*{
  margin:0;
  padding:0;
  box-sizing:border-box;
}

body{
  background:#0f0f0f;
  color:white;
  font-family:sans-serif;
}

.app{
  max-width:500px;
  margin:auto;
  min-height:100vh;
  position:relative;
}

.header{
  height:60px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:0 15px;
  border-bottom:1px solid #222;
  position:sticky;
  top:0;
  background:#0f0f0f;
  z-index:100;
}

.logo{
  font-size:24px;
  font-weight:bold;
}

.feed{
  padding:15px;
  padding-bottom:100px;
}

.create-post{
  background:#1a1a1a;
  padding:15px;
  border-radius:18px;
  margin-bottom:20px;
}

.create-post textarea{
  width:100%;
  min-height:100px;
  background:#111;
  border:none;
  outline:none;
  color:white;
  padding:15px;
  border-radius:12px;
  resize:none;
  font-size:16px;
}

.create-post button{
  margin-top:12px;
  width:100%;
  height:45px;
  border:none;
  border-radius:12px;
  background:#ff004f;
  color:white;
  font-size:16px;
  font-weight:bold;
}

.post-card{
  background:#1a1a1a;
  border-radius:18px;
  overflow:hidden;
  margin-bottom:20px;
  padding-bottom:15px;
}

.post-top{
  display:flex;
  align-items:center;
  gap:10px;
  padding:15px;
}

.avatar{
  width:45px;
  height:45px;
  border-radius:50%;
  background:#444;
}

.post-user h3{
  font-size:16px;
}

.post-user span{
  color:#aaa;
  font-size:12px;
}

.post-content{
  padding:0 15px 15px;
  line-height:1.5;
  font-size:16px;
}

.bottom-nav{
  position:fixed;
  bottom:0;
  width:100%;
  max-width:500px;
  height:65px;
  background:#161616;
  display:flex;
  align-items:center;
  justify-content:space-around;
  border-top:1px solid #222;
}

.bottom-nav button{
  background:none;
  border:none;
  color:white;
  font-size:22px;
}

.add-btn{
  width:50px;
  height:50px;
  border-radius:50%;
  background:#ff004f !important;
}

@media (min-width:768px){

  body{
    background:#111;
  }

  .app{
    max-width:1200px;
    display:grid;
    grid-template-columns:
      250px
      1fr
      300px;
    gap:20px;
    padding:20px;
  }

  .header{
    grid-column:2/3;
    border-radius:18px;
    border:1px solid #222;
  }

  .feed{
    grid-column:2/3;
    padding:20px 0 120px;
  }

  .bottom-nav{
    left:0;
    top:0;
    width:250px;
    height:100vh;
    max-width:none;
    flex-direction:column;
    justify-content:center;
    gap:30px;
    border-right:1px solid #222;
    border-top:none;
  }

  .bottom-nav button{
    font-size:26px;
  }

  .post-card{
    border:1px solid #222;
  }

}
.post-actions{
  display:flex;
  padding:0 15px;
}

.post-actions button{
  background:none;
  border:none;
  color:white;
  font-size:16px;
  padding:10px 0;
}
.comment-box{
  display:flex;
  gap:10px;
  padding:15px;
}

.comment-box input{
  flex:1;
  height:45px;
  border:none;
  outline:none;
  border-radius:12px;
  padding:0 15px;
  background:#111;
  color:white;
}

.comment-box button{
  border:none;
  padding:0 20px;
  border-radius:12px;
  background:#ff004f;
  color:white;
}