:root{
    --bg1: #0b1220;
    --bg2: #12132b;
    --accent1: #57c7ff; /* aqua */
    --accent2: #7f5cff; /* purple */
    --panel: rgba(255,255,255,0.03);
    --glass: rgba(255,255,255,0.02);
    --muted: rgba(255,255,255,0.6);
  }
  
  *{box-sizing:border-box}
  html,body{height:100%; margin:0; font-family:Inter, "Segoe UI", Roboto, Arial, sans-serif; -webkit-font-smoothing:antialiased;}
  body{
    background: radial-gradient(1200px 600px at 10% 10%, rgba(97,61,255,0.12), transparent),
                radial-gradient(900px 400px at 90% 90%, rgba(6,173,255,0.06), transparent),
                linear-gradient(180deg,var(--bg1),var(--bg2));
    color:#e6eef6;
    display:flex;
    align-items:center;
    justify-content:center;
    padding:28px;
  }
  
  /* layout */
  .app{
    width:1000px;
    max-width:96%;
    height:720px;
    display:grid;
    grid-template-columns:260px 1fr;
    gap:18px;
  }
  
  /* sidebar */
  .sidebar{
    background:linear-gradient(180deg, rgba(255,255,255,0.02), rgba(255,255,255,0.01));
    border-radius:14px;
    padding:20px;
    box-shadow:0 10px 30px rgba(6,10,20,0.6);
    display:flex;
    flex-direction:column;
    align-items:center;
  }
  .brand{display:flex;align-items:center;gap:12px}
  .logo{width:48px;height:48px;border-radius:10px;object-fit:cover;box-shadow:0 6px 18px rgba(127,92,255,0.12);}
  .brand h1{margin:0;font-size:18px;color:var(--accent2)}
  .tag{margin-top:12px;color:var(--muted);font-size:13px;text-align:center;padding:0 6px}
  .credits{margin-top:auto;color:rgba(255,255,255,0.25);font-size:12px}
  
  /* main panel */
  .main{
    background: linear-gradient(180deg, rgba(12,15,22,0.6), rgba(8,10,16,0.6));
    border-radius:14px;
    padding:12px;
    display:flex;
    flex-direction:column;
    box-shadow: 0 10px 30px rgba(6,10,20,0.6), inset 0 1px 0 rgba(255,255,255,0.02);
  }
  
  /* header */
  .chat-header{display:flex;align-items:center;justify-content:space-between;padding:8px 12px;border-bottom:1px solid rgba(255,255,255,0.02)}
  .chat-info{display:flex;align-items:center;gap:12px}
  .avatar img{width:48px;height:48px;border-radius:50%;object-fit:cover;box-shadow:0 6px 18px rgba(127,92,255,0.12)}
  .title{font-weight:700}
  .subtitle{font-size:13px;color:var(--muted)}
  
  /* chat box */
  .chat-box{
    flex:1;
    overflow:auto;
    padding:18px;
    display:flex;
    flex-direction:column;
    gap:10px;
    scrollbar-width:thin;
    scrollbar-color: rgba(255,255,255,0.12) transparent;
  }
  
  .message{
    max-width:78%;
    padding:12px 14px;
    border-radius:14px;
    line-height:1.45;
    box-shadow:0 6px 18px rgba(2,6,12,0.7);
    word-break:break-word;
    background:var(--panel);
  }
  
  /* user / ai */
  .message.user{
    align-self:flex-end;
    background: linear-gradient(90deg, rgba(79,195,247,0.12), rgba(127,92,255,0.06));
    color:var(--accent1);
    border:1px solid rgba(79,195,247,0.06);
    text-align:right;
  }
  .message.ai{
    align-self:flex-start;
    background: linear-gradient(90deg, rgba(127,92,255,0.06), rgba(79,195,247,0.06));
    color:var(--accent2);
    border:1px solid rgba(127,92,255,0.06);
    text-align:left;
  }
  
  /* typing animation bubble */
  .typing {
    display:inline-block;
    height:10px;
    width:54px;
    background:transparent;
  }
  .typing span {
    display:inline-block;
    width:8px;height:8px;border-radius:50%;
    background: rgba(255,255,255,0.18);
    margin:0 4px;
    transform: translateY(0);
    animation: bounce 1s infinite ease-in-out;
  }
  .typing span:nth-child(2){ animation-delay:.12s }
  .typing span:nth-child(3){ animation-delay:.24s }
  @keyframes bounce{
    0%,100%{ transform: translateY(0); opacity:0.5; }
    50%{ transform: translateY(-6px); opacity:1; }
  }
  
  /* composer */
  .composer{
    display:flex;
    gap:12px;
    padding:12px;
    border-top:1px solid rgba(255,255,255,0.02);
    align-items:flex-end;
  }
  .composer textarea{
    flex:1;
    min-height:48px;
    max-height:120px;
    resize:none;
    padding:10px 12px;
    border-radius:10px;
    border:1px solid rgba(255,255,255,0.04);
    background: linear-gradient(180deg, rgba(255,255,255,0.01), rgba(255,255,255,0.00));
    color: #e6eef6;
    outline:none;
    font-size:14px;
  }
  .controls{display:flex;flex-direction:row;gap:8px}
  .controls button{
    padding:10px 14px;border-radius:10px;border:none;background:linear-gradient(90deg,var(--accent1),var(--accent2));color:#071018;font-weight:700;cursor:pointer;box-shadow:0 8px 20px rgba(127,92,255,0.12);
  }
  
  /* responsive */
  @media (max-width:900px){
    .app{grid-template-columns: 1fr; height:100vh}
    .sidebar{display:none}
  }