style.css

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Anonymous Pro', monospace;
}

body {
    color: black;
    background: white;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid black;
    border-bottom: 1px solid black;
    padding: 10px;
    flex-wrap: wrap;
}

h1 {
    margin: auto 30px;
    text-align: center;
}

.nav {
    display: flex;
    justify-content: space-around;
    align-items: center;
    margin: auto 30px;
    flex-wrap: wrap;
}  

.nav li {
    display: inline-block;
}

a {
    color: black;
    text-decoration-color: red;
}

a:visited {
    color: red;
    text-decoration-color: black;
}

a:hover {
    color: black;
    text-decoration: none;
}

.btn-toggle {
    margin-left: 10px;
    border: none;
    background: inherit;
    cursor: pointer;
}

.btn-toggle img {
    height: 25px;
}

.about-me-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid black;
    padding: 10px;
}

.about-me-container img {
    height: 350px;
}

.projects-conteiner {
    border-bottom: 1px solid black;
    padding: 10px;
}

.skills-container {
    display: flex;
    justify-content: space-around;
    border-bottom: 1px solid black;
    padding: 10px;
}

.skills-container img {
    height: 25px;
}

h2 {
    text-align: center;
}

h2,
p {
    margin: 10px 50px;
}

.contact-container {
    display: flex;
    justify-content: space-around;
    border-bottom: 1px solid black;
    padding: 10px;
}

.contact-img {
    height: 350px;
    display: block;
    margin-left: auto;
    margin-right: auto;
}

.contact-container img {
    height: 25px;
}

footer {
    text-align: center;
    border-bottom: 1px solid black;
}

@media only screen and (max-width: 768px) {
    header {
        justify-content: center;
    }

    .nav {
        margin: auto;
    }

    .about-me-container {
        flex-wrap: wrap;
        justify-content: center;
    }
}

/* Dark Mode styles */
body.dark-theme {
    color: #eee;
    background: rgb(32, 33, 36);
}

body.dark-theme a {
    color: white;
    text-decoration-color: red;
}

body.dark-theme a:visited {
    color: #809fff;
    text-decoration-color: white;
}

body.dark-theme a:hover {
    color: white;
    text-decoration: none;
}

body.dark-theme .btn-toggle img,
body.dark-theme .skills-container img,
body.dark-theme .contact-container img {
    filter: invert(100%);
}

body.dark-theme header {
    border-top: 1px solid white;
    border-bottom: 1px solid white;
}

body.dark-theme .about-me-container,
body.dark-theme .projects-conteiner,
body.dark-theme .skills-container,
body.dark-theme .contact-container,
body.dark-theme footer {
    border-bottom: 1px solid white;
}