* {
    box-sizing: border-box;
    scroll-behavior: smooth;
    font-size: 100%;
    padding: 0;
    margin: 0;
}


/* light-dark themes */
:root {
    --bg-color1: #ffffff;
    --bg-color2: #e9e9e9;
    --header-color: #000000;
    --header-desktop-bg: rgba(255, 255, 255, 0.7);
    --font-main: #08111c;
    --ham-header: #000000;
    --ham-bg-color: rgba(170, 181, 196, 0.7);
    --overlay-color: rgba(147, 147, 147, 0.4);
    --ul-color: #141d2c;
    --ul-hover: #3f5883;
    --card-img-color: #d7d7d7;
    --card-text-color: #c9c9c9;
    --pill-color: rgba(162, 162, 162, 0.7);
    --CV-bg-color: #141d2c;
    --CV-text-color: #ffffff;
    --CV-hover: #273957;
    --scrollbar-track-color: #ffffff;
    --contact-link-hover: rgba(165, 165, 165, 0.7);
    --body-color: #ffffff;
}

[data-theme="dark"] {
    --bg-color1: #08111c;
    --bg-color2: #141d2c;
    --header-color: #ffffff;
    --header-desktop-bg: rgba(8, 17, 28, 0.7);
    --font-main: #d7d7d7;
    --ham-header: #ffffff;
    --ham-bg-color: rgba(8, 17, 28, 0.7);
    --overlay-color: rgba(80, 80, 80, 0.4);
    --ul-color: #b2b2b2;
    --ul-hover: #ffffff;
    --card-img-color: #344868;
    --card-text-color: #25334a;
    --pill-color: rgba(105, 105, 105, 0.5);
    --CV-bg-color: #dfdfdf;
    --CV-text-color: #000000;
    --CV-hover: #c6c6c6;
    --scrollbar-track-color: #000000;
    --contact-link-hover: rgba(73, 73, 73, 0.7);
    --body-color: #08111c;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --bg-color1: #08111c;
        --bg-color2: #141d2c;
        --header-color: #ffffff;
        --font-main: #d7d7d7;
        --ham-header: #ffffff;
        --ham-bg-color: rgba(8, 17, 28, 0.7);
        --overlay-color: rgba(80, 80, 80, 0.4);
        --ul-color: #b2b2b2;
        --ul-hover: #ffffff;
        --card-img-color: #344868;
        --card-text-color: #25334a;
        --pill-color: rgba(105, 105, 105, 0.5);
        --CV-bg-color: #dfdfdf;
        --CV-text-color: #000000;
        --CV-hover: #c6c6c6;
        --scrollbar-track-color: #000000;
        --contact-link-hover: rgba(73, 73, 73, 0.7);
        --body-color: #08111c;
    }
}


body {
    overflow-y: auto;
    background-color: var(--body-color);
}

body.hamburger-open {
    overflow-y: hidden;
}


#header-mobile {
    position: sticky;
    top: 0;
    display: flex;
    width: 100%;
    height: 60px;
    background-color: var(--bg-color1);
    justify-content: center;
    align-items: center;
    z-index: 10;
}

#header-desktop {
    display: none;
}

h1 {
    font-size: 1.7rem;
    font-family: 'Open Sans', serif;
}

#title:link,
#title:visited {
    text-decoration: none;
    color: var(--header-color);
}


svg#hamburger-btn {
    width: 40px;
    height: auto;
}

#hamburger-btn {
    right: 0;
    border: none;
    background: none;
    cursor: pointer;
    color: var(--header-color);
}

#hamburger-menu {
    position: absolute;
    right: 15px;
    z-index: 20;
}

#hamburger-container {
    position: fixed;
    top: 0;
    right: -60%;
    height: 100%;
    width: 60%;
    background-color: var(--ham-bg-color);
    backdrop-filter: blur(10px);
    transition: right 0.3s ease-in-out, opacity 0.3s ease-in-out;
    z-index: 1000;
    font-size: 2rem;
    overflow-y: scroll;
    -ms-overflow-style: none;
    scrollbar-width: none;
    opacity: 0;
}

#hamburger-container.open {
    right: 0;
    opacity: 1;
}

#ham-start {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
    padding: 10px 15px;
}

#ham-start p {
    font-size: 1.7rem;
    font-family: 'Open Sans', serif;
    font-weight: 600;
    color: var(--ham-header);
}

span#close-ham {
    cursor: pointer;
    color: var(--header-color);
}


#ul-mobile {
    padding-bottom: 10px;
}

#ul-mobile li a {
    font-family: 'Roboto', serif;
    font-size: 1.3rem;
    padding: 0 15px;
}

#ul-mobile li a:link,
#ul-mobile li a:visited,
#ul-mobile li a:link {
    color: var(--ul-color);
    transition: color 0.4s ease;
    text-decoration: none;
}

#ul-mobile li a:hover {
    color: var(--ul-hover);
}


#theme-container {
    display: flex;
    flex-direction: row;
    font-family: 'Roboto', serif;
    font-size: 1.3rem;
    padding: 10px 15px;
    gap: 12px;
}

#theme-container p {
    color: var(--ul-color);
    font-size: inherit;
}

#theme-container i {
    color: var(--ul-color);
    transition: color 0.4s ease;
    cursor: pointer;
    padding-top: 2px;
}

#theme-container i:hover {
    color: var(--ul-hover);
}

.theme-toggle {
    background: none;
    border: none;
}


#overlay-mobile {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--overlay-color);
    opacity: 0;
    backdrop-filter: blur(0);
    visibility: hidden;
    transition: opacity 0.4s ease, backdrop-filter 0.4s ease;
    z-index: 2;
}

.line {
    height: 5px;
    border-top: 1px solid rgb(66, 66, 66);
    line-height: 80%;
}


h2 {
    text-align: center;
    font-family: 'Open Sans', serif;
    font-weight: 100;
    color: var(--header-color);
    font-size: 1rem;
}

.h2-pill {
    background-color: var(--pill-color);
    border-radius: 10px;
    max-width: fit-content;
    padding: 3px 8px;
    margin: 0 auto 10px;
}

p {
    font-family: 'Roboto', serif;
    font-weight: 400;
    color: var(--font-main);
    font-size: 1rem;
}


.main {
    padding: 25px 15px;
}

#home {
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background-color: var(--bg-color1);
}

#img-grid-container {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 200px;
    height: auto;
    z-index: 0;
    padding: 10px 0 15px;
}

#img-grid-container img {
    width: 100%;
    height: auto;
}

svg#dot-grid {
    position: absolute;
    top: -10px;
    left: 20px;
    z-index: -1;
    width: 200px;
    height: auto;
    pointer-events: none;
    fill: var(--header-color);
}


#about {
    background-color: var(--bg-color2);
}


#skills {
    background-color: var(--bg-color1);
}

#skills img {
    width: 70px;
    height: auto;
}

#skills-box {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(auto-fill);
    row-gap: 1rem;
}

#skills-box div {
    text-align: center;
}

.skill {
    cursor: pointer;
    transition: transform 0.3s;
    padding-bottom: 10px;
}

.skill:hover {
    transform: scale(1.1);
}


#projects {
    background-color: var(--bg-color2);
}

#projects-container {
    display: flex;
    justify-content: center;
    align-items: center;
}

h3 {
    font-family: 'Open Sans', serif;
    font-weight: 600;
    color: var(--header-color);
    padding-bottom: 3px;
}

.card {
    box-shadow: 0 4px 8px 0 rgba(0,0,0,0.2);
    transition: 0.3s;
    width: 85%;
    border-radius: 10px;
    text-align: center;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}
  
.card:hover {
    box-shadow: 0 8px 18px 0 rgba(0,0,0,0.2);
}

.card-img-container {
    background-color: var(--card-img-color);
    flex: 1;
    padding: 10px 0;
}

.card-img-container img {
    width: 220px;
    height: auto;
    border-radius: 8px;
}

.card-text-container {
    text-align: center;
    background-color: var(--card-text-color);
    flex: 1;
    padding: 8px 18px;
}

.card-text-container p {
    text-align: left;
    padding-bottom: 5px;
}

.card-text-container a {
    text-align: left;
    display: block;
}


#contact {
    background-color: var(--bg-color1);
    text-align: center;
}

#contact-container-main {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

#icons-container {
    display: flex;
    flex-direction: row;
    gap: 7px;
    padding-top: 5px;
    justify-content: center;
    align-items: center;
}

a.contact-link:link,
a.contact-link:visited {
    background-color: none;
    text-decoration: none;
}

.contact-link i {
    font-size: 1.5rem;
    color: var(--font-main);
    padding: 5px;
}

.contact-link i:hover {
    background-color: var(--contact-link-hover);
    border-radius: 5px;
    transition: background-color 0.3s ease;
}

#CV {
    max-width: fit-content;
    border: none;
    background-color: var(--CV-bg-color);
    border-radius: 10px;
    padding: 6px 10px;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

#CV:hover {
    background-color: var(--CV-hover);
}

#CV-text {
    color: var(--CV-text-color);
}


#back-to-top {
    position: fixed;
    bottom: 15px;
    left: 15px;
    z-index: 99;
    border: none;
    outline: none;
    background-color: rgb(95, 95, 95);
    color: rgb(255, 255, 255);
    cursor: pointer;
    padding: 10px;
    border-radius: 40%;
    opacity: 0;
    visibility: hidden;
    transform: scale(1, 1);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}

#back-to-top i {
    font-size: 1rem;
}
  
#back-to-top:hover {
    background-color: rgb(74, 74, 74);
    opacity: 0.9 !important;
    transform: scale(1.15, 1.15);
}

#back-to-top.show {
    opacity: 0.7;
    visibility: visible;
}


footer {
    background-color: var(--bg-color2);
    text-align: center;
    margin-top: -1px;
    padding: 12px 0;
}


#home + #about,
#about + #skills,
#skills + #projects,
#projects + #contact {
    margin-top: -1px;
}


/* scrollbar */
::-webkit-scrollbar {
    width: 8px;
}
  
::-webkit-scrollbar-track {
    background-color: var(--scrollbar-track-color);
}
   
::-webkit-scrollbar-thumb {
    background: rgb(109, 109, 109); 
    border-radius: 8px;
}
  
::-webkit-scrollbar-thumb:hover {
    background: rgb(80, 80, 80);
}




/* responsive design */

@media only screen and (min-width: 768px) {
    #header-mobile {
        display: none;
    }

    #header-desktop {
        position: sticky;
        top: 0;
        display: flex;
        flex-direction: row;
        width: 100%;
        height: 60px;
        background-color: var(--header-desktop-bg);
        backdrop-filter: blur(10px);
        justify-content: space-between;
        align-items: center;
        padding: 0 5rem;
        z-index: 10;
    }

    #header-right-group {
        display: flex;
        flex-direction: row;
        gap: 1rem;
    }

    #ul-desktop {
        display: flex;
        flex-direction: row;
        list-style-type: none;
        gap: 10px;
    }
    
    #ul-desktop li a {
        font-family: 'Roboto', serif;
        font-size: 1.3rem;
    }
    
    #ul-desktop li a:link,
    #ul-desktop li a:visited,
    #ul-desktop li a:link {
        color: var(--ul-color);
        transition: color 0.4s ease;
        text-decoration: none;
    }
    
    #ul-desktop li a:hover {
        color: var(--ul-hover);
    }

    #vertical-line {
        border-left: 2px solid var(--font-main);
        height: 25px;
    }

    .theme-toggle {
        color: var(--ul-color);
        transition: color 0.4s ease;
        cursor: pointer;
        padding-top: 2px;
        font-size: 1.2rem;
    }
    
    .theme-toggle:hover {
        color: var(--ul-hover);
    }


    .main {
        padding: 50px 80px;
    }

    .h2-pill {
        border-radius: 10px;
        max-width: fit-content;
        padding: 3px 8px;
        margin: 0 auto 15px;
    }


    #home {
        display: flex;
        flex-direction: row-reverse;
        justify-content: center;
        align-items: center;
        gap: 4rem;
    }

    #img-grid-container {
        position: relative;
        display: flex;
        justify-content: center;
        align-items: center;
        width: 800px;
        height: auto;
        z-index: 0;
        padding: 10px 0 15px;
    }
    
    #img-grid-container img {
        width: 100%;
        height: auto;
    }
    
    svg#dot-grid {
        position: absolute;
        top: -10px;
        left: 20px;
        z-index: -1;
        width: 100%;
        height: auto;
        pointer-events: none;
        fill: var(--header-color);
    }


    #skills {
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
    }

    #skills-box {
        display: grid;
        grid-template-columns: repeat(3, 1fr);
        grid-auto-rows: auto;
        min-width: fit-content;
        gap: 3rem;
    }


    .card {
        width: 50%;
        border-radius: 10px;
    }


    #contact {
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
    }

    #contact-container-main {
        display: grid;
        grid-template-columns: auto auto;
        column-gap: 2rem;
        row-gap: 1.5rem;
        width: 60%;
    }

    #socials-container {
        grid-row: 1 / 4;
    }
}

@media only screen and (min-width: 1200px) {
    #header-desktop {
        height: 70px;
        padding: 0 9rem;
    }


    .main {
        padding: 70px 170px;
    }


    #skills img {
        width: 80px;
        height: auto;
    }


    .card-img-container img {
        width: 370px;
        height: auto;
        border-radius: 8px;
    }


    footer {
        padding: 20px 0;
    }
}