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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

.header {
    text-align: center;
    color: white;
    margin-bottom: 30px;
}

.header h1 {
    font-size: 3rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 20px;
    height: 70vh;
}

.chat-interface {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.feature-buttons {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    justify-content: center;
}

.feature-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 15px 20px;
    border: none;
    border-radius: 10px;
    background: linear-gradient(45deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
    font-weight: 600;
}

.feature-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.feature-btn span:first-child {
    font-size: 1.5rem;
}

.chat-area {
    display: flex;
    flex-direction: column;
    height: calc(100% - 80px);
}

.messages {
    flex: 1;
    overflow-y: auto;
    padding: 15px;
    background: #f8f9fa;
    border-radius: 10px;
    margin-bottom: 15px;
}

.message {
    margin-bottom: 15px;
    padding: 10px 15px;
    border-radius: 10px;
    max-width: 80%;
}

.message.system {
    background: #e3f2fd;
    color: #1976d2;
    text-align: center;
    max-width: 100%;
}

.input-area {
    display: flex;
    gap: 10px;
}

#messageInput {
    flex: 1;
    padding: 12px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 25px;
    font-size: 1rem;
    outline: none;
    transition: border-color 0.3s ease;
}

#messageInput:focus {
    border-color: #4facfe;
}

#sendBtn {
    padding: 12px 25px;
    background: linear-gradient(45deg, #4facfe 0%, #00f2fe 100%);
    color: white;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

#sendBtn:hover {
    transform: translateY(-1px);
    box-shadow: 0 3px 10px rgba(0,0,0,0.2);
}

.sidebar {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
}

.sidebar h3 {
    color: #333;
    margin-bottom: 15px;
    text-align: center;
}

.users-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.user {
    padding: 10px;
    background: #f0f0f0;
    border-radius: 8px;
    transition: background 0.3s ease;
}

.user:hover {
    background: #e0e0e0;
}

@media (max-width: 768px) {
    .main-content {
        grid-template-columns: 1fr;
        height: auto;
    }
    
    .feature-buttons {
        flex-wrap: wrap;
    }
    
    .header h1 {
        font-size: 2rem;
    }
}