bottom:clamp(24px,3vw,40px)}
.section__title{font-size:clamp(28px,3.6vw,44px)}
.section__lede{font-size:1.02rem;line-height:1.75;color:var(--ink-soft);max-width:56ch}
.section__foot{margin-top:clamp(24px,3vw,36px);display:flex;flex-wrap:wrap;gap:.75rem}

.grid{display:grid;gap:clamp(16px,2.2vw,28px);grid-template-columns:minmax(0,1fr)}
.grid--2,.grid--3,.grid--4{grid-template-columns:minmax(0,1fr)}
@media (min-width:640px){
  .grid--2,.grid--3,.grid--4{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (min-width:1000px){
  .grid--3{grid-template-columns:repeat(3,minmax(0,1fr))}
  .grid--4{grid-template-columns:repeat(4,minmax(0,1fr))}
}
@media (min-width:900px){
  .grid--stagger > :nth-child(even){margin-top:clamp(20px,3vw,48px)}
}

.eyebrow{
  display:inline-block;font-family:var(--font-mono);font-size:.7rem;
  letter-spacing:.22em;text-transform:uppercase;color:var(--violet);
}

/* ---------- cards ---------- */
.card{
  position:relative;display:flex;flex-direction:column;gap:.6rem;
  padding:clamp(18px,2vw,26px);background:var(--paper-raised);
  border:1px solid var(--line);box-shadow:var(--shadow-paper);
  transition:transform .18s ease,box-shadow .18s ease,border-color .18s ease;
}
.card:hover,.card:focus-within{
  transform:translateY(-3px);border-color:var(--lake);box-shadow:var(--shadow-lift);
}
.card__label{
  font-family:var(--font-mono);font-size:.7rem;letter-spacing:.16em;
  text-transform:uppercase;color:var(--violet);
}
.card__title{font-size:1.2rem;font-weight:800;line-height:1.3}
.card__text{font-size:.94rem;line-height:1.72;color:var(--ink-soft)}
.card__meta{
  display:flex;flex-wrap:wrap;gap:.4rem;margin-top:auto;padding-top:.7rem;
  border-top:1px dashed var(--line);font-family:var(--font-mono);
  font-size:.7rem;letter-spacing:.05em;color:var(--ink-soft);
}
.card--accent{border-left:4px solid var(--coral)}

/* ---------- figure / image containers ---------- */
.figure{margin:0;display:flex;flex-direction:column;gap:.6rem}
.figure__frame{
  position:relative;overflow:hidden;aspect-ratio:4/3;
  border:1px solid var(--line);background:var(--mist);
  box-shadow:6px 6px 0 rgba(217,201,168,.5);
}
.figure__frame--wide{aspect-ratio:16/9}
.figure__frame--square{aspect-ratio:1/1}
.figure__img{width:100%;height:100%;object-fit:cover;transition:transform .3s ease}
.figure:hover .figure__img{transform:scale(1.03)}
.figure__caption{
  font-family:var(--font-mono);font-size:.7rem;letter-spacing:.05em;
  color:var(--ink-soft);line-height:1.6;
}

/* ---------- tags ---------- */
.tag{
  display:inline-flex;align-items:center;gap:.35rem;
  padding:.24rem .6rem;font-family:var(--font-mono);font-size:.7rem;
  letter-spacing:.06em;border:1px solid var(--line);border-radius:var(--radius);
  background:var(--paper-raised);color:var(--ink);white-space:nowrap;
}
.tag--lake{color:var(--lake-deep);border-color:rgba(30,111,140,.42);background:rgba(30,111,140,.09)}
.tag--teal{color:var(--teal-deep);border-color:rgba(28,154,139,.42);background:rgba(28,154,139,.1)}
.tag--coral{color:var(--coral-deep);border-color:rgba(229,103,77,.45);background:rgba(229,103,77,.12)}
.tag--violet{color:var(--violet);border-color:rgba(91,75,196,.38);background:rgba(91,75,196,.1)}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:.5rem;
  padding:.78rem 1.35rem;border:1px solid transparent;border-radius:var(--radius);
  font-family:var(--font-display);font-weight:700;font-size:.94rem;line-height:1;
  cursor:pointer;transition:background-color .18s ease,color .18s ease,border-color .18s ease,transform .18s ease;
}
.btn--primary{background:var(--coral-deep);color:#fff;box-shadow:3px 3px 0 rgba(23,49,58,.2)}
.btn--primary:hover{background:#9C3120;transform:translateY(-2px)}
.btn--ghost{background:transparent;color:var(--ink);border-color:var(--ink)}
.btn--ghost:hover{background:var(--ink);color:var(--paper-raised)}
.btn--quiet{background:var(--mist);color:var(--ink);border-color:var(--mist)}
.btn--quiet:hover{background:var(--teal);border-color:var(--teal);color:var(--paper-raised)}
.btn--onink{background:transparent;color:var(--paper-raised);border-color:rgba(253,251,246,.45)}
.btn--onink:hover{background:var(--mist);border-color:var(--mist);color:var(--ink)}

/* ---------- breadcrumb ---------- */
.breadcrumb{padding-block:1rem 0}
.breadcrumb__list{
  display:flex;flex-wrap:wrap;align-items:center;gap:.45rem;
  font-family:var(--font-mono);font-size:.74rem;letter-spacing:.05em;color:var(--ink-soft);
}
.breadcrumb__item{display:inline-flex;align-items:center;gap:.45rem}
.breadcrumb__item + .breadcrumb__item::before{content:"/";color:var(--line)}
.breadcrumb__link{color:var(--lake);border-bottom:1px solid rgba(30,111,140,.35)}
.breadcrumb__link:hover{border-bottom-color:var(--coral);color:var(--coral-deep)}

/* ---------- step list (skill-tree path) ---------- */
.step-list{display:grid;gap:.55rem}
.step-list__item{
  position:relative;display:grid;grid-template-columns:2.6rem minmax(0,1fr);gap:.9rem;
  align-items:start;padding:1rem 1.1rem;background:var(--paper-raised);
  border:1px solid var(--line);box-shadow:3px 3px 0 rgba(217,201,168,.45);
}
.step-list__item::before{
  content:"";position:absolute;left:2.28rem;top:100%;width:2px;height:.55rem;
  background:var(--line);
}
.step-list__item:last-child::before{display:none}
.step-list__num{
  font-family:var(--font-mono);font-size:.78rem;letter-spacing:.06em;
  color:var(--teal-deep);padding-top:.15rem;
}
.step-list__label{font-family:var(--font-display);font-weight:800;font-size:1rem}
.step-list__text{font-size:.9rem;line-height:1.7;color:var(--ink-soft)}

/* ---------- prose ---------- */
.prose{max-width:74ch;font-size:1rem;line-height:1.8;color:var(--ink)}
.prose > * + *{margin-top:1rem}
.prose h2{font-size:clamp(1.3rem,2.2vw,1.65rem);margin-top:2rem}
.prose h3{font-size:1.12rem;margin-top:1.6rem}
.prose ul,.prose ol{display:grid;gap:.5rem;padding-left:1.2rem;list-style:disc}
.prose ol{list-style:decimal}
.prose a{color:var(--lake);text-decoration:underline;text-underline-offset:3px}
.prose a:hover{color:var(--coral-deep)}

/* ---------- to top ---------- */
.to-top{
  position:fixed;right:clamp(12px,3vw,28px);bottom:clamp(12px,3vw,28px);z-index:70;
  display:inline-flex;align-items:center;gap:.4rem;padding:.62rem .95rem;
  background:var(--ink);color:var(--paper-raised);border:1px solid var(--ink);
  font-family:var(--font-mono);font-size:.72rem;letter-spacing:.08em;cursor:pointer;
  opacity:0;visibility:hidden;transform:translateY(8px);border-radius:var(--radius);
  transition:opacity .2s ease,transform .2s ease,visibility .2s ease,background-color .18s ease;
}
.to-top.is-visible{opacity:1;visibility:visible;transform:none}
.to-top:hover{background:var(--lake);border-color:var(--lake)}

/* ---------- responsive ---------- */
@media (max-width:1080px){
  .site-footer__top{grid-template-columns:minmax(0,1fr) minmax(0,1fr)}
  .site-footer__contact{grid-column:1 / -1}
}
@media (max-width:900px){
  .nav-toggle{display:inline-flex}
  .primary-nav{
    display:none;flex-basis:100%;width:100%;margin-left:0;margin-top:.3rem;
    padding-top:.75rem;border-top:1px solid var(--line);
  }
  .site-header[data-open] .primary-nav{display:block}
  .primary-nav__list{flex-direction:column;align-items:stretch;gap:0}
  .primary-nav__item + .primary-nav__item{border-top:1px dashed var(--line)}
  .primary-nav__link{
    display:flex;align-items:baseline;gap:.6rem;padding:.85rem .2rem;font-size:1.05rem;
  }
  .primary-nav__link::after{display:none}
  .primary-nav__link[aria-current="page"]{
    color:var(--lake-deep);background:rgba(30,111,140,.08);
    box-shadow:inset 3px 0 0 var(--lake);padding-left:.7rem;
  }
  .primary-nav__meta{display:block;margin-top:.7rem;padding-top:.6rem;border-top:1px solid var(--line)}
  .site-header__utility-label{display:none}
  .site-header__utility-inner{min-height:34px;gap:.9rem}
  .utility-nav__link{font-size:.74rem}
  .utility-cta{font-size:.72rem;padding:.26rem .65rem}
  .site-footer__legal-inner{justify-content:flex-start}
  .legal-links{margin-left:0}
}
@media (max-width:760px){
  .site-footer__top{grid-template-columns:minmax(0,1fr)}
  .site-footer__contact{grid-column:auto}
  .footer-nav{grid-template-columns:repeat(2,minmax(0,1fr))}
}
@media (max-width:420px){
  .brand__tagline{display:none}
  .utility-cta{margin-left:0}
  .footer-nav{grid-template-columns:minmax(0,1fr);gap:1.6rem}
}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
  }
  html{scroll-behavior:auto}
  .card:hover,.card:focus-within,
  .btn:hover,.utility-cta:hover,
  .figure:hover .figure__img{transform:none}
  .to-top{transform:none}
}