*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family:Arial,sans-serif;
}

body{
    background:#f0f8ff;
}

header{
    background:#0077cc;
    color:yellow;
    text-align:center;
    padding:20px;
}

nav{
    background:#005fa3;
    text-align:center;
    padding:15px;
}

nav button{
    padding:10px 20px;
    margin:5px;
    border:none;
    border-radius:5px;
    background: white;
    color:#005fa3;
    font-weight:bold;
    cursor:pointer;
}

nav button:hover{
    background:yellow;
}

.container{
    width:80%;
    margin:30px auto;
}

.page{
    display:none;
    background:green;
    padding:20px;
    border-radius:10px;
    box-shadow:0 0 10px white;
}

.page img{
    width:220px;
    display:block;
    margin:20px auto;
    border-radius:10px;
}

.page h2{
    color:#0077cc;
    text-align:center;
    margin-bottom:15px;
}

.page p{
    font-size:18px;
    line-height:30px;
    text-align:justify;
}

#welcome{
    display:block;
    background:blue;
    padding:40px;
    border-radius:10px;
    text-align:center;
    box-shadow:0 0 10px gray;
}
*{
    margin:0;
    padding:0;
    box-sizing:border-box;
    font-family:Arial,sans-serif;
}

body{
    background:#f0f8ff;
}

header{
    background:#0077cc;
    color:yellow;
    text-align:center;
    padding:20px;
    position:relative;
}

nav{
    background:#005fa3;
    text-align:center;
    padding:15px;
}

nav button{
    padding:10px 20px;
    margin:5px;
    border:none;
    border-radius:5px;
    background:white;
    color:#005fa3;
    font-weight:bold;
    cursor:pointer;
}

nav button:hover{
    background:yellow;
}

.container{
    width:80%;
    margin:30px auto;
}

.page{
    display:none;
    background:white;
    padding:20px;
    border-radius:10px;
    box-shadow:0 0 10px gray;
}

.page img{
    width:220px;
    display:block;
    margin:20px auto;
    border-radius:10px;
}

.page h2{
    color:#0077cc;
    text-align:center;
    margin-bottom:15px;
}

.page p{
    font-size:18px;
    line-height:30px;
    text-align:justify;
}

#welcome{
    display:block;
    background:white;
    padding:40px;
    border-radius:10px;
    text-align:center;
    box-shadow:0 0 10px gray;
}

/* ==========================
   BACK BUTTON
========================== */

.back-btn{
    position: absolute;
    left: 30px;
    top: 50%;
    transform: translateY(-50%);

    width: 50px;
    height: 50px;

    border: none;
    border-radius: 50%;
    outline: none;

    background: #ffffff;
    color: #333333;

    display: flex;
    align-items: center;
    justify-content: center;

    font-size: 18px;
    cursor: pointer;
    font-weight: 600;

    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);

    transition:
        all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.back-btn:hover{
    transform: translateY(-50%) scale(1.1);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.back-btn:active{
    transform: translateY(-50%) scale(0.95);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}