* { margin:0; padding:0; box-sizing:border-box; }
:root {
    --primary: #6c5ce7; --primary-dark: #5b4fcf; --secondary: #00cec9;
    --accent: #fd79a8; --dark: #2d3436; --light: #f9f9f9; --gray: #dfe6e9;
    --card-shadow: 0 10px 30px rgba(108,92,231,0.1);
    --transition: all 0.3s ease;
}
body { font-family:'Poppins',sans-serif; line-height:1.6; color:var(--dark); background-color:var(--light); }
.container { width:90%; max-width:1200px; margin:0 auto; padding:0 15px; }

/* Header */
header { background:rgba(255,255,255,0.95); box-shadow:0 5px 20px rgba(0,0,0,0.05); position:fixed; width:100%; top:0; z-index:1000; backdrop-filter:blur(10px); }
.navbar { display:flex; justify-content:space-between; align-items:center; padding:20px 0; }
.logo { display:flex; align-items:center; font-family:'Orbitron',sans-serif; font-weight:700; font-size:28px; color:var(--primary); text-decoration:none; letter-spacing:1px; }
.logo i { color:var(--secondary); margin-right:8px; }
.logo span { color:var(--accent); }
.nav-links { display:flex; list-style:none; }
.nav-links li { margin-left:25px; position:relative; }
.nav-links a { text-decoration:none; color:var(--dark); font-weight:500; font-size:15px; transition:var(--transition); padding:5px 0; }
.nav-links a:hover { color:var(--primary); }

/* Underline effect – only for top-level non-dropdown items */
.nav-links > li:not(.dropdown) > a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 3px;
    background: var(--primary);
    bottom: -5px;
    left: 0;
    transition: var(--transition);
}
.nav-links > li:not(.dropdown) > a:hover::after,
.nav-links > li:not(.dropdown) > a.active::after {
    width: 100%;
}

.dropdown-content {
    position:absolute; top:100%; left:0; background:white; min-width:220px;
    box-shadow:0 10px 30px rgba(0,0,0,0.1); border-radius:10px;
    opacity:0; visibility:hidden; transform:translateY(10px);
    transition:var(--transition); padding:10px 0; z-index:1001;
    max-height:400px; overflow-y:auto;
}
.dropdown:hover .dropdown-content { opacity:1; visibility:visible; transform:translateY(0); }
.dropdown-content a { display:block; padding:12px 20px; color:var(--dark); font-size:14px; text-decoration:none; transition:var(--transition); }
.dropdown-content a:hover { background:rgba(108,92,231,0.05); color:var(--primary); padding-left:25px; }
.dropdown-content a i { margin-right:10px; width:18px; text-align:center; }
.menu-toggle { display:none; font-size:24px; cursor:pointer; color:var(--primary); }

/* Footer */
footer { background-color:var(--dark); color:white; padding:60px 0 30px; margin-top:60px; }
.footer-content { display:grid; grid-template-columns:repeat(auto-fit,minmax(250px,1fr)); gap:40px; margin-bottom:40px; }
.footer-logo { font-family:'Orbitron',sans-serif; font-weight:700; font-size:28px; color:white; margin-bottom:20px; display:inline-block; text-decoration:none; }
.footer-logo span { color:var(--accent); }
.footer-about p { color:#bbb; margin-bottom:20px; }
.footer-links h4, .footer-social h4 { font-size:1.2rem; margin-bottom:20px; color:white; }
.footer-links ul { list-style:none; }
.footer-links li { margin-bottom:10px; }
.footer-links a { color:#bbb; text-decoration:none; transition:var(--transition); }
.footer-links a:hover { color:var(--secondary); padding-left:5px; }
.social-icons { display:flex; gap:15px; }
.social-icon { width:40px; height:40px; background:rgba(255,255,255,0.1); border-radius:50%; display:flex; align-items:center; justify-content:center; color:white; text-decoration:none; transition:var(--transition); }
.social-icon:hover { background:var(--primary); transform:translateY(-5px); }
.copyright { text-align:center; padding-top:30px; border-top:1px solid rgba(255,255,255,0.1); color:#bbb; font-size:14px; }

/* Notes page specific */
.notes-header {
    background: linear-gradient(135deg, #6c5ce7 0%, #5b4fcf 100%);
    color: white;
    padding: 120px 0 60px;
    text-align: center;
    margin-top: 80px;
}
.notes-header h1 { font-size: 3rem; margin-bottom: 20px; }
.notes-header p { font-size: 1.2rem; max-width: 800px; margin: 0 auto; opacity: 0.9; }
.topic-buttons {
    background: white;
    padding: 30px;
    border-radius: 15px;
    box-shadow: var(--card-shadow);
    margin: 40px 0;
}
.topic-buttons h2 { margin-bottom: 20px; color: var(--primary); }
.button-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 12px;
}
.topic-btn {
    background: #f8f9fa;
    padding: 10px 15px;
    border-radius: 8px;
    text-decoration: none;
    color: var(--dark);
    font-weight: 500;
    transition: var(--transition);
    border-left: 4px solid var(--primary);
    display: block;
    text-align: center;
}
.topic-btn:hover {
    background: var(--primary);
    color: white;
    transform: translateX(5px);
}
.topic-section {
    background: white;
    border-radius: 15px;
    padding: 30px;
    margin-bottom: 40px;
    box-shadow: var(--card-shadow);
    scroll-margin-top: 100px;
}
.topic-section h2 {
    color: var(--primary);
    border-bottom: 3px solid var(--secondary);
    padding-bottom: 10px;
    margin-bottom: 25px;
    font-size: 2rem;
}
.explanation {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 20px;
}
.english, .hindi {
    flex: 1 1 300px;
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
}
.english h3, .hindi h3 {
    color: var(--primary);
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
}
.code-block {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 20px;
    border-radius: 10px;
    font-family: 'Source Code Pro', monospace;
    overflow-x: auto;
    margin: 20px 0;
}
.code-block pre { margin: 0; }
.btn-top {
    display: inline-block;
    margin-top: 20px;
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}
.btn-top:hover { text-decoration: underline; }

/* Homepage specific: hero, resources, about */
.hero { background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%); color:white; padding:200px 0 100px; text-align:center; }
.hero h1 { font-size:3.5rem; margin-bottom:20px; }
.hero p { font-size:1.2rem; max-width:700px; margin:0 auto; opacity:0.9; }
.resources-section { padding: 80px 0; background: #f8f9fa; }
.section-header { text-align: center; margin-bottom: 50px; }
.section-header h2 { font-size: 2.5rem; color: var(--primary); margin-bottom: 15px; }
.resource-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}
.resource-card {
    background: white;
    border-radius: 15px;
    padding: 30px 20px;
    box-shadow: var(--card-shadow);
    text-align: center;
    transition: var(--transition);
}
.resource-card:hover { transform: translateY(-10px); box-shadow: 0 20px 40px rgba(108,92,231,0.2); }
.resource-icon { font-size: 4rem; color: var(--primary); margin-bottom: 20px; }
.resource-card h3 { margin-bottom: 10px; }
.resource-card p { color: #666; margin-bottom: 20px; }
.resource-btn {
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 10px 25px;
    border-radius: 50px;
    text-decoration: none;
    transition: var(--transition);
}
.resource-btn:hover { background: var(--primary-dark); transform: scale(1.05); }

/* Modern About Section (for index) */
.about-section {
    padding: 100px 0;
    background: white;
}
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 50px;
    align-items: center;
}
.about-content h2 {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 20px;
}
.about-content h2 span {
    color: var(--secondary);
}
.about-content p {
    color: #555;
    margin-bottom: 30px;
    font-size: 1.1rem;
    line-height: 1.8;
}
.stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
    margin-top: 30px;
}
.stat-item {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    transition: var(--transition);
}
.stat-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--card-shadow);
}
.stat-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 5px;
}
.stat-label {
    color: #777;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 1px;
}
.features {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
}
.feature-card {
    background: linear-gradient(145deg, #ffffff, #f5f5f5);
    padding: 30px 20px;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    transition: var(--transition);
    border-bottom: 4px solid transparent;
}
.feature-card:hover {
    transform: translateY(-5px);
    border-bottom-color: var(--primary);
    box-shadow: 0 15px 40px rgba(108,92,231,0.15);
}
.feature-icon {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 15px;
}
.feature-card h4 {
    font-size: 1.2rem;
    margin-bottom: 10px;
    color: var(--dark);
}
.feature-card p {
    color: #777;
    font-size: 0.9rem;
    line-height: 1.6;
}
.about-cta {
    margin-top: 40px;
    display: inline-block;
    background: var(--primary);
    color: white;
    padding: 15px 40px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid transparent;
}
.about-cta:hover {
    background: transparent;
    color: var(--primary);
    border-color: var(--primary);
}
.section-placeholder {
    padding: 60px 0;
    text-align: center;
    background: white;
}
.section-placeholder:nth-child(even) {
    background: #f8f9fa;
}
.section-placeholder h2 {
    font-size: 2rem;
    color: var(--primary);
    margin-bottom: 20px;
}

/* Mobile menu styles */
@media (max-width:768px) {
    .notes-header h1 { font-size:2rem; }
    .nav-links { display: none; }
    .nav-links.active {
        display: flex !important;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        background: white;
        padding: 20px;
        box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        z-index: 999;
    }
    .nav-links.active li {
        margin: 10px 0 !important;
        width: 100%;
    }
    .nav-links.active a {
        width: 100%;
        display: block;
    }
    .dropdown-content {
        position: static;
        box-shadow: none;
        padding-left: 20px;
        opacity: 1;
        visibility: visible;
        transform: none;
        background: transparent;
        max-height: none;
        overflow-y: visible;
    }
    .menu-toggle {
        display: block !important;
    }
}

/* Responsive about section */
@media (max-width: 992px) {
    .about-grid {
        grid-template-columns: 1fr;
    }
    .features {
        order: -1; /* features appear first on mobile */
    }
}

/* Resources page category headings (added for external resources) */
.resource-category {
    margin-bottom: 50px;
}
.resource-category h2 {
    color: var(--primary);
    font-size: 2rem;
    margin-bottom: 30px;
    border-bottom: 3px solid var(--secondary);
    padding-bottom: 10px;
}