/* ================= ROOT ================= */
:root {
  --header-h: 80px;
  --footer-h: 48px;

  --primary: #0b5ed7;
  --accent: #22c55e;

  --glass-light: rgba(255,255,255,0.92);
  --glass-dark: rgba(15,23,42,0.92);

  --text-light: #1e293b;
  --text-dark: #e5e7eb;
}

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

html, body {
  width: 100%;
  overflow-x: hidden;
}

/* ================= BODY BACKGROUND ================= */
body {
  font-family: "Roboto", sans-serif;
  color: var(--text-light);

  background-image: url("../assets/images/iitism-ground.jpg");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;

  position: relative;
}

/* Dark overlay (lighter than before) */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.30);   /* 🔹 reduced darkness */
  z-index: -2;
}

/* Reduced blur layer */
body::after {
  content: "";
  position: fixed;
  inset: 0;
  backdrop-filter: blur(1px);    /* 🔹 reduced blur */
  -webkit-backdrop-filter: blur(1px);
  z-index: -1;
}

/* ================= DARK MODE ================= */
body.dark {
  color: var(--text-dark);
}

/* ================= HEADER ================= */
.top-header {
  position: fixed;
  top: 0;
  left: 0;
  height: var(--header-h);
  width: 100%;
  z-index: 1000;

  background: rgba(10,25,48,0.96);
  backdrop-filter: blur(6px);

  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 24px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.logo {
  height: 52px;
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.inst {
  font-size: 15px;
  font-weight: 600;
  color: #ffffff;
}

.dept {
  font-size: 12px;
  color: #c7d2fe;
}

/* Theme toggle */
#themeToggle {
  background: var(--accent);
  border: none;
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 16px;
  cursor: pointer;
}

/* ================= HERO ================= */
.hero {
  margin-top: var(--header-h);
  padding: 50px 20px 40px;
  text-align: center;
  color: #ffffff;
}

.hero-photo {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  border: 4px solid #ffffff;
  object-fit: cover;
  margin-bottom: 16px;
}

.hero h1 {
  font-size: 32px;
  font-weight: 700;
}

.hero h2 {
  font-size: 18px;
  font-weight: 500;
  margin: 6px 0 10px;
  opacity: 0.95;
}

.hero p {
  font-size: 14px;
  line-height: 1.6;
}

/* ================= BUTTONS ================= */
.button-group {
  margin-top: 18px;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
}

.btn, .btn-outline {
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 13px;
  text-decoration: none;
}

.btn {
  background: var(--primary);
  color: white;
}

.btn-outline {
  border: 1px solid white;
  color: white;
}

/* ================= TABS (WHITE BOX REMOVED) ================= */
.tabs {
  max-width: 1100px;
  margin: 20px auto calc(var(--footer-h) + 30px);
  padding: 0 16px;
}

/* 🔥 NO WHITE BACKGROUND ANYMORE */
.tab-buttons {
  position: sticky;
  top: var(--header-h);
  z-index: 900;

  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;

  padding: 12px 0;
  background: transparent;     /* ✅ removed white box */
  backdrop-filter: none;
}

.tab-btn {
  border: none;
  padding: 8px 18px;
  border-radius: 20px;
  font-size: 14px;
  cursor: pointer;

  background: rgba(255,255,255,0.85);
  transition: all 0.25s ease;
}

.tab-btn:hover {
  transform: translateY(-2px);
}

.tab-btn.active {
  background: var(--primary);
  color: white;
}

/* ================= TAB CONTENT ================= */
.tab-content {
  display: none;
  margin-top: 22px;
}

.tab-content.active {
  display: block;
}

/* ================= CARD ================= */
.card {
  background: var(--glass-light);
  padding: 26px;
  border-radius: 16px;
  box-shadow: 0 18px 40px rgba(0,0,0,0.25);
}

body.dark .card {
  background: var(--glass-dark);
}

/* ================= TIMELINE ================= */
.timeline {
  list-style: none;
  border-left: 4px solid var(--primary);
  padding-left: 18px;
}

.timeline li {
  margin-bottom: 14px;
}

.timeline span {
  font-weight: 600;
  color: var(--primary);
}

/* ================= FOOTER ================= */
.footer {
  position: fixed;
  bottom: 0;
  left: 0;
  height: var(--footer-h);
  width: 100%;

  background: rgba(10,25,48,0.96);
  color: white;
  font-size: 13px;

  display: flex;
  align-items: center;
  justify-content: center;
}

/* ================= MOBILE ================= */
@media (max-width: 768px) {

  body {
    background-attachment: scroll; /* important for mobile */
  }

  .hero h1 {
    font-size: 26px;
  }

  .hero h2 {
    font-size: 16px;
  }

  .logo {
    height: 44px;
  }

  .tab-buttons {
    top: calc(var(--header-h) + 4px);
  }
}