:root {
    --bg-chat: #ffffff;
    --text-primary: #374151;
    --border-color: #e5e7eb;
    --input-area-bg: #f9fafb;
    --send-btn-bg: #1e40af;
    --send-btn-hover: #1d4ed8;
    --chat-max-width: 600px;
}

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

/* BODY */
body {
    font-family: 'Inter', sans-serif;
    background-color: #f5f7fb;
    color: var(--text-primary);
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

/* CONTAINER */
.app-container {
    width: 100%;
    height: 100%;
    padding: 20px;
}

/* CHAT BOX */
.chat-interface {
    width: 100%;
    max-width: var(--chat-max-width);
    height: 90vh;
    margin: auto;
    background: var(--bg-chat);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    box-shadow: 0 12px 30px rgba(0,0,0,0.08);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* CHAT AREA */
.chat-messages {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* BOT MESSAGE */
.assistant-message .message-content {
    background: #f9fafb;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    padding: 14px 16px;
    font-size: 14px;
    line-height: 1.6;
    max-width: 80%;
}

/* USER MESSAGE */
.user-message {
    align-self: flex-end;
}

.user-message .message-content {
    background: #e0edff;
    border-radius: 12px;
    padding: 12px 16px;
    color: #1e3a8a;
    max-width: 80%;
}

/* INPUT AREA */
.chat-input-area {
    padding: 14px;
    display: flex;
    gap: 10px;
    background: var(--input-area-bg);
    border-top: 1px solid var(--border-color);
}

/* INPUT */
#message-input {
    flex: 1;
    padding: 12px;
    border-radius: 10px;
    border: 1px solid #d1d5db;
    font-size: 14px;
    outline: none;
    transition: 0.2s;
}

#message-input:focus {
    border-color: #1e40af;
    box-shadow: 0 0 0 2px rgba(30,64,175,0.1);
}

#message-input::placeholder {
    color: #9ca3af;
}

/* BUTTON */
.send-button {
    background: var(--send-btn-bg);
    color: white;
    border: none;
    border-radius: 10px;
    padding: 0 18px;
    font-weight: 500;
    cursor: pointer;
    transition: 0.2s;
}

.send-button:hover {
    background: var(--send-btn-hover);
}

.send-button:disabled {
    background: #e5e7eb;
    color: #9ca3af;
    cursor: not-allowed;
}

/* TYPING INDICATOR */
.typing-indicator {
    padding: 10px 20px;
    display: flex;
    gap: 5px;
}

.dot {
    width: 6px;
    height: 6px;
    background: #9ca3af;
    border-radius: 50%;
    animation: typing 1.4s infinite;
}

@keyframes typing {
    0%, 80%, 100% { opacity: 0.3; }
    40% { opacity: 1; }
}