/* =====================================================================
   Vertical Flight Systems (VFS) Purdue
   Light, university/student-club theme. Purdue black & gold on white.
   ===================================================================== */

:root {
  --white:     #ffffff;
  --paper:     #f6f4ef;   /* warm off-white section band */
  --paper-2:   #efece4;
  --ink:       #16161a;   /* headings / primary text */
  --ink-2:     #4b4b52;   /* body */
  --ink-3:     #7c7c84;   /* muted */
  --line:      #e4e0d7;
  --line-2:    #d8d3c7;

  --gold:      #ceb888;   /* Boilermaker Gold (brand, decorative) */
  --gold-ink:  #8a6a1f;   /* darker gold for links / small accents on white */
  --gold-soft: #f0e7d4;
  --charcoal:  #17171b;   /* footer / dark banner */

  --maxw: 1160px;
  --gutter: clamp(20px, 5vw, 60px);

  --sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --display: "Space Grotesk", "Inter", system-ui, sans-serif;
  --mono: "Space Mono", ui-monospace, "SFMono-Regular", Menlo, monospace;

  --ease: cubic-bezier(.22, 1, .36, 1);
  --shadow: 0 18px 50px rgba(30, 26, 15, .10);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--white);
  color: var(--ink-2);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: var(--gold-ink); text-decoration: none; }
a:hover { text-decoration: underline; }
::selection { background: var(--gold); color: #1b1500; }

h1, h2, h3, h4 { color: var(--ink); font-family: var(--display); font-weight: 600; letter-spacing: -.02em; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 var(--gutter); }
.narrow { max-width: 820px; }
.section { padding: clamp(60px, 9vw, 116px) 0; }
.band { background: var(--paper); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.dark-band { background: var(--charcoal); color: #d9d6cf; }
.dark-band h1, .dark-band h2, .dark-band h3 { color: #fff; }

.kicker {
  font-family: var(--mono);
  font-size: 12px; letter-spacing: .22em; text-transform: uppercase;
  color: var(--gold-ink); margin: 0 0 16px;
  display: inline-flex; align-items: center; gap: 11px;
}
.kicker::before { content: ""; width: 24px; height: 2px; background: var(--gold); }

.h-sec { font-size: clamp(27px, 4.2vw, 42px); line-height: 1.1; margin: 0 0 18px; }
.lead { font-size: clamp(17px, 1.9vw, 20px); color: var(--ink-2); margin: 0 0 20px; }
.muted { color: var(--ink-3); }

/* buttons */
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  font-family: var(--mono); font-size: 12.5px; letter-spacing: .06em; text-transform: uppercase;
  padding: 13px 22px; border-radius: 2px; border: 1.5px solid var(--ink);
  color: var(--ink); background: transparent; cursor: pointer;
  transition: background .25s var(--ease), color .25s var(--ease), transform .25s var(--ease), border-color .25s var(--ease);
}
.btn:hover { background: var(--ink); color: #fff; text-decoration: none; transform: translateY(-2px); }
.btn .arw { transition: transform .25s var(--ease); }
.btn:hover .arw { transform: translateX(3px); }
.btn-gold { border-color: var(--gold); background: var(--gold); color: #1b1500; }
.btn-gold:hover { background: #c1a86f; border-color: #c1a86f; color: #1b1500; }
.btn-light { border-color: rgba(255,255,255,.5); color: #fff; background: rgba(255,255,255,.12); backdrop-filter: blur(6px); -webkit-backdrop-filter: blur(6px); }
.btn-light:hover { background: #fff; color: var(--ink); border-color: #fff; }
.btns { display: flex; flex-wrap: wrap; gap: 13px; }

/* =====================================================================
   NAV
   ===================================================================== */
.nav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.9);
  backdrop-filter: blur(12px) saturate(140%);
  border-bottom: 1px solid var(--line);
}
.nav-inner { max-width: var(--maxw); margin: 0 auto; padding: 0 var(--gutter);
  height: 70px; display: flex; align-items: center; justify-content: space-between; }
.brand { display: flex; align-items: center; gap: 12px; }
.brand img { height: 34px; width: auto; background: var(--charcoal); padding: 6px 8px; border-radius: 6px; box-sizing: content-box; }
.brand .bt { display: flex; flex-direction: column; line-height: 1.05; }
.brand .bt b { font-family: var(--display); font-weight: 600; font-size: 15px; color: var(--ink); letter-spacing: 0; }
.brand .bt span { font-family: var(--mono); font-size: 9.5px; letter-spacing: .2em; text-transform: uppercase; color: var(--ink-3); }
.brand:hover { text-decoration: none; }

.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a { font-size: 14.5px; color: var(--ink-2); position: relative; }
.nav-links a:hover { color: var(--ink); text-decoration: none; }
.nav-links a::after { content: ""; position: absolute; left: 0; bottom: -7px; height: 2px; width: 0; background: var(--gold); transition: width .28s var(--ease); }
.nav-links a:hover::after, .nav-links a.active::after { width: 100%; }
.nav-links a.active { color: var(--ink); }

.nav-toggle { display: none; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav-toggle span { display: block; width: 24px; height: 2px; background: var(--ink); margin: 5px 0; transition: transform .3s var(--ease), opacity .3s var(--ease); }
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* =====================================================================
   HERO (home)
   ===================================================================== */
.hero { position: relative; overflow: hidden; color: #f5f4f1; background:
  /* continuous fade: dark atmosphere up top -> the drone's baked floor-fog -> white page */
  linear-gradient(to bottom,
    transparent 0%, transparent 50%,
    rgba(255,255,255,.03) 62%,
    rgba(255,255,255,.10) 73%,
    rgba(255,255,255,.30) 83%,
    rgba(255,255,255,.66) 91%,
    rgba(255,255,255,.93) 96.5%,
    #fff 100%),
  radial-gradient(130% 100% at 50% 8%, #1b1710 0%, #0d0b08 55%, #060504 100%); }
.hero::before { /* faint gold grid */
  content: ""; position: absolute; inset: 0; z-index: 0;
  background-image: linear-gradient(rgba(206,184,136,.07) 1px, transparent 1px), linear-gradient(90deg, rgba(206,184,136,.07) 1px, transparent 1px);
  background-size: 62px 62px;
  mask-image: radial-gradient(ellipse 85% 72% at 50% 42%, #000 15%, transparent 80%);
  opacity: .8; }
/* (the fade into the white page below is now handled by the .hero background gradient) */

.hero-stage { position: relative; max-width: 1200px; margin: 0 auto; padding: clamp(22px, 3vw, 40px) var(--gutter) clamp(34px, 5vw, 54px);
  min-height: min(90vh, 840px); display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; }
.hero-word { position: relative; z-index: 2; margin: 0; font-family: var(--display); font-weight: 700;
  font-size: clamp(34px, 8.6vw, 110px); line-height: .8; letter-spacing: -.03em; color: #f5f4f1;
  text-shadow: 0 2px 30px rgba(0,0,0,.55); user-select: none; }
.hero-word span { display: block; }
.hero-word .pu { color: #dcb659; }
.hero-craft { position: relative; z-index: 3; width: 100vw; max-width: none;
  margin: clamp(-78px, -6.5vw, -46px) calc(50% - 50vw) clamp(6px, 1.6vw, 14px);
  filter: brightness(1.06) drop-shadow(0 26px 44px rgba(0,0,0,.55)); }

/* heavy fog / atmosphere behind the aircraft */
.hero-fog { position: absolute; inset: 0; z-index: 1; pointer-events: none; overflow: hidden; }
.hero-fog span { position: absolute; border-radius: 50%; }
.hero-fog .glow { width: 74vw; height: 58vh; left: 50%; top: 56%; transform: translate(-50%,-50%); filter: blur(60px);
  background: radial-gradient(closest-side, rgba(236,208,138,.60), rgba(236,208,138,0) 72%); }
.hero-fog .f1 { width: 66vw; height: 50vh; left: 26%; top: 42%; transform: translate(-50%,-50%); filter: blur(90px);
  background: radial-gradient(closest-side, rgba(206,184,136,.40), transparent 72%); animation: fogdrift 26s ease-in-out infinite alternate; }
.hero-fog .f2 { width: 62vw; height: 48vh; left: 74%; top: 52%; transform: translate(-50%,-50%); filter: blur(90px);
  background: radial-gradient(closest-side, rgba(176,142,80,.38), transparent 72%); animation: fogdrift 32s ease-in-out infinite alternate-reverse; }
.hero-fog .f3 { width: 104vw; height: 38vh; left: 50%; top: 86%; transform: translate(-50%,-50%); filter: blur(90px);
  background: radial-gradient(closest-side, rgba(232,226,214,.22), transparent 74%); }
.hero-fog .f4 { width: 52vw; height: 40vh; left: 50%; top: 14%; transform: translate(-50%,-50%); filter: blur(100px);
  background: radial-gradient(closest-side, rgba(150,128,84,.30), transparent 72%); animation: fogdrift 38s ease-in-out infinite alternate; }
@keyframes fogdrift { from { transform: translate(-50%,-50%) scale(1); } to { transform: translate(-42%,-54%) scale(1.12); } }
.hero-copy { position: relative; z-index: 6; max-width: 640px; }
.hero-copy .kicker { justify-content: center; color: #dcb659; }
.hero-copy .kicker::before { background: #dcb659; }
.hero-tag { font-family: var(--display); font-weight: 400; font-size: clamp(18px, 2.4vw, 25px); color: #26211a; line-height: 1.35; margin: 0 0 26px; text-shadow: 0 1px 12px rgba(255,255,255,.55); }
.hero-copy .btns { justify-content: center; }
/* copy sits on the light lower half of the hero now, so the secondary button goes dark-on-light */
.hero-copy .btn-light { border-color: rgba(20,16,8,.4); color: var(--ink); background: rgba(255,255,255,.4);
  backdrop-filter: blur(6px); -webkit-backdrop-filter: blur(6px); }
.hero-copy .btn-light:hover { background: var(--ink); color: #fff; border-color: var(--ink); }

/* =====================================================================
   SUB-PAGE HEADER
   ===================================================================== */
.pagehead { position: relative; background:
  radial-gradient(110% 120% at 85% 0%, var(--gold-soft), transparent 60%), var(--paper);
  border-bottom: 1px solid var(--line); padding: clamp(48px, 8vw, 96px) 0 clamp(40px, 6vw, 64px); }
.pagehead h1 { font-size: clamp(34px, 6vw, 60px); line-height: 1.02; margin: 0 0 16px; }
.pagehead p { max-width: 620px; font-size: clamp(16px, 1.8vw, 19px); color: var(--ink-2); margin: 0; }

/* =====================================================================
   GENERIC CONTENT PIECES
   ===================================================================== */
/* two-column feature (image + text), alternating */
.feature { display: grid; grid-template-columns: 1fr 1fr; gap: clamp(30px, 5vw, 66px); align-items: center; }
.feature + .feature { margin-top: clamp(56px, 8vw, 100px); }
.feature.flip .f-media { order: 2; }
.f-media { border-radius: 5px; overflow: hidden; border: 1px solid var(--line); box-shadow: var(--shadow); }
.f-media img { width: 100%; height: 100%; object-fit: cover; }
.f-body h2, .f-body h3 { font-size: clamp(23px, 3.2vw, 34px); margin: 0 0 16px; line-height: 1.12; }
.f-body p { margin: 0 0 15px; }
.f-body p:last-child { margin-bottom: 0; }

/* figure with caption */
figure { margin: 0; }
.shot { border-radius: 5px; overflow: hidden; border: 1px solid var(--line); box-shadow: var(--shadow); }
.shot img { width: 100%; display: block; }
figcaption { font-family: var(--mono); font-size: 11.5px; letter-spacing: .04em; color: var(--ink-3); margin-top: 10px; }

/* image strip / mosaic */
.mosaic { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.mosaic .shot img { aspect-ratio: 4/3; object-fit: cover; }
.mosaic .span2 { grid-column: span 2; }
.mosaic .span2 .shot img, .mosaic .tall .shot img { aspect-ratio: auto; height: 100%; }

/* facts row (plain, understated) */
.facts { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); border-radius: 5px; overflow: hidden; }
.fact { background: var(--white); padding: 26px 24px; }
.fact b { display: block; font-family: var(--display); font-weight: 600; font-size: clamp(22px, 2.6vw, 29px); color: var(--ink); letter-spacing: -.01em; }
.fact b .u { color: var(--gold-ink); }
.fact span { font-size: 13.5px; color: var(--ink-3); }

/* key/value list */
.kv { border-top: 1px solid var(--line); }
.kv .row { display: grid; grid-template-columns: 165px 1fr; gap: 16px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.kv dt { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-ink); margin-top: 3px; }
.kv dd { margin: 0; color: var(--ink); }
.kv dd small { display: block; color: var(--ink-3); font-size: 14px; }

/* timeline (development milestones) */
.timeline { display: grid; gap: 0; margin-top: 8px; }
.mile { display: grid; grid-template-columns: 150px 1fr; gap: 26px; padding: 22px 0; border-top: 1px solid var(--line); align-items: start; }
.mile:last-child { border-bottom: 1px solid var(--line); }
.mile .when { font-family: var(--mono); font-size: 12px; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-ink); padding-top: 3px; }
.mile .what b { display: block; font-family: var(--display); font-weight: 600; color: var(--ink); font-size: 18px; margin-bottom: 5px; }
.mile .what span { color: var(--ink-2); font-size: 15px; }
.mile.next .when { color: var(--ink); }
.mile.next .what b::after { content: " — planned"; font-family: var(--mono); font-weight: 400; font-size: 11px; letter-spacing: .08em; color: var(--gold-ink); text-transform: uppercase; }

/* callout / notice */
.callout { border: 1px solid var(--line-2); border-left: 3px solid var(--gold); background: var(--paper); border-radius: 4px; padding: 22px 26px; }
.callout p { margin: 0; color: var(--ink-2); }

/* cards (link previews on home) */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.card { border: 1px solid var(--line); border-radius: 6px; overflow: hidden; background: var(--white); transition: transform .3s var(--ease), box-shadow .3s var(--ease), border-color .3s var(--ease); }
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow); border-color: var(--line-2); text-decoration: none; }
.card .c-img { aspect-ratio: 16/10; overflow: hidden; }
.card .c-img img { width: 100%; height: 100%; object-fit: cover; transition: transform .5s var(--ease); }
.card:hover .c-img img { transform: scale(1.05); }
.card .c-b { padding: 22px 22px 24px; }
.card .c-b .k { font-family: var(--mono); font-size: 11px; letter-spacing: .12em; text-transform: uppercase; color: var(--gold-ink); }
.card .c-b h3 { font-size: 20px; margin: 9px 0 8px; }
.card .c-b p { margin: 0; color: var(--ink-2); font-size: 14.5px; }
.card .c-b .go { display: inline-block; margin-top: 14px; font-family: var(--mono); font-size: 12px; letter-spacing: .06em; text-transform: uppercase; color: var(--ink); }

/* =====================================================================
   TEAM
   ===================================================================== */
.team-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.member { border: 1px solid var(--line); border-radius: 6px; overflow: hidden; background: var(--white); transition: transform .3s var(--ease), box-shadow .3s var(--ease); }
.member:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.member .ph { aspect-ratio: 4/5; overflow: hidden; background: var(--paper-2); }
.member .ph img { width: 100%; height: 100%; object-fit: cover; object-position: center 22%; }
.member .ph.ph-logo { display: flex; align-items: center; justify-content: center; background:
  radial-gradient(circle at 50% 36%, rgba(206,184,136,.20), transparent 62%), linear-gradient(160deg, #23232a, #101012); }
.member .ph.ph-logo img { width: 55%; height: auto; object-fit: contain; }
.member .m-b { padding: 18px 20px 22px; }
.member .m-b .role { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-ink); }
.member .m-b b { display: block; font-family: var(--display); font-weight: 600; color: var(--ink); font-size: 18px; margin-top: 7px; }
.member .m-b small { color: var(--ink-3); font-size: 13px; }

/* =====================================================================
   SPONSORS
   ===================================================================== */
.logo-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; }
.logo-cell { border: 1px solid var(--line); border-radius: 6px; background: var(--white);
  display: flex; align-items: center; justify-content: center; padding: 34px 30px; min-height: 150px; transition: box-shadow .3s var(--ease), transform .3s var(--ease); }
.logo-cell:hover { box-shadow: var(--shadow); transform: translateY(-3px); }
.logo-cell img { max-height: 74px; max-width: 80%; width: auto; object-fit: contain; }

/* =====================================================================
   CONTACT
   ===================================================================== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: clamp(30px, 5vw, 64px); align-items: start; }
.ccard { border: 1px solid var(--line); border-radius: 6px; padding: 20px 22px; display: flex; justify-content: space-between; align-items: center; gap: 16px; transition: border-color .25s var(--ease), box-shadow .25s var(--ease); }
.ccard + .ccard { margin-top: 12px; }
.ccard:hover { border-color: var(--line-2); box-shadow: var(--shadow); text-decoration: none; }
.ccard .role { font-family: var(--mono); font-size: 11px; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-ink); }
.ccard b { display: block; font-family: var(--display); font-weight: 600; color: var(--ink); margin-top: 5px; }
.ccard .em { font-family: var(--mono); font-size: 13px; color: var(--ink-2); }

/* =====================================================================
   FOOTER
   ===================================================================== */
.footer { background: var(--charcoal); color: #b8b5ad; padding: clamp(46px, 7vw, 70px) 0 34px; }
.footer a { color: #d9d6cf; }
.footer a:hover { color: var(--gold); }
.footer-top { display: grid; grid-template-columns: 1.4fr 1fr 1fr; gap: 40px; padding-bottom: 40px; border-bottom: 1px solid rgba(255,255,255,.1); }
.footer .f-brand img { height: 46px; margin-bottom: 16px; }
.footer .f-brand p { color: #97948d; font-size: 14px; max-width: 320px; margin: 0; }
.footer h4 { color: #fff; font-family: var(--mono); font-weight: 400; font-size: 11px; letter-spacing: .18em; text-transform: uppercase; margin: 0 0 16px; }
.footer .f-col > a { display: block; font-size: 14.5px; margin-bottom: 10px; }
.socials { display: flex; gap: 12px; margin-top: 4px; }
.socials a { display: inline-flex; align-items: center; justify-content: center; width: 40px; height: 40px; line-height: 0; padding: 0; border: 1px solid rgba(255,255,255,.18); border-radius: 50%; transition: background .25s var(--ease), border-color .25s var(--ease); }
.socials a:hover { background: var(--gold); border-color: var(--gold); text-decoration: none; }
.socials a:hover svg { fill: #1b1500; }
.socials svg { display: block; width: 18px; height: 18px; fill: #d9d6cf; transition: fill .25s var(--ease); }
.footer-bottom { padding-top: 26px; display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; font-size: 12.5px; color: #86837c; }
.footer-bottom .eo { max-width: 640px; }
.footer-bottom .eo a { color: #b8b5ad; text-decoration: underline; }

/* =====================================================================
   REVEAL
   ===================================================================== */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity .7s var(--ease), transform .7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .hero-fog span { animation: none !important; }
  html { scroll-behavior: auto; }
}

/* =====================================================================
   RESPONSIVE
   ===================================================================== */
@media (max-width: 900px) {
  .feature, .contact-grid { grid-template-columns: 1fr; }
  .feature.flip .f-media { order: 0; }
  .feature .f-media { max-height: 420px; }
  .cards { grid-template-columns: 1fr 1fr; }
  .team-grid { grid-template-columns: 1fr 1fr; }
  .facts { grid-template-columns: 1fr 1fr; }
  .mosaic { grid-template-columns: 1fr 1fr; }
  .footer-top { grid-template-columns: 1fr 1fr; }
  .footer .f-brand { grid-column: 1 / -1; }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .nav-links {
    position: fixed; inset: 70px 0 auto 0; flex-direction: column; align-items: flex-start; gap: 0;
    background: #fff; border-bottom: 1px solid var(--line); padding: 8px var(--gutter) 22px;
    transform: translateY(-8px); opacity: 0; pointer-events: none; transition: opacity .28s var(--ease), transform .28s var(--ease);
  }
  .nav-links.open { transform: none; opacity: 1; pointer-events: auto; }
  .nav-links a { width: 100%; padding: 14px 0; border-bottom: 1px solid var(--line); font-size: 16px; }
  .nav-links a::after { display: none; }
  .nav-toggle { display: block; }
  .cards, .team-grid, .facts, .mosaic { grid-template-columns: 1fr; }
  .kv .row { grid-template-columns: 1fr; gap: 3px; }
  .mile { grid-template-columns: 1fr; gap: 6px; }
  .footer-top { grid-template-columns: 1fr; gap: 30px; }
  .hero-craft { width: 100vw; margin-top: clamp(6px, 2vw, 14px); }
  /* shorter hero on mobile so the copy sits in the light lower zone (readable dark text)
     instead of floating in the dark vertical center of a 90vh stage */
  .hero-stage { min-height: auto; padding-top: clamp(26px, 9vw, 46px); padding-bottom: clamp(26px, 8vw, 40px); }
  .hero-copy { margin-top: clamp(14px, 6vw, 30px); }
  .hero-tag { text-shadow: 0 1px 10px rgba(255,255,255,.85); }
  .hero { background:
    linear-gradient(to bottom,
      transparent 0%, transparent 40%,
      rgba(255,255,255,.06) 50%,
      rgba(255,255,255,.24) 60%,
      rgba(255,255,255,.66) 70%,
      rgba(255,255,255,.95) 79%,
      #fff 86%),
    radial-gradient(130% 100% at 50% 8%, #1b1710 0%, #0d0b08 55%, #060504 100%); }
}