/* EduStation design system v5: bright launchpad, clay 3D, highlighter. Shared by every page. */
@font-face{font-family:"Archivo";font-style:normal;font-display:swap;font-weight:100 900;font-stretch:62% 125%;src:url(fonts/archivo-latin.woff2) format("woff2");unicode-range:U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD}
@font-face{font-family:"Archivo";font-style:normal;font-display:swap;font-weight:100 900;font-stretch:62% 125%;src:url(fonts/archivo-latin-ext.woff2) format("woff2");unicode-range:U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF}
@font-face{font-family:"Kalam";font-style:normal;font-display:swap;font-weight:400;src:url(fonts/kalam-400.woff2) format("woff2")}
@font-face{font-family:"Kalam";font-style:normal;font-display:swap;font-weight:700;src:url(fonts/kalam-700.woff2) format("woff2")}
@view-transition{navigation:auto}

:root{
  --font:"Archivo","Helvetica Neue",Arial,system-ui,sans-serif;
  --hand:"Kalam","Segoe Print","Bradley Hand",cursive;
  --hl:#ffd93b;--hl-ink:#161100;
  --ok:#22c977;--ok-ink:#03210f;
  --review:#9b6bff;--review-ink:#14002e;
  --pen:#ff5a4f;--pen-ink:#2a0300;
  --phy:#6b86ff;--chem:#22c977;--math:#ff8f40;--amazon:#ff9900;
  --r-xl:28px;--r-l:18px;--r-m:12px;--r-s:7px;
  --ease:cubic-bezier(.16,1,.3,1);--spring:var(--ease);
  --nav-h:64px;
  --t-xs:.8125rem;--t-s:.9375rem;--t-m:1.0625rem;--t-l:1.3125rem;
  --t-xl:clamp(1.55rem,1.1rem + 1.9vw,2.25rem);
  --t-2xl:clamp(2.2rem,1.2rem + 4.2vw,3.75rem);
  --wrap:1200px;--gut:clamp(1.1rem,4vw,2.5rem);
  interpolate-size:allow-keywords;
}
@supports (transition-timing-function:linear(0,1)){
  :root{--spring:linear(0,.009,.035 2.1%,.141,.281 6.7%,.723 12.9%,.938 16.7%,1.017,1.077,1.121,1.149 24.3%,1.159,1.163,1.161,1.154 29.9%,1.129 32.8%,1.051 39.6%,1.017 43.1%,.991,.977 51%,.974 53.8%,.975 57.1%,.997 69.8%,1.003 76.9%,1)}
}
:root,[data-theme="dark"]{
  color-scheme:dark;
  --bg:#0a1030;--panel:#101943;--panel-2:#152056;--panel-3:#1d2a6a;
  --text:#eef1fb;--dim:#a9b2da;--faint:#7a84b5;
  --rule:rgba(150,168,255,.2);--rule-2:rgba(150,168,255,.1);
  --link:#aebcff;--accent:var(--hl);--accent-text:var(--hl);
  --grid:rgba(130,150,255,.08);--chart:#6b86ff;
  --shadow:0 30px 70px -30px rgba(0,0,12,.8);
  --primary:#6f7cff;--primary-ink:#ffffff;--glow:rgba(111,124,255,.35);--card-shadow:0 24px 50px -30px rgba(0,0,10,.9);
}
[data-theme="light"]{
  color-scheme:light;
  --bg:#f4f6ff;--panel:#fff;--panel-2:#eef1ff;--panel-3:#e2e6fb;
  --text:#10153a;--dim:#4a5079;--faint:#646a90;
  --rule:rgba(16,21,58,.13);--rule-2:rgba(16,21,58,.07);
  --link:#3442f0;--accent:#3d4cff;--accent-text:#3442f0;--hl:#ffc21a;--hl-ink:#2a1d00;
  --grid:rgba(61,76,255,.14);--chart:#3d4cff;
  --shadow:0 30px 60px -30px rgba(40,50,140,.4);
  --primary:#3d4cff;--primary-ink:#ffffff;--glow:rgba(61,76,255,.28);--card-shadow:0 22px 44px -28px rgba(40,50,140,.45);
}

/* ---------- base ---------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%;scroll-padding-top:calc(var(--nav-h) + 1rem)}
@media (prefers-reduced-motion:no-preference){html{scroll-behavior:smooth}}
body{font-family:var(--font);font-size:var(--t-m);line-height:1.6;background:var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;overflow-x:clip;min-height:100svh;transition:background-color .3s}
body::before{content:"";position:fixed;inset:0;z-index:-1;pointer-events:none;background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);background-size:32px 32px;-webkit-mask-image:radial-gradient(ellipse 95% 70% at 50% 0,#000 25%,transparent 100%);mask-image:radial-gradient(ellipse 95% 70% at 50% 0,#000 25%,transparent 100%)}
[data-theme="light"] body::before{background-image:radial-gradient(var(--grid) 1.1px,transparent 1.4px);background-size:26px 26px;-webkit-mask-image:radial-gradient(ellipse 100% 65% at 50% 0,#000 20%,transparent 100%);mask-image:radial-gradient(ellipse 100% 65% at 50% 0,#000 20%,transparent 100%)}
h1,h2,h3,h4{font-weight:800;line-height:1.05;letter-spacing:-.015em;text-wrap:balance}
p{text-wrap:pretty}
a{color:inherit;text-decoration:none}
img,svg,canvas{display:block;max-width:100%}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer;background:none;border:0}
::selection{background:var(--hl);color:var(--hl-ink)}
:focus-visible{outline:2.5px solid var(--accent);outline-offset:3px;border-radius:6px}
.sr{position:absolute!important;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
.skip{position:fixed;left:1rem;top:-4rem;z-index:1000;background:var(--hl);color:var(--hl-ink);padding:.7rem 1rem;border-radius:var(--r-s);font-weight:700;transition:top .2s}
.skip:focus{top:1rem}
.wrap{max-width:var(--wrap);margin-inline:auto;padding-inline:var(--gut)}
.section{padding-block:clamp(4rem,9vw,7.5rem)}
.dim{color:var(--dim)}.faint{color:var(--faint)}.small{font-size:var(--t-xs)}
.num{font-variant-numeric:tabular-nums lining-nums}
.hand{font-family:var(--hand);font-weight:700}
.link{color:var(--link);text-decoration:underline;text-decoration-thickness:1.5px;text-underline-offset:.2em;text-decoration-color:color-mix(in srgb,var(--link) 45%,transparent)}
.link:hover{text-decoration-color:currentColor}
.hl{color:var(--accent-text);font-weight:700}
[data-theme="light"] .hl{color:inherit;background:linear-gradient(transparent 52%,var(--hl) 52% 92%,transparent 92%)}
.lede{font-size:var(--t-l);line-height:1.5;color:var(--dim);max-width:36em}

/* ---------- section heading ---------- */
.sh{display:grid;gap:1rem;margin-bottom:clamp(2rem,5vw,3.25rem);max-width:46rem}
.sh h2,.h2{font-size:var(--t-2xl);font-stretch:116%;font-weight:850;letter-spacing:-.025em;line-height:1}
.sh p{color:var(--dim);font-size:var(--t-l);line-height:1.5;max-width:38em}
.page-head{padding-top:calc(var(--nav-h) + clamp(2.5rem,7vw,5.5rem));padding-bottom:clamp(1.5rem,4vw,2.75rem)}
.page-title{font-size:clamp(2.6rem,1rem + 7vw,6.5rem);font-weight:900;font-stretch:125%;letter-spacing:-.035em;line-height:.92;margin-bottom:1.1rem}

/* ---------- kinetic type (width axis) ---------- */
.kinetic .line{display:block}
.kinetic .w{display:inline-block;white-space:nowrap}
.kinetic .ch{display:inline-block;animation:es-wide 1.05s var(--ease) both;animation-delay:calc(var(--i,0) * 24ms + 100ms)}
.kinetic .soft .ch{animation-name:es-rise;animation-delay:calc(var(--i,0) * 12ms + 620ms)}
@keyframes es-wide{from{opacity:0;font-stretch:62%;translate:0 .3em}to{opacity:1;font-stretch:125%;translate:0 0}}
@keyframes es-rise{from{opacity:0;translate:0 .7em}to{opacity:1;translate:0 0}}
html.js .kinetic:not(.split){opacity:0;animation:es-show 0s 1.2s forwards}
@keyframes es-show{to{opacity:1}}

/* ---------- buttons ---------- */
.btn{--bb:var(--panel-2);--bf:var(--text);display:inline-flex;align-items:center;justify-content:center;gap:.55rem;min-height:48px;padding:.75rem 1.4rem;border-radius:999px;border:1px solid var(--rule);background:var(--bb);color:var(--bf);font-weight:750;font-size:var(--t-s);line-height:1.2;white-space:nowrap;transition:translate .6s var(--spring),scale .25s var(--ease),background-color .25s,border-color .25s,box-shadow .35s}
.btn:hover{border-color:color-mix(in srgb,var(--text) 45%,transparent)}
.btn:active{scale:.96}
.btn-hl{--bb:var(--hl);--bf:var(--hl-ink);border-color:transparent}
.btn-hl:hover{border-color:transparent;box-shadow:0 12px 34px -10px color-mix(in srgb,var(--hl) 75%,transparent)}
.btn-ghost{--bb:transparent}
.btn-amz{--bb:var(--amazon);--bf:#1a0f00;border-color:transparent}
.btn-sm{min-height:40px;padding:.5rem 1rem;font-size:var(--t-xs)}
.btn svg{width:18px;height:18px;flex:none}
.btn:disabled{opacity:.45;cursor:not-allowed}

/* ---------- top nav ---------- */
.progress{position:fixed;inset:0 0 auto 0;height:3px;z-index:130;background:var(--hl);transform-origin:0 50%;transform:scaleX(0);pointer-events:none}
@supports (animation-timeline:scroll()){.progress{animation:es-grow linear both;animation-timeline:scroll(root block)}}
@keyframes es-grow{to{transform:scaleX(1)}}
.topnav{position:fixed;inset:0 0 auto 0;z-index:110;height:var(--nav-h);display:flex;align-items:center;gap:1rem;padding-inline:var(--gut);background:color-mix(in srgb,var(--bg) 78%,transparent);backdrop-filter:blur(14px) saturate(140%);-webkit-backdrop-filter:blur(14px) saturate(140%);border-bottom:1px solid var(--rule-2);transition:translate .45s var(--ease);view-transition-name:es-nav}
.topnav.hide{translate:0 -100%}
.brand{display:inline-flex;align-items:center;gap:.6rem;font-weight:900;font-stretch:125%;font-size:1.12rem;letter-spacing:-.02em}
.brand-mark{width:30px;height:30px;border-radius:8px;background:var(--hl);color:var(--hl-ink);display:grid;place-items:center;font-size:1rem;font-weight:900}
.navlinks{display:flex;gap:.2rem;margin-inline:auto}
.navlinks a{padding:.5rem .85rem;border-radius:999px;font-size:var(--t-s);font-weight:650;color:var(--dim);transition:color .2s,background-color .2s}
.navlinks a:hover{color:var(--text);background:var(--panel)}
.navlinks a[aria-current="page"]{color:var(--text);background:var(--panel-2)}
.navtools{display:flex;align-items:center;gap:.45rem;margin-left:auto}
.navlinks+.navtools{margin-left:0}
.iconbtn{width:42px;height:42px;border-radius:50%;display:grid;place-items:center;border:1px solid var(--rule);transition:background-color .2s}
.iconbtn:hover{background:var(--panel)}
.iconbtn svg{width:19px;height:19px}
[data-theme="dark"] .i-moon,[data-theme="light"] .i-sun{display:none}
.searchbtn{display:flex;align-items:center;gap:.55rem;height:42px;padding:0 .55rem 0 .85rem;border-radius:999px;border:1px solid var(--rule);color:var(--faint);font-size:var(--t-xs);font-weight:600}
.searchbtn svg{width:16px;height:16px}
.searchbtn kbd{font:inherit;font-size:.7rem;border:1px solid var(--rule);border-radius:6px;padding:.1rem .4rem;color:var(--dim)}
@media (max-width:980px){.navlinks,.searchbtn{display:none}.navlinks+.navtools{margin-left:auto}}
@media (max-width:480px){.yt span{display:none}.yt{padding-inline:.8rem}}

/* ---------- mobile tab bar ---------- */
.tabbar{display:none}
@media (max-width:980px){
  .tabbar{position:fixed;left:.6rem;right:.6rem;bottom:calc(.6rem + env(safe-area-inset-bottom));z-index:110;display:grid;grid-template-columns:repeat(5,1fr);height:62px;border-radius:20px;background:color-mix(in srgb,var(--panel) 90%,transparent);backdrop-filter:blur(16px) saturate(150%);-webkit-backdrop-filter:blur(16px) saturate(150%);border:1px solid var(--rule);box-shadow:var(--shadow);view-transition-name:es-tabbar}
  .tabbar a,.tabbar button{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:3px;font-size:.66rem;font-weight:700;color:var(--faint)}
  .tabbar svg{width:22px;height:22px}
  .tabbar [aria-current="page"]{color:var(--text)}
  .tabbar [aria-current="page"] svg{color:var(--accent-text)}
  body{padding-bottom:calc(84px + env(safe-area-inset-bottom))}
}

/* ---------- surfaces + spotlight ---------- */
.panel{background:var(--panel);border:1px solid var(--rule-2);border-radius:var(--r-xl)}
.box{background:var(--panel);border:1px solid var(--rule-2);border-radius:var(--r-l);padding:clamp(1.25rem,3vw,2rem)}
.two{display:grid;grid-template-columns:1fr 1fr;gap:1.25rem}
@media (max-width:820px){.two{grid-template-columns:1fr}}
.spot{position:relative;isolation:isolate;overflow:hidden}
.spot::before{content:"";position:absolute;inset:0;z-index:-1;background:radial-gradient(440px circle at var(--mx,50%) var(--my,-30%),color-mix(in srgb,var(--hl) 14%,transparent),transparent 60%);opacity:0;transition:opacity .35s}
.spot:hover::before{opacity:1}

/* ---------- NTA question-palette squares ---------- */
.q{--qc:var(--panel-3);position:relative;display:inline-grid;place-items:center;flex:none;width:2.4rem;height:2.4rem;border-radius:8px;background:var(--qc);border:1px solid var(--rule);font-weight:850;font-size:.95rem;color:var(--text);transition:background-color .4s,border-radius .4s,color .4s,scale .5s var(--spring)}
.q.sm{width:1.15rem;height:1.15rem;border-radius:4px}
.q.ok{--qc:var(--ok);color:var(--ok-ink);border-color:transparent}
.q.no{--qc:var(--pen);color:var(--pen-ink);border-color:transparent}
.q.yl{--qc:var(--hl);color:var(--hl-ink);border-color:transparent}
.q.rv{--qc:var(--review);color:var(--review-ink);border-color:transparent;border-radius:50%}
.q.rv.tick::after{content:"";position:absolute;right:-3px;bottom:-3px;width:42%;height:42%;border-radius:50%;background:var(--ok);border:2px solid var(--bg)}
.legend{list-style:none;display:flex;flex-wrap:wrap;gap:.6rem 1.3rem;font-size:var(--t-xs);color:var(--dim)}
.legend>*{display:flex;align-items:center;gap:.5rem}

/* ---------- forms ---------- */
.field{display:grid;gap:.45rem}
.field label,.lbl{font-size:var(--t-xs);font-weight:700;color:var(--dim)}
.input{width:100%;min-height:52px;padding:.75rem 1rem;border-radius:var(--r-m);background:var(--panel-2);border:1px solid var(--rule);font-size:1.05rem;transition:border-color .2s,box-shadow .2s}
.input:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 4px color-mix(in srgb,var(--accent) 22%,transparent)}
.hint{font-size:var(--t-xs);color:var(--faint)}
.seg{display:inline-flex;padding:4px;border-radius:999px;background:var(--panel-2);border:1px solid var(--rule)}
.seg button{min-height:40px;padding:.45rem 1.05rem;border-radius:999px;font-weight:750;font-size:var(--t-s);color:var(--dim);transition:background-color .3s,color .3s}
.seg button[aria-pressed="true"]{background:var(--hl);color:var(--hl-ink)}
.chips{display:flex;flex-wrap:wrap;gap:.45rem}
.chip{min-height:40px;padding:.45rem .95rem;border-radius:999px;border:1px solid var(--rule);font-weight:700;font-size:var(--t-s);color:var(--dim);transition:background-color .2s,color .2s,border-color .2s}
.chip:hover{color:var(--text)}
.chip[aria-pressed="true"]{border-color:var(--text);color:var(--text);background:var(--panel-2)}

/* ---------- tables + FAQ ---------- */
.tbl{position:relative;overflow-x:auto;border:1px solid var(--rule-2);border-radius:var(--r-l);background:var(--panel)}
.tbl table{width:100%;border-collapse:collapse;min-width:600px;font-size:var(--t-s)}
.tbl th,.tbl td{padding:.95rem 1.2rem;text-align:left;border-bottom:1px solid var(--rule-2)}
.tbl th{font-size:var(--t-xs);font-weight:750;color:var(--faint);background:var(--panel-2)}
.tbl tr:last-child td{border-bottom:0}
.tbl td:first-child{font-weight:800;font-variant-numeric:tabular-nums}
.tbl tbody tr:hover{background:var(--panel-2)}
.qa{border-top:1px solid var(--rule)}
.qa:last-child{border-bottom:1px solid var(--rule)}
.qa summary{list-style:none;cursor:pointer;display:flex;justify-content:space-between;align-items:center;gap:1.5rem;padding:1.3rem 0;font-weight:750;font-size:1.12rem}
.qa summary::-webkit-details-marker{display:none}
.qa summary::after{content:"";flex:none;width:14px;height:14px;background:linear-gradient(var(--accent-text),var(--accent-text)) center/100% 2px no-repeat,linear-gradient(var(--accent-text),var(--accent-text)) center/2px 100% no-repeat;transition:rotate .45s var(--spring)}
.qa[open] summary::after{rotate:135deg}
.qa p{padding:0 0 1.4rem;color:var(--dim);max-width:62ch}
.qa::details-content{block-size:0;overflow-y:clip;transition:block-size .45s var(--ease),content-visibility .45s allow-discrete}
.qa[open]::details-content{block-size:auto}

/* ---------- bookshelf (home + books) ---------- */
.shelf{display:flex;align-items:flex-end;gap:6px;height:330px;padding:28px 1rem 0;overflow-x:auto;scrollbar-width:none}
.shelf::-webkit-scrollbar{display:none}
.spine{--c:var(--phy);flex:none;position:relative;width:var(--w,58px);height:var(--h,90%);writing-mode:vertical-rl;display:flex;justify-content:space-between;align-items:center;padding:1rem 0;border-radius:5px 5px 2px 2px;background:linear-gradient(90deg,color-mix(in srgb,var(--c) 72%,#000) 0 7%,var(--c) 14% 84%,color-mix(in srgb,var(--c) 78%,#000) 95%);font-weight:850;font-stretch:108%;font-size:.8rem;line-height:1.15;transition:translate .6s var(--spring),rotate .6s var(--spring),box-shadow .3s;box-shadow:inset 0 0 0 1px rgba(0,0,0,.18)}
.spine:first-child{margin-left:auto}.spine:last-child{margin-right:auto}
.spine .sp-t{max-height:72%}
.spine .sp-a{font-weight:650;font-size:.68rem;opacity:.8}
.s-phy{--c:var(--phy);color:#fff}.s-chem{--c:var(--chem);color:#04210f}.s-math{--c:var(--math);color:#2a1200}
.spine.must::after{content:"";position:absolute;top:-16px;left:50%;width:16px;height:16px;translate:-50% 0;background:var(--hl);border-radius:2px 2px 0 0}
.spine:hover,.spine:focus-visible{translate:0 -20px;rotate:-2deg;box-shadow:0 22px 30px -14px rgba(0,0,0,.6)}
.shelf-board{height:14px;border-radius:3px;background:linear-gradient(var(--panel-3),var(--panel-2));box-shadow:0 18px 30px -18px rgba(0,0,0,.7)}
@media (max-width:600px){.shelf{height:270px}}

/* ---------- hand annotations ---------- */
.anno{position:absolute;z-index:3;pointer-events:none;display:flex;align-items:flex-start;gap:.3rem;color:var(--accent-text);font-family:var(--hand);font-weight:700;font-size:1.12rem;line-height:1.15}
[data-theme="light"] .anno{color:var(--pen)}
.anno svg{overflow:visible;flex:none}
.anno path{fill:none;stroke:currentColor;stroke-width:2.4;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:1;stroke-dashoffset:1;transition:stroke-dashoffset 1.1s .3s var(--ease)}
.anno .anno-t{opacity:0;rotate:-3deg;transition:opacity .6s .9s}
.anno.in path{stroke-dashoffset:0}
.anno.in .anno-t{opacity:1}
.on-touch{display:none}
@media (hover:none){.on-fine{display:none}.on-touch{display:inline}}

/* ---------- odometer ---------- */
.odo{display:inline-flex;align-items:flex-end;line-height:1.1;height:1.1em;overflow:hidden;font-variant-numeric:tabular-nums;vertical-align:bottom}
.odo-col{display:inline-block;height:1.1em;overflow:hidden}
.odo-strip{display:flex;flex-direction:column;transition:transform 1.9s var(--ease)}
.odo-strip>span{display:block;height:1.1em;line-height:1.1}
.odo>span[aria-hidden]:not(.odo-col){display:inline-block;height:1.1em;line-height:1.1}

/* ---------- reveal (used sparingly) ---------- */
html.js [data-reveal]{opacity:0;translate:0 26px;transition:opacity .9s var(--ease),translate .9s var(--ease)}
html.js [data-reveal].in{opacity:1;translate:0 0}

/* ---------- toast ---------- */
.es-toast{position:fixed;left:50%;bottom:calc(1.4rem + env(safe-area-inset-bottom));translate:-50% 180%;z-index:900;max-width:min(92vw,460px);background:var(--text);color:var(--bg);font-weight:650;font-size:var(--t-s);padding:.85rem 1.15rem;border-radius:14px;box-shadow:var(--shadow);transition:translate .6s var(--spring)}
.es-toast.show{translate:-50% 0}
@media (max-width:980px){.es-toast{bottom:calc(86px + env(safe-area-inset-bottom))}}

/* ---------- command palette ---------- */
.es-pal{margin:12vh auto auto;width:min(620px,calc(100vw - 2rem));max-height:72vh;padding:0;border:1px solid var(--rule);border-radius:var(--r-l);background:var(--panel);color:var(--text);box-shadow:var(--shadow);overflow:hidden;opacity:0;translate:0 -10px;scale:.98;transition:opacity .25s,translate .4s var(--ease),scale .4s var(--ease),overlay .3s allow-discrete,display .3s allow-discrete}
.es-pal[open]{opacity:1;translate:0 0;scale:1}
@starting-style{.es-pal[open]{opacity:0;translate:0 -10px;scale:.98}}
.es-pal::backdrop{background:rgba(5,8,25,.55);backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px)}
.es-pal input{width:100%;border:0;border-bottom:1px solid var(--rule);background:transparent;padding:1.1rem 1.25rem;font-size:1.05rem;outline:none}
.es-pal ul{list-style:none;max-height:52vh;overflow:auto;padding:.4rem}
.es-pal li{display:flex;justify-content:space-between;gap:1rem;align-items:center;padding:.75rem .9rem;border-radius:10px;cursor:pointer;color:var(--dim)}
.es-pal li[aria-selected="true"]{background:var(--panel-2);color:var(--text)}
.es-pal li small{color:var(--faint);font-size:.75rem}
.es-pal .empty{cursor:default}

/* ---------- footer ---------- */
.foot{border-top:1px solid var(--rule-2);margin-top:clamp(3rem,8vw,6rem);padding-block:3.5rem 2.5rem}
.foot-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:2rem}
.foot-brand p{max-width:30ch;margin:.9rem 0 1.1rem;font-size:var(--t-s)}
.foot h2{font-size:var(--t-s);font-weight:800;margin-bottom:.9rem}
.foot ul{list-style:none;display:grid;gap:.5rem}
.foot ul a{color:var(--dim);font-size:var(--t-s)}
.foot ul a:hover{color:var(--text)}
.foot-note{margin-top:2.5rem;padding-top:1.5rem;border-top:1px solid var(--rule-2);display:flex;flex-wrap:wrap;justify-content:space-between;gap:1rem 2rem;color:var(--faint);font-size:var(--t-xs)}
.foot-note nav{display:flex;gap:1.2rem}
.foot-note a:hover{color:var(--text)}
@media (max-width:760px){.foot-grid{grid-template-columns:1fr 1fr}.foot-brand{grid-column:1/-1}}

/* ---------- view transitions ---------- */
::view-transition-old(root){animation:es-vt-out .3s var(--ease) both}
::view-transition-new(root){animation:es-vt-in .5s var(--ease) both}
@keyframes es-vt-out{to{opacity:0;transform:translateY(-10px)}}
@keyframes es-vt-in{from{opacity:0;transform:translateY(16px)}}
html.vt-theme::view-transition-old(root),html.vt-theme::view-transition-new(root),
html.vt-local::view-transition-old(root),html.vt-local::view-transition-new(root){animation:none;mix-blend-mode:normal}

@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}
  ::view-transition-group(*),::view-transition-old(*),::view-transition-new(*){animation:none!important}
  html.js [data-reveal]{opacity:1;translate:none}
}
@media print{.topnav,.tabbar,.progress,.es-toast{display:none}body{padding:0}}

/* ---------- v4 additions ---------- */
.foot-aff{margin-top:2.25rem;max-width:72ch}
.prose{max-width:68ch}
.prose h2{font-size:var(--t-xl);font-stretch:112%;margin:2.6rem 0 .8rem}
.prose p,.prose li{color:var(--dim);margin-bottom:.9rem}
.prose ul{padding-left:1.2rem}
.prose li::marker{color:var(--accent-text)}
.prose strong{color:var(--text)}
.prose a{color:var(--link);text-decoration:underline;text-underline-offset:.2em}
.meta-line{color:var(--faint);font-size:var(--t-s)}
.math{font-family:"Archivo","Cambria Math","STIX Two Math","Noto Sans Math","Segoe UI Symbol",system-ui,sans-serif;font-variant-numeric:tabular-nums}
.faq-grid{display:grid;grid-template-columns:.8fr 1.2fr;gap:clamp(2rem,5vw,4rem)}
@media (max-width:820px){.faq-grid{grid-template-columns:1fr}}
.stickybar{position:sticky;top:calc(var(--nav-h) + .6rem);z-index:90;transition:top .45s var(--ease)}
html.nav-up .stickybar{top:.6rem}
@keyframes es-flash{0%,60%{box-shadow:0 0 0 3px var(--hl)}100%{box-shadow:0 0 0 3px transparent}}
:target{scroll-margin-top:calc(var(--nav-h) + 4.5rem)}

/* ---------- v5 additions ---------- */
.btn-primary{--bb:var(--primary);--bf:var(--primary-ink);border-color:transparent;box-shadow:0 12px 30px -12px var(--glow)}
.btn-primary:hover{border-color:transparent;box-shadow:0 16px 38px -12px var(--glow)}
.btn-lg{min-height:56px;padding:.95rem 1.7rem;font-size:var(--t-m)}
.badge-new{display:inline-flex;align-items:center;gap:.35rem;font-size:.72rem;font-weight:850;padding:.25rem .6rem;border-radius:999px;background:var(--hl);color:var(--hl-ink)}
.img3d{display:block;height:auto;user-select:none;-webkit-user-drag:none;pointer-events:none}
.mob-search{display:none}
@media (max-width:980px){.mob-search{display:grid}}

/* ===== v5: shared motion + page heads ===== */
@keyframes pop{from{opacity:0;scale:.55;translate:0 40px}to{opacity:1;scale:1;translate:0 0}}
@keyframes float{0%,100%{translate:0 0;rotate:var(--r0,0deg)}50%{translate:0 -14px;rotate:var(--r1,2deg)}}
.ph5{position:relative;isolation:isolate;overflow:clip;padding:calc(var(--nav-h) + clamp(1.25rem,4vw,3rem)) 0 clamp(1.25rem,3.5vw,2.5rem)}
.ph5::before,.ph5::after{content:"";position:absolute;z-index:-1;border-radius:50%;filter:blur(70px);pointer-events:none}
.ph5::before{width:min(700px,90vw);aspect-ratio:1;right:-12vw;top:-14vw;background:radial-gradient(circle at 40% 40%,rgba(61,76,255,.28),rgba(139,92,246,.16) 45%,transparent 70%)}
.ph5::after{width:min(420px,60vw);aspect-ratio:1;left:-12vw;top:40%;background:radial-gradient(circle,rgba(255,194,26,.22),transparent 65%)}
[data-theme="dark"] .ph5::before{background:radial-gradient(circle at 40% 40%,rgba(111,124,255,.3),rgba(139,92,246,.2) 45%,transparent 70%)}
.ph5-grid{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);gap:clamp(1rem,3vw,2.5rem);align-items:center}
.ph5 .crumb{display:inline-flex;align-items:center;gap:.5rem;font-size:var(--t-xs);font-weight:750;color:var(--dim);margin-bottom:1rem;padding:.35rem .8rem;border-radius:999px;background:var(--panel);border:1px solid var(--rule-2);box-shadow:var(--card-shadow)}
.ph5 .crumb b{color:var(--text)}
.ph5 h1{font-size:clamp(2.3rem,.9rem + 3.6vw,3.8rem);font-weight:900;font-stretch:112%;letter-spacing:-.035em;line-height:1;margin-bottom:1rem}
.ph5 .lede{font-size:var(--t-l);color:var(--dim);line-height:1.5;max-width:34em}
.ph5 .facts{display:flex;flex-wrap:wrap;gap:.5rem;margin-top:1.3rem;list-style:none;padding:0}
.ph5 .facts li{padding:.42rem .85rem;border-radius:999px;background:var(--panel);border:1px solid var(--rule-2);box-shadow:var(--card-shadow);font-size:var(--t-xs);font-weight:750}
.ph5-art{position:relative;aspect-ratio:1/.78;width:100%;max-width:520px;justify-self:center}
.ph5-art .a{position:absolute;left:var(--x);top:var(--y);width:var(--w);animation:pop 1s var(--spring) both;animation-delay:calc(var(--i) * 120ms + 150ms)}
.ph5-art .a img{width:100%;height:auto;animation:float var(--t,7s) ease-in-out infinite;animation-delay:calc(var(--i) * -1.4s);filter:drop-shadow(0 22px 20px rgba(40,50,140,.22))}
[data-theme="dark"] .ph5-art .a img{filter:drop-shadow(0 22px 22px rgba(0,0,0,.5))}
@media (max-width:860px){.ph5-grid{grid-template-columns:1fr;gap:0}.ph5-art{max-width:250px;margin:.4rem auto -.6rem}}
@media (prefers-reduced-motion:reduce){.ph5-art .a,.ph5-art .a img{animation:none}}
@keyframes es-wide5{from{opacity:0;font-stretch:62%;translate:0 .3em}to{opacity:1;font-stretch:112%;translate:0 0}}
.ph5 .kinetic .ch{animation-name:es-wide5}
/* shelf props (home + books) */
.shelf-wrap{position:relative}
.shelf-wrap .shelf{height:330px}
.prop{position:absolute;bottom:14px;z-index:1;pointer-events:none}
.prop img{width:100%;height:auto;filter:drop-shadow(0 16px 14px rgba(40,50,140,.22))}
.prop-l{left:4%;width:clamp(120px,11vw,160px)}
.prop-r{right:4%;width:clamp(140px,13vw,190px)}
.prop-l img{rotate:-6deg}
@media (max-width:1100px){.prop{display:none}}
.spine{gap:.7rem}
.spine .sp-t{max-height:70%;overflow:hidden}
[hidden]{display:none!important}