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

body {
    font-family: 'Arial', sans-serif;
    line-height: 1.6;
    color: #2c3e50; /* was #333 */
    background: linear-gradient(135deg, #f7f9fc 0%, #eff4ff 100%); /* was #f5f7fa -> #e4e8ed */
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Floating Elements */
.floating-element {
    position: fixed;
    font-size: 2rem;
    animation: float 6s ease-in-out infinite;
    z-index: 1;
    opacity: 0.7;
    text-shadow: 0 2px 4px rgba(0,0,0,0.08); /* was 0.1 */
}

.floating-element:nth-child(1) { /* DNA emoji */
    top: 20%;
    left: 10%;
    animation-delay: 0s;
    color: #0ea5e9; /* teal-blue accent; was #4CAF50 */
}

.floating-element:nth-child(2) { /* Microscope emoji */
    top: 60%;
    right: 15%;
    animation-delay: 2s;
    color: #3b82f6; /* blue; was #2196F3 */
}

.floating-element:nth-child(3) { /* Art emoji */
    bottom: 20%;
    left: 20%;
    animation-delay: 4s;
    color: #6366f1; /* indigo; was #9C27B0 */
}

@keyframes float {
    0%, 100% { transform: translateY(0px) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(180deg); }
}

/* Header */
header {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06); /* was 0.1 */
    box-shadow: 0 2px 10px rgba(0,0,0,0.04); /* was 0.05 */
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-container {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.logo {
    font-size: 2.5rem;
    font-weight: bold;
    color: #2c3e50; /* Keep logo red */
    line-height: 1;
    letter-spacing: 1px;
}

.logo-tagline {
    font-size: 0.9rem;
    color: #667a8a; /* was #666 */
    margin-top: 3px;
    letter-spacing: 0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    color: #2c3e50; /* was black */
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    text-shadow: 0 1px 2px rgba(0,0,0,0.18); /* was 0.3 */
}

.nav-links a:hover {
    color: #264aa3; /* was #ffcccc */
    transform: translateY(-2px);
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #2c3e50; /* was #cc0000 */
    position: relative;
    z-index: 2;
    text-shadow: 0 2px 4px rgba(0,0,0,0.22); /* was 0.3 */
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 1rem;
    animation: slideInDown 1s ease-out;
}

.hero p {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    animation: slideInUp 1s ease-out 0.3s both;
}

.cta-button {
    display: inline-block;
    padding: 15px 30px;
    background: linear-gradient(45deg, #4f86ff, #2563eb); /* was #ff3333 -> #cc0000 */
    color: white;
    text-decoration: none;
    border-radius: 50px;
    font-weight: bold;
    transition: all 0.3s ease;
    animation: pulse 2s infinite;
    border: none;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(37, 99, 235, 0.35); /* was red shadow */
}

.cta-button:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 35px rgba(37, 99, 235, 0.35);
    background: linear-gradient(45deg, #2563eb, #4f86ff);
}

/* Main Content */
.main-content {
    background: white;
    position: relative;
    z-index: 2;
    padding: 4rem 0;
    margin-top: -50px;
    border-radius: 50px 50px 0 0;
    box-shadow: 0 -10px 30px rgba(0,0,0,0.06); /* was 0.1 */
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: #2c3e50; /* was #cc0000 */
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(45deg, #4f86ff, #2563eb); /* was red gradient */
    border-radius: 2px;
}

/* Course Cards */
.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: white;
    padding: 2rem;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(37, 99, 235, 0.08); /* was rgba(204,0,0,0.1) */
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    border: 1px solid rgba(37, 99, 235, 0.12); /* was red */
}

.course-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(37, 99, 235, 0.12), transparent); /* was rgba(255, 51, 51, 0.1) */
    transition: left 0.6s ease;
}

.course-card:hover::before {
    left: 100%;
}

.course-card:hover {
    transform: translateY(-10px) scale(1.02);
    box-shadow: 0 20px 40px rgba(37, 99, 235, 0.15); /* was red */
}

.course-icon {
    font-size: 3rem;
    text-align: center;
    margin-bottom: 1rem;
    color: #2563eb; /* was #cc0000 */
}

.course-card h3 {
    font-size: 1.8rem;
    margin-bottom: 1rem;
    color: #2563eb; /* was #cc0000 */
    text-align: center;
}

.course-card p {
    color: #667a8a; /* was #666 */
    text-align: center;
    margin-bottom: 1.5rem;
}

.course-button {
    display: block;
    width: 100%;
    padding: 12px;
    background: linear-gradient(45deg, #4f86ff, #2563eb); /* was red gradient */
    color: white;
    text-decoration: none;
    border-radius: 25px;
    text-align: center;
    font-weight: bold;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

.course-button:hover {
    background: linear-gradient(45deg, #2563eb, #4f86ff);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(37, 99, 235, 0.28); /* was red */
}

/* Grade Selection Page */
.grade-selection {
    display: none;
    padding: 2rem 0;
}

.grade-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
    margin-top: 2rem;
}

.grade-card {
    background: linear-gradient(135deg, #60a5fa, #2563eb); /* was #ff3333 -> #cc0000 */
    color: white;
    padding: 1.5rem;
    border-radius: 15px;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(37, 99, 235, 0.20); /* was red */
}

.grade-card::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.22) 0%, transparent 70%); /* slight tweak */
    transition: opacity 0.3s ease;
    opacity: 0;
}

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

.grade-card:hover {
    transform: translateY(-5px) rotate(2deg);
    box-shadow: 0 15px 30px rgba(37, 99, 235, 0.28); /* was red */
}

.grade-card h4 {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

.back-button {
    background: #3b82f6; /* was #ff3333 */
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1rem;
    margin-bottom: 2rem;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(37, 99, 235, 0.18); /* was red */
}

.back-button:hover {
    background: #2563eb; /* was #e60000 */
    transform: translateY(-2px);
    box-shadow: 0 6px 15px rgba(37, 99, 235, 0.28); /* was red */
}

/* Game Platform */
.game-platform {
    display: none;
    background: linear-gradient(135deg, #60a5fa, #2563eb); /* was red gradient */
    color: white;
    padding: 2rem;
    border-radius: 20px;
    margin: 2rem 0;
    text-align: center;
    box-shadow: 0 10px 30px rgba(37, 99, 235, 0.22); /* was red */
}

.game-interface {
    background: rgba(255, 255, 255, 0.12); /* was 0.1 */
    backdrop-filter: blur(10px);
    border-radius: 15px;
    padding: 2rem;
    margin: 2rem 0;
    border: 1px solid rgba(255, 255, 255, 0.22); /* was 0.2 */
}

.game-button {
    background: #60a5fa; /* was #ff6666 */
    color: white;
    padding: 15px 30px;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1.1rem;
    margin: 10px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 10px rgba(37, 99, 235, 0.20); /* was red */
}

.game-button:hover {
    background: #3b82f6; /* was #ff4d4d */
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(37, 99, 235, 0.28); /* was red */
}

/* Footer */
footer {
    background: #1f2937; /* was #990000 */
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
    color: #cfe0ff; /* was #ffcccc */
}

.footer-section a {
    color: #93c5fd; /* was #ffcccc */
    text-decoration: none;
    transition: all 0.3s ease;
}

.footer-section a:hover {
    color: #ffffff;
    text-decoration: underline;
}

/* Animations */
@keyframes slideInDown {
    from { transform: translateY(-100px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

@keyframes slideInUp {
    from { transform: translateY(100px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

@keyframes pulse {
    0% { box-shadow: 0 0 0 0 rgba(79, 134, 255, 0.60); } /* was red */
    70% { box-shadow: 0 0 0 20px rgba(79, 134, 255, 0); }
    100% { box-shadow: 0 0 0 0 rgba(79, 134, 255, 0); }
}

@keyframes loading {
    from { width: 0%; }
    to { width: 100%; }
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 { font-size: 2.5rem; }
    .hero p { font-size: 1.2rem; }
    .nav-links { display: none; }
    .grade-grid { grid-template-columns: repeat(3, 1fr); }
    .section-title { font-size: 2rem; }
    .course-card { padding: 1.5rem; }
    .logo-main { font-size: 2rem; }
    .logo-tagline { font-size: 0.8rem; }
}
/*blur subject under development */
.course-button[aria-disabled="true"] {
  opacity: 0.6;
  cursor: not-allowed;
}
.course-button[aria-disabled="true"]:hover {
  transform: none; /* if you have hover effects, neutralize them */
}