/* ============================================================
   eLearnBuddy — landing page
   Modern dark mode · gradient theme
   ============================================================ */

:root{
   /* palette */
   --bg:            #07070d;
   --bg-soft:       #0c0c16;
   --surface:       rgba(255,255,255,0.04);
   --surface-2:     rgba(255,255,255,0.06);
   --border:        rgba(255,255,255,0.08);
   --border-strong: rgba(255,255,255,0.14);
   --text:          #f4f4f8;
   --text-dim:      #a6a6bd;
   --text-mute:     #7a7a93;

   /* brand gradients */
   --grad-brand:    linear-gradient(135deg,#818cf8 0%,#22d3ee 100%);
   --grad-warm:     linear-gradient(135deg,#f472b6 0%,#a78bfa 100%);
   --grad-cool:     linear-gradient(135deg,#34d399 0%,#22d3ee 100%);
   --grad-glow:     radial-gradient(600px circle at 50% 0%,rgba(129,140,248,.25),transparent 70%);

   /* misc */
   --radius:        16px;
   --radius-sm:     12px;
   --radius-lg:     24px;
   --maxw:          1180px;
   --shadow:        0 24px 60px -20px rgba(0,0,0,.7);
   --ease:          cubic-bezier(.16,1,.3,1);
}

/* ---------- reset ---------- */
*,*::before,*::after{box-sizing:border-box}
*{margin:0}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
   font-family:'Inter',system-ui,-apple-system,sans-serif;
   background:var(--bg);
   color:var(--text);
   line-height:1.6;
   -webkit-font-smoothing:antialiased;
   overflow-x:hidden;
   position:relative;
}
/* ---------- transparent scrollbar ---------- */
html{
   scrollbar-width:thin;                               /* Firefox: thin, native-style */
   scrollbar-color:rgba(255,255,255,.25) transparent;  /* thumb, track */
}
html::-webkit-scrollbar{width:10px;height:10px;background:transparent}
html::-webkit-scrollbar-track{background:transparent}
html::-webkit-scrollbar-thumb{
   background:rgba(255,255,255,.25);
   border:2px solid transparent;
   border-radius:999px;
   background-clip:padding-box;
}
html::-webkit-scrollbar-thumb:hover{background:rgba(255,255,255,.28)}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
button{font-family:inherit;cursor:pointer;border:none;background:none;color:inherit}
h1,h2,h3,h4{line-height:1.1;letter-spacing:-.02em;font-weight:800}
ul{list-style:none;padding:0}

/* ---------- layout ---------- */
.container{width:100%;max-width:var(--maxw);margin-inline:auto;padding-inline:24px}
.container--narrow{max-width:760px}
.section{padding-block:clamp(64px,9vw,120px);position:relative}

/* ---------- ambient background ---------- */
.bg-fx{position:fixed;inset:0;z-index:-1;overflow:hidden;pointer-events:none}
.blob{position:absolute;border-radius:50%;filter:blur(90px);opacity:.5;will-change:transform}
.blob-1{width:560px;height:560px;background:#6366f1;top:-160px;left:-120px;animation:float1 18s var(--ease) infinite alternate}
.blob-2{width:480px;height:480px;background:#06b6d4;top:10%;right:-140px;opacity:.4;animation:float2 22s var(--ease) infinite alternate}
.blob-3{width:620px;height:620px;background:#d946ef;bottom:-220px;left:30%;opacity:.28;animation:float3 26s var(--ease) infinite alternate}
@keyframes float1{to{transform:translate(120px,80px) scale(1.15)}}
@keyframes float2{to{transform:translate(-100px,120px) scale(1.1)}}
@keyframes float3{to{transform:translate(-80px,-100px) scale(1.2)}}
.grid-overlay{
   position:absolute;inset:0;
   background-image:linear-gradient(rgba(255,255,255,.025) 1px,transparent 1px),
                    linear-gradient(90deg,rgba(255,255,255,.025) 1px,transparent 1px);
   background-size:56px 56px;
   mask-image:radial-gradient(ellipse 80% 60% at 50% 0%,#000 40%,transparent 100%);
}

/* ---------- helpers ---------- */
.grad-text{
   background:linear-gradient(120deg,#a78bfa,#22d3ee 60%,#34d399);
   background-size:200% 200%;
   -webkit-background-clip:text;background-clip:text;
   color:transparent;
   animation:gradShift 8s ease infinite;
}
@keyframes gradShift{0%,100%{background-position:0% 50%}50%{background-position:100% 50%}}

.eyebrow{
   display:inline-block;font-size:13px;font-weight:600;letter-spacing:.12em;
   text-transform:uppercase;color:#9fb0ff;margin-bottom:16px;
}

/* ---------- buttons ---------- */
.btn{
   display:inline-flex;align-items:center;justify-content:center;gap:9px;
   font-weight:600;font-size:15px;padding:12px 20px;border-radius:999px;
   transition:transform .25s var(--ease),box-shadow .25s var(--ease),background .25s;
   white-space:nowrap;
}
.btn svg{transition:transform .25s var(--ease)}
.btn--sm{padding:9px 16px;font-size:14px}
.btn--lg{padding:15px 28px;font-size:16px}
.btn--block{width:100%}
.btn--primary{
   background:var(--grad-brand);color:#0a0a14;
   box-shadow:0 8px 30px -6px rgba(129,140,248,.5);
}
.btn--primary:hover{transform:translateY(-2px);box-shadow:0 14px 40px -8px rgba(34,211,238,.55)}
.btn--primary:hover svg{transform:translateX(3px)}
.btn--ghost{
   background:var(--surface);color:var(--text);
   border:1px solid var(--border-strong);backdrop-filter:blur(10px);
}
.btn--ghost:hover{transform:translateY(-2px);background:var(--surface-2);border-color:rgba(255,255,255,.25)}

/* ---------- nav ---------- */
.nav{
   position:fixed;top:0;left:0;right:0;z-index:100;
   transition:background .3s,backdrop-filter .3s,border-color .3s;
   border-bottom:1px solid transparent;
}
.nav.is-scrolled{
   background:rgba(10,10,18,.72);backdrop-filter:blur(16px) saturate(160%);
   border-bottom-color:var(--border);
}
.nav__inner{display:flex;align-items:center;justify-content:space-between;height:72px}
.brand{display:flex;align-items:center;gap:10px}
.brand__logo{height:30px;width:auto;display:block}
.nav__links{display:flex;gap:30px;font-size:15px;color:var(--text-dim);font-weight:500}
.nav__links a{position:relative;transition:color .2s}
.nav__links a::after{
   content:"";position:absolute;left:0;bottom:-6px;height:2px;width:0;
   background:var(--grad-brand);border-radius:2px;transition:width .3s var(--ease);
}
.nav__links a:hover{color:var(--text)}
.nav__links a:hover::after{width:100%}
.nav__links a.is-active{color:var(--text)}
.nav__links a.is-active::after{width:100%}
.nav__cta{display:flex;align-items:center;gap:14px}
.nav__toggle{display:none;flex-direction:column;gap:5px;padding:8px}
.nav__toggle span{width:22px;height:2px;background:var(--text);border-radius:2px;transition:.3s}

/* ---------- hero ---------- */
.hero{padding-top:150px;padding-bottom:40px}
.hero__grid{display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center}
.pill{
   display:inline-flex;align-items:center;gap:9px;font-size:13.5px;font-weight:500;
   padding:7px 15px;border-radius:999px;background:var(--surface);
   border:1px solid var(--border-strong);color:var(--text-dim);
   backdrop-filter:blur(10px);margin-bottom:26px;
}
.pill__dot{width:7px;height:7px;border-radius:50%;background:#34d399;box-shadow:0 0 0 4px rgba(52,211,153,.2);animation:pulse 2s infinite}
@keyframes pulse{50%{box-shadow:0 0 0 8px rgba(52,211,153,0)}}
.hero__title{font-size:clamp(38px,6vw,66px);font-weight:900;margin-bottom:22px}
.hero__sub{font-size:clamp(16px,1.6vw,19px);color:var(--text-dim);max-width:540px;margin-bottom:34px}
.hero__sub b{color:var(--text);font-weight:600}
.hero__actions{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:34px}
.hero__meta{color:var(--text-mute);font-size:14.5px;font-weight:500}
.jumpin{margin-top:64px}
.jumpin__label{font-size:13px;color:var(--text-mute);text-transform:uppercase;letter-spacing:.12em;margin-bottom:16px;text-align:center;}
.jumpin__row{display:flex;flex-wrap:wrap;justify-content:center;gap:12px}
.jumpin__row a{
   display:inline-flex;align-items:center;gap:9px;font-weight:600;font-size:15px;
   padding:11px 18px;border-radius:12px;background:var(--surface);
   border:1px solid var(--border);transition:transform .25s var(--ease),border-color .25s,background .25s;
}
.jumpin__row a span{font-size:17px}
.jumpin__row a:hover{transform:translateY(-3px);border-color:var(--border-strong);background:var(--surface-2)}

/* dashboard mockup */
.hero__visual{position:relative;perspective:1400px}
.window{
   background:linear-gradient(180deg,rgba(20,20,32,.9),rgba(12,12,22,.95));
   border:1px solid var(--border-strong);border-radius:var(--radius-lg);
   box-shadow:var(--shadow);overflow:hidden;
   transform:rotateY(-8deg) rotateX(4deg);
   transition:transform .5s var(--ease);
   backdrop-filter:blur(20px);
}
.hero__visual:hover .window{transform:rotateY(-3deg) rotateX(2deg)}
.window__bar{display:flex;align-items:center;gap:8px;padding:12px 16px;border-bottom:1px solid var(--border);background:rgba(255,255,255,.02)}
.dot{width:11px;height:11px;border-radius:50%}
.dot--r{background:#ff5f57}.dot--y{background:#febc2e}.dot--g{background:#28c840}
.window__url{margin-left:12px;font-size:12px;color:var(--text-mute);font-family:'JetBrains Mono',monospace}
.window__body{display:grid;grid-template-columns:56px 1fr;min-height:300px}
.mini-nav{border-right:1px solid var(--border);padding:16px 8px;display:flex;flex-direction:column;gap:12px;align-items:center}
.mini-nav__logo{width:32px;height:32px;border-radius:9px;background:var(--grad-brand);margin-bottom:8px}
.mini-nav__item{width:26px;height:26px;border-radius:8px;background:var(--surface-2)}
.mini-nav__item.active{background:var(--grad-brand)}
.mini-main{padding:18px}
.mini-head__title{font-weight:700;font-size:15px}
.mini-head__sub{font-size:12px;color:var(--text-mute);margin-bottom:18px}
.mini-cards{display:grid;grid-template-columns:1fr 1fr 1fr;gap:10px;margin-bottom:18px}
.mini-card{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:12px}
.mini-card__label{display:block;font-size:10.5px;color:var(--text-mute)}
.mini-card__val{display:block;font-size:19px;font-weight:800;margin:3px 0 8px}
.mini-bar{height:5px;background:rgba(255,255,255,.08);border-radius:3px;overflow:hidden}
.mini-bar i{display:block;height:100%;background:var(--grad-brand);border-radius:3px}
.mini-chart{display:flex;align-items:flex-end;gap:6px;height:80px}
.mini-chart span{flex:1;background:linear-gradient(180deg,#818cf8,#22d3ee);border-radius:4px 4px 0 0;opacity:.85;animation:grow .8s var(--ease) both}
@keyframes grow{from{transform:scaleY(0);transform-origin:bottom}}
.float-card{
   position:absolute;display:flex;align-items:center;gap:10px;
   background:rgba(16,16,26,.85);border:1px solid var(--border-strong);
   border-radius:14px;padding:12px 16px;backdrop-filter:blur(14px);
   box-shadow:var(--shadow);font-size:13px;
}
.float-card__icon{font-size:20px}
.float-card b{display:block;font-size:13px}.float-card small{color:var(--text-mute)}
.float-card--tl{top:20px;left:-30px;animation:bob 5s ease-in-out infinite}
.float-card--br{bottom:30px;right:-24px;animation:bob 5s ease-in-out infinite .8s}
@keyframes bob{50%{transform:translateY(-12px)}}

/* logos */
.logos{margin-top:80px;text-align:center}
.logos__label{font-size:13px;color:var(--text-mute);text-transform:uppercase;letter-spacing:.12em;margin-bottom:24px}
.logos__row{display:flex;flex-wrap:wrap;justify-content:center;gap:14px 40px;font-weight:600;color:var(--text-mute);opacity:.75}
.logos__row span{transition:color .2s,opacity .2s;font-size:17px}
.logos__row span:hover{color:var(--text);opacity:1}

/* ---------- stats ---------- */
.stats{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;padding-block:20px}
.stat{text-align:center;padding:28px 16px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--border)}
.stat__num{display:block;font-size:clamp(30px,4vw,44px);font-weight:900;background:var(--grad-cool);-webkit-background-clip:text;background-clip:text;color:transparent}
.stat__label{display:block;color:var(--text-dim);font-size:14px;margin-top:6px}

/* ---------- section head ---------- */
.section__head{text-align:center;max-width:640px;margin:0 auto 56px}
.section__title{font-size:clamp(28px,4vw,44px);font-weight:900}
.section__sub{color:var(--text-dim);font-size:17px;margin-top:16px}

/* ---------- feature grid ---------- */
.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.card{
   background:var(--surface);border:1px solid var(--border);
   border-radius:var(--radius);padding:28px;position:relative;overflow:hidden;
   transition:transform .35s var(--ease),border-color .35s,background .35s;
}
.card::before{
   content:"";position:absolute;inset:0;border-radius:inherit;padding:1px;
   background:linear-gradient(135deg,rgba(129,140,248,.4),transparent 40%);
   -webkit-mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);
   -webkit-mask-composite:xor;mask-composite:exclude;opacity:0;transition:opacity .35s;
}
.card:hover{transform:translateY(-6px);border-color:transparent;background:var(--surface-2)}
.card:hover::before{opacity:1}
.feature__icon{
   width:52px;height:52px;border-radius:14px;display:grid;place-items:center;margin-bottom:18px;
   background:linear-gradient(135deg,var(--c1),var(--c2));
   color:#0a0a14;font-size:22px;
   box-shadow:0 12px 30px -12px var(--c2);
}
.feature h3{font-size:19px;margin-bottom:8px}
.feature p{color:var(--text-dim);font-size:15px}

/* ---------- tabs ---------- */
.tabs{max-width:960px;margin:0 auto}
.tabs__list{display:flex;justify-content:center;gap:6px;padding:6px;background:var(--surface);border:1px solid var(--border);border-radius:999px;margin:0 auto 32px;position:relative}
.tabs__btn{
   padding:11px 24px;border-radius:999px;font-weight:600;font-size:15px;
   color:var(--text-dim);transition:color .25s,background .25s var(--ease),box-shadow .25s var(--ease);z-index:1;position:relative;
}
.tabs__btn.is-active{
   color:#0a0a14;background:var(--grad-brand);
   box-shadow:0 8px 24px -8px rgba(129,140,248,.55);
}
.tabs__panels{position:relative}
.tab-panel{display:none;grid-template-columns:1fr 1fr;gap:40px;align-items:center;animation:fadeIn .5s var(--ease)}
.tab-panel.is-active{display:grid}
.tab-panel[hidden]{display:none}
@keyframes fadeIn{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:none}}
.tab-panel__text h3{font-size:26px;margin-bottom:14px}
.tab-panel__text p{color:var(--text-dim);margin-bottom:22px;font-size:16px}
.checklist{display:flex;flex-direction:column;gap:12px;margin-bottom:26px}
.checklist li{position:relative;padding-left:32px;font-size:15px;color:var(--text)}
.checklist li::before{
   content:"✓";position:absolute;left:0;top:0;width:22px;height:22px;
   display:grid;place-items:center;border-radius:50%;font-size:12px;font-weight:700;
   background:var(--grad-brand);color:#0a0a14;
}
.checklist--muted li{color:var(--text-dim)}
.tab-panel__art{
   height:320px;border-radius:var(--radius-lg);border:1px solid var(--border);
   position:relative;overflow:hidden;box-shadow:var(--shadow);
}
.art--student{background:radial-gradient(120% 120% at 0% 0%,#f59e0b 0%,#0b0b16 62%)}
.art--faculty{background:radial-gradient(120% 120% at 100% 0%,#0ea5e9 0%,#0b0b16 62%)}
.art--admin{background:radial-gradient(120% 120% at 50% 100%,#8b5cf6 0%,#0b0b16 62%)}
.tab-panel__art::after{
   content:"";position:absolute;inset:0;
   background:
      linear-gradient(90deg,rgba(255,255,255,.06) 1px,transparent 1px) 0 0/30px 30px,
      linear-gradient(rgba(255,255,255,.06) 1px,transparent 1px) 0 0/30px 30px;
   mask-image:radial-gradient(ellipse at center,#000,transparent 80%);
}
.tab-panel__art span{
   position:absolute;font-size:40px;filter:drop-shadow(0 8px 20px rgba(0,0,0,.5));
   animation:bob 4s ease-in-out infinite;
}

/* ---------- steps ---------- */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;counter-reset:step}
.step{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:30px;position:relative}
.step__num{
   display:grid;place-items:center;width:48px;height:48px;border-radius:14px;
   background:var(--grad-brand);color:#0a0a14;font-weight:800;font-size:20px;margin-bottom:18px;
}
.step h3{font-size:20px;margin-bottom:10px}
.step p{color:var(--text-dim);font-size:15px}

/* ---------- principles ---------- */
.princ{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.princ__card{
   background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);
   padding:30px;transition:transform .35s var(--ease),border-color .35s,background .35s;
}
.princ__card:hover{transform:translateY(-5px);border-color:var(--border-strong);background:var(--surface-2)}
.princ__icon{
   display:grid;place-items:center;width:50px;height:50px;border-radius:14px;
   font-size:22px;margin-bottom:18px;color:#0a0a14;
   background:linear-gradient(135deg,var(--c1),var(--c2));
   box-shadow:0 12px 30px -12px var(--c2);
}
.princ__card h3{font-size:20px;margin-bottom:10px}
.princ__card p{color:var(--text-dim);font-size:15px}

/* ---------- faq ---------- */
.faq{display:flex;flex-direction:column;gap:12px}
.faq__item{
   background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-sm);
  padding:4px 22px;transition:border-color .3s,background .3s;
  interpolate-size:allow-keywords;
  overflow:hidden;
}
.faq__item[open]{border-color:var(--border-strong);background:var(--surface-2)}
.faq__item::details-content{block-size:0;overflow:clip;content-visibility:hidden;transition:
  block-size 150ms ease,content-visibility 150ms ease;
  transition-behavior:allow-discrete;
}
.faq__item[open]::details-content{block-size:auto;content-visibility:visible}
.faq__item summary{
   list-style:none;cursor:pointer;display:flex;justify-content:space-between;align-items:center;
   padding:20px 0;font-weight:600;font-size:17px;
}
.faq__item summary::-webkit-details-marker{display:none}
.faq__icon{position:relative;width:20px;height:20px;flex-shrink:0;transition:transform .3s var(--ease)}
.faq__icon::before,.faq__icon::after{
   content:"";position:absolute;background:var(--text);border-radius:2px;top:50%;left:50%;
   transform:translate(-50%,-50%);transition:transform .3s var(--ease);
}
.faq__icon::before{width:14px;height:2px}
.faq__icon::after{width:2px;height:14px}
.faq__item[open] .faq__icon::after{transform:translate(-50%,-50%) rotate(90deg);opacity:0}
.faq__item p{color:var(--text-dim);padding-bottom:20px;font-size:15.5px}

/* ---------- cta ---------- */
.cta{
   position:relative;text-align:center;padding:clamp(40px,6vw,72px) clamp(24px,5vw,64px);
   border-radius:var(--radius-lg);overflow:hidden;
   background:linear-gradient(135deg,rgba(129,140,248,.14),rgba(34,211,238,.1));
   border:1px solid var(--border-strong);
}
.cta__glow{position:absolute;inset:-40%;background:var(--grad-glow);animation:spin 20s linear infinite;pointer-events:none}
@keyframes spin{to{transform:rotate(360deg)}}
.cta h2{font-size:clamp(28px,4vw,42px);position:relative;margin-bottom:14px}
.cta p{color:var(--text-dim);font-size:17px;position:relative;margin-bottom:28px}
.cta__actions{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;position:relative}

/* ---------- footer ---------- */
.footer{border-top:1px solid var(--border);margin-top:60px;padding-top:60px;background:var(--bg-soft)}
.footer__grid{display:grid;grid-template-columns:1.6fr repeat(4,1fr);gap:40px;padding-bottom:44px}
.footer__tag{color:var(--text-mute);font-size:14px;max-width:260px;margin:18px 0 20px}
.socials{display:flex;gap:10px}
.socials a{
   width:38px;height:38px;display:grid;place-items:center;border-radius:10px;
   background:var(--surface);border:1px solid var(--border);font-weight:700;font-size:14px;
   transition:transform .25s var(--ease),border-color .25s;
}
.socials a:hover{transform:translateY(-3px);border-color:var(--border-strong)}
.footer__col h4{font-size:14px;margin-bottom:16px;color:var(--text)}
.footer__col a{display:block;color:var(--text-dim);font-size:14px;padding:6px 0;transition:color .2s}
.footer__col a:hover{color:var(--text)}
.footer__bottom{
   display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:12px;
   padding-top:24px;padding-bottom:32px;border-top:1px solid var(--border);
   color:var(--text-mute);font-size:13.5px;
}

/* ---------- reveal animation ---------- */
.js .reveal{opacity:0;transform:translateY(28px);transition:opacity .7s var(--ease),transform .7s var(--ease)}
.js .reveal.is-visible{opacity:1;transform:none}

/* ---------- responsive ---------- */
@media(max-width:980px){
   .hero__grid{grid-template-columns:1fr;gap:48px}
   .hero__visual{order:2}
    .feature-grid,.steps,.princ{grid-template-columns:repeat(2,1fr)}
   .stats{grid-template-columns:repeat(2,1fr)}
   .footer__grid{grid-template-columns:1fr 1fr 1fr}
   .tab-panel{grid-template-columns:1fr}
   .tab-panel__art{height:220px}
}
@media(max-width:760px){
   .nav__links{
      position:fixed;inset:72px 0 auto 0;flex-direction:column;gap:0;
      background:rgba(10,10,18,.97);backdrop-filter:blur(16px);
      padding:12px 24px 24px;border-bottom:1px solid var(--border);
      transform:translateY(calc(-100% - 80px));transition:transform .4s var(--ease);
   }
   .nav__links.is-open{transform:none}
   .nav__links a{padding:14px 0;border-bottom:1px solid var(--border)}
    .nav__links a::after{display:none}
    .nav__links a.is-active{color:var(--text);border-bottom-color:var(--border-strong)}
    .nav__toggle{display:flex}
   .nav__cta .btn--ghost{display:none}
    .feature-grid,.steps,.princ,.stats{grid-template-columns:1fr}
   .footer__grid{grid-template-columns:1fr 1fr}
   .footer__brand{grid-column:1/-1}
}
@media(max-width:480px){
   .footer__grid{grid-template-columns:1fr}
   .float-card--tl{left:0}.float-card--br{right:0}
}

@media(prefers-reduced-motion:reduce){
   *,*::before,*::after{animation:none!important;transition:none!important}
   .js .reveal{opacity:1;transform:none}
}
section[id],main[id]{scroll-margin-top:96px}