body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f8f9fa;
    color: #333;
}

header {
    background-color: #343a40;
    color: white;
    padding: 30px 0;
    text-align: center;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

nav ul {
    list-style: none;
    padding: 0;
    margin: 20px 0;
    display: flex;
    justify-content: center;
    gap: 20px;
}

nav a {
    color: #ffffff;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1rem;
    transition: color 0.3s ease;
}

nav a:hover {
    color: #ffc107;
}

section {
    padding: 40px 20px;
    max-width: 1000px;
    margin: auto;
}

h2 {
    color: #212529;
    border-bottom: 2px solid #dee2e6;
    padding-bottom: 10px;
    margin-bottom: 30px;
}

.portfolio-items {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 20px;
}

.portfolio-items div {
    background-color: #2c2c2c;
    color: #fff;
    border: 1px solid #444;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.portfolio-items div:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.2);
}

footer {
    text-align: center;
    padding: 30px;
    background-color: #343a40;
    color: #f8f9fa;
    font-size: 1rem;
    margin-top: 60px;
    border-top: 3px solid #e1e1e1;
}

body.dark-mode {
    background-color: #1e1e1e;
    color: #f8f9fa;
}

body.dark-mode header {
    background-color: #212121;
    color: #ffffff;
}

body.dark-mode nav a {
    color: #f8f9fa;
}

body.dark-mode h2 {
    color: #f8f9fa;
    border-color: #444;
}

body.dark-mode .portfolio-items div {
    background-color: #ffffff;
    color: #333;
    border: 1px solid #dee2e6;
    box-shadow: 0 2px 6px rgba(0,0,0,0.3);
}

body.dark-mode footer {
    background-color: #121212;
    color: #bbbbbb;
}

body, .portfolio-items div {
    transition: background-color 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}