/* ===================================
       1. GLOBAL RESET & BASE
       =================================== */
    *, *::before, *::after {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: 'Poppins', sans-serif;
      background: #0f0c29;
      color: #e0e7ff;
      min-height: 100vh;
      overflow-x: hidden;
      transition: background 0.8s ease;
    }

    body.dark {
      background: #0a0719;
    }

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

    button {
      cursor: pointer;
      border: none;
      outline: none;
      font-family: inherit;
    }

    /* ===================================
       2. HERO BACKGROUND ANIMATION
       =================================== */
    .hero {
      position: relative;
      min-height: 100vh;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      text-align: center;
      padding: 0 5%;
      overflow: hidden;
    }

    .hero::before {
      content: '';
      position: absolute;
      inset: 0;
      z-index: -2;
      background: 
        radial-gradient(circle at 20% 80%, #7c3aed 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, #ec4899 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, #3b82f6 0%, transparent 40%);
      opacity: 0.65;
      animation: smoothFloat 28s ease-in-out infinite;
      will-change: transform;
    }

    .hero::after {
      content: '';
      position: absolute;
      inset: 0;
      z-index: -1;
      background: linear-gradient(135deg, #1e1b4b 0%, #2d1b69 60%, #4c1d95 100%);
      opacity: 0.95;
    }

    @keyframes smoothFloat {
      0%, 100% { transform: translate(0, 0) scale(1); }
      33% { transform: translate(4%, -4%) scale(1.03); }
      66% { transform: translate(-3%, 3%) scale(1.02); }
    }

    @media (prefers-reduced-motion: reduce) {
      .hero::before { animation: none; }
    }

    /* ===================================
       3. HEADER
       =================================== */
    header {
      position: fixed;
      top: 0;
      width: 100%;
      padding: clamp(1.2rem, 3vw, 2rem) 5% clamp(1.5rem, 4vw, 2.5rem);
      display: flex;
      justify-content: space-between;
      align-items: center;
      background: rgba(15, 12, 41, 0.4);
      backdrop-filter: blur(30px);
      border-bottom: 1px solid rgba(124, 58, 237, 0.2);
      z-index: 1000;
      box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
      transition: all 0.4s ease;
    }

    .logo {
      font-size: clamp(2.2rem, 6vw, 3rem);
      font-weight: 900;
      background: linear-gradient(135deg, #a78bfa, #ec4899, #60a5fa);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      transition: transform 0.4s ease;
      cursor: pointer;
    }

    .logo:hover {
      transform: scale(1.05) rotate(2deg);
    }

    nav {
      display: flex;
      align-items: center;
      gap: clamp(2rem, 5vw, 4rem);
    }

    nav a {
      font-weight: 600;
      font-size: clamp(1.1rem, 2.5vw, 1.3rem);
      position: relative;
      transition: all 0.4s ease;
      padding: 0.5rem 0;
    }

    nav a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      width: 0;
      height: 3px;
      background: linear-gradient(135deg, #7c3aed, #ec4899);
      border-radius: 4px;
      transition: all 0.5s ease;
      transform: translateX(-50%);
    }

    nav a:hover::after,
    nav a.active::after {
      width: 100%;
    }

    nav a:hover,
    nav a.active {
      color: #fbbf24;
      transform: translateY(-4px);
    }

    .login-btn {
      background: linear-gradient(135deg, #7c3aed, #ec4899);
      color: white;
      padding: 0.9rem 2.2rem;
      border-radius: 60px;
      font-weight: 700;
      box-shadow: 0 10px 30px rgba(124, 58, 237, 0.5);
      transition: all 0.5s ease;
    }

    .login-btn:hover {
      transform: translateY(-8px) scale(1.1);
      box-shadow: 0 25px 50px rgba(124, 58, 237, 0.7);
    }

    .toggle-dark {
      font-size: 2.2rem;
      background: none;
      margin-left: 1.5rem;
      transition: transform 0.3s;
    }

    .toggle-dark:hover {
      transform: rotate(20deg);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 8px;
      cursor: pointer;
      z-index: 1001;
    }

    .hamburger div {
      width: 40px;
      height: 5px;
      background: #c4b5fd;
      border-radius: 3px;
      transition: all 0.4s ease;
    }

    /* ===================================
       4. PAGE HERO (MATHS PAGE)
       =================================== */
    .page-hero {
      position: relative;
      min-height: 70vh;
      display: flex;
      flex-direction: column;
      justify-content: center;
      align-items: center;
      text-align: center;
      padding: clamp(100px, 15vw, 180px) 5% 80px;
      margin-top: 80px;
      overflow: hidden;
    }

    .page-hero::before {
      content: '';
      position: absolute;
      inset: 0;
      z-index: -2;
      background: 
        radial-gradient(circle at 20% 80%, #7c3aed 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, #ec4899 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, #3b82f6 0%, transparent 40%);
      opacity: 0.6;
      animation: smoothFloat 28s ease-in-out infinite;
    }

    .page-hero::after {
      content: '';
      position: absolute;
      inset: 0;
      z-index: -1;
      background: linear-gradient(135deg, #1e1b4b 0%, #2d1b69 60%, #4c1d95 100%);
      opacity: 0.95;
    }

    .page-hero h1 {
      font-size: clamp(3.5rem, 9vw, 6rem);
      font-weight: 900;
      margin-bottom: 1.5rem;
      background: linear-gradient(135deg, #c4b5fd, #fbbf24, #ec4899);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    .page-hero p {
      font-size: clamp(1.4rem, 4vw, 2rem);
      max-width: 800px;
      opacity: 0.9;
    }

    /* ===================================
       5. FIXED SEARCH BAR - NO SHIFTING
       =================================== */
    .search-container {
      position: fixed;
      top: 140px; /* Below header */
      left: 50%;
      transform: translateX(-50%);
      width: 90%;
      max-width: 800px;
      margin: 0;
      z-index: 50;
      transition: top 0.4s ease;
    }

    .search-container input {
      width: 100%;
      padding: clamp(1rem, 3vw, 1.5rem) clamp(2rem, 5vw, 3rem);
      font-size: clamp(1.1rem, 3vw, 1.4rem);
      border: none;
      border-radius: 60px;
      background: rgba(30, 27, 75, 0.7);
      backdrop-filter: blur(20px);
      color: white;
      outline: none;
      box-shadow: 0 20px 50px rgba(0,0,0,0.4);
      transition: all 0.4s ease;
    }

    .search-container input::placeholder {
      color: rgba(255,255,255,0.7);
    }

    .search-container input:focus {
      transform: scale(1.03);
      box-shadow: 0 30px 70px rgba(124,58,237,0.5);
      background: rgba(30, 27, 75, 0.9);
    }

    /* ===================================
       6. SUBJECT GRID
       =================================== */
    .subject-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(min(320px, 100%), 1fr));
      gap: clamp(2rem, 5vw, 3rem);
      width: 90%;
      max-width: 1400px;
      margin: 200px auto 6rem; /* Clear space for fixed search */
      padding: 0 5%;
    }

    .subject-card {
      background: rgba(30, 27, 75, 0.4);
      backdrop-filter: blur(30px);
      border-radius: 40px;
      padding: clamp(2rem, 5vw, 3rem);
      text-align: center;
      box-shadow: 0 30px 80px rgba(124, 58, 237, 0.3);
      border: 1px solid rgba(167, 139, 250, 0.2);
      transition: all 0.8s ease;
      cursor: pointer;
      position: relative;
      overflow: hidden;
    }

    .subject-card::before {
      content: '';
      position: absolute;
      inset: 0;
      background: linear-gradient(135deg, rgba(124,58,237,0.2), rgba(236,72,153,0.2));
      opacity: 0;
      transition: opacity 0.6s ease;
    }

    .subject-card:hover::before {
      opacity: 1;
    }

    .subject-card:hover {
      transform: translateY(-20px) scale(1.05);
      box-shadow: 0 50px 100px rgba(124, 58, 237, 0.5);
    }

    .subject-card h2 {
      font-size: clamp(1.6rem, 4vw, 2.2rem);
      margin-bottom: 1rem;
      background: linear-gradient(135deg, #c4b5fd, #fbbf24);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      font-weight: 800;
      position: relative;
      z-index: 1;
    }

    .subject-card p {
      font-size: clamp(1rem, 2.5vw, 1.2rem);
      opacity: 0.9;
      position: relative;
      z-index: 1;
    }

    /* Loader */
    .loader {
      border: 5px solid rgba(255,255,255,0.2);
      border-top: 5px solid #fbbf24;
      border-radius: 50%;
      width: 60px;
      height: 60px;
      animation: spin 1s linear infinite;
      margin: 40px auto;
    }

    @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
    }

    .loading-text {
      text-align: center;
      font-size: 1.4rem;
      margin-top: 20px;
      opacity: 0.8;
    }

    /* ===================================
       7. FOOTER
       =================================== */
    footer {
      background: linear-gradient(135deg, #1e1b4b, #0f0c29);
      padding: clamp(4rem, 8vw, 6rem) 5%;
      text-align: center;
      border-top: 1px solid rgba(124, 58, 237, 0.3);
    }

    footer p {
      font-size: clamp(1rem, 2vw, 1.3rem);
      opacity: 0.9;
    }

    footer span {
      background: linear-gradient(135deg, #a78bfa, #ec4899);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      font-weight: 700;
    }

    /* ===================================
       8. RESPONSIVE
       =================================== */
    @media (max-width: 768px) {
      .hamburger { display: flex; }
      nav {
        position: fixed;
        top: 100%;
        left: -100%;
        width: 100%;
        background: rgba(15, 12, 41, 0.95);
        flex-direction: column;
        padding: 4rem 0;
        transition: left 0.6s ease;
        gap: 2.5rem;
        align-items: center;
        backdrop-filter: blur(30px);
      }
      nav.active { left: 0; }
      .search-container { top: 110px; width: 92%; }
      .subject-grid { margin-top: 180px; }
    }

    @media (max-width: 480px) {
      .search-container { top: 100px; }
      .subject-grid { margin-top: 160px; }
      .page-hero { padding-top: 140px; }
    }