:root {
  --bg: #0B0B0D;
  --surface: #111214;
  --text: #F5F5F7;
  --muted: #B3B3B8;
  --accent: #65E3FF;
  --border: #1F1F23;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, sans-serif;
  line-height: 1.65;
  overflow-x: hidden;
}

/* NAVIGATION */
nav {
  display: flex;
  justify-content: space-between;
  padding: 1rem 4rem;
  position: sticky;
  top: 1rem;
  margin: 0 2rem;
  background: rgba(17,18,20,0.6);
  backdrop-filter: blur(14px) saturate(140%);
  border: 1px solid var(--border);
  border-radius: 18px;
  z-index: 10;
}

nav a {
  color: var(--muted);
  margin-left: 2rem;
  text-decoration: none;
  font-weight: 500;
}

nav a:hover {
  color: var(--accent);
}

.logo {
  font-weight: 700;
  font-size: 1.2rem;
}

.logo span {
  color: var(--accent);
}

/* HERO SECTION */
.hero {
  min-height: 95vh;
  display: flex;
  align-items: center;
  padding: 0 6rem;
  position: relative;

}

.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 50% 30%, rgba(101,227,255,0.12), transparent 60%);
  pointer-events: none;
}

.hero > div {
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3.6rem;
  line-height: 1.1;
  max-width: 820px;
}

.hero p {
  margin-top: 1.6rem;
  max-width: 620px;
  color: var(--muted);
  font-size: 1.05rem;
}

/* SECTIONS */
section {
  padding: 6rem;
}

section h2 {
  font-size: 2.4rem;
  margin-bottom: 3rem;
}

.dark {
  background: var(--surface);
}

/* RESEARCH CARDS */
.research-card {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 3rem;
  margin-bottom: 5rem;
}

.meta {
  color: var(--muted);
  font-size: 0.9rem;
  margin-bottom: 1rem;
  display: block;
}

.tags span {
  display: inline-block;
  background: #1a1f2b;
  padding: 0.4rem 0.8rem;
  border-radius: 999px;
  margin: 0.3rem 0.3rem 0 0;
  font-size: 0.8rem;
}

.media img {
  width: 100%;
  border-radius: 12px;
  border: 1px solid var(--border);
  margin-bottom: 1rem;
}

/* FOOTER */
footer {
  padding: 2rem;
  text-align: center;
  color: var(--muted);
  border-top: 1px solid var(--border);
}

/* MODAL */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.65);
  backdrop-filter: blur(6px);
  display: none;
  place-items: center;
  z-index: 100;
}

.modal {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 2.5rem 3rem;
  text-align: center;
}

.modal button {
  margin-top: 1.5rem;
  background: var(--accent);
  border: none;
  padding: 0.6rem 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  cursor: pointer;
}

/* RESPONSIVE */
@media (max-width: 900px) {
  nav {
    padding: 1rem 2rem;
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;
  }

  .hero {
    padding: 3rem;
    flex-direction: column;
    text-align: center;
  }

  .hero h1 {
    font-size: 2.5rem;
  }

  section {
    padding: 3rem 1.5rem;
  }

  .research-card {
    grid-template-columns: 1fr;
  }

  .research-card .media {
    margin-top: 2rem;
  }
}


/* NAV LINKS */
nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 4rem;
  position: sticky;
  top: 1rem;
  margin: 0 2rem;
  background: rgba(17,18,20,0.6);
  backdrop-filter: blur(14px) saturate(140%);
  border: 1px solid var(--border);
  border-radius: 18px;
  z-index: 10;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 500;
}

.nav-links a:hover {
  color: var(--accent);
}

/* HAMBURGER ICON */
.hamburger {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 28px;
  height: 22px;
  cursor: pointer;
  background: rgba(255,255,255,0.1);
  padding: 5px;
  border-radius: 12px;
  backdrop-filter: blur(10px);
}

.hamburger span {
  display: block;
  height: 3px;
  width: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: all 0.3s ease;
}

/* SHOW HAMBURGER ON MOBILE */
@media (max-width: 900px) {
  .nav-links {
    position: absolute;
    top: 70px; /* height of nav */
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(17,18,20,0.85);
    backdrop-filter: blur(14px) saturate(140%);
    gap: 1rem;
    padding: 1rem 2rem;
    border-radius: 0 0 18px 18px;
    display: none; /* hide by default */
  }

  .nav-links.active {
    display: flex;
  }

  .hamburger {
    display: flex;
  }
}


.hamburger.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.open span:nth-child(2) {
  opacity: 0;
}

.hamburger.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}


.hero-bg {
  background:
    linear-gradient(
      to bottom,
      rgba(11, 11, 13, 0.35),
      rgba(11, 11, 13, 0.85)
    ),
    url("../images/bg.png") center / cover no-repeat;
}

/* GLOBAL LINK STYLE */
a {
  position: relative;
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.25s ease;
}

/* Underline animation */
a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 100%;
  height: 1.5px;
  background: linear-gradient(
    90deg,
    transparent,
    var(--accent),
    transparent
  );
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 0.25s ease;
  opacity: 0.9;
}

a:hover {
  color: #9ff0ff;
}

a:hover::after {
  transform: scaleX(1);
}


nav a {
  color: var(--muted);
  font-weight: 500;
}

nav a::after {
  bottom: -6px;
}

nav a:hover {
  color: var(--accent);
}