:root {
    /* Light theme variables */
    --primary-color: #111111;
    --secondary-color: #1a1a1a;
    --accent-color: #4a4a4a;
    --text-color: #333333;
    --light-gray: #f8f9fa;
    --border-color: #e9ecef;
    --bg-color: white;
    --card-bg: #f8f9fa;
    --spacing: 2rem;
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --primary-color: #ffffff;
    --secondary-color: #e0e0e0;
    --accent-color: #9e9e9e;
    --text-color: #f0f0f0;
    --light-gray: #2a2a2a;
    --border-color: #404040;
    --bg-color: #1a1a1a;
    --card-bg: #2a2a2a;
}

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

body {
    font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
    line-height: 1.8;
    color: var(--text-color);
    background-color: var(--bg-color);
    transition: var(--transition);
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 1rem;
    right: 1rem;
    z-index: 1000;
    background: transparent;
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: var(--transition);
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing);
}

/* Hero Section - keeping the original dark gradient */
.hero {
    background: linear-gradient(135deg, #111111, #1a1a1a);
    color: white;
    padding: 6rem 0;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.hero h2 {
    font-size: 1.8rem;
    font-weight: 300;
    margin-bottom: 1.5rem;
    opacity: 0.9;
}

/* Sections */
.section {
    padding: var(--spacing) 0;
    border-bottom: 1px solid var(--border-color);
}

.section h2 {
    color: var(--text-color);
    margin-bottom: calc(var(--spacing) * 1.5);
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 2rem;
    font-weight: 600;
}

.section h2 i {
    color: var(--accent-color);
}

/* Profile Section */
.profile-content {
    max-width: 900px;
    margin: 0 auto;
}

.profile-content p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
}

/* Timeline */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 2px;
    background: var(--accent-color);
    opacity: 0.3;
}

.timeline-item {
    padding-left: 2.5rem;
    margin-bottom: 3rem;
    position: relative;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -6px;
    top: 0;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--accent-color);
}

.timeline-date {
    font-weight: 600;
    color: var(--accent-color);
    margin-bottom: 0.75rem;
    font-size: 1.1rem;
}

.timeline-content {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.timeline-content:hover {
    transform: translateX(10px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.timeline-content h3 {
    color: var(--text-color);
    margin-bottom: 0.5rem;
    font-size: 1.4rem;
}

.timeline-content h4 {
    color: #a0a0a0;
    margin-bottom: 1rem;
    font-size: 1.1rem;
    font-weight: 500;
}

.timeline-content ul {
    list-style-type: none;
    margin-left: 0;
}

.timeline-content li {
    margin-bottom: 0.5rem;
    position: relative;
    padding-left: 1.5rem;
}

.timeline-content li::before {
    content: '•';
    color: var(--accent-color);
    position: absolute;
    left: 0;
}

/* Projects Grid */
.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: calc(var(--spacing) * 1.5);
}

.project-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.project-card h3 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-size: 1.4rem;
}

.project-content p {
    margin-bottom: 1rem;
}

.project-content ul {
    list-style-type: none;
    margin-left: 0;
}

.project-content li {
    margin-bottom: 0.5rem;
    position: relative;
    padding-left: 1.5rem;
}

.project-content li::before {
    content: '→';
    color: var(--accent-color);
    position: absolute;
    left: 0;
}

/* Skills Grid */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: calc(var(--spacing) * 1.5);
}

.skill-category {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.skill-category:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.skill-category h3 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

.skill-category li {
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.1rem;
}

.skill-category li i {
    color: var(--accent-color);
    font-size: 1.2rem;
}

/* Certifications */
.cert-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: calc(var(--spacing) * 1.5);
}

.cert-item {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
}

.cert-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.cert-item h3 {
    color: var(--text-color);
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
}

.cert-item ul {
    list-style: none;
}

.cert-item li {
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.1rem;
}

.cert-item li i {
    color: var(--accent-color);
}

/* Footer - keeping dark background */
.footer {
    background: #111111;
    color: white;
    padding: calc(var(--spacing) * 1.5) 0;
    text-align: center;
}

.footer p {
    opacity: 0.9;
    margin-bottom: 0.5rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero {
        padding: 4rem 0;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero h2 {
        font-size: 1.4rem;
    }

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

    .timeline::before {
        left: 1rem;
    }

    .timeline-item {
        padding-left: 3rem;
    }

    .project-grid,
    .skills-grid,
    .cert-grid {
        grid-template-columns: 1fr;
    }
}