@font-face{font-family:"Poppins";font-weight:500;font-display:swap;src:url(../fonts/poppins-500.woff2) format("woff2")}
@font-face{font-family:"Poppins";font-weight:700;font-display:swap;src:url(../fonts/poppins-700.woff2) format("woff2")}
@font-face{font-family:"Inter";font-weight:400;font-display:swap;src:url(../fonts/inter-400.woff2) format("woff2")}
@font-face{font-family:"Inter";font-weight:600;font-display:swap;src:url(../fonts/inter-600.woff2) format("woff2")}

:root{
  --ink:#14233a;          /* Stanford navy: text, structure */
  --signal:#e8742a;       /* safety orange: actions, active tab */
  --signal-text:#b4500f;  /* orange for text links on white */
  --teal:#2f7f86;         /* secondary information */
  --mist:#eef1f5;         /* quiet panels */
  --rule:#d5dbe3;         /* hairlines and outlines */
  --muted:#5b6675;        /* secondary text */
  --paper:#ffffff;
  --wrap:1160px;
  --display:"Poppins",system-ui,sans-serif;
  --body:"Inter",system-ui,sans-serif;
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
body{margin:0;background:var(--paper);color:var(--ink);font:400 1.0625rem/1.6 var(--body)}
img{max-width:100%;height:auto;display:block}
a{color:var(--signal-text);text-underline-offset:.18em}
a:hover{color:var(--ink)}
:focus-visible{outline:3px solid var(--signal);outline-offset:3px}
h1,h2,h3{font-family:var(--display);font-weight:700;line-height:1.15;margin:0 0 .5em;letter-spacing:-.01em}
h1{font-size:clamp(2.2rem,4.6vw,3.6rem);letter-spacing:-.025em}
h2{font-size:clamp(1.6rem,2.8vw,2.3rem)}
h3{font-size:1.15rem}
p{margin:0 0 1em;max-width:68ch}
.lead{font-size:1.2rem;line-height:1.55;color:var(--ink)}
.wrap{max-width:var(--wrap);margin:0 auto;padding:0 24px}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:absolute;left:12px;top:-60px;background:var(--ink);color:#fff;padding:10px 16px;z-index:10}
.skip:focus{top:12px}

/* buttons */
.btn{display:inline-block;font:700 1rem/1 var(--display);text-decoration:none;color:var(--ink);background:var(--signal);padding:16px 24px;border-radius:6px;border:2px solid var(--signal)}
.btn:hover{background:#f08a46;border-color:#f08a46;color:var(--ink)}
.btn-ghost{background:transparent;border-color:var(--ink)}
.btn-ghost:hover{background:var(--ink);color:#fff;border-color:var(--ink)}
.btn-light{background:#fff;border-color:#fff}
.btn-light:hover{background:var(--signal);border-color:var(--signal)}
.btn-small{padding:11px 16px;font-size:.92rem}

/* header */
.top{border-bottom:1px solid var(--rule);background:#fff;position:sticky;top:0;z-index:5}
.top-in{display:flex;align-items:center;gap:28px;min-height:76px}
.brand{display:flex;align-items:center;gap:14px;text-decoration:none;color:var(--ink);margin-right:auto}
.brand img{width:132px}
.brand-name{font:500 .95rem/1.2 var(--display);border-left:1px solid var(--rule);padding-left:14px}
.nav{display:flex;gap:24px;list-style:none;margin:0;padding:0}
.nav a{color:var(--ink);text-decoration:none;font-weight:600;font-size:.97rem}
.nav a:hover{color:var(--signal-text)}

/* hero */
.hero{padding:72px 0 64px}
.hero-in{display:grid;grid-template-columns:1.05fr .95fr;gap:48px;align-items:center}
.hero-copy .lead{max-width:34em}
.actions{display:flex;flex-wrap:wrap;gap:14px;margin:28px 0 30px}
.facts{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:1fr 1fr;gap:10px 28px;color:var(--muted);font-size:.95rem}
.facts li{padding-left:22px;position:relative}
.facts li::before{content:"";position:absolute;left:0;top:.5em;width:10px;height:10px;border:2px solid var(--teal);border-radius:2px}
.hero-art{position:relative;height:460px;background:var(--mist);border-radius:10px;overflow:hidden}
.hc{position:absolute;width:40%;top:50%;left:50%;border:1px solid var(--rule);box-shadow:0 22px 40px -18px rgba(20,35,58,.45);transform:translate(-50%,-50%)}
.hc1{animation:fanL .9s .15s cubic-bezier(.2,.7,.2,1) both}
.hc2{animation:fanR .9s .15s cubic-bezier(.2,.7,.2,1) both}
.hc3{z-index:2}
@keyframes fanL{to{transform:translate(-108%,-52%) rotate(-7deg)}}
@keyframes fanR{to{transform:translate(8%,-48%) rotate(6deg)}}
@media (prefers-reduced-motion:reduce){
  .hc1,.hc2{animation:none}
  .hc1{transform:translate(-108%,-52%) rotate(-7deg)}
  .hc2{transform:translate(8%,-48%) rotate(6deg)}
}

/* notice */
.notice{background:var(--ink);color:#fff}
.notice-in{display:flex;align-items:center;justify-content:space-between;gap:24px;padding-top:18px;padding-bottom:18px}
.notice p{margin:0;max-width:none}
.notice-link{color:#fff;font-weight:600;white-space:nowrap;text-decoration-color:var(--signal);text-decoration-thickness:2px}
.notice-link:hover{color:var(--signal)}

/* range: the ring-binder index */
.range{padding:88px 0 96px}
.range-head{display:grid;grid-template-columns:260px 1fr;gap:40px;align-items:start;margin-bottom:36px}
.range-head h2{margin:0}
.range-head p{margin:0;color:var(--muted)}
.binder{display:grid;grid-template-columns:260px 1fr;align-items:start}
.tabs{position:sticky;top:96px;display:flex;flex-direction:column;gap:6px;padding-right:0}
.tab{all:unset;cursor:pointer;display:grid;grid-template-columns:40px 1fr auto;align-items:center;gap:12px;padding:8px 14px 8px 8px;border:1px solid var(--rule);border-right:0;border-radius:8px 0 0 8px;background:#fff;color:var(--ink);font-size:.9rem;line-height:1.25;margin-right:-1px;position:relative}
.tab:hover{background:var(--mist)}
.tab:focus-visible{outline:3px solid var(--signal);outline-offset:-3px}
.tab-letter{display:grid;place-items:center;width:40px;height:40px;border:2px solid var(--ink);border-radius:5px;font:700 1rem var(--display)}
.tab[data-filter=all] .tab-letter{font-size:.78rem}
.tab-count{color:var(--muted);font-size:.85rem}
.tab[aria-pressed=true]{background:var(--mist);border-color:var(--ink);z-index:1}
.tab[aria-pressed=true]::after{content:"";position:absolute;right:-1px;top:0;bottom:0;width:3px;background:var(--mist)}
.tab[aria-pressed=true] .tab-letter{background:var(--signal);border-color:var(--signal)}
.shelf{border:1px solid var(--ink);border-radius:0 10px 10px 10px;background:var(--mist);padding:28px 28px 8px;min-height:640px}
.group{margin-bottom:34px}
.group[hidden]{display:none}
.group h3{display:flex;align-items:center;gap:12px;font-size:1.25rem;margin-bottom:18px}
.g-letter{display:grid;place-items:center;width:34px;height:34px;background:var(--ink);color:#fff;border-radius:5px;font-size:.95rem}
.grid{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(330px,1fr));gap:14px}
.card-link{display:grid;grid-template-columns:84px 1fr;grid-template-rows:auto auto 1fr auto;column-gap:16px;height:100%;text-decoration:none;color:var(--ink);background:#fff;border-radius:6px;padding:14px;border:1px solid transparent}
.card-link:hover{border-color:var(--ink)}
.cover{grid-row:1/5;align-self:start;border:1px solid var(--rule);border-radius:3px;overflow:hidden}
.code{justify-self:start;font:700 .76rem var(--display);color:var(--ink);border:1.5px solid var(--ink);border-radius:4px;padding:1px 6px;margin-bottom:6px}
.card-title{font:700 1rem/1.25 var(--display);margin-bottom:4px}
.card-sub{font-size:.86rem;line-height:1.45;color:var(--muted);margin-bottom:10px}
.card-meta{display:flex;flex-wrap:wrap;align-items:baseline;gap:4px 14px;white-space:nowrap;font-size:.88rem;color:var(--muted)}
.price{font-weight:600;color:var(--ink)}
.card-cta{margin-left:auto;font-weight:600;color:var(--signal-text);text-decoration:underline;text-decoration-color:var(--signal);text-underline-offset:.2em}
.card-link:hover .card-cta{color:var(--ink)}

/* bundle */
.bundle{background:var(--ink);color:#fff;padding:80px 0}
.bundle-in{display:grid;grid-template-columns:260px 1fr;gap:56px;align-items:center}
.bundle-cover{border:1px solid rgba(255,255,255,.25);box-shadow:0 26px 50px -20px rgba(0,0,0,.6);transform:rotate(-3deg)}
.bundle .lead{color:#fff}
.bundle-price{display:flex;align-items:baseline;gap:16px;margin:8px 0 26px}
.now{font:700 2.4rem var(--display);color:var(--signal)}
.was{color:#c9d1dc}

/* steps */
.steps{padding:88px 0}
.step-list{list-style:none;counter-reset:s;margin:28px 0 0;padding:0;display:grid;grid-template-columns:repeat(3,1fr);gap:36px}
.step-list li{counter-increment:s;border-top:3px solid var(--ink);padding-top:18px}
.step-list li::before{content:counter(s);display:block;font:700 2rem var(--display);color:var(--signal-text);margin-bottom:6px}
.step-list p{color:var(--muted);font-size:.98rem}

/* about */
.about{background:var(--mist);padding:88px 0}
.about-in{display:grid;grid-template-columns:1.4fr 1fr;gap:56px;align-items:start}
.creds{margin:0;background:#fff;border:1px solid var(--rule);border-radius:10px;padding:8px 24px}
.creds div{padding:16px 0;border-bottom:1px solid var(--rule)}
.creds div:last-child{border-bottom:0}
.creds dt{font-size:.85rem;color:var(--muted);margin-bottom:2px}
.creds dd{margin:0;font-weight:600}

/* help */
.help{padding:88px 0}
.help-in{display:grid;grid-template-columns:260px 1fr;gap:40px}
.qa details{border-bottom:1px solid var(--rule)}
.qa details:first-child{border-top:1px solid var(--rule)}
.qa summary{cursor:pointer;list-style:none;padding:20px 40px 20px 0;font:700 1.05rem var(--display);position:relative}
.qa summary::-webkit-details-marker{display:none}
.qa summary::after{content:"";position:absolute;right:8px;top:50%;width:12px;height:12px;border-right:2.5px solid var(--ink);border-bottom:2.5px solid var(--ink);transform:translateY(-70%) rotate(45deg);transition:transform .2s}
.qa details[open] summary::after{transform:translateY(-30%) rotate(225deg)}
@media (prefers-reduced-motion:reduce){.qa summary::after{transition:none}}
.qa details p{color:var(--muted);padding-bottom:6px}

/* contact */
.contact{padding:0 0 88px}
.contact-in{max-width:calc(var(--wrap) - 48px);border:1px solid var(--ink);border-radius:10px;padding:36px 40px;display:grid;grid-template-columns:260px 1fr;gap:40px;align-items:center}
.contact h2{margin:0}
.contact p{margin:0;font-size:1.1rem}

/* footer */
.foot{background:var(--ink);color:#c9d1dc;padding:64px 0 28px;font-size:.95rem}
.foot a{color:#fff}
.foot a:hover{color:var(--signal)}
.foot-in{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:48px}
.foot-brand img{width:170px;margin-bottom:16px}
.foot-h{font:700 1rem var(--display);color:#fff;margin-bottom:12px}
.foot ul{list-style:none;margin:0;padding:0;display:grid;gap:8px}
.legal{border-top:1px solid rgba(255,255,255,.18);margin-top:44px;padding-top:24px;font-size:.85rem}
.legal p{max-width:none;margin-bottom:6px}

/* text pages */
.prose-page{padding:72px 0 96px}
.prose{max-width:760px}
.prose h2{font-size:1.4rem;margin-top:1.6em}
.prose ul{padding-left:1.2em}
.prose li{margin-bottom:.4em}

/* responsive */
@media (max-width:980px){
  .hero-in,.about-in{grid-template-columns:1fr}
  .hero-art{height:380px}
  .range-head,.help-in,.contact-in{grid-template-columns:1fr;gap:12px}
  .binder{grid-template-columns:1fr}
  .tabs{position:sticky;top:76px;z-index:3;flex-direction:row;overflow-x:auto;gap:6px;padding:10px 0;background:#fff;scrollbar-width:thin}
  .tab{grid-template-columns:auto;border:1px solid var(--rule);border-radius:8px 8px 0 0;padding:6px;margin:0}
  .tab-name,.tab-count{display:none}
  .tab[aria-pressed=true]::after{display:none}
  .shelf{border-radius:0 0 10px 10px;padding:20px 16px 4px}
  .bundle-in{grid-template-columns:180px 1fr;gap:32px}
  .foot-in{grid-template-columns:1fr 1fr}
  .foot-brand{grid-column:1/-1}
}
@media (max-width:720px){
  body{font-size:1rem}
  .nav{display:none}
  .brand-name{display:none}
  .hero{padding:44px 0 40px}
  .facts{grid-template-columns:1fr}
  .notice-in{flex-direction:column;align-items:flex-start;gap:8px}
  .grid{grid-template-columns:1fr}
  .card-link{grid-template-columns:64px 1fr}
  .card-sub{display:none}
  .bundle-in{grid-template-columns:1fr}
  .bundle-cover{width:180px}
  .step-list{grid-template-columns:1fr;gap:24px}
  .contact-in{padding:28px 22px;margin:0 24px}
  .hero-art{height:280px}
  .card-cta{margin-left:0;flex-basis:100%}
  .foot-in{grid-template-columns:1fr}
}