/* ============================================================
   koushikdeb.com — portfolio stylesheet
   Palette: midnight navy · teal · amber
   ============================================================ */

:root {
  --bg: #070c18;
  --bg-2: #0b1226;
  --bg-3: #101a33;
  --card: rgba(255, 255, 255, 0.045);
  --card-border: rgba(255, 255, 255, 0.09);
  --text: #e8eefb;
  --muted: #94a3bd;
  --teal: #2dd4bf;
  --teal-dim: rgba(45, 212, 191, 0.14);
  --amber: #fbbf24;
  --amber-dim: rgba(251, 191, 36, 0.14);
  --font-display: "Space Grotesk", "Segoe UI", sans-serif;
  --font-body: "Inter", "Segoe UI", sans-serif;
  --radius: 16px;
  --nav-h: 68px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--nav-h) + 12px); }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16.5px;
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--teal); text-decoration: none; }
img { max-width: 100%; height: auto; display: block; }
strong { color: var(--text); font-weight: 600; }

::selection { background: var(--teal); color: #04231e; }

/* ---------- scroll progress ---------- */
.progress-bar {
  position: fixed; top: 0; left: 0; height: 3px; width: 0;
  background: linear-gradient(90deg, var(--teal), var(--amber));
  z-index: 1001;
  transition: width 80ms linear;
}

/* ---------- nav ---------- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--nav-h);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 clamp(16px, 4vw, 48px);
  background: rgba(7, 12, 24, 0.55);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s, background 0.3s;
}
.nav.scrolled {
  background: rgba(7, 12, 24, 0.85);
  border-bottom-color: var(--card-border);
}
.nav-logo { display: flex; align-items: center; gap: 10px; }
.logo-mark {
  font-family: var(--font-display); font-weight: 700; font-size: 15px;
  color: #04231e; background: linear-gradient(135deg, var(--teal), #6ee7d8);
  width: 38px; height: 38px; border-radius: 11px;
  display: grid; place-items: center;
  box-shadow: 0 0 22px rgba(45, 212, 191, 0.35);
}
.logo-text { font-family: var(--font-display); font-weight: 600; color: var(--text); font-size: 15.5px; }
.logo-text .accent { color: var(--teal); }

.nav-links { display: flex; align-items: center; gap: clamp(10px, 1.6vw, 26px); list-style: none; }
.nav-links a {
  color: var(--muted); font-size: 14.5px; font-weight: 500;
  transition: color 0.25s;
  position: relative;
}
.nav-links a:not(.nav-cta)::after {
  content: ""; position: absolute; left: 0; bottom: -6px; height: 2px; width: 0;
  background: var(--teal); border-radius: 2px; transition: width 0.25s;
}
.nav-links a:hover, .nav-links a.active { color: var(--text); }
.nav-links a:not(.nav-cta):hover::after, .nav-links a.active:not(.nav-cta)::after { width: 100%; }
.nav-cta {
  border: 1px solid var(--teal); color: var(--teal) !important;
  padding: 7px 16px; border-radius: 999px; transition: all 0.25s;
}
.nav-cta:hover { background: var(--teal); color: #04231e !important; box-shadow: 0 0 24px rgba(45,212,191,.4); }

.nav-toggle { display: none; background: none; border: none; cursor: pointer; padding: 8px; }
.nav-toggle span {
  display: block; width: 24px; height: 2px; background: var(--text);
  margin: 5px 0; border-radius: 2px; transition: transform .3s, opacity .3s;
}
.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 ---------- */
.hero {
  position: relative; min-height: 100svh;
  display: flex; align-items: center;
  padding: calc(var(--nav-h) + 40px) clamp(20px, 6vw, 90px) 80px;
  overflow: hidden;
}
.hero-bg {
  position: absolute; inset: 0;
  background:
    linear-gradient(180deg, rgba(7,12,24,.55) 0%, rgba(7,12,24,.35) 45%, var(--bg) 100%),
    url("/assets/hero-bg.jpg") center 40% / cover no-repeat;
  animation: heroZoom 24s ease-in-out infinite alternate;
}
@keyframes heroZoom { from { transform: scale(1); } to { transform: scale(1.09); } }

#particles { position: absolute; inset: 0; width: 100%; height: 100%; }

.orb {
  position: absolute; border-radius: 50%; filter: blur(90px); opacity: .35;
  pointer-events: none;
}
.orb-1 {
  width: 420px; height: 420px; top: -120px; right: -80px;
  background: radial-gradient(circle, rgba(45,212,191,.5), transparent 65%);
  animation: drift 16s ease-in-out infinite alternate;
}
.orb-2 {
  width: 360px; height: 360px; bottom: -100px; left: -90px;
  background: radial-gradient(circle, rgba(251,191,36,.4), transparent 65%);
  animation: drift 20s ease-in-out infinite alternate-reverse;
}
@keyframes drift {
  from { transform: translate(0, 0) scale(1); }
  to   { transform: translate(50px, 36px) scale(1.15); }
}

.hero-inner { position: relative; z-index: 2; max-width: 820px; }

.hero-greeting {
  font-size: 17px; color: var(--teal); font-weight: 500; letter-spacing: .4px;
  margin-bottom: 10px;
  animation: fadeUp .8s .1s both;
}
#greeting { display: inline-block; min-width: 5.5ch; }
.wave { display: inline-block; margin: 0 6px; animation: wave 2.4s .8s 2; transform-origin: 70% 70%; }
@keyframes wave {
  0%, 100% { transform: rotate(0); } 15% { transform: rotate(18deg); }
  30% { transform: rotate(-10deg); } 45% { transform: rotate(16deg); }
  60% { transform: rotate(-6deg); } 75% { transform: rotate(8deg); }
}

.hero-name {
  font-family: var(--font-display);
  font-size: clamp(48px, 9vw, 96px);
  font-weight: 700; line-height: 1.04; letter-spacing: -1.5px;
  animation: fadeUp .8s .22s both;
}
.hero-name .grad {
  background: linear-gradient(100deg, var(--teal) 10%, #7ce8d8 45%, var(--amber) 95%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

.hero-role {
  font-family: var(--font-display);
  font-size: clamp(19px, 3vw, 28px); font-weight: 500;
  color: var(--text); margin-top: 14px; min-height: 1.5em;
  animation: fadeUp .8s .34s both;
}
.cursor { color: var(--teal); animation: blink 1s steps(1) infinite; font-weight: 400; }
@keyframes blink { 50% { opacity: 0; } }

.hero-tag {
  color: var(--muted); max-width: 620px; margin-top: 18px; font-size: 17px;
  animation: fadeUp .8s .46s both;
}

.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 32px; animation: fadeUp .8s .58s both; }

.btn {
  font-family: var(--font-display); font-weight: 600; font-size: 15px;
  padding: 13px 26px; border-radius: 999px; display: inline-block;
  transition: transform .25s, box-shadow .25s, background .25s, color .25s;
}
.btn:hover { transform: translateY(-3px); }
.btn-primary {
  background: linear-gradient(120deg, var(--teal), #4be0c8);
  color: #04231e;
  box-shadow: 0 8px 28px rgba(45, 212, 191, 0.35);
}
.btn-primary:hover { box-shadow: 0 12px 36px rgba(45, 212, 191, 0.5); }
.btn-ghost {
  border: 1px solid var(--card-border); color: var(--text);
  background: rgba(255,255,255,.03);
}
.btn-ghost:hover { border-color: var(--teal); color: var(--teal); box-shadow: 0 8px 24px rgba(45,212,191,.15); }

.hero-social { display: flex; gap: 10px; margin-top: 34px; animation: fadeUp .8s .7s both; }
.hero-social a {
  width: 46px; height: 46px; border-radius: 13px;
  display: grid; place-items: center;
  background: rgba(255,255,255,.05); border: 1px solid var(--card-border);
  color: var(--muted); transition: all .25s;
}
.hero-social a:hover {
  color: var(--teal); border-color: var(--teal);
  transform: translateY(-4px); box-shadow: 0 10px 26px rgba(45,212,191,.2);
}

.scroll-cue {
  position: absolute; bottom: 26px; left: 50%; transform: translateX(-50%);
  width: 26px; height: 42px; border: 2px solid var(--muted); border-radius: 14px;
  z-index: 2; opacity: .7;
}
.scroll-cue span {
  position: absolute; top: 7px; left: 50%; width: 4px; height: 8px;
  background: var(--teal); border-radius: 3px; transform: translateX(-50%);
  animation: cue 1.8s ease-in-out infinite;
}
@keyframes cue { 0% { top: 7px; opacity: 1; } 70% { top: 22px; opacity: 0; } 100% { top: 7px; opacity: 0; } }

@keyframes fadeUp { from { opacity: 0; transform: translateY(26px); } to { opacity: 1; transform: none; } }

/* ---------- marquee ---------- */
.marquee {
  overflow: hidden; border-block: 1px solid var(--card-border);
  background: var(--bg-2); padding: 14px 0;
  mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
  -webkit-mask-image: linear-gradient(90deg, transparent, #000 8%, #000 92%, transparent);
}
.marquee-track {
  display: flex; gap: 34px; width: max-content;
  animation: marquee 30s linear infinite;
  font-family: var(--font-display); font-size: 15px; color: var(--muted);
  white-space: nowrap;
}
.marquee:hover .marquee-track { animation-play-state: paused; }
.marquee-track span:nth-child(even) { color: var(--teal); font-size: 9px; align-self: center; }
@keyframes marquee { to { transform: translateX(-50%); } }

/* ---------- stats ---------- */
.stats {
  display: flex; flex-wrap: wrap; justify-content: center;
  gap: clamp(24px, 5vw, 72px);
  padding: clamp(44px, 7vw, 76px) 24px;
}
.stat { text-align: center; }
.stat-num {
  display: block; font-family: var(--font-display);
  font-size: clamp(38px, 5.5vw, 58px); font-weight: 700;
  background: linear-gradient(120deg, var(--teal), var(--amber));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.stat-label { color: var(--muted); font-size: 14.5px; }

/* ---------- sections ---------- */
.section { max-width: 1120px; margin: 0 auto; padding: clamp(60px, 9vw, 110px) clamp(20px, 5vw, 40px); }

.section-title {
  font-family: var(--font-display);
  font-size: clamp(32px, 5vw, 46px); font-weight: 700; letter-spacing: -0.8px;
  margin-bottom: clamp(36px, 5vw, 56px);
  display: flex; flex-direction: column; gap: 8px;
}
.section-kicker {
  font-size: 13.5px; font-weight: 500; letter-spacing: 2.5px; text-transform: uppercase;
  color: var(--teal); font-family: var(--font-body);
}

/* reveal-on-scroll */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- about ---------- */
.about-grid {
  display: grid; grid-template-columns: minmax(280px, 420px) 1fr;
  gap: clamp(32px, 5vw, 64px); align-items: center;
}
.about-visual { position: relative; }
.about-frame {
  border-radius: 22px; overflow: hidden;
  border: 1px solid var(--card-border);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.5), 0 0 60px rgba(45, 212, 191, 0.08);
  transform: rotate(-2deg); transition: transform .5s;
}
.about-visual:hover .about-frame { transform: rotate(0deg) scale(1.02); }
.float-chip {
  position: absolute; font-family: var(--font-display); font-size: 13.5px; font-weight: 600;
  background: rgba(11, 18, 38, 0.92); border: 1px solid var(--card-border);
  padding: 9px 15px; border-radius: 999px; backdrop-filter: blur(8px);
  box-shadow: 0 10px 30px rgba(0,0,0,.4);
}
.chip-a { top: 18px; right: -14px; animation: floaty 5s ease-in-out infinite; color: var(--teal); }
.chip-b { bottom: 24px; left: -14px; animation: floaty 6s .8s ease-in-out infinite; color: var(--amber); }
@keyframes floaty { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-10px); } }

.about-text p { color: var(--muted); margin-bottom: 18px; }
.about-points { list-style: none; margin-top: 8px; }
.about-points li {
  padding: 9px 0; color: var(--text); font-size: 15.5px;
  border-bottom: 1px dashed rgba(255,255,255,.08);
}
.about-points li:last-child { border-bottom: none; }

/* ---------- timeline ---------- */
.timeline { position: relative; padding-left: 34px; }
.timeline::before {
  content: ""; position: absolute; left: 8px; top: 6px; bottom: 6px; width: 2px;
  background: linear-gradient(180deg, var(--teal), rgba(45,212,191,.06));
  border-radius: 2px;
}
.tl-item { position: relative; margin-bottom: 28px; }
.tl-dot {
  position: absolute; left: -34px; top: 26px; width: 18px; height: 18px;
  border-radius: 50%; background: var(--bg);
  border: 3px solid var(--teal); z-index: 1;
}
.tl-dot.current { box-shadow: 0 0 0 0 rgba(45,212,191,.5); animation: pulse 2.2s infinite; }
.tl-dot.alt { border-color: var(--amber); }
@keyframes pulse {
  0% { box-shadow: 0 0 0 0 rgba(45,212,191,.45); }
  70% { box-shadow: 0 0 0 14px rgba(45,212,191,0); }
  100% { box-shadow: 0 0 0 0 rgba(45,212,191,0); }
}
.tl-card {
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 26px 28px;
  transition: transform .3s, border-color .3s, box-shadow .3s;
}
.tl-card:hover {
  transform: translateX(8px); border-color: rgba(45,212,191,.4);
  box-shadow: 0 16px 44px rgba(0,0,0,.35);
}
.tl-head { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 6px; }
.tl-head h3 { font-family: var(--font-display); font-size: 21px; }
.tl-period { font-size: 13.5px; color: var(--amber); font-weight: 600; letter-spacing: .3px; }
.tl-role { color: var(--teal); font-weight: 600; font-size: 15px; margin: 4px 0 10px; }
.tl-card > p:not(.tl-role) { color: var(--muted); font-size: 15.5px; }

.tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.tags span {
  font-size: 12.5px; font-weight: 500; color: var(--teal);
  background: var(--teal-dim); border: 1px solid rgba(45,212,191,.25);
  padding: 4px 12px; border-radius: 999px;
  transition: background .25s, transform .25s;
}
.tags span:hover { background: rgba(45,212,191,.28); transform: translateY(-2px); }
.tags.lg span { font-size: 14px; padding: 7px 16px; }

/* ---------- research ---------- */
.phd-banner {
  display: flex; gap: 20px; align-items: center;
  background: linear-gradient(120deg, var(--teal-dim), var(--amber-dim));
  border: 1px solid rgba(45,212,191,.3);
  border-radius: var(--radius); padding: 26px 30px; margin-bottom: 30px;
}
.phd-icon { font-size: 40px; }
.phd-banner h3 { font-family: var(--font-display); font-size: 20px; margin-bottom: 4px; }
.phd-banner p { color: var(--muted); font-size: 15.5px; }
.lang-chip {
  display: inline-block; background: rgba(255,255,255,.09); border-radius: 7px;
  padding: 1px 9px; font-size: 13.5px; color: var(--text); margin: 0 1px;
}

.featured-paper {
  position: relative;
  background: var(--bg-3);
  border: 1px solid rgba(251,191,36,.35);
  border-radius: var(--radius); padding: 30px 32px; margin-bottom: 40px;
  overflow: hidden;
}
.featured-paper::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(600px circle at 90% -20%, rgba(251,191,36,.12), transparent 45%);
  pointer-events: none;
}
.featured-badge {
  display: inline-block; font-size: 12.5px; font-weight: 700; letter-spacing: 1.4px;
  text-transform: uppercase; color: #1c1503;
  background: linear-gradient(120deg, var(--amber), #fde68a);
  padding: 4px 14px; border-radius: 999px; margin-bottom: 14px;
}
.featured-paper h3 { font-family: var(--font-display); font-size: clamp(19px, 2.6vw, 24px); line-height: 1.35; margin-bottom: 10px; }
.paper-meta { color: var(--amber); font-size: 14.5px; margin-bottom: 10px; }
.featured-paper > p:last-child { color: var(--muted); font-size: 15.5px; }

.pub-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
  gap: 18px;
}
.pub-card {
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 22px 24px;
  display: flex; flex-direction: column; gap: 8px;
  transition: transform .3s, border-color .3s, box-shadow .3s;
}
.pub-card:hover {
  transform: translateY(-6px); border-color: rgba(45,212,191,.4);
  box-shadow: 0 18px 44px rgba(0,0,0,.4);
}
.pub-year {
  font-family: var(--font-display); font-weight: 700; font-size: 13px;
  color: var(--teal); letter-spacing: 1px;
}
.pub-card h4 { font-family: var(--font-display); font-size: 16.5px; line-height: 1.4; font-weight: 600; }
.pub-card p { color: var(--muted); font-size: 13.8px; }
.pub-cite {
  margin-top: auto; font-size: 12.5px; color: var(--amber); font-weight: 600;
}

.scholar-cta {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
  gap: 20px; margin-top: 36px;
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 24px 30px;
}
.scholar-metrics { display: flex; flex-wrap: wrap; gap: 26px; color: var(--muted); font-size: 15px; }
.scholar-metrics strong { color: var(--teal); font-family: var(--font-display); font-size: 22px; margin-right: 6px; }

/* ---------- patents ---------- */
.patent-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.patent-card {
  position: relative; background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 30px 26px;
  transition: transform .3s, border-color .3s, box-shadow .3s;
}
.patent-card:hover {
  transform: translateY(-8px); border-color: rgba(251,191,36,.45);
  box-shadow: 0 20px 50px rgba(0,0,0,.4);
}
.patent-status {
  position: absolute; top: 18px; right: 18px;
  font-size: 12px; font-weight: 700; color: #baf7d0;
  background: rgba(34,197,94,.14); border: 1px solid rgba(34,197,94,.35);
  padding: 3px 11px; border-radius: 999px;
}
.patent-icon { font-size: 38px; margin-bottom: 14px; }
.patent-card h3 { font-family: var(--font-display); font-size: 18.5px; line-height: 1.4; margin-bottom: 10px; }
.patent-card p { color: var(--muted); font-size: 14.5px; margin-bottom: 16px; }
.patent-id { font-size: 12.5px; color: var(--teal); font-family: monospace; letter-spacing: .4px; }

/* ---------- books ---------- */
.book-feature {
  display: grid; grid-template-columns: 300px 1fr;
  gap: clamp(32px, 5vw, 64px); align-items: center;
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: clamp(28px, 4vw, 48px);
  overflow: hidden; position: relative;
}
.book-feature::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(500px circle at 12% 50%, rgba(251,191,36,.08), transparent 55%);
  pointer-events: none;
}
.book-visual { perspective: 1200px; display: grid; place-items: center; }
.book-3d {
  position: relative; width: 190px; height: 268px;
  transform-style: preserve-3d;
  transform: rotateY(-24deg) rotateX(4deg);
  animation: bookSway 7s ease-in-out infinite alternate;
}
@keyframes bookSway {
  from { transform: rotateY(-28deg) rotateX(4deg) translateY(0); }
  to   { transform: rotateY(-14deg) rotateX(2deg) translateY(-10px); }
}
.book-cover {
  position: absolute; inset: 0;
  background: linear-gradient(155deg, #14213f 0%, #0d1730 55%, #1d2b52 100%);
  border: 1px solid rgba(251,191,36,.4);
  border-radius: 4px 12px 12px 4px;
  display: flex; flex-direction: column; justify-content: center; align-items: center; gap: 12px;
  padding: 22px; text-align: center;
  box-shadow: 18px 26px 50px rgba(0,0,0,.55);
}
.book-cover-kicker {
  font-size: 11px; letter-spacing: 2.5px; text-transform: uppercase;
  color: var(--amber); font-weight: 700;
}
.book-cover-title {
  font-family: var(--font-display); font-size: 26px; font-weight: 700; color: var(--text);
  border-block: 1px solid rgba(255,255,255,.18); padding: 14px 6px;
}
.book-cover-author { font-size: 13px; color: var(--muted); letter-spacing: 1px; }
.book-spine {
  position: absolute; top: 2px; bottom: 2px; left: -14px; width: 14px;
  background: linear-gradient(90deg, #0a1024, #182647);
  transform: rotateY(-72deg); transform-origin: right;
  border-radius: 3px 0 0 3px;
}
.book-status {
  display: inline-block; font-size: 12.5px; font-weight: 700; letter-spacing: 1.2px;
  text-transform: uppercase; color: var(--amber);
  background: var(--amber-dim); border: 1px solid rgba(251,191,36,.35);
  padding: 5px 14px; border-radius: 999px; margin-bottom: 16px;
}
.book-info h3 { font-family: var(--font-display); font-size: clamp(22px, 3vw, 28px); margin-bottom: 12px; }
.book-info p { color: var(--muted); max-width: 560px; }
.book-hint { margin-top: 14px; font-size: 15px; }

/* ---------- skills ---------- */
.skill-groups { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 20px; }
.skill-group {
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 26px 28px;
  transition: border-color .3s, transform .3s;
}
.skill-group:hover { border-color: rgba(45,212,191,.35); transform: translateY(-4px); }
.skill-group h3 { font-family: var(--font-display); font-size: 17.5px; margin-bottom: 16px; }

/* ---------- education ---------- */
.edu-grid { display: grid; grid-template-columns: 1.15fr 1fr; gap: clamp(28px, 4vw, 48px); }
.edu-card {
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 24px 26px; margin-bottom: 16px;
  transition: transform .3s, border-color .3s;
}
.edu-card:hover { transform: translateX(6px); border-color: rgba(45,212,191,.4); }
.edu-year { font-size: 13px; font-weight: 700; color: var(--amber); letter-spacing: 1px; text-transform: uppercase; }
.edu-card h3 { font-family: var(--font-display); font-size: 18.5px; margin: 6px 0 6px; }
.edu-card p { color: var(--muted); font-size: 15px; }

.cert-list { list-style: none; }
.cert-list li {
  display: flex; align-items: center; gap: 14px;
  padding: 13px 16px; margin-bottom: 10px;
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: 12px; font-size: 14.8px;
  transition: transform .3s, border-color .3s;
}
.cert-list li:hover { transform: translateX(6px); border-color: rgba(251,191,36,.4); }
.cert-badge {
  flex-shrink: 0; font-family: var(--font-display); font-size: 11.5px; font-weight: 700;
  color: var(--amber); background: var(--amber-dim); border: 1px solid rgba(251,191,36,.3);
  padding: 4px 10px; border-radius: 8px; min-width: 52px; text-align: center;
}

/* ---------- contact ---------- */
.contact { text-align: center; }
.contact .section-title { align-items: center; }
.contact-lede { color: var(--muted); max-width: 560px; margin: -20px auto 40px; }

.mail-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(175px, 1fr));
  gap: 16px; max-width: 1060px; margin: 0 auto;
}
.mail-card {
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  background: var(--card); border: 1px solid var(--card-border);
  border-radius: var(--radius); padding: 28px 10px;
  transition: transform .3s, border-color .3s, box-shadow .3s;
}
.mail-card:hover {
  transform: translateY(-8px); border-color: var(--teal);
  box-shadow: 0 20px 50px rgba(45, 212, 191, 0.15);
}
.mail-emoji { font-size: 34px; margin-bottom: 6px; transition: transform .3s; }
.mail-card:hover .mail-emoji { transform: scale(1.25) rotate(-8deg); }
.mail-addr { font-family: var(--font-display); font-weight: 600; color: var(--text); font-size: 13px; letter-spacing: -0.2px; overflow-wrap: anywhere; }

.contact-links { display: flex; flex-wrap: wrap; justify-content: center; gap: 14px; margin-top: 40px; }

/* ---------- footer ---------- */
.footer {
  text-align: center; padding: 44px 20px 36px;
  border-top: 1px solid var(--card-border);
  color: var(--muted); font-size: 14.5px;
}
.footer-sub { margin-top: 6px; font-size: 13px; opacity: .8; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }
  .book-feature { grid-template-columns: 1fr; text-align: center; }
  .book-info p { margin-inline: auto; }
  .about-visual { max-width: 420px; margin: 0 auto; }
  .edu-grid { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: fixed; top: var(--nav-h); right: 0; left: 0;
    flex-direction: column; align-items: flex-start; gap: 0;
    background: rgba(7, 12, 24, 0.97); backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--card-border);
    max-height: 0; overflow: hidden; transition: max-height .4s ease;
  }
  .nav-links.open { max-height: 480px; }
  .nav-links li { width: 100%; }
  .nav-links a { display: block; padding: 15px 28px; width: 100%; }
  .nav-links a:not(.nav-cta)::after { display: none; }
  .nav-cta { margin: 10px 24px 18px; display: inline-block; width: auto !important; }
  .hero { padding-left: 22px; padding-right: 22px; }
  .scroll-cue { display: none; }
  .tl-card:hover { transform: none; }
}

/* ---------- reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
}