body {
    margin: 0;
    font-family: system-ui, sans-serif;
    background: #f4f6f8;
    height: 100vh;
    display: flex;
    justify-content: center;
}

#app {
    width: 100%;
    max-width: 850px;
    display: flex;
    flex-direction: column;
    height: 100vh;
    background: white;
    border-left: 1px solid #ddd;
    border-right: 1px solid #ddd;
}

header {
    padding: 20px;
    background: #1d4ed8;
    color: white;
    border-bottom: 3px solid #0f2f8f;
}

header h1 {
    margin: 0;
    font-size: 1.4rem;
}

.subtitle {
    font-size: 0.8rem;
    opacity: 0.8;
}

#chat-window {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
}

.message {
    padding: 12px 16px;
    margin-bottom: 16px;
    border-radius: 10px;
    max-width: 80%;
    line-height: 1.4;
    font-size: 1rem;
}

.user {
    background: #dbeafe;
    margin-left: auto;
    border: 1px solid #93c5fd;
}

.bot {
    background: #f3f4f6;
    border: 1px solid #ddd;
}

#typing-indicator {
    padding: 10px 20px;
    font-size: 0.9rem;
    color: #555;
}

.hidden {
    display: none;
}

footer {
    padding: 15px;
    display: flex;
    gap: 10px;
    border-top: 1px solid #ddd;
    background: #fafafa;
}

textarea {
    flex: 1;
    padding: 12px;
    font-size: 1rem;
    border-radius: 8px;
    border: 1px solid #ccc;
}

button {
    padding: 12px 20px;
    font-size: 1rem;
    background: #2563eb;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

button:hover {
    background: #1d4ed8;
}