:root {
    --bg-color: #0a0e27;
    --surface-color: #111827;
    --card-color: rgba(17, 24, 39, 0.8);
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --text-tertiary: #6b7280;
    --accent-color: #3b82f6;
    --accent-hover: #2563eb;
    --accent-glow: rgba(59, 130, 246, 0.3);
    --border-color: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.12);
    --user-msg-bg: #3b82f6;
    --bot-msg-bg: rgba(31, 41, 55, 0.9);
    --success-color: #10b981;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-color);
    background-image: 
        radial-gradient(at 0% 0%, rgba(59, 130, 246, 0.08) 0px, transparent 50%),
        radial-gradient(at 100% 100%, rgba(139, 92, 246, 0.08) 0px, transparent 50%);
    color: var(--text-primary);
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    width: 100%;
    max-width: 1000px;
    height: 92vh;
    max-height: 900px;
    margin: 0 20px;
    background: var(--card-color);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    overflow: hidden;
    position: relative;
}

/* Header */
header {
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: rgba(17, 24, 39, 0.5);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 12px;
}

.logo {
    width: 40px;
    height: 40px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent-color), #6366f1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    flex-shrink: 0;
}

.header-title {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

h1 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.3;
    letter-spacing: 0.015em;
    text-transform: uppercase;
}

.subtitle {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    font-weight: 500;
    letter-spacing: 0.02em;
}

.status-indicator {
    width: 8px;
    height: 8px;
    background-color: var(--success-color);
    border-radius: 50%;
    box-shadow: 0 0 8px var(--success-color);
    margin-left: 8px;
}

/* Mode Selector */
.mode-selector {
    display: flex;
    align-items: center;
}

.mode-tabs {
    display: flex;
    background: rgba(31, 41, 55, 0.6);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 4px;
    gap: 4px;
}

.mode-tab {
    padding: 8px 16px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: inherit;
}

.mode-tab:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.mode-tab.active {
    background: var(--accent-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

.mode-tab.active:hover {
    background: var(--accent-hover);
}

/* Chat Area */
.chat-area {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
    scroll-behavior: smooth;
}

.welcome-message {
    text-align: center;
    padding: 40px 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.welcome-icon {
    width: 64px;
    height: 64px;
    border-radius: 16px;
    background: rgba(59, 130, 246, 0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent-color);
    margin-bottom: 8px;
}

.welcome-message h2 {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.welcome-message p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    max-width: 400px;
    line-height: 1.6;
}

.message {
    max-width: 75%;
    padding: 14px 18px;
    border-radius: 16px;
    line-height: 1.6;
    font-size: 0.9375rem;
    position: relative;
    animation: fadeIn 0.3s ease;
    word-wrap: break-word;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.message.user {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--user-msg-bg), var(--accent-hover));
    color: white;
    border-bottom-right-radius: 4px;
    box-shadow: var(--shadow-md);
}

.message.bot {
    align-self: flex-start;
    background: var(--bot-msg-bg);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
    color: var(--text-primary);
}

.message.bot strong {
    color: var(--text-primary);
    font-weight: 600;
}

.message.bot em {
    color: var(--text-secondary);
    font-style: italic;
}

.sources {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border-color);
    font-size: 0.8125rem;
    color: var(--text-tertiary);
    line-height: 1.5;
}

/* Input Area */
.input-area {
    padding: 20px 24px;
    background: rgba(17, 24, 39, 0.6);
    border-top: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: 12px;
}

.icon-btn {
    width: 44px;
    height: 44px;
    border: 1px solid var(--border-color);
    background: rgba(31, 41, 55, 0.6);
    border-radius: 12px;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s ease;
    flex-shrink: 0;
}

.icon-btn:hover {
    background: rgba(31, 41, 55, 0.9);
    border-color: var(--border-hover);
    color: var(--text-primary);
    transform: translateY(-1px);
}

#reset-btn:hover {
    color: #ef4444;
    border-color: rgba(239, 68, 68, 0.4);
    background: rgba(239, 68, 68, 0.1);
}

.input-wrapper {
    flex: 1;
    position: relative;
}

input[type="text"] {
    width: 100%;
    background: rgba(31, 41, 55, 0.8);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 12px 18px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9375rem;
    transition: all 0.2s ease;
}

input[type="text"]::placeholder {
    color: var(--text-tertiary);
}

input[type="text"]:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px var(--accent-glow);
    background: rgba(31, 41, 55, 0.95);
}

.send-btn {
    background: var(--accent-color);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 12px;
    font-weight: 600;
    font-size: 0.9375rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: var(--shadow-sm);
    font-family: inherit;
}

.send-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.send-btn:active {
    transform: translateY(0);
}

.send-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

/* Typing Indicator */
.typing {
    align-self: flex-start;
    background: var(--bot-msg-bg);
    border: 1px solid var(--border-color);
    padding: 14px 18px;
    border-radius: 16px;
    display: flex;
    gap: 6px;
    display: none;
}

.typing.show {
    display: flex;
}

.dot {
    width: 8px;
    height: 8px;
    background: var(--text-secondary);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out;
}

.dot:nth-child(1) {
    animation-delay: -0.32s;
}

.dot:nth-child(2) {
    animation-delay: -0.16s;
}

@keyframes bounce {
    0%, 80%, 100% {
        transform: scale(0.8);
        opacity: 0.5;
    }
    40% {
        transform: scale(1);
        opacity: 1;
    }
}

/* Scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.15);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        height: 100vh;
        max-height: 100vh;
        border-radius: 0;
        margin: 0;
    }
    
    header {
        padding: 16px;
    }
    
    .subtitle {
        display: none;
    }
    
    .chat-area {
        padding: 16px;
    }
    
    .message {
        max-width: 85%;
    }
}