:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --text-color: #1f2937;
    --light-text: #6b7280;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-color);
    line-height: 1.6;
    background-color: var(--bg-white);
}

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

/* Navigation */
.navbar {
    position: sticky;
    top: 0;
    background-color: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    box-shadow: var(--shadow);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-brand {
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 40px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 100px 0;
    text-align: center;
}

.hero-content h1 {
    font-size: 56px;
    margin-bottom: 10px;
    font-weight: 700;
}

.hero-subtitle {
    font-size: 28px;
    margin-bottom: 20px;
    opacity: 0.95;
}

.hero-description {
    font-size: 18px;
    margin-bottom: 40px;
    opacity: 0.9;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Buttons */
.btn {
    padding: 12px 30px;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
    border: none;
    cursor: pointer;
    font-size: 16px;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background-color: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background-color: white;
    color: var(--primary-color);
}

.btn-large {
    padding: 16px 40px;
    font-size: 18px;
}

/* Sections */
section {
    padding: 80px 0;
}

section h2 {
    font-size: 42px;
    margin-bottom: 50px;
    text-align: center;
    color: var(--text-color);
}

/* About Section */
.about {
    background-color: var(--bg-light);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
}

.about-content p {
    font-size: 18px;
    margin-bottom: 20px;
    color: var(--light-text);
    line-height: 1.8;
}

.about-links {
    display: flex;
    gap: 30px;
    margin-top: 40px;
    justify-content: center;
}

.link-item {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.link-item:hover {
    color: var(--secondary-color);
}

/* Projects Section */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.project-card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 30px;
    transition: all 0.3s ease;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 15px;
}

.project-header h3 {
    font-size: 22px;
    color: var(--text-color);
}

.project-links {
    display: flex;
    gap: 15px;
}

.project-links a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 14px;
    transition: color 0.3s ease;
}

.project-links a:hover {
    color: var(--secondary-color);
}

.project-card p {
    color: var(--light-text);
    margin-bottom: 20px;
}

.project-tags {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.tag {
    background-color: var(--bg-light);
    color: var(--primary-color);
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 500;
}

/* Skills Section */
.skills {
    background-color: var(--bg-light);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
}

.skill-category h3 {
    font-size: 20px;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.skill-category ul {
    list-style: none;
}

.skill-category li {
    padding: 10px 0;
    color: var(--light-text);
    border-bottom: 1px solid var(--border-color);
    transition: color 0.3s ease;
}

.skill-category li:last-child {
    border-bottom: none;
}

.skill-category li:hover {
    color: var(--primary-color);
}

/* Contact Section */
.contact {
    text-align: center;
}

.contact-intro {
    font-size: 18px;
    color: var(--light-text);
    margin-bottom: 40px;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.contact-content {
    margin-bottom: 40px;
}

.contact-links {
    display: flex;
    gap: 30px;
    justify-content: center;
    margin-top: 30px;
}

.contact-links a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s ease;
}

.contact-links a:hover {
    color: var(--secondary-color);
}

/* Footer */
.footer {
    background-color: var(--text-color);
    color: white;
    padding: 30px 0;
    text-align: center;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        gap: 20px;
        font-size: 14px;
    }

    .hero-content h1 {
        font-size: 36px;
    }

    .hero-subtitle {
        font-size: 20px;
    }

    section h2 {
        font-size: 32px;
        margin-bottom: 40px;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 300px;
    }

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

    .about-links {
        flex-direction: column;
        gap: 15px;
    }

    .contact-links {
        flex-direction: column;
        gap: 15px;
    }
}

@media (max-width: 480px) {
    .navbar .container {
        height: auto;
        padding: 15px 0;
        flex-direction: column;
        gap: 15px;
    }

    .nav-links {
        flex-direction: column;
        text-align: center;
        gap: 10px;
    }

    .hero-content h1 {
        font-size: 28px;
    }

    .hero-subtitle {
        font-size: 18px;
    }

    .hero-description {
        font-size: 16px;
    }

    section {
        padding: 50px 0;
    }

    section h2 {
        font-size: 24px;
    }
}