3-4.css

*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    list-style: none;
    text-decoration: none;
    font-family: 'Josefin Sans', sans-serif;
}

body {
    font-family: sans-serif;
}

header {
    box-shadow: 0px 3px 10px rgba(0, 0, 0, 0.3);
    position: sticky;
    top: 0px;
    background: white;
}

nav {
    min-height: 10vh;
    margin: auto;
    width: 90%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

nav h1,
nav ul {
    font-size: 1.5rem;
    flex: 1;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: space-between;
}

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

.null {
    position: absolute;
    z-index: -2;
}

main {
    max-width: 1500px;
    margin: 0 auto;
}

main h1 {
    margin: 20px auto;
    padding: 25px;
}

#lap {
    padding: 30px 0;
    margin: 0 auto;
}

#sect-lap {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-wrap: wrap;
    text-align: center;
}

#sect-lap a {
    margin: 10px 10px;
    align-self: flex-end;
}

#sect-lap a img {
    width: 200px;
    margin: 20px;
}

#sect-lap a p {
    text-decoration: none;
    color: black;
}

#acc {
    padding: 30px 0;
    margin: 0 auto;
}

#sect-acce {
    display: flex;
    justify-content: space-around;
    align-items: center;
    flex-wrap: wrap;
    text-align: center;
}

#sect-acce a {
    margin: 20px 10px;
    align-self: flex-end;
}

#sect-acce a img {
    width: 200px;
    margin: 20px;
}

#sect-acce a p {
    text-decoration: none;
    color: black;
}

footer {
    min-height: 10vh;
    margin: 10px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

nav div button {
    position: relative;
    margin-top: auto;
    margin: auto;
}

nav div button  {
    background: none;
    color: black;
    width: 150px;
    height: 50px;
    border: 1px solid #77767910;
    font-size: 18px;
    border-radius: 4px;
    transition: .6s;
    overflow: hidden;
}

nav div button:focus {
    outline: none;
}

nav div button:before {
    content: "";
    display: block;
    position: absolute;
    width: 60px;
    height: 100%;
    left: 0;
    top: 0;
    opacity: .5s;
    filter: blur(30px);
    transform: translateX(-130px) skewX(-15deg);
}

nav div button:after {
    content: "";
    display: block;
    position: absolute;
    background: rgba(255,255,255,.2);
    width: 30px;
    left: 30px;
    height: 100%;
    top: 0;
    opacity: 0;
    filter: blur(30px);
    transform: translate(-100px) scaleX(-15deg);
}

nav div button:hover {
    background: #0c0c0ca2;
    cursor: pointer;
    color: white;
}

nav div button:hover::before {
    transform: translate(300px) skewX(-15deg);
    opacity: .6;
    transition: .7s;
}

nav div button:hover::after {
    transform: translate(300px) skewX(-15deg);
    opacity: 1;
    transition: .7s;
}

.btn {
    display: inline-block;
    width: 40px;
    height: 40px;
    background: #f1f1f1;
    margin: 15px;
    border-radius: 30%;
    box-shadow: 0 5px 15px -5px #00000070;
    color: #3498db;
    overflow: hidden;
    position: relative;
    text-align: center;
}

.btn i{
  line-height: 40px;
  font-size: 25px;
  transition: 0.2s linear;
}

.btn:hover i{
  transform: scale(1.3);
  color: #f1f1f1;
}

.btn::before{
  content: "";
  position: absolute;
  width: 120%;
  height: 120%;
  background: #db5534;
  transform: rotate(45deg);
  left: -110%;
  top: 90%;
}

.btn:hover::before{
  animation: aaa 0.7s 1;
  top: -10%;
  left: -10%;
}

@keyframes aaa {
  0%{
    left: -110%;
    top: 90%;
  }50%{
    left: 10%;
    top: -30%;
  }100%{
    top: -10%;
    left: -10%;
  }
}

@media (max-width: 768px) {
    nav h1,
    nav ul {
        font-size: 1rem;
    }

    #sect-lap a img {
        width: 150px;
    }

    #sect-acce a img {
        width: 150px;
    }

    nav div button  {
        width: 100px;
    }
}

@media (min-width: 768px) and (max-width: 1024px) {
    nav h1,
    nav ul {
        font-size: 1rem;
    }

    #sect-lap a img {
        width: 150px;
    }

    #sect-acce a img {
        width: 150px;
    }

    nav div button  {
        width: 100px;
    }
}

@media (max-width: 468px) {
    nav h1,
    nav ul {
        font-size: 0.9rem;
    }

    #sect-lap a img {
        width: 130px;
    }

    #sect-acce a img {
        width: 130px;
    }

    nav div button  {
        width: 80px;
    }

    main h1 {
        font-size: 20px;
    }
}