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

:root {
  --bg: #242526;            
  --panel: #171a1f;         
  --text: #e6e7ea;          
  --muted: #9aa3b2;         
  --brand: #5a63ff;         
  --radius: 12px;
  --shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  --hero-url: url("../src/hero-image.jpg"); 
}

html,
body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font: 500 16px/1.5 system-ui, Segoe UI, Roboto, Inter, sans-serif;
}

img {
  display: block;
  max-width: 100%;              
}

.app {
  position: relative;
  height: 100dvh;
  display: grid;
  grid-template-columns: 320px 1fr;
}


@media (max-width: 600px) {
  .app {
    grid-template-columns: 1fr;
  }
}

.sidebar {
  border-right: 1px solid #222831;
  padding: 16px;
  background: #121617;
}
@media (max-width: 600px) {

    .sidebar {
        display: block;
        position: fixed;
        top: 0;
        left: 0;
        bottom: 0;
        height: 100vh;
        width: 100vw;      
        max-width: 260px;
        padding: 16px;
        background: #121617;
        box-shadow: 2px 0 12px rgba(0, 0, 0, 0.5);
        transform: translateX(-100%);  
        transition: transform 0.3s ease;
        z-index: 30;
    }

    .app:not(.collapsed) .sidebar {
        transform: translateX(0);
    }

    .collapse-btn-closed {
        display: grid;
        position: fixed;
        top: 16px;
        left: 16px;
        z-index: 40;
        width: 32px;
        height: 32px;
        background: #0f1216;
        border: 1px solid #2a3040;
        border-radius: 8px;
        place-items: center;
        cursor: pointer;
    }
    .collapse-btn-closed:hover {
        background: #1a1f27;
    }

    .collapse-btn-open {
        display: none;
    }

}

.sidebar.collapsed {
  display: none;
}

.app.collapsed {
  grid-template-columns: 1fr;
}
.app.collapsed .sidebar {
  display: none;
}


.brand {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}
.logo-full {
  width: 140px;
  height: auto;
}

.collapse-btn-open {
  background: transparent;
  border: none;
  cursor: pointer;
}

.collapse-btn-open img {
  width: 25px;
  height: 25px;
}

.collapse-btn-closed {
  display: none;
}
.app.collapsed .collapse-btn-closed {
  display: grid;
  position: absolute;
  top: 16px;
  left: 16px;
  z-index: 20;
  width: 32px;
  height: 32px;
  background: #0f1216;
  border: 1px solid #2a3040;
  border-radius: 8px;
  place-items: center;
  cursor: pointer;
}
.app.collapsed .collapse-btn-closed:hover {
  background: #1a1f27;
}

.app.collapsed .collapse-btn-open {
  display: none;
}


.new-chat {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  background: transparent;
  color: var(--text);
  padding: 12px 14px;
  border-radius: 10px;
  border: 2px solid #353839;
  cursor: pointer;
  margin-top: 2rem;
}

.new-chat:hover {
  border-color: #2f3542;
}
.new-chat img {
  width: 20px;
  height: 20px;
}

.conversations h2 {
  font-size: 13px;
  color: white;
  margin: 20px 0 8px;
  letter-spacing: 0.04em;
}

.conv-list {
  display: grid;
  gap: 8px;
  margin-top: 8px;
}

.conv-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-radius: 16px;
  background: transparent;
  color: var(--text);
  cursor: pointer;
}

.conv-item[aria-current="true"] {
  background: #242526;
}

.conv-item .conv-icon {
  width: 20px;
  height: 20px;
}

.conv-item .conv-title {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.conv-item .action-icon {
  width: 18px;
  height: 18px;
  cursor: pointer;
  opacity: 0.7;
}

.conv-item .action-icon:hover {
  opacity: 1;
}

.conv-item.editing .conv-title,
.conv-item.editing .action-icon {
  display: none;
}


.conv-item.editing .edit-input {
  flex: 1;
  padding: 8px 10px;
  background: #171a1f;
  border: 1px solid #2a3040;
  border-radius: 8px;
  color: var(--text);
  outline: none;
}

.conv-item.editing .confirm-btn,
.conv-item.editing .cancel-btn {
  width: 32px;
  height: 32px;
  display: grid;
  place-items: center;
  border: 1px solid #2a3040;
  border-radius: 8px;
  cursor: pointer;
  background: var(--panel);
}

.conv-item.editing .confirm-btn:hover,
.conv-item.editing .cancel-btn:hover {
  background: #1a1f27;
}

.conv-item.editing .confirm-btn img,
.conv-item.editing .cancel-btn img {
  width: 16px;
  height: 16px;
}

.chat {
  position: relative;
  display: grid;
  place-items: center;
  background: var(--bg);
}

.chat::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 200px; 
  background:
    radial-gradient(1000px 400px at 50% 0%, rgba(255,255,255,0.08), transparent 60%),
    linear-gradient(180deg, rgba(0,0,0,0.3), rgba(0,0,0,0.6)),
    var(--hero-url);
  background-size: cover;
  background-position: top center;
  z-index: 0;
}


.chat-card {
  position: relative;
  z-index: 1;
  width: min(770px, 86vw);
  height: min(79vh, 680px);
  display: grid;
  grid-template-rows: 1fr auto;
  background: #242526;
  border: 1px solid #262b36;
  border-radius: 10px;
  box-shadow: 0 30px 60px rgba(0, 0, 0, 0.45);
  overflow: hidden;
}

.messages {
  list-style: none;
  padding: 22px 22px 10px;
  overflow-y: auto;
  display: grid;
  gap: 16px;       
  align-content: start;
}

.msg {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  max-width: 75%;   
}
.msg.user {
  justify-self: flex-end;
  flex-direction: row-reverse; 
}
.msg .msg-icon {
  width: 20px;
  height: 20px;
  margin-top: 4px;  
}
.msg .bubble {
  max-width: 100%;
  line-height: 1.4;
  padding: 12px 16px;
  border-radius: 14px;
  box-shadow: var(--shadow);
}
.msg.ai .bubble {
  background: var(--panel);
  color: var(--text);
  border-top-left-radius: 6px;
}
.msg.user .bubble {
  background: var(--brand);
  color: #fff;
  border-top-right-radius: 6px;
}

.composer {
  display: flex;
  padding: 14px;
  border-top: 1px solid #222831;
  background: transparent;
}

.composer input {
  flex: 1;
  padding: 14px 16px;
  border: 1px solid #6c7173;
  border-right: none;
  border-radius: 12px 0 0 12px;
  background: transparent;
  color: var(--text);
}

.composer .send {
  width: 48px;
  display: grid;
  place-items: center;
  border: 1px solid #6c7173;
  border-left: none;
  border-radius: 0 12px 12px 0;
  background: transparent;
  cursor: pointer;
}

.composer .send:hover {
  background: #1a1f27;
}

.composer .send img {
  width: 18px;
  height: 18px;
  filter: invert(80%);   
}


.visually-hidden {
  position: absolute;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  height: 1px;
  width: 1px;
  overflow: hidden;
  white-space: nowrap;
}


.author-info {
  font-size: 14px;
  text-align: center;
  margin: 16px 0;
  color: #8b94a5;
}

.author-info a {
  color: #cfd5e3;
  text-decoration: none;
}

.author-info a:hover {
  text-decoration: underline;
}



@media (max-width: 1024px) {
  .app {
    grid-template-columns: 280px 1fr;
  }
  .chat-card {
    width: min(700px, 90vw);
    height: min(78vh, 640px);
  }
}

@media (max-width: 600px) {

    .chat-card {
    width: 100%;
    height: calc(100vh - 140px);
    border-radius: 0;
  }

  .app.collapsed .collapse-btn-open {
    display: none;
  }

  .app.collapsed .collapse-btn-closed {
    display: grid;
  }
}

@media (max-width: 480px) {

  .chat-card {
    height: calc(100vh - 120px);
  }

  .conv-item .conv-icon,
  .conv-item .action-icon {
    width: 16px;
    height: 16px;
  }

}

@media (min-width: 601px) {

 .app.collapsed {
    grid-template-columns: 1fr;
  }
  
  .app.collapsed .sidebar {
    display: none;
  }

  .app.collapsed .collapse-btn-closed {
    display: grid;
    position: absolute;
    top: 16px;
    left: 16px;
    z-index: 20;
    width: 32px;
    height: 32px;
    background: #0f1216;
    border: 1px solid #2a3040;
    border-radius: 8px;
    place-items: center;
    cursor: pointer;
  }

}