/* =============================================================
   Vasanthakumar Kalaikkovan — Portfolio
   Dark, glass, neon-accented immersive 3D portfolio styles
   ============================================================= */

:root{
  --bg:            #05070d;
  --bg-soft:       #0a0f1a;
  --panel:         rgba(255,255,255,0.045);
  --panel-border:  rgba(255,255,255,0.09);
  --panel-hover:   rgba(255,255,255,0.08);
  --text:          #eaeef7;
  --text-muted:    #8d97ad;
  --cyan:          #4fd8ff;
  --violet:        #8a5cff;
  --pink:          #ff5cb0;
  --gradient:      linear-gradient(120deg, var(--cyan), var(--violet) 55%, var(--pink));
  --radius:        18px;
  --radius-sm:     12px;
  --maxw:          1180px;
  --font-head:     'Sora', 'Inter', system-ui, sans-serif;
  --font-body:     'Inter', system-ui, sans-serif;
  --font-mono:     'JetBrains Mono', monospace;
}

*, *::before, *::after{ box-sizing:border-box; }

html{ scroll-behavior:smooth; }

body{
  margin:0;
  background:var(--bg);
  color:var(--text);
  font-family:var(--font-body);
  line-height:1.6;
  overflow-x:hidden;
  -webkit-font-smoothing:antialiased;
}

::selection{ background:var(--violet); color:#fff; }

::-webkit-scrollbar{ width:10px; }
::-webkit-scrollbar-track{ background:var(--bg); }
::-webkit-scrollbar-thumb{ background:linear-gradient(var(--cyan), var(--violet)); border-radius:10px; }

h1,h2,h3{ font-family:var(--font-head); margin:0 0 .4em; letter-spacing:-0.01em; }

a{ color:inherit; text-decoration:none; }

img{ max-width:100%; display:block; }

/* ---------- Backdrop layers ---------- */
#bg-canvas{
  position:fixed; inset:0;
  width:100%; height:100%;
  z-index:0;
  pointer-events:none;
}

.grid-floor{
  position:fixed; inset:0;
  z-index:0;
  pointer-events:none;
  background-image:
    linear-gradient(rgba(79,216,255,0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(79,216,255,0.05) 1px, transparent 1px);
  background-size:56px 56px;
  mask-image:radial-gradient(ellipse 80% 60% at 50% 0%, #000 10%, transparent 70%);
  -webkit-mask-image:radial-gradient(ellipse 80% 60% at 50% 0%, #000 10%, transparent 70%);
  opacity:0.6;
}

.cursor-glow{
  position:fixed; top:0; left:0;
  width:420px; height:420px;
  border-radius:50%;
  pointer-events:none;
  z-index:1;
  background:radial-gradient(circle, rgba(79,216,255,0.08), transparent 70%);
  transform:translate(-50%,-50%);
  transition:opacity .3s ease;
  will-change:transform;
}
@media (hover:none){ .cursor-glow{ display:none; } }

main, .nav, .footer{ position:relative; z-index:2; }

/* ---------- Reveal-on-scroll ---------- */
.reveal{
  opacity:0;
  transform:translateY(28px);
  transition:opacity .8s cubic-bezier(.2,.7,.2,1), transform .8s cubic-bezier(.2,.7,.2,1);
}
.reveal.in-view{ opacity:1; transform:translateY(0); }

/* ---------- Nav ---------- */
.nav{
  position:fixed; top:0; left:0; right:0;
  z-index:50;
  display:flex; align-items:center; justify-content:space-between;
  padding:16px clamp(20px, 5vw, 56px);
  background:rgba(5,7,13,0.35);
  backdrop-filter:blur(14px);
  -webkit-backdrop-filter:blur(14px);
  border-bottom:1px solid rgba(255,255,255,0.06);
  transition:background .3s ease, padding .3s ease;
}
.nav.scrolled{ background:rgba(5,7,13,0.75); }

.nav-brand{ display:flex; align-items:center; gap:10px; font-family:var(--font-head); }
.brand-mark{
  width:34px; height:34px; border-radius:10px;
  display:grid; place-items:center;
  background:var(--gradient);
  color:#03050a; font-weight:800; font-size:.85rem;
}
.brand-text{ font-size:.95rem; font-weight:600; display:flex; flex-direction:column; line-height:1.1; }
.brand-text em{ font-style:normal; color:var(--text-muted); font-size:.72rem; font-weight:500; }

.nav-links{ display:flex; align-items:center; gap:28px; font-size:.92rem; }
.nav-links a{ color:var(--text-muted); position:relative; padding:4px 0; transition:color .2s ease; }
.nav-links a:hover{ color:var(--text); }
.nav-links a[data-nav]::after{
  content:''; position:absolute; left:0; bottom:-2px; height:2px; width:0;
  background:var(--gradient); transition:width .25s ease;
}
.nav-links a[data-nav]:hover::after, .nav-links a[data-nav].active::after{ width:100%; }
.nav-links a[data-nav].active{ color:var(--text); }

/* `.nav-links .nav-cta` (not just `.nav-cta`) so this out-specificities the
   `.nav-links a{ padding:4px 0 }` rule above — otherwise that rule silently
   wins and the button ends up with zero left/right padding. */
.nav-links .nav-cta{
  padding:10px 36px; border-radius:999px;
  background:var(--gradient); color:#03050a !important; font-weight:600;
}

.nav-toggle{
  display:none; flex-direction:column; gap:5px;
  background:none; border:none; cursor:pointer; padding:6px;
}
.nav-toggle span{ width:22px; height:2px; background:var(--text); border-radius:2px; transition:transform .25s ease, opacity .25s ease; }
.nav-toggle[aria-expanded="true"] span:nth-child(1){ transform:translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2){ opacity:0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3){ transform:translateY(-7px) rotate(-45deg); }

/* ---------- Hero ----------
   Two explicit columns: text stays left-aligned in its own lane; the 3D robot
   animation is confined to a right-hand stage so the two never overlap. */
.hero{
  position:relative;
  min-height:100vh;
  display:flex; align-items:center;
  gap:clamp(40px, 6vw, 80px);
  padding:140px clamp(20px, 6vw, 80px) 80px;
  overflow:hidden;
}
.hero-stage{
  position:relative;
  flex:1 1 420px;
  align-self:stretch;
  min-height:480px;
  min-width:280px;
  z-index:1;
  order:2; /* markup puts the stage first for a sensible DOM/reading order; visually it sits on the right */
}
#hero-canvas{
  position:absolute; inset:0;
  width:100%; height:100%;
  z-index:0;
  pointer-events:none;
}
.hero-inner{
  position:relative; z-index:1;
  flex:0 1 520px; max-width:520px;
  padding-right:16px;
  order:1;
}

@media (max-width: 980px){
  .hero{ flex-direction:column; align-items:stretch; padding-top:120px; }
  .hero-inner{ flex:none; max-width:100%; }
  /* Stage/canvas/HUD repositioning for this breakpoint is defined further
     down, AFTER the base .hero-hud rule — CSS source order is the tiebreaker
     between equal-specificity selectors, so it must come later to win. */
}

.eyebrow{
  font-family:var(--font-mono);
  text-transform:uppercase; letter-spacing:.18em;
  font-size:.78rem; color:var(--cyan); margin-bottom:18px;
}

.hero-title{
  font-size:clamp(2.4rem, 5.6vw, 3.6rem);
  font-weight:800; line-height:1.08;
  overflow-wrap:break-word; word-break:break-word;
}
.hero-title .line{ display:block; }

.gradient-text{
  background:var(--gradient);
  -webkit-background-clip:text; background-clip:text; color:transparent;
}

.hero-role{
  font-family:var(--font-mono);
  font-size:clamp(1rem, 2vw, 1.25rem);
  color:var(--text-muted);
  margin:22px 0 18px;
  min-height:1.6em;
}
.typed{ color:var(--text); }
.cursor-blink{ color:var(--cyan); animation:blink 1s step-end infinite; }
@keyframes blink{ 50%{ opacity:0; } }

.hero-desc{ max-width:640px; color:var(--text-muted); font-size:1.02rem; }
.hero-desc strong{ color:var(--text); font-weight:600; }

.hero-actions{ display:flex; flex-wrap:wrap; gap:14px; margin:32px 0 46px; }

.btn{
  display:inline-flex; align-items:center; gap:8px;
  padding:13px 22px; border-radius:999px;
  font-weight:600; font-size:.92rem;
  border:1px solid var(--panel-border);
  transition:transform .25s ease, background .25s ease, border-color .25s ease, box-shadow .25s ease;
  cursor:pointer;
}
.btn-primary{
  background:var(--gradient); color:#03050a; border:none;
  box-shadow:0 10px 30px -10px rgba(79,216,255,0.5);
}
.btn-primary:hover{ transform:translateY(-2px); box-shadow:0 16px 34px -10px rgba(79,216,255,0.65); }
.btn-ghost{ background:var(--panel); color:var(--text); }
.btn-ghost:hover{ background:var(--panel-hover); border-color:rgba(255,255,255,0.2); transform:translateY(-2px); }

.hero-stats{ display:flex; flex-wrap:wrap; gap:clamp(24px,4vw,52px); }
.stat{ display:flex; align-items:baseline; gap:4px; flex-wrap:wrap; }
.stat-num{ font-family:var(--font-head); font-size:2rem; font-weight:800; color:var(--text); }
.stat-suffix{ font-size:1.4rem; font-weight:800; color:var(--cyan); }
.stat-label{ width:100%; font-size:.78rem; color:var(--text-muted); text-transform:uppercase; letter-spacing:.06em; }

/* ---------- Hero HUD (simulation-dashboard readout) ----------
   Anchored to the corners of .hero-stage (not the whole hero) so it only ever
   overlays the robot animation, never the text column. */
.hero-hud{
  position:absolute; z-index:2;
  top:16px; left:16px;
  display:flex; flex-direction:column; gap:6px;
  padding:14px 16px;
  background:rgba(6,10,18,0.55);
  border:1px solid var(--panel-border);
  border-radius:var(--radius-sm);
  backdrop-filter:blur(10px);
  font-family:var(--font-mono);
  font-size:.72rem;
  color:var(--text-muted);
  pointer-events:none;
  min-width:172px;
}
.hero-hud-right{
  left:auto; right:16px;
  min-width:0; align-items:flex-end; text-align:right;
}
.hud-row{ display:flex; align-items:center; gap:8px; justify-content:space-between; }
.hero-hud-right .hud-row{ justify-content:flex-end; }
.hud-title{ color:var(--cyan); letter-spacing:.08em; font-weight:600; gap:6px; }
.hud-arrow{ color:var(--violet); }
.hud-caption{ color:var(--text-muted); font-size:.68rem; }
.hud-key{ letter-spacing:.06em; }
.hud-val{ color:var(--text); font-weight:500; }
.hud-dot{
  width:7px; height:7px; border-radius:50%;
  background:var(--cyan);
  box-shadow:0 0 8px 2px rgba(79,216,255,0.8);
  animation:hudPulse 1.6s ease-in-out infinite;
}
@keyframes hudPulse{ 0%,100%{ opacity:1; } 50%{ opacity:.35; } }

/* Stacked (mobile) layout: the HUD used to float absolutely on top of the
   canvas, which is what kept colliding with the robots. Here it gets its own
   flow space instead — HUD-top → canvas → HUD-bottom, sandwiched with real
   gaps, so nothing ever overlaps the animation. Placed AFTER the base
   .hero-hud rule above so it actually wins the cascade at this breakpoint. */
@media (max-width: 980px){
  .hero-stage{
    flex:none; width:100%; min-height:0; order:-1;
    display:flex; flex-direction:column; gap:14px;
    padding:14px 0;
  }
  #hero-canvas{
    position:relative; inset:auto;
    width:100%; height:280px;
    order:2;
  }
  .hero-hud{
    position:static; order:1;
    left:auto; right:auto; top:auto; bottom:auto; transform:none;
    width:100%; max-width:none;
    align-items:center; text-align:center;
  }
  .hero-hud .hud-row{ justify-content:center; }
  .hero-hud-right{ order:3; align-items:center; text-align:center; }
  .hero-hud-right .hud-row{ justify-content:center; }
}

/* Just a size/spacing tweak for small phones — position/order for the stacked
   layout is already handled by the 980px rule above (HUD-top → canvas →
   HUD-bottom, all in normal flow, never overlapping the animation). */
@media (max-width: 480px){
  .hero-hud{ padding:10px 14px; gap:4px; font-size:.62rem; }
  #hero-canvas{ height:240px; }
}

/* ---------- Hero tooltip (for clickable orbiting tech labels) ---------- */
.hero-tooltip{
  position:absolute; z-index:3;
  max-width:230px;
  padding:12px 14px;
  background:rgba(8,13,24,0.92);
  border:1px solid rgba(79,216,255,0.4);
  border-radius:var(--radius-sm);
  font-size:.8rem; color:var(--text);
  pointer-events:none;
  opacity:0; transform:translate(-50%, -12px) scale(.96);
  transition:opacity .18s ease, transform .18s ease;
  box-shadow:0 12px 30px -10px rgba(0,0,0,0.6);
}
.hero-tooltip.visible{ opacity:1; transform:translate(-50%, -22px) scale(1); }
.hero-tooltip strong{ display:block; color:var(--cyan); font-family:var(--font-mono); font-size:.72rem; letter-spacing:.06em; margin-bottom:4px; }

.scroll-cue{
  position:absolute; bottom:34px; left:50%; transform:translateX(-50%);
  display:flex; flex-direction:column; align-items:center; gap:8px;
  font-size:.7rem; letter-spacing:.18em; text-transform:uppercase; color:var(--text-muted);
  z-index:1;
}
.scroll-cue span{
  width:1px; height:34px;
  background:linear-gradient(var(--cyan), transparent);
  position:relative;
  overflow:hidden;
}
.scroll-cue span::after{
  content:''; position:absolute; top:-100%; left:0; width:100%; height:100%;
  background:linear-gradient(var(--cyan), transparent);
  animation:scrollDown 1.8s ease-in-out infinite;
}
@keyframes scrollDown{ to{ top:100%; } }

/* ---------- Sections ---------- */
.section{
  max-width:var(--maxw);
  margin:0 auto;
  padding:120px clamp(20px, 5vw, 40px);
}

.section-head{ max-width:720px; margin-bottom:56px; }
.tag{
  display:inline-block; font-family:var(--font-mono); font-size:.76rem;
  letter-spacing:.14em; text-transform:uppercase; color:var(--violet);
  padding:6px 14px; border:1px solid var(--panel-border); border-radius:999px;
  background:var(--panel); margin-bottom:18px;
}
.section-head h2{ font-size:clamp(1.7rem, 3.6vw, 2.6rem); font-weight:700; }
.section-sub{ color:var(--text-muted); font-size:1rem; margin-top:6px; }

/* ---------- About ---------- */
.about-grid{ display:grid; grid-template-columns:1.1fr .9fr; gap:56px; align-items:start; }
.about-copy{ font-size:1.08rem; color:var(--text-muted); }
.about-copy strong{ color:var(--text); }

.about-facts{ display:grid; grid-template-columns:1fr 1fr; gap:16px; }
.fact-card{
  background:var(--panel); border:1px solid var(--panel-border); border-radius:var(--radius-sm);
  padding:20px; transition:border-color .25s ease, transform .25s ease;
}
.fact-card h3{ font-size:.72rem; text-transform:uppercase; letter-spacing:.1em; color:var(--cyan); margin-bottom:8px; }
.fact-card p{ margin:0; font-size:.92rem; color:var(--text); }

@media (max-width: 880px){
  .about-grid{ grid-template-columns:1fr; }
  .about-facts{ grid-template-columns:1fr 1fr; }
}

/* ---------- Tilt (3D hover) cards, shared ---------- */
.tilt{ transform-style:preserve-3d; will-change:transform; }

/* ---------- Skills ---------- */
.skills-grid{
  display:grid;
  grid-template-columns:repeat(auto-fit, minmax(280px, 1fr));
  gap:22px;
}
.skill-card{
  position:relative;
  background:var(--panel);
  border:1px solid var(--panel-border);
  border-radius:var(--radius);
  padding:26px 24px;
  cursor:pointer;
  transition:border-color .3s ease, background .3s ease;
  overflow:hidden;
}
.skill-card::before{
  content:''; position:absolute; inset:0;
  background:radial-gradient(400px circle at var(--mx,50%) var(--my,50%), rgba(79,216,255,0.12), transparent 60%);
  opacity:0; transition:opacity .3s ease; pointer-events:none;
}
.skill-card:hover::before{ opacity:1; }
.skill-card:hover{ border-color:rgba(79,216,255,0.35); }

.skill-icon{ font-size:1.6rem; margin-bottom:14px; display:block; }
.skill-card h3{ font-size:1.02rem; font-weight:700; margin-bottom:8px; }
.skill-tags{
  display:flex; flex-wrap:wrap; gap:8px; margin-top:14px;
  max-height:0; opacity:0; overflow:hidden;
  transition:max-height .4s ease, opacity .4s ease, margin-top .4s ease;
}
.skill-card.open .skill-tags{ max-height:400px; opacity:1; }
.skill-tags span{
  font-family:var(--font-mono); font-size:.74rem;
  padding:5px 10px; border-radius:999px;
  background:rgba(255,255,255,0.06); border:1px solid var(--panel-border);
  color:var(--text-muted);
}
.skill-preview{ font-size:.86rem; color:var(--text-muted); }
.skill-expand-hint{
  position:absolute; top:24px; right:22px;
  font-size:.7rem; color:var(--text-muted); font-family:var(--font-mono);
  transition:transform .3s ease;
}
.skill-card.open .skill-expand-hint{ transform:rotate(45deg); }

/* ---------- Timeline ---------- */
.timeline{ position:relative; padding-left:32px; }
.timeline::before{
  content:''; position:absolute; left:5px; top:6px; bottom:6px; width:2px;
  background:linear-gradient(var(--cyan), var(--violet) 50%, transparent);
}
.timeline-item{ position:relative; padding-bottom:52px; }
.timeline-item:last-child{ padding-bottom:0; }
.timeline-dot{
  position:absolute; left:-32px; top:6px;
  width:12px; height:12px; border-radius:50%;
  background:var(--bg); border:2px solid var(--cyan);
  box-shadow:0 0 0 4px rgba(79,216,255,0.12);
}
.timeline-item.current .timeline-dot{
  background:var(--cyan);
  animation:dotPulse 2.2s ease-in-out infinite;
}
@keyframes dotPulse{
  0%,100%{ box-shadow:0 0 0 6px rgba(79,216,255,0.2), 0 0 18px rgba(79,216,255,0.8); }
  50%{ box-shadow:0 0 0 9px rgba(79,216,255,0.12), 0 0 26px rgba(79,216,255,1); }
}

.tl-card{
  background:var(--panel); border:1px solid var(--panel-border); border-radius:var(--radius);
  padding:28px 26px;
}
.tl-head{ display:flex; flex-wrap:wrap; justify-content:space-between; align-items:baseline; gap:10px; margin-bottom:6px; }
.tl-role{ font-size:1.15rem; font-weight:700; }
.tl-period{ font-family:var(--font-mono); font-size:.78rem; color:var(--cyan); white-space:nowrap; }
.tl-company{ color:var(--text-muted); font-size:.92rem; margin-bottom:16px; }
.tl-company strong{ color:var(--text); }
.badge-current{
  display:inline-block; margin-left:10px; font-size:.65rem; letter-spacing:.08em;
  text-transform:uppercase; padding:2px 9px; border-radius:999px;
  background:rgba(79,216,255,0.14); color:var(--cyan); border:1px solid rgba(79,216,255,0.4);
  vertical-align:middle;
}
.tl-bullets{ margin:0; padding-left:1.1em; display:grid; gap:8px; color:var(--text-muted); font-size:.94rem; }
.tl-bullets li::marker{ color:var(--violet); }

/* ---------- Education ---------- */
.education-grid{ display:grid; grid-template-columns:repeat(auto-fit, minmax(260px,1fr)); gap:22px; }
.edu-card{
  background:var(--panel); border:1px solid var(--panel-border); border-radius:var(--radius);
  padding:30px 26px; transition:border-color .3s ease;
}
.edu-card:hover{ border-color:rgba(138,92,255,0.4); }
.edu-icon{ font-size:2rem; margin-bottom:14px; }
.edu-meta{ color:var(--text-muted); font-size:.9rem; margin-top:6px; }

/* ---------- Contact ---------- */
.section-contact{ position:relative; text-align:left; }
.contact-grid{ display:grid; grid-template-columns:repeat(auto-fit, minmax(230px,1fr)); gap:18px; }
.contact-card{
  display:flex; flex-direction:column; gap:6px;
  background:var(--panel); border:1px solid var(--panel-border); border-radius:var(--radius);
  padding:24px; transition:transform .3s ease, border-color .3s ease, background .3s ease;
}
a.contact-card:hover{ border-color:rgba(79,216,255,0.4); background:var(--panel-hover); transform:translateY(-4px); }
.contact-icon{ font-size:1.5rem; }
.contact-label{ font-size:.72rem; text-transform:uppercase; letter-spacing:.1em; color:var(--text-muted); }
.contact-value{ font-weight:600; font-size:.98rem; word-break:break-word; }

/* ---------- Footer ---------- */
.footer{
  display:flex; flex-wrap:wrap; gap:12px; align-items:center; justify-content:space-between;
  padding:28px clamp(20px, 5vw, 56px) 40px;
  color:var(--text-muted); font-size:.82rem;
  border-top:1px solid rgba(255,255,255,0.06);
}
.to-top{ color:var(--cyan); font-weight:600; }

/* ---------- Responsive ---------- */
@media (max-width: 860px){
  .nav-links{
    position:fixed; top:68px; left:0; right:0;
    flex-direction:column; align-items:flex-start; gap:0;
    background:rgba(6,9,16,0.97); backdrop-filter:blur(16px);
    padding:12px clamp(20px,5vw,56px) 24px;
    transform:translateY(-8px); opacity:0; pointer-events:none;
    transition:transform .3s ease, opacity .3s ease;
    border-bottom:1px solid rgba(255,255,255,0.08);
  }
  .nav-links.open{ transform:translateY(0); opacity:1; pointer-events:auto; }
  .nav-links a{ width:100%; padding:14px 0; border-bottom:1px solid rgba(255,255,255,0.05); }
  .nav-cta{ margin-top:10px; text-align:center; }
  .nav-toggle{ display:flex; }
}

@media (max-width: 600px){
  .hero{ padding-top:120px; }
  .section{ padding:88px 20px; }
}

@media (prefers-reduced-motion: reduce){
  html{ scroll-behavior:auto; }
  .reveal{ transition:none; opacity:1; transform:none; }
}