/* ===========================
   CSS Variables & Base Styles
   =========================== */
:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --text-color: #1f2937;
    --light-bg: #f9fafb;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --spacing-unit: 1rem;
}

* {
    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: #ffffff;
}

/* ===========================
   Container & Layout
   =========================== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-unit);
}

/* ===========================
   Navigation
   =========================== */
.navbar {
    position: sticky;
    top: 0;
    background: white;
    border-bottom: 1px solid var(--border-color);
    z-index: 100;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.nav-wrapper {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

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

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

@media (max-width: 768px) {
    .nav-menu {
        gap: 1rem;
        font-size: 0.9rem;
    }
}

/* ===========================
   Hero Section
   =========================== */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 6rem var(--spacing-unit);
    text-align: center;
}

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

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    opacity: 0.9;
}

.hero-description {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    opacity: 0.85;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* ===========================
   Buttons
   =========================== */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    border: 2px solid transparent;
    cursor: pointer;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

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

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

@media (max-width: 768px) {
    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1.2rem;
    }

    .hero {
        padding: 4rem var(--spacing-unit);
    }
}

/* ===========================
   About Section
   =========================== */
.about {
    padding: 4rem var(--spacing-unit);
    background-color: var(--light-bg);
}

.about h2 {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.about-text {
    line-height: 1.8;
}

.about-text p {
    margin-bottom: 1.5rem;
    font-size: 1rem;
}

.skills h3 {
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.skill-item {
    background: white;
    padding: 1rem;
    border-radius: 0.5rem;
    border-left: 4px solid var(--primary-color);
    font-weight: 500;
}

@media (max-width: 768px) {
    .about-content {
        grid-template-columns: 1fr;
    }

    .about h2 {
        font-size: 1.8rem;
    }
}

/* ===========================
   Experience Section
   =========================== */
.experience {
    padding: 4rem var(--spacing-unit);
}

.experience h2 {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
}

.timeline {
    max-width: 700px;
    margin: 0 auto;
}

.timeline-item {
    display: flex;
    margin-bottom: 2rem;
    position: relative;
}

.timeline-marker {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--primary-color);
    margin-right: 2rem;
    margin-top: 0.5rem;
    flex-shrink: 0;
}

.timeline-item:not(:last-child)::before {
    content: '';
    position: absolute;
    left: 5px;
    top: 25px;
    width: 2px;
    height: calc(100% + 2rem);
    background-color: var(--border-color);
}

.timeline-content h3 {
    font-size: 1.3rem;
    margin-bottom: 0.3rem;
}

.timeline-company {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 0.2rem;
}

.timeline-date {
    color: #6b7280;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.timeline-content p:last-child {
    color: #4b5563;
    line-height: 1.6;
}

@media (max-width: 768px) {
    .experience h2 {
        font-size: 1.8rem;
    }

    .timeline-marker {
        margin-right: 1.5rem;
    }
}

/* ===========================
   Projects Section
   =========================== */
.projects {
    padding: 4rem var(--spacing-unit);
    background-color: var(--light-bg);
}

.projects h2 {
    font-size: 2.5rem;
    margin-bottom: 3rem;
    text-align: center;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.project-card {
    background: white;
    border-radius: 0.5rem;
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    transition: all 0.3s;
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.1);
    transform: translateY(-4px);
}

.project-header {
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 1rem;
    margin-bottom: 1rem;
}

.project-header h3 {
    font-size: 1.2rem;
}

.project-card p {
    flex-grow: 1;
    color: #6b7280;
    margin-bottom: 1rem;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tag {
    background-color: #e0e7ff;
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    font-size: 0.8rem;
    font-weight: 500;
}

.project-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s;
    align-self: flex-start;
}

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

@media (max-width: 768px) {
    .projects h2 {
        font-size: 1.8rem;
    }
}

/* ===========================
   Contact Section
   =========================== */
.contact {
    padding: 4rem var(--spacing-unit);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    text-align: center;
}

.contact h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.contact > .container > p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
}

.contact-links {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.contact-link {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background: white;
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: all 0.3s;
}

.contact-link:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

@media (max-width: 768px) {
    .contact h2 {
        font-size: 1.8rem;
    }
}

/* ===========================
   Footer
   =========================== */
.footer {
    background-color: #1f2937;
    color: white;
    text-align: center;
    padding: 2rem var(--spacing-unit);
    border-top: 1px solid var(--border-color);
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .nav-menu {
        gap: 0.5rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .container {
        padding: 0 1rem;
    }
}