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

html {
    scroll-behavior: smooth;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    background: #f8fafc;
    color: #172033;
    line-height: 1.6;
}

/* ================= NAVBAR ================= */

header {
    background: white;
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid #e5e7eb;
}

.navbar {
    max-width: 1200px;
    margin: auto;
    height: 75px;

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

    padding: 0 20px;
}

.logo {
    font-size: 28px;
    font-weight: bold;
}

.logo span,
footer span {
    color: #6366f1;
}

.nav-links {
    display: flex;
    gap: 30px;
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: #374151;
    font-weight: 500;
}

.nav-links a:hover {
    color: #6366f1;
}

.nav-btn {
    text-decoration: none;
    background: #6366f1;
    color: white;
    padding: 10px 20px;
    border-radius: 8px;
}

/* ================= HERO ================= */

.hero {
    max-width: 1200px;
    margin: auto;
    min-height: 600px;
    padding: 80px 20px;

    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 60px;
}

.hero-text {
    flex: 1;
}

.small-title {
    color: #6366f1;
    font-size: 14px;
    font-weight: bold;
    letter-spacing: 2px;
    margin-bottom: 15px;
}

.hero h1 {
    font-size: 64px;
    line-height: 1.1;
    margin-bottom: 25px;
}

.hero h1 span {
    color: #6366f1;
}

.hero-description {
    color: #64748b;
    font-size: 18px;
    max-width: 550px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    margin-top: 30px;
}

.btn {
    text-decoration: none;
    padding: 13px 25px;
    border-radius: 8px;
    font-weight: bold;
}

.primary {
    background: #6366f1;
    color: white;
}

.secondary {
    border: 1px solid #6366f1;
    color: #6366f1;
}

.hero-image {
    flex: 1;
}

.hero-image img {
    width: 100%;
    border-radius: 25px;
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.15);
}
h2{
    font-size:40px
}
/* ================= SECTIONS ================= */

.section {
    max-width: 1200px;
    margin: auto;
    padding: 80px 20px;
}

.section-title {
    text-align: center;
    margin-bottom: 50px;
}

.section-title p {
    color: #6366f1;
    font-weight: bold;
    letter-spacing: 2px;
}

.section-title h2 {
    font-size: 40px;
    margin-top: 5px;
}


/* ================= SKILLS ================= */

.skills-container {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.skill-card {
    background: white;
    padding: 30px;
    border-radius: 18px;
    flex: 1 1 250px;

    border: 1px solid #e5e7eb;

    transition: 0.3s;
}

.skill-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
}

.icon {
    font-size: 40px;
    margin-bottom: 15px;
}

.skill-card h3 {
    font-size: 23px;
    margin-bottom: 10px;
}

.skill-card p {
    color: #64748b;
    margin-bottom: 20px;
}

.skill-card a {
    color: #6366f1;
    text-decoration: none;
    font-weight: bold;
}


/* ================= LESSONS ================= */

.lessons-section {
    background: white;
    padding: 90px 20px;
}

.lesson {
    max-width: 1100px;
    margin: 0 auto 100px;

    display: flex;
    align-items: center;
    gap: 60px;
}

.lesson.reverse {
    flex-direction: row-reverse;
}

.lesson-image {
    flex: 1;
}

.lesson-image img {
    width: 100%;
    height: 450px;
    object-fit: cover;
    border-radius: 20px;
}

.lesson-content {
    flex: 1;
}

.lesson-number {
    color: #6366f1;
    font-weight: bold;
    font-size: 18px;
}

.lesson-content h2 {
    font-size: 42px;
    margin-bottom: 10px;
}

.lesson-content h3 {
    font-size: 22px;
    margin-bottom: 15px;
}

.lesson-content h4 {
    margin-top: 20px;
    margin-bottom: 8px;
}

.lesson-content p {
    color: #64748b;
}

pre {
    background: #111827;
    color: #e5e7eb;
    padding: 20px;
    border-radius: 12px;
    overflow-x: auto;
    margin-top: 10px;
}

code {
    font-family: Consolas, monospace;
}

.formula {
    background: #eef2ff;
    color: #4338ca;
    padding: 15px;
    border-radius: 10px;
    font-weight: bold;
}

.example-box {
    background: #f8fafc;
    border-left: 4px solid #6366f1;
    padding: 12px 15px;
    margin-top: 10px;
}

.lesson-list {
    padding-left: 25px;
    color: #64748b;
}

.result {
    background: #dcfce7;
    color: #166534;
    padding: 12px 20px;
    border-radius: 8px;
    font-weight: bold;
}

.learn-btn {
    display: inline-block;
    margin-top: 25px;
    padding: 12px 22px;
    background: #6366f1;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
}


/* ================= ABOUT ================= */

.about {
    max-width: 1200px;
    margin: auto;
    padding: 100px 20px;

    display: flex;
    gap: 80px;
    align-items: center;
}

.about > div {
    flex: 1;
}

.about h2 {
    font-size: 45px;
    line-height: 1.2;
    margin-bottom: 20px;
}

.about p {
    color: #64748b;
}

.about-skills {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
}

.about-skills div {
    width: 45%;
    background: white;
    border: 1px solid #e5e7eb;
    padding: 25px;
    border-radius: 15px;
}

.about-skills strong {
    display: block;
    font-size: 20px;
}

.about-skills span {
    color: #64748b;
}


/* ================= FOOTER ================= */

footer {
    text-align: center;
    background: #111827;
    color: white;
    padding: 50px 20px;
}

footer h2 {
    font-size: 30px;
    margin-bottom: 10px;
}

footer p {
    color: #9ca3af;
}

.copyright {
    margin-top: 25px;
    font-size: 14px;
}


/* ================= RESPONSIVE ================= */

@media (max-width: 850px) {

    .nav-links {
        display: none;
    }

    .hero {
        flex-direction: column;
        text-align: center;
        padding-top: 50px;
    }

    .hero h1 {
        font-size: 45px;
    }

    .hero-buttons {
        justify-content: center;
    }

    .lesson,
    .lesson.reverse {
        flex-direction: column;
        gap: 35px;
    }

    .lesson-image,
    .lesson-content {
        width: 100%;
    }

    .lesson-image img {
        height: 300px;
    }

    .about {
        flex-direction: column;
    }

    .about-skills {
        width: 100%;
    }
}


@media (max-width: 500px) {

    .nav-btn {
        display: none;
    }

    .hero h1 {
        font-size: 38px;
    }

    .section-title h2 {
        font-size: 32px;
    }

    .lesson-content h2 {
        font-size: 34px;
    }

    .about h2 {
        font-size: 35px;
    }

    .about-skills div {
        width: 100%;
    }
}