/* Reset & Font */
@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600&display=swap');
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

body {
    background: linear-gradient(#f1fff4, #cbfff4);
}

/* Tombol Toggle */
.chatbot-toggler {
    position: fixed;
    bottom: 40px;
    right: 45px;
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 50%;
    background: #053838;
    color: white;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

/* Container Chatbot */
.chatbot {
    position: fixed;
    right: 30px;
    bottom: 100px;
    width: 620px;
    max-width: 90%;
    background: white;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
    transform: scale(0.5);
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s ease;
}

body.show-chatbot .chatbot {
    transform: scale(1);
    opacity: 1;
    pointer-events: auto;
}

/* Header Chatbot */
.chatbot header {
    background: #053838;
    padding: 16px 20px;
    color: white;
    text-align: center;
    border-radius: 15px 15px 0 0;
}

.chatbot header h2 {
    font-size: 1.2rem;
}

/* Area Chat */
.chatbox {
    height: 400px;
    overflow-y: auto;
    padding: 20px;
}

.chatbox .chat {
    display: flex;
    margin-bottom: 15px;
}

.chatbox .incoming {
    justify-content: flex-start;
}

.chatbox .outgoing {
    justify-content: flex-end;
}

.chatbox .chat p {
    max-width: 75%;
    padding: 12px 16px;
    border-radius: 10px;
    background: #f1f1f1;
    color: #333;
}

.chatbox .incoming p {
    border-radius: 10px 10px 10px 0;
}

.chatbox .outgoing p {
    background: #053838;
    color: white;
    border-radius: 10px 10px 0 10px;
}

/* Input Chat */
.chat-input {
    display: flex;
    gap: 10px;
    padding: 15px;
    border-top: 1px solid #ddd;
}

.chat-input textarea {
    flex: 1;
    border: none;
    outline: none;
    resize: none;
    max-height: 120px;
    padding: 10px;
    font-size: 0.95rem;
}

#send-btn {
    align-self: flex-end;
    color: #053838;
    cursor: pointer;
    font-size: 1.5rem;
}

/* Responsif */
@media (max-width: 490px) {
    .chatbot {
        right: 0;
        bottom: 0;
        width: 100%;
        height: 100%;
        border-radius: 0;
    }
}

Langkah 3: Logika JavaScript (script.js)

// 1. SELEKSI ELEMEN DOM
const chatbotToggler = document.querySelector(".chatbot-toggler");
const closeBtn = document.querySelector(".close-btn");
const chatbox = document.querySelector(".chatbox");
const chatInput = document.querySelector(".chat-input textarea");
const sendChatBtn = document.querySelector(".chat-input span");

// 2. VARIABEL KONFIGURASI
let userMessage = null; // Menyimpan pesan pengguna
const inputInitHeight = chatInput.scrollHeight; // Tinggi awal textarea
const API_KEY = ""; // API Key Gemini
const API_URL = `https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:generateContent?key=${API_KEY}`;

// 3. FUNGSI PEMBUAT ELEMEN CHAT
const createChatLi = (message, className) => {
  const chatLi = document.createElement("li");
  chatLi.classList.add("chat", `${className}`);
  
  // Template untuk pesan masuk/keluar
  let chatContent = className === "outgoing" 
    ? `<p></p>` 
    : `<span class="material-symbols-outlined">smart_toy</span><p></p>`;
  
  chatLi.innerHTML = chatContent;
  chatLi.querySelector("p").textContent = message;
  return chatLi;
};

// 4. FUNGSI GENERATE RESPONSE DARI API
const generateResponse = async (chatElement) => {
  const messageElement = chatElement.querySelector("p");
  
  // Konfigurasi request API
  const requestOptions = {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({
      contents: [{
        role: "user",
        parts: [{ text: userMessage }]
      }]
    })
  };

  try {
    // Eksekusi API call
    const response = await fetch(API_URL, requestOptions);
    const data = await response.json();
    
    // Error handling untuk response tidak OK
    if (!response.ok) {
      throw new Error(data.error.message);
    }
    
    // Format dan tampilkan response
    const formattedResponse = data.candidates[0].content.parts[0].text.replace(
      /\*\*(.*?)\*\*/g, 
      '$1' // Hapus markdown bold (**)
    );
    messageElement.textContent = formattedResponse;
  } catch (error) {
    // Tampilkan error ke user
    messageElement.classList.add("error");
    messageElement.textContent = error.message;
  } finally {
    // Auto-scroll ke pesan terbaru
    chatbox.scrollTo(0, chatbox.scrollHeight);
  }
};

// 5. HANDLE CHAT USER
const handleChat = () => {
  userMessage = chatInput.value.trim();
  
  // Validasi input kosong
  if (!userMessage) return;
  
  // Reset input field
  chatInput.value = "";
  chatInput.style.height = `${inputInitHeight}px`;
  
  // Tampilkan pesan user
  chatbox.appendChild(createChatLi(userMessage, "outgoing"));
  chatbox.scrollTo(0, chatbox.scrollHeight);
  
  // Delay untuk simulasi "typing"
  setTimeout(() => {
    // Tampilkan status "Thinking..."
    const incomingChatLi = createChatLi("Thinking...", "incoming");
    chatbox.appendChild(incomingChatLi);
    chatbox.scrollTo(0, chatbox.scrollHeight);
    
    // Generate response dari API
    generateResponse(incomingChatLi);
  }, 600);
};

// 6. EVENT LISTENERS
// Auto-resize textarea
chatInput.addEventListener("input", () => {
  chatInput.style.height = `${inputInitHeight}px`;
  chatInput.style.height = `${chatInput.scrollHeight}px`;
});

// Handle Enter key
chatInput.addEventListener("keydown", (e) => {
  if (e.key === "Enter" && !e.shiftKey && window.innerWidth > 800) {
    e.preventDefault();
    handleChat();
  }
});

// Handle click events
sendChatBtn.addEventListener("click", handleChat);
closeBtn.addEventListener("click", () => 
  document.body.classList.remove("show-chatbot")
);
chatbotToggler.addEventListener("click", () => 
  document.body.classList.toggle("show-chatbot")
);

Cara Mendapatkan API Key

1. Kunjungi Google AI Studio
2. Buat project baru
3. Klik “Create API Key”
4. Salin kunci ke variabel API_KEY

Masalah Umum:

1. API error: Pastikan API key valid
2. Tampilan rusak: Cek path file CSS/JS
3. Ikon tidak muncul: Verifikasi koneksi internet

Optimasi Performa:

// Debounce untuk input
let timeout;
chatInput.addEventListener('input', () => {
    clearTimeout(timeout);
    timeout = setTimeout(handleChat, 1000);
});

Kesimpulan

Dalam tutorial ini kita telah membuat:
✅ Antarmuka chatbot responsif
✅ Sistem kirim pesan real-time
✅ Integrasi AI dengan Gemini API
✅ Error handling dasar

Ide Pengembangan Lanjutan:

1. Tambahkan autentikasi pengguna
2. Simpan riwayat chat di localStorage
3. Implementasi voice recognition