body, html {
  margin: 0; padding: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: #090C12; color: #E8ECF2;
  height: 100%;
}
.screen { display: none; height: 100vh; flex-direction: column; }
.screen.active { display: flex; }

/* Kimlik doğrulama */
.auth-form {
  width: 400px; margin: auto; padding: 2rem;
  background: #10151C; border-radius: 16px;
  display: flex; flex-direction: column; gap: 1rem;
}
.auth-form input, .auth-form button {
  padding: 0.8rem; border-radius: 8px; border: 1px solid #1C2430;
  background: #0F131A; color: #E8ECF2;
}
.auth-form button { background: #5B9EFF; border: none; cursor: pointer; }

/* Ana sohbet */
header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 1rem 2rem; background: #10151C; border-bottom: 1px solid #1C2430;
}
#chat-container { flex: 1; display: flex; flex-direction: column; }
#chat-area { flex: 1; overflow-y: auto; padding: 1rem; }
#input-area { display: flex; gap: 0.5rem; padding: 1rem; background: #10151C; }
#message-input { flex: 1; resize: none; background: #0F131A; color: #E8ECF2; border-radius: 8px; padding: 0.8rem; }

.message { margin-bottom: 1rem; padding: 0.8rem; border-radius: 12px; max-width: 80%; }
.message.user { margin-left: auto; background: #161C25; }
.message.assistant { margin-right: auto; background: #10151C; }
.file-item { display: flex; justify-content: space-between; padding: 1rem; border-bottom: 1px solid #1C2430; }