body {
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
    margin: 0;
    padding: 0;
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    min-height: 100%;
    height: 100%;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    height: 100%;
}

/* HEADER & NAV */

.header {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 20px rgba(139, 92, 246, 0.3);
}

.header .max-w-7xl {
    position: relative;
}

.desktop-center-nav {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
}

.nav-link-desktop {
    color: #ffffff;
    transition: all 0.3s ease;
    font-weight: 500;
    display: inline-block;
    text-decoration: none;
}

.nav-link-desktop:hover {
    color: #e5e7eb;
    transform: scale(1.08);
}

/* Dropdown */

.dropdown {
    position: relative;
}

.dropdown-content {
    display: none;
    position: absolute;
    top: 110%;
    left: 0;
    background: #ffffff;
    min-width: 220px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.12);
    border-radius: 12px;
    margin-top: 8px;
    overflow: hidden;
    animation: fadeInDown 0.25s ease;
    z-index: 1000;
}

.dropdown.open .dropdown-content {
    display: block;
}

.dropdown-content a {
    color: #4a5568;
    padding: 12px 20px;
    text-decoration: none;
    display: block;
    transition: all 0.2s ease;
    font-size: 14px;
}

.dropdown-content a:hover {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    padding-left: 28px;
}

/* Mobile menu */

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    color: #ffffff;
    font-size: 24px;
    cursor: pointer;
}

.mobile-menu {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: #16a34a; /* GREEN slide-down */
    padding: 16px 24px 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    border-radius: 0 0 16px 16px;
    transform-origin: top;
    transform: scaleY(0.95) translateY(-10px);
    opacity: 0;
    pointer-events: none;
    transition: transform 0.2s ease, opacity 0.2s ease;
    z-index: 999;
}

.mobile-menu.open {
    transform: scaleY(1) translateY(0);
    opacity: 1;
    pointer-events: auto;
}

.mobile-menu a {
    display: block;
    color: #f9fafb;
    padding: 8px 0;
    text-decoration: none;
    font-weight: 500;
    font-size: 15px;
}

.mobile-menu a:hover {
    text-decoration: underline;
}

/* PAGE HEADER */

.page-header {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    padding: 80px 20px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.page-header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1200 120'><path d='M0,0 Q300,60 600,30 T1200,0 L1200,120 L0,120 Z' fill='rgba(255,255,255,0.1)'/></svg>") repeat-x bottom;
    background-size: 1200px 120px;
    opacity: 0.3;
}

.page-header h1 {
    font-size: 46px;
    font-weight: 900;
    margin-bottom: 16px;
    position: relative;
    z-index: 1;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    animation: slideInDown 0.6s ease;
}

.page-header p {
    font-size: 20px;
    max-width: 760px;
    margin: 0 auto;
    opacity: 0.95;
    position: relative;
    z-index: 1;
    animation: slideInUp 0.6s ease;
}

/* Animations */

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(5deg);
    }
}

.float-animation {
    animation: float 3s ease-in-out infinite;
}

/* MAIN CALCULATOR */

.calculator-container {
    max-width: 1400px;
    margin: -60px auto 60px;
    padding: 0 20px;
    position: relative;
    z-index: 10;
}

.calculator-card {
    background: #ffffff;
    border-radius: 24px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
    animation: slideUp 0.6s ease;
    margin-bottom: 24px;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card-title {
    font-size: 28px;
    font-weight: 800;
    color: #6366f1;
    margin-bottom: 32px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.calc-tabs {
    display: flex;
    gap: 12px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.calc-tab {
    padding: 12px 24px;
    background: #f5f3ff;
    border: 2px solid #e5e7eb;
    border-radius: 12px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    color: #4a5568;
    font-size: 15px;
}

.calc-tab:hover {
    border-color: #8b5cf6;
    transform: translateY(-2px);
}

.calc-tab.active {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    border-color: #8b5cf6;
}

.input-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-bottom: 24px;
}

.input-group {
    margin-bottom: 20px;
}

.input-label {
    font-weight: 600;
    color: #6d28d9;
    margin-bottom: 8px;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    display: block;
}

.input-field {
    width: 100%;
    padding: 14px;
    border: 2px solid #8b5cf6;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s ease;
    color: #1e293b;
    background: #ffffff;
}

.input-field:focus {
    outline: none;
    border-color: #6366f1;
    box-shadow: 0 0 0 4px rgba(139, 92, 246, 0.1);
    transform: scale(1.02);
}

select.input-field {
    cursor: pointer;
}

/* Subjects list */

.subject-list {
    background: linear-gradient(135deg, #f5f3ff 0%, #ede9fe 100%);
    padding: 24px;
    border-radius: 16px;
    border: 2px solid #8b5cf6;
    margin-bottom: 24px;
}

.subject-item {
    background: #ffffff;
    padding: 16px;
    border-radius: 12px;
    margin-bottom: 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border: 2px solid #c4b5fd;
    transition: all 0.3s ease;
}

.subject-item:hover {
    transform: translateX(4px);
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.2);
}

.subject-info {
    flex: 1;
}

.subject-name {
    font-weight: 700;
    color: #5b21b6;
    font-size: 16px;
    margin-bottom: 4px;
}

.subject-details {
    font-size: 13px;
    color: #7c3aed;
}

.remove-btn {
    padding: 8px 16px;
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    color: #ffffff;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 13px;
}

.remove-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.add-btn {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: #ffffff;
    border: none;
    border-radius: 12px;
    font-size: 16px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 16px;
}

.add-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(16, 185, 129, 0.4);
}

.calculate-btn {
    width: 100%;
    padding: 18px;
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    border: none;
    border-radius: 12px;
    font-size: 20px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
    margin-top: 24px;
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(139, 92, 246, 0.4);
}

/* RESULTS */

.result-display {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    padding: 40px;
    border-radius: 20px;
    color: #ffffff;
    margin-bottom: 32px;
}

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-top: 32px;
}

.result-card {
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    padding: 24px;
    border-radius: 16px;
    text-align: center;
    border: 2px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.result-card:hover {
    background: rgba(255, 255, 255, 0.25);
    transform: translateY(-4px);
}

.result-title {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 12px;
    opacity: 0.95;
}

.result-value {
    font-size: 32px;
    font-weight: 900;
    margin-bottom: 8px;
}

.result-subtitle {
    font-size: 14px;
    opacity: 0.85;
}

.schedule-table {
    width: 100%;
    background: #ffffff;
    border-radius: 12px;
    overflow: hidden;
    margin-top: 24px;
    border-collapse: collapse;
}

.schedule-table th {
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    padding: 16px;
    text-align: left;
    font-weight: 700;
}

.schedule-table td {
    padding: 16px;
    border-bottom: 1px solid #e5e7eb;
    color: #4a5568;
}

.schedule-table tr:hover {
    background: #f5f3ff;
}

/* ADSENSE */

.adsense-container {
    background: linear-gradient(135deg, #f5f3ff 0%, #ede9fe 100%);
    border-radius: 16px;
    padding: 20px;
    margin: 24px 0;
    min-height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px dashed #c4b5fd;
}

.adsense-placeholder {
    text-align: center;
    color: #5b21b6;
    font-size: 14px;
}

/* DOWNLOAD BUTTONS */

.download-buttons {
    display: flex;
    gap: 12px;
    margin-top: 24px;
}

.download-btn {
    flex: 1;
    padding: 14px 24px;
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    color: #ffffff;
    border: none;
    border-radius: 10px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.download-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.3);
}

/* INFO BOXES */

.info-box {
    background: linear-gradient(135deg, #f5f3ff 0%, #ede9fe 100%);
    padding: 20px;
    border-radius: 12px;
    border-left: 4px solid #6366f1;
    margin-top: 24px;
}

.info-title {
    font-weight: 700;
    color: #5b21b6;
    margin-bottom: 8px;
    font-size: 16px;
}

.info-text {
    color: #6d28d9;
    font-size: 14px;
    line-height: 1.6;
}

/* BLOG CONTENT */

.blog-section {
    max-width: 900px;
    margin: 80px auto;
    padding: 0 20px;
}

.blog-content {
    background: #ffffff;
    border-radius: 24px;
    padding: 40px 32px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.08);
    line-height: 1.8;
    margin-bottom: 32px;
}

.blog-content h2 {
    font-size: 32px;
    font-weight: 900;
    color: #1a202c;
    margin-bottom: 24px;
    background: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.blog-content h3 {
    font-size: 24px;
    font-weight: 700;
    color: #2d3748;
    margin-top: 28px;
    margin-bottom: 16px;
}

.blog-content h4 {
    font-size: 20px;
    font-weight: 600;
    color: #4a5568;
    margin-top: 24px;
    margin-bottom: 12px;
}

.blog-content p {
    color: #4a5568;
    font-size: 16px;
    margin-bottom: 18px;
}

.blog-content ul,
.blog-content ol {
    color: #4a5568;
    margin-left: 24px;
    margin-bottom: 18px;
}

.blog-content li {
    margin-bottom: 8px;
    line-height: 1.7;
}

.blog-content strong {
    color: #6366f1;
    font-weight: 700;
}

.blog-content a {
    color: #6366f1;
    text-decoration: underline;
}

.blog-content a:hover {
    color: #4f46e5;
}

/* Highlight & example boxes */

.highlight-box {
    background: linear-gradient(135deg, #f5f3ff 0%, #ede9fe 100%);
    padding: 24px;
    border-radius: 12px;
    border-left: 4px solid #6366f1;
    margin: 24px 0;
    font-size: 15px;
}

.example-box {
    background: #f5f3ff;
    padding: 20px;
    border-radius: 12px;
    border-left: 4px solid #8b5cf6;
    margin: 18px 0;
    font-size: 15px;
}

/* FAQ */

.faq-wrapper {
    margin-top: 24px;
}

.faq-item {
    margin-bottom: 18px;
}

.faq-item h4 {
    font-size: 18px;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 6px;
}

/* FOOTER */

.footer {
    background: linear-gradient(135deg, #2d3748 0%, #1a202c 100%);
    color: #ffffff;
    padding: 60px 0 20px;
    margin-top: 80px;
}

.footer-column h3 {
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 20px;
    color: #a0aec0;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.footer-column ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.footer-column ul li {
    margin-bottom: 12px;
}

.footer-column ul li a {
    color: #cbd5e0;
    text-decoration: none;
    transition: all 0.3s ease;
    display: inline-block;
}

.footer-column ul li a:hover {
    color: #8b5cf6;
    transform: translateX(5px);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 40px;
    padding-top: 30px;
    text-align: center;
    color: #a0aec0;
}

/* RESPONSIVE */

@media (max-width: 1024px) {
    .desktop-center-nav {
        position: static;
        transform: none;
    }
}

@media (max-width: 768px) {
    /* Hide ALL desktop nav on mobile */
    .desktop-center-nav,
    .nav-links,
    .nav-links-right,
    .dropdown {
        display: none !important;
    }

    /* Show hamburger button */
    .mobile-menu-btn {
        display: block;
    }

    .page-header h1 {
        font-size: 32px;
    }

    .page-header p {
        font-size: 16px;
    }

    .calculator-card {
        padding: 24px;
    }

    .input-grid {
        grid-template-columns: 1fr;
    }

    .result-grid {
        grid-template-columns: 1fr;
    }

    .blog-content {
        padding: 28px 20px;
    }

    .blog-content h2 {
        font-size: 26px;
    }

    .blog-content h3 {
        font-size: 20px;
    }

    .download-buttons {
        flex-direction: column;
    }

    .calc-tabs {
        justify-content: center;
    }

    .calc-tab {
        font-size: 13px;
        padding: 10px 16px;
    }

    .subject-item {
        flex-direction: column;
        gap: 12px;
        align-items: flex-start;
    }
}