* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
:root {
    --main-color: #30ABE8;
    --backg-color: #1F2937;
    --text-color: #ffffff;
    --border-color: #d8d9db7d;
}
.light {
    --backg-color: #F6F7F8;
    --text-color: #1F2937;
    --border-color: #d8d9db;
}
.container {
    padding-left: 15px;
    padding-right: 15px;
    margin-left: auto;
    margin-right: auto;
}
@media (min-width: 768px) {
    .container {
        width: 750px;
    }
}
@media (min-width: 992px) {
    .container {
        width: 970px;
    }
}
@media (min-width: 1200px) {
    .container {
        width: 1170px;
    }
}
body {
    font-family: sans-serif;
    background-color: var(--backg-color);
    color: var(--text-color);
    transition: 0.3s;
}
header {
    padding: 25px 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
}
.logo i {
    color: var(--main-color);
    font-size: 20px;
}
.logo span {
    font-size: 18px;
    font-weight: bold;
}
.theme img {
    width: 30px;
    height: 30px;
    cursor: pointer;
}
.categories ul {
    list-style: none;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 40px 0;
}
.categories ul li {
    padding: 15px 20px;
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: 0.3s;
}
@media(max-width:767px) {
    .categories ul li {
        padding: 15px;
        font-size: 15px;
    }
}
.categories ul li:first-child {
    border-radius: 15px 0 0 15px;
}
.categories ul li:last-child {
    border-radius: 0 15px 15px 0;
}
.categories ul li:hover,
.categories ul li.active {
    background-color: var(--main-color);
}
.gallery {
    min-height: 50vh;
    margin: 30px 0 50px;
    text-align: center;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 40px;
}
.card {
    height: 270px;
    padding: 5px;
    border: 1px solid var(--border-color);
    border-radius: 15px;
    overflow: hidden;
}
.card img {
    width: 100%;
    height: 100%;
    border-radius: 15px;
    object-fit: cover;
    object-position: center;
    cursor: pointer;
    transition: 0.5s;
}
.card img:hover {
    transform: scale(1.05);
}
footer {
    text-align: center;
    color: var(--text-color);
    padding: 25px 0;
    border-top: 1px solid var(--border-color);
}
footer a {
    color: var(--main-color);
    text-decoration: none;
    font-size: 18px;
}
.top {
    width: 35px;
    height: 35px;
    background-color: var(--main-color);
    color: white;
    border-radius: 10px;
    font-size: 25px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.3s;
    position: fixed;
    bottom: 20px;
    right: 20px;
    z-index: 100;
    justify-content: center;
    align-items: center;
    padding-top: 10px;
    display: none;
}
.viewer {
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    min-height: 100vh;
    background-color: #1f29379e;
    display: none;
    justify-content: center;
    align-items: center;
}
.viewer button {
    border: none;
    outline: none;
    background-color: transparent;
    color: var(--main-color);
    font-size: 40px;
    font-weight: bold;
    position: absolute;
    right: 40px;
    top: 40px;
    cursor: pointer;
    user-select: none;
}
.img-holder {
    width: 50%;
    margin: auto;
    padding: 30px;
    border-radius: 20px;
    background-color: white;
    position: relative;
}
@media(max-width:991px) {
    .img-holder {
        width: 80%;
    }
}
@media(max-width:767px) {
    .img-holder {
        margin: 15px;
        width: 100%;
    }
}
.img-holder img {
    width: 100%;
    height: 100%;
    max-height: 80vh;
    border-radius: 20px;
    position: relative;
    z-index: 2;
}
.img-holder .previous,
.img-holder .next {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    z-index: 1;
    font-size: 25px;
    font-weight: bold;
    padding: 10px;
    background-color: var(--main-color);
    color: white;
    cursor: pointer;
}
.img-holder .previous {
    left: 0;
}
.img-holder .next {
    right: 0;
}