/* --- General Styles & Professional Theme --- */
:root {
    --primary-color: #1e3d59; /* Professional navy blue */
    --secondary-color: #007bff;
    --accent-color: #28a745; /* For Julia */
    --matlab-color: #e97e00; /* MATLAB orange */
    --python-color: #3776ab; /* Python blue */
    --julia-color: #9558b2; /* Julia purple */
    --bg-color: #ffffff;
    --light-gray-bg: #f8f9fa;
    --text-color: #343a40;
    --text-muted: #6c757d;
    --border-color: #e9ecef;
    --shadow: 0 2px 10px rgba(0,0,0,0.08);
}

body {
    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    line-height: 1.7;
}

.container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 20px;
}

section {
    padding: 80px 0;
}

/* --- Header / Navigation --- */
.main-header {
    background-color: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow);
}
.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.6em;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}
.logo img {
    height: 45px;
    width: 45px;
    border-radius: 8px;
}
.main-nav a {
    color: var(--text-color);
    text-decoration: none;
    margin-left: 30px;
    font-weight: 500;
    transition: color 0.3s;
}
.main-nav a:hover, .main-nav a.active {
    color: var(--primary-color);
}

/* --- Hero Section --- */
.hero {
    text-align: center;
    padding: 120px 0;
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
}
.hero h1 {
    font-size: 3.2em;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 25px;
    color: var(--primary-color);
}
.hero .subtitle {
    font-size: 1.3em;
    color: var(--text-muted);
    max-width: 800px;
    margin: 0 auto 35px auto;
    line-height: 1.6;
}
.instructor-badge {
    display: inline-block;
    background-color: var(--primary-color);
    color: white;
    padding: 12px 24px;
    border-radius: 25px;
    margin-bottom: 30px;
    font-weight: 600;
    font-size: 1.1em;
}
.cta-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-top: 40px;
}
.cta-button {
    display: inline-block;
    background-color: var(--primary-color);
    color: #fff !important;
    text-decoration: none;
    padding: 16px 32px;
    border-radius: 8px;
    text-align: center;
    font-weight: 600;
    transition: all 0.3s;
    font-size: 1.1em;
    box-shadow: var(--shadow);
}
.cta-button:hover {
    background-color: var(--secondary-color);
    transform: translateY(-3px);
    box-shadow: 0 4px 15px rgba(0,0,0,0.15);
}
.cta-button.secondary {
    background-color: transparent;
    color: var(--primary-color) !important;
    border: 2px solid var(--primary-color);
}
.cta-button.secondary:hover {
    background-color: var(--primary-color);
    color: white !important;
}

/* --- Credentials Section --- */
.credentials {
    padding: 60px 0;
    background-color: var(--light-gray-bg);
    border-top: 1px solid var(--border-color);
}
.credentials-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}
.credentials h2 {
    font-size: 2em;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--primary-color);
}
.credentials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 40px;
}
.credential-item {
    background: white;
    padding: 25px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
}
.credential-item .icon {
    font-size: 2.5em;
    margin-bottom: 15px;
    color: var(--primary-color);
}
.credential-item h3 {
    font-size: 1.2em;
    font-weight: 600;
    margin-bottom: 10px;
}

/* --- Programming Languages Section --- */
.languages {
    padding: 80px 0;
}
.section-header {
    text-align: center;
    margin-bottom: 60px;
}
.section-header h2 {
    font-size: 2.5em;
    font-weight: 700;
    margin-bottom: 15px;
    color: var(--primary-color);
}
.section-header p {
    font-size: 1.2em;
    color: var(--text-muted);
    max-width: 700px;
    margin: 0 auto;
}
.languages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 40px;
}
.language-card {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: all 0.3s;
    border-top: 4px solid;
}
.language-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}
.language-card.matlab { border-top-color: var(--matlab-color); }
.language-card.python { border-top-color: var(--python-color); }
.language-card.julia { border-top-color: var(--julia-color); }

.language-header {
    padding: 30px 30px 20px;
    display: flex;
    align-items: center;
    gap: 15px;
}
.language-icon {
    width: 50px;
    height: 50px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2em;
    color: white;
    font-weight: bold;
}
.language-card.matlab .language-icon { background: var(--matlab-color); }
.language-card.python .language-icon { background: var(--python-color); }
.language-card.julia .language-icon { background: var(--julia-color); }

.language-info h3 {
    font-size: 1.5em;
    font-weight: 700;
    margin: 0 0 5px 0;
}
.language-info .tagline {
    color: var(--text-muted);
    font-size: 0.95em;
}
.language-content {
    padding: 0 30px 30px;
}
.language-features {
    list-style: none;
    padding: 0;
    margin: 20px 0;
}
.language-features li {
    padding: 8px 0;
    border-bottom: 1px solid #f0f0f0;
    display: flex;
    align-items: center;
    gap: 10px;
}
.language-features li:last-child { border-bottom: none; }
.language-features li::before {
    content: "✓";
    color: var(--accent-color);
    font-weight: bold;
}

/* --- Services Section --- */
.services {
    background-color: var(--light-gray-bg);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}
.services-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 40px;
}
.service-item {
    background: white;
    padding: 35px;
    border-radius: 15px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}
.service-item:hover {
    transform: translateY(-5px);
}
.service-item .icon {
    font-size: 3.5em;
    margin-bottom: 20px;
    color: var(--primary-color);
}
.service-item h3 {
    font-size: 1.4em;
    font-weight: 600;
    margin-bottom: 15px;
}
.service-item p {
    color: var(--text-muted);
    line-height: 1.6;
}

/* --- Featured Courses Section --- */
.course-card {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 15px;
    overflow: hidden;
    transition: all 0.3s;
    box-shadow: var(--shadow);
}
.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.15);
}
.course-card img {
    width: 100%;
    height: 220px;
    object-fit: cover;
    display: block;
}
.course-card-content {
    padding: 30px;
}
.course-card-content h3 {
    font-size: 1.5em;
    font-weight: 600;
    margin-bottom: 15px;
}
.course-card-content p {
    color: var(--text-muted);
    margin-bottom: 25px;
    line-height: 1.6;
}
.course-card-content a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 1.1em;
    transition: color 0.3s;
}
.course-card-content a:hover {
    color: var(--secondary-color);
}

/* --- Testimonials Section --- */
.testimonials {
    background-color: var(--light-gray-bg);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}        
.testimonial-slider-wrapper {
    max-width: 900px;
    margin: 0 auto;
    overflow: hidden;
}
.testimonial-slider {
    display: flex;
    transition: transform 1.0s ease-in-out;
}
.testimonial-card {
    flex: 0 0 100%;
    box-sizing: border-box;
    background-color: var(--bg-color);
    padding: 40px;
    border-radius: 15px;
    border: 1px solid var(--border-color);
    text-align: center;
    box-shadow: var(--shadow);
}
.testimonial-card p {
    font-size: 1.2em;
    font-style: italic;
    margin-bottom: 25px;
    min-height: 100px;
    line-height: 1.6;
}
.testimonial-card .author {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.1em;
}

/* --- Footer --- */
.main-footer {
    padding: 50px 0;
    text-align: center;
    color: var(--text-muted);
    background-color: var(--primary-color);
    color: white;
}
.main-footer .logo {
    justify-content: center;
    margin-bottom: 20px;
    color: white;
}

/* --- Responsive --- */
@media (max-width: 768px) {
    .main-nav { display: none; }
    .hero h1 { font-size: 2.5em; }
    .hero .subtitle { font-size: 1.1em; }
    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }
    .cta-button {
        width: 100%;
        max-width: 300px;
    }
    section { padding: 60px 0; }
    .languages-grid,
    .services-grid {
        grid-template-columns: 1fr;
    }
}

/* --- Additional Styling --- */
.highlight {
    color: var(--primary-color);
    font-weight: 600;
}

.stats-row {
    display: flex;
    justify-content: center;
    gap: 60px;
    margin-top: 30px;
    flex-wrap: wrap;
}
.stat-item {
    text-align: center;
}
.stat-number {
    font-size: 2.5em;
    font-weight: 700;
    color: var(--primary-color);
    display: block;
}
.stat-label {
    font-size: 0.9em;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}