/* =========================================================
   YOUSUF AL AHSAN — Portfolio
   Tokens
========================================================= */
:root{
  --bg-primary:#0E1116;
  --bg-secondary:#0B0F16;
  --bg-elevated:#151B24;
  --bg-elevated-2:#1B2330;
  --border:rgba(255,255,255,0.09);
  --border-strong:rgba(255,255,255,0.16);
  --text-primary:#F5F7FA;
  --text-secondary:#9AA5B4;
  --text-muted:#6B7688;

  --accent-blue:#3E7BFA;
  --accent-blue-soft:#7FB0FF;
  --accent-blue-dim:rgba(62,123,250,0.14);
  --available-green:#34D399;

  --font-display:'Space Grotesk', 'Hind Siliguri', sans-serif;
  --font-bn:'Hind Siliguri', 'Space Grotesk', sans-serif;
  --font-body:'Inter', 'Hind Siliguri', sans-serif;

  --radius-sm:10px;
  --radius-md:16px;
  --radius-lg:24px;

  --shadow-glow:0 0 0 1px var(--border), 0 20px 60px -20px rgba(62,123,250,0.25);
  --ease:cubic-bezier(.16,.8,.24,1);

  color-scheme: dark;
}

html[data-theme="light"]{
  --bg-primary:#F6F8FB;
  --bg-secondary:#FFFFFF;
  --bg-elevated:#FFFFFF;
  --bg-elevated-2:#EEF2F8;
  --border:rgba(15,23,42,0.09);
  --border-strong:rgba(15,23,42,0.16);
  --text-primary:#11151D;
  --text-secondary:#525C6B;
  --text-muted:#8892A0;

  --accent-blue:#2F6FED;
  --accent-blue-soft:#5D93F5;
  --accent-blue-dim:rgba(47,111,237,0.09);
  --available-green:#0FA372;

  --shadow-glow:0 0 0 1px var(--border), 0 20px 60px -25px rgba(47,111,237,0.20);
  color-scheme: light;
}

*,*::before,*::after{box-sizing:border-box;}
html{scroll-behavior:smooth; scroll-padding-top:84px;}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto;}
}

body{
  margin:0;
  background:var(--bg-primary);
  color:var(--text-primary);
  font-family:var(--font-bn);
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
  transition:background .35s var(--ease), color .35s var(--ease);
  overflow-x:hidden;
}

h1,h2,h3,.font-display{font-family:var(--font-display);}
p,li,a,span{font-family:inherit;}

img,svg{display:block; max-width:100%;}
a{color:inherit; text-decoration:none;}

.skip-link{
  position:absolute; left:-9999px; top:0; z-index:200;
  background:var(--accent-blue); color:#fff; padding:.75rem 1.25rem; border-radius:0 0 10px 0;
}
.skip-link:focus{left:0;}

:focus-visible{outline:2px solid var(--accent-blue); outline-offset:3px; border-radius:4px;}

/* =========================================================
   Layout helpers
========================================================= */
.section-inner{
  max-width:1160px;
  margin:0 auto;
  padding:0 24px;
}
.section{padding:110px 0;}
.section-alt{background:var(--bg-secondary);}
@media (max-width:720px){
  .section{padding:76px 0;}
}

.eyebrow{
  font-family:var(--font-display);
  font-size:.8rem;
  letter-spacing:.12em;
  text-transform:uppercase;
  color:var(--accent-blue);
  font-weight:600;
  margin:0 0 12px;
  display:flex; align-items:center; gap:8px;
}
.eyebrow::before{
  content:"";
  width:16px; height:1px;
  background:var(--accent-blue);
  display:inline-block;
}

.section-title{
  font-size:clamp(1.6rem, 2.6vw, 2.3rem);
  font-weight:600;
  line-height:1.35;
  margin:0 0 20px;
  max-width:760px;
}
.section-note{
  color:var(--text-secondary);
  max-width:640px;
  margin:-6px 0 40px;
}

/* =========================================================
   Buttons
========================================================= */
.btn{
  display:inline-flex; align-items:center; gap:10px;
  padding:14px 26px;
  border-radius:100px;
  font-family:var(--font-bn);
  font-weight:600;
  font-size:.98rem;
  border:1px solid transparent;
  cursor:pointer;
  transition:transform .25s var(--ease), background .25s var(--ease), border-color .25s var(--ease), box-shadow .25s var(--ease);
}
.btn svg{width:16px; height:16px;}
.btn-primary{
  background:var(--accent-blue);
  color:#fff;
  box-shadow:0 10px 30px -10px rgba(62,123,250,0.55);
}
.btn-primary:hover{transform:translateY(-2px); box-shadow:0 16px 34px -10px rgba(62,123,250,0.6);}
.btn-ghost{
  background:transparent;
  border-color:var(--border-strong);
  color:var(--text-primary);
}
.btn-ghost:hover{border-color:var(--accent-blue); color:var(--accent-blue); transform:translateY(-2px);}

.hero-cta{display:flex; flex-wrap:wrap; gap:14px; margin:34px 0 26px;}

/* =========================================================
   Nav
========================================================= */
.site-nav{
  position:fixed; top:0; left:0; right:0; z-index:100;
  padding:18px 0;
  transition:background .3s var(--ease), padding .3s var(--ease), border-color .3s var(--ease), backdrop-filter .3s var(--ease);
  border-bottom:1px solid transparent;
}
.site-nav.is-scrolled{
  padding:12px 0;
  background:color-mix(in srgb, var(--bg-primary) 78%, transparent);
  backdrop-filter:blur(14px) saturate(140%);
  border-bottom-color:var(--border);
}
.nav-inner{
  max-width:1160px; margin:0 auto; padding:0 24px;
  display:flex; align-items:center; justify-content:space-between;
}
.nav-brand{display:flex; align-items:center; gap:10px; font-family:var(--font-display); font-weight:700; font-size:1.15rem;}
.brand-mark{
  width:10px; height:10px; border-radius:3px;
  background:linear-gradient(135deg, var(--accent-blue-soft), var(--accent-blue));
  box-shadow:0 0 14px rgba(62,123,250,.7);
}
.brand-accent{color:var(--accent-blue);}

.nav-links{display:flex; gap:30px;}
.nav-links a{
  font-size:.94rem; color:var(--text-secondary); font-weight:500;
  position:relative; padding:4px 0;
  transition:color .2s var(--ease);
}
.nav-links a:hover{color:var(--text-primary);}
.nav-links a::after{
  content:""; position:absolute; left:0; bottom:-2px; width:0; height:1.5px;
  background:var(--accent-blue); transition:width .25s var(--ease);
}
.nav-links a:hover::after{width:100%;}

.nav-actions{display:flex; align-items:center; gap:14px;}
.theme-toggle{
  width:38px; height:38px; border-radius:50%;
  display:flex; align-items:center; justify-content:center;
  background:var(--bg-elevated); border:1px solid var(--border);
  color:var(--text-primary); cursor:pointer;
}
.theme-toggle svg{width:17px; height:17px;}
.theme-toggle .icon-moon{display:none;}
html[data-theme="light"] .theme-toggle .icon-sun{display:none;}
html[data-theme="light"] .theme-toggle .icon-moon{display:block;}

.nav-burger{
  display:none; width:38px; height:38px; border-radius:50%;
  border:1px solid var(--border); background:var(--bg-elevated);
  flex-direction:column; align-items:center; justify-content:center; gap:4px;
  cursor:pointer;
}
.nav-burger span{width:16px; height:1.6px; background:var(--text-primary); transition:transform .25s var(--ease), opacity .25s var(--ease);}
.nav-burger.is-open span:nth-child(1){transform:translateY(5.6px) rotate(45deg);}
.nav-burger.is-open span:nth-child(2){opacity:0;}
.nav-burger.is-open span:nth-child(3){transform:translateY(-5.6px) rotate(-45deg);}

@media (max-width:860px){
  .nav-links{
    position:fixed; top:0; right:0; height:100vh; width:min(78vw,320px);
    background:var(--bg-elevated); border-left:1px solid var(--border);
    flex-direction:column; padding:100px 32px 32px; gap:22px;
    transform:translateX(100%); transition:transform .35s var(--ease);
  }
  .nav-links.is-open{transform:translateX(0);}
  .nav-links a{font-size:1.05rem;}
  .nav-burger{display:flex;}
}

/* =========================================================
   Hero
========================================================= */
.hero{
  position:relative;
  padding:168px 0 100px;
  background:
    radial-gradient(60% 50% at 82% 12%, var(--accent-blue-dim), transparent 60%),
    var(--bg-primary);
  overflow:hidden;
}
.hero-inner{
  max-width:1160px; margin:0 auto; padding:0 24px;
  display:grid; grid-template-columns:1.1fr .9fr; gap:60px; align-items:center;
}
.hero-name{
  font-size:clamp(2.2rem, 5vw, 3.6rem);
  font-weight:700; letter-spacing:-.01em;
  margin:6px 0 2px; line-height:1.05;
}
.hero-name-bn{
  font-family:var(--font-bn); font-size:1.2rem; color:var(--text-secondary); margin:0 0 18px; font-weight:500;
}
.hero-title{
  font-size:1.05rem; color:var(--text-secondary); font-weight:500; margin:0 0 16px;
}
.hero-title .dot{color:var(--accent-blue); margin:0 4px;}
.hero-tagline{
  font-family:var(--font-display); font-style:italic; font-size:1.2rem;
  color:var(--accent-blue-soft); margin:0 0 20px;
}
.hero-intro{
  max-width:520px; color:var(--text-secondary); font-size:1.02rem;
}

.status-badge{
  display:inline-flex; align-items:center; gap:9px;
  padding:9px 16px; border-radius:100px;
  background:var(--bg-elevated); border:1px solid var(--border);
  font-size:.86rem; font-weight:600;
}
.status-dot{
  width:8px; height:8px; border-radius:50%; background:var(--available-green);
  box-shadow:0 0 0 0 rgba(52,211,153,.55);
  animation:pulse-dot 2.2s infinite;
}
@keyframes pulse-dot{
  0%{box-shadow:0 0 0 0 rgba(52,211,153,.55);}
  70%{box-shadow:0 0 0 8px rgba(52,211,153,0);}
  100%{box-shadow:0 0 0 0 rgba(52,211,153,0);}
}

/* Hero visual — signature signal glyph */
.hero-visual{position:relative; display:flex; justify-content:center;}
.signal-card{
  position:relative; width:100%; max-width:400px; aspect-ratio:9/8;
  background:var(--bg-elevated);
  border:1px solid var(--border);
  border-radius:var(--radius-lg);
  box-shadow:var(--shadow-glow);
  padding:16px;
}
.signal-svg{width:100%; height:100%;}
.grid-dots circle{fill:var(--border-strong);}
.signal-path{
  stroke-dasharray:900;
  stroke-dashoffset:900;
  animation:draw-signal 2.2s var(--ease) .3s forwards;
}
.signal-nodes circle{
  fill:var(--bg-elevated); stroke:var(--accent-blue); stroke-width:2.5;
  opacity:0; transform-origin:center;
  animation:node-pop .5s var(--ease) forwards;
}
.signal-nodes circle:nth-child(1){animation-delay:.7s;}
.signal-nodes circle:nth-child(2){animation-delay:1s;}
.signal-nodes circle:nth-child(3){animation-delay:1.3s;}
.signal-nodes circle:nth-child(4){animation-delay:1.6s;}
.node-final{fill:var(--accent-blue); animation-delay:1.9s !important;}
@keyframes draw-signal{to{stroke-dashoffset:0;}}
@keyframes node-pop{
  0%{opacity:0; transform:scale(0);}
  70%{opacity:1; transform:scale(1.3);}
  100%{opacity:1; transform:scale(1);}
}
.node-final{animation-name:node-pop-glow;}
@keyframes node-pop-glow{
  0%{opacity:0; transform:scale(0);}
  70%{opacity:1; transform:scale(1.4); filter:drop-shadow(0 0 10px var(--accent-blue));}
  100%{opacity:1; transform:scale(1); filter:drop-shadow(0 0 6px var(--accent-blue));}
}

.orbit-badge{
  position:absolute;
  font-family:var(--font-display); font-size:.72rem; font-weight:600;
  padding:7px 13px; border-radius:100px;
  background:var(--bg-elevated-2); border:1px solid var(--border);
  color:var(--text-secondary);
  animation:float-badge 5s ease-in-out infinite;
}
.badge-1{top:8%; left:-6%; animation-delay:0s;}
.badge-2{top:20%; right:-8%; animation-delay:.6s;}
.badge-3{bottom:14%; left:-8%; animation-delay:1.1s;}
.badge-4{bottom:2%; right:2%; animation-delay:1.7s;}
@keyframes float-badge{
  0%,100%{transform:translateY(0);}
  50%{transform:translateY(-8px);}
}

@media (prefers-reduced-motion: reduce){
  .signal-path,.signal-nodes circle,.orbit-badge,.status-dot,.reveal{animation:none !important; transition:none !important;}
  .signal-path{stroke-dashoffset:0;}
  .signal-nodes circle{opacity:1; transform:scale(1);}
}

@media (max-width:900px){
  .hero-inner{grid-template-columns:1fr; gap:56px; text-align:left;}
  .hero-visual{order:-1; max-width:340px; margin:0 auto;}
  .hero{padding-top:140px;}
}
@media (max-width:520px){
  .orbit-badge{display:none;}
}

/* =========================================================
   About
========================================================= */
.about-grid{
  display:grid; grid-template-columns:1.05fr .95fr; gap:70px; align-items:start;
}
.about-text{color:var(--text-secondary); max-width:540px;}
.about-edu{
  padding:16px 18px; border-left:2px solid var(--accent-blue);
  background:var(--bg-elevated); border-radius:0 var(--radius-sm) var(--radius-sm) 0;
  font-size:.95rem;
}
.about-facts{list-style:none; margin:28px 0 0; padding:0; display:flex; flex-direction:column; gap:14px;}
.about-facts li{display:flex; align-items:center; gap:14px; color:var(--text-secondary); font-size:.95rem;}
.fact-num{
  font-family:var(--font-display); font-weight:700; color:var(--accent-blue);
  min-width:56px;
}

.what-i-do{background:var(--bg-elevated); border:1px solid var(--border); border-radius:var(--radius-lg); padding:32px;}
.pillar-list{display:flex; flex-direction:column; gap:22px; margin-top:8px;}
.pillar{display:flex; gap:16px; align-items:flex-start;}
.pillar-icon{
  width:42px; height:42px; flex:none; border-radius:var(--radius-sm);
  background:var(--accent-blue-dim); color:var(--accent-blue);
  display:flex; align-items:center; justify-content:center;
}
.pillar-icon svg{width:20px; height:20px;}
.pillar h3{margin:0 0 4px; font-size:1rem; font-weight:600;}
.pillar p{margin:0; color:var(--text-secondary); font-size:.9rem;}

@media (max-width:860px){
  .about-grid{grid-template-columns:1fr;}
}

/* =========================================================
   Skills
========================================================= */
.skills-block{margin-bottom:34px;}
.skills-block:last-child{margin-bottom:0;}
.skills-label{
  font-size:.85rem; text-transform:uppercase; letter-spacing:.06em;
  color:var(--text-muted); font-weight:600; margin:0 0 16px;
}
.tag-row{display:flex; flex-wrap:wrap; gap:12px;}
.tag{
  padding:10px 18px; border-radius:100px;
  background:var(--bg-elevated); border:1px solid var(--border);
  font-size:.9rem; font-weight:500; color:var(--text-secondary);
  transition:border-color .25s var(--ease), color .25s var(--ease), transform .25s var(--ease);
}
.tag:hover{border-color:var(--accent-blue); color:var(--text-primary); transform:translateY(-2px);}
.tag-primary{
  background:var(--accent-blue-dim); border-color:rgba(62,123,250,.3); color:var(--text-primary); font-weight:600;
}

/* =========================================================
   Services
========================================================= */
.services-grid{
  display:grid; grid-template-columns:repeat(3, 1fr); gap:20px;
}
.service-card{
  background:var(--bg-elevated); border:1px solid var(--border); border-radius:var(--radius-md);
  padding:30px; transition:transform .3s var(--ease), border-color .3s var(--ease), box-shadow .3s var(--ease);
}
.service-card:hover{transform:translateY(-4px); border-color:var(--border-strong); box-shadow:0 20px 40px -24px rgba(0,0,0,.4);}
.service-featured{
  grid-column:span 2;
  background:linear-gradient(155deg, var(--accent-blue-dim), var(--bg-elevated) 60%);
  border-color:rgba(62,123,250,.35);
}
.service-icon{
  width:46px; height:46px; border-radius:12px;
  background:var(--accent-blue); color:#fff;
  display:flex; align-items:center; justify-content:center; margin-bottom:18px;
}
.service-featured .service-icon{width:52px; height:52px;}
.service-icon svg{width:22px; height:22px;}
.service-card h3{margin:0 0 10px; font-size:1.08rem; font-weight:600;}
.service-card p{margin:0; color:var(--text-secondary); font-size:.92rem;}
.service-tags{list-style:none; display:flex; flex-wrap:wrap; gap:8px; padding:0; margin:18px 0 0;}
.service-tags li{
  font-size:.78rem; font-weight:600; padding:6px 12px; border-radius:100px;
  background:var(--bg-primary); border:1px solid var(--border); color:var(--text-secondary);
}

@media (max-width:860px){
  .services-grid{grid-template-columns:1fr 1fr;}
  .service-featured{grid-column:span 2;}
}
@media (max-width:560px){
  .services-grid{grid-template-columns:1fr;}
  .service-featured{grid-column:span 1;}
}

/* =========================================================
   Journey / Timeline
========================================================= */
.timeline{
  list-style:none; margin:0; padding:0;
  position:relative;
  max-width:720px;
}
.timeline::before{
  content:""; position:absolute; left:7px; top:8px; bottom:8px; width:1.5px;
  background:linear-gradient(var(--accent-blue), transparent 95%);
  opacity:.4;
}
.timeline-item{
  position:relative; padding:0 0 42px 40px;
}
.timeline-item:last-child{padding-bottom:0;}
.timeline-marker{
  position:absolute; left:0; top:4px; width:16px; height:16px; border-radius:50%;
  background:var(--bg-primary); border:2px solid var(--accent-blue);
}
.timeline-marker::after{
  content:""; position:absolute; inset:3px; border-radius:50%; background:var(--accent-blue);
}
.timeline-year{
  font-family:var(--font-display); font-size:.78rem; font-weight:700; letter-spacing:.05em;
  color:var(--accent-blue); text-transform:uppercase;
}
.timeline-item h3{margin:6px 0 6px; font-size:1.05rem; font-weight:600;}
.timeline-item p{margin:0; color:var(--text-secondary); max-width:520px;}

/* =========================================================
   Worked on / Selected work
========================================================= */
.worked-grid{
  display:grid; grid-template-columns:repeat(4, 1fr); gap:14px; margin-bottom:64px;
}
.worked-card{
  background:var(--bg-elevated); border:1px solid var(--border); border-radius:var(--radius-md);
  padding:22px 20px; transition:border-color .25s var(--ease), transform .25s var(--ease);
}
.worked-card:hover{border-color:var(--accent-blue); transform:translateY(-3px);}
.worked-card h3{margin:0; font-size:.95rem; font-weight:600; line-height:1.4;}

.selected-empty{
  border:1.5px dashed var(--border-strong); border-radius:var(--radius-md);
  padding:46px 24px; text-align:center;
  color:var(--text-muted); font-size:.95rem;
  background:repeating-linear-gradient(135deg, var(--bg-elevated) 0 18px, var(--bg-secondary) 18px 36px);
}

@media (max-width:860px){
  .worked-grid{grid-template-columns:repeat(2,1fr);}
}
@media (max-width:520px){
  .worked-grid{grid-template-columns:1fr;}
}

/* =========================================================
   Why work with me
========================================================= */
.why-grid{
  display:grid; grid-template-columns:repeat(4, 1fr); gap:18px;
}
.why-card{
  background:var(--bg-primary); border:1px solid var(--border); border-radius:var(--radius-md);
  padding:26px 22px;
}
.why-card h3{margin:0 0 10px; font-size:1rem; font-weight:600; color:var(--accent-blue-soft);}
.why-card p{margin:0; color:var(--text-secondary); font-size:.9rem;}

@media (max-width:860px){.why-grid{grid-template-columns:1fr 1fr;}}
@media (max-width:560px){.why-grid{grid-template-columns:1fr;}}

/* =========================================================
   Contact
========================================================= */
.contact-section{
  background:
    radial-gradient(50% 60% at 15% 20%, var(--accent-blue-dim), transparent 65%),
    var(--bg-primary);
}
.contact-grid{
  display:grid; grid-template-columns:1.1fr .9fr; gap:60px; align-items:center;
}
.contact-card{
  background:var(--bg-elevated); border:1px solid var(--border); border-radius:var(--radius-lg);
  padding:14px; display:flex; flex-direction:column; gap:4px;
}
.contact-row{
  display:flex; align-items:center; gap:14px; padding:16px;
  border-radius:var(--radius-sm);
  transition:background .2s var(--ease);
  font-size:.95rem; font-weight:500;
}
.contact-row:hover{background:var(--bg-elevated-2);}
.contact-icon{
  width:38px; height:38px; flex:none; border-radius:10px;
  background:var(--accent-blue-dim); color:var(--accent-blue);
  display:flex; align-items:center; justify-content:center;
}
.contact-icon svg{width:18px; height:18px;}

@media (max-width:860px){
  .contact-grid{grid-template-columns:1fr; gap:40px;}
}

/* =========================================================
   Footer
========================================================= */
.site-footer{
  background:var(--bg-secondary); border-top:1px solid var(--border);
  padding:48px 0 32px;
}
.footer-inner{max-width:1160px; margin:0 auto; padding:0 24px;}
.footer-tagline{
  max-width:560px; color:var(--text-secondary); margin:0 0 32px; font-size:.98rem;
}
.footer-row{
  display:flex; align-items:center; justify-content:space-between; flex-wrap:wrap; gap:18px;
  padding-top:24px; border-top:1px solid var(--border);
}
.footer-copy{margin:0; font-size:.85rem; color:var(--text-muted); font-family:var(--font-display);}
.footer-links{display:flex; gap:22px;}
.footer-links a{font-size:.88rem; color:var(--text-secondary); font-weight:500;}
.footer-links a:hover{color:var(--accent-blue);}
.back-to-top{
  width:38px; height:38px; border-radius:50%;
  background:var(--bg-elevated); border:1px solid var(--border); color:var(--text-primary);
  display:flex; align-items:center; justify-content:center; cursor:pointer;
  transition:transform .25s var(--ease), border-color .25s var(--ease);
}
.back-to-top svg{width:16px; height:16px;}
.back-to-top:hover{transform:translateY(-3px); border-color:var(--accent-blue);}

/* =========================================================
   Reveal on scroll
========================================================= */
.reveal{
  opacity:0; transform:translateY(22px);
  transition:opacity .7s var(--ease), transform .7s var(--ease);
}
.reveal.is-visible{opacity:1; transform:translateY(0);}
@media (prefers-reduced-motion: reduce){
  .reveal{opacity:1; transform:none; transition:none;}
}