:root {
    /* Colors */
    --bg-sidebar: #0d0d0d;
    --bg-main: #141414;
    --bg-surface: #262626;
    --bg-surface-hover: #333333;
    --border-subtle: #2f2f2f;
    --border-focus: #525252;
    
    /* Text */
    --text-primary: #ececec;
    --text-secondary: #9e9e9e;
    --text-inverse: #0d0d0d;
    
    /* Actions */
    --action-primary: #ffffff;
    --action-primary-hover: #e5e5e5;
    
    /* Layout */
    --font-inter: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --sidebar-width: 260px;
    --max-chat-width: 768px;
}

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

body {
    background-color: var(--bg-main);
    color: var(--text-primary);
    font-family: var(--font-inter);
    height: 100vh;
    overflow: hidden;
    -webkit-font-smoothing: antialiased;
}

/* Layout Framework */
.app-container {
    display: flex;
    height: 100%;
    width: 100%;
}

/* Sidebar Components */
.sidebar {
    width: var(--sidebar-width);
    background-color: var(--bg-sidebar);
    display: flex;
    flex-direction: column;
    height: 100%;
    flex-shrink: 0;
    z-index: 50;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.sidebar-header {
    padding: 12px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.w-full { width: 100%; }

.btn-primary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background-color: var(--action-primary);
    color: var(--text-inverse);
    border: none;
    border-radius: 8px;
    padding: 10px 14px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-primary:hover {
    background-color: var(--action-primary-hover);
}

.btn-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 8px;
    background: transparent;
    color: var(--text-secondary);
    border: none;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-icon:hover {
    background-color: var(--bg-surface);
    color: var(--text-primary);
}

.sidebar-content {
    flex: 1;
    overflow-y: auto;
    padding: 0 12px;
}

.sidebar-content::-webkit-scrollbar {
    width: 4px;
}
.sidebar-content::-webkit-scrollbar-thumb {
    background: var(--border-subtle);
    border-radius: 4px;
}

.section-title {
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 12px 12px 8px 12px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* History Chat List */
.chat-history-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.chat-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 12px;
    border-radius: 8px;
    font-size: 0.875rem;
    color: var(--text-primary);
    cursor: pointer;
    transition: background-color 0.2s;
    border: none;
    background: transparent;
    text-align: left;
}

.chat-item:hover {
    background-color: var(--bg-surface);
}

.chat-item.active {
    background-color: var(--bg-surface);
    font-weight: 500;
}

.chat-title {
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    flex: 1;
}

.delete-chat-btn {
    opacity: 0;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 4px;
    transition: opacity 0.2s, color 0.2s;
}

.chat-item:hover .delete-chat-btn {
    opacity: 1;
}

.delete-chat-btn:hover {
    color: #ef4444;
}

.sidebar-footer {
    padding: 12px;
    border-top: 1px solid var(--border-subtle);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 8px;
    border-radius: 8px;
    cursor: pointer;
}

.user-profile:hover {
    background-color: var(--bg-surface);
}

.avatar-circle {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    background: linear-gradient(135deg, #10b981, #3b82f6);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    font-weight: 600;
    color: white;
}

.user-name {
    font-size: 0.875rem;
    font-weight: 500;
}

/* Main Content Area */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    position: relative;
    background-color: var(--bg-main);
    width: 100%;
}

.top-nav {
    display: flex;
    align-items: center;
    padding: 12px 16px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 10;
}

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

.brand {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1rem;
    font-weight: 500;
}

.version-badge {
    font-size: 0.65rem;
    background-color: var(--bg-surface);
    padding: 2px 6px;
    border-radius: 4px;
    color: var(--text-secondary);
}

/* Messages Viewer */
.messages-area {
    flex: 1;
    overflow-y: auto;
    padding: 60px 0 0 0; /* Clear top-nav */
    display: flex;
    flex-direction: column;
    scroll-behavior: smooth;
    align-items: center;
}

/* Zero State Welcome */
.welcome-message {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin-top: 15vh;
    max-width: var(--max-chat-width);
    width: 100%;
    padding: 0 24px;
    animation: fadeScale 0.4s ease-out;
}

.welcome-icon {
    width: 64px;
    height: 64px;
    border-radius: 16px;
    background-color: var(--bg-surface);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    color: var(--action-primary);
}

.welcome-message h1 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 40px;
    text-align: center;
}

.quick-prompts {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    width: 100%;
}

.prompt-chip {
    background-color: transparent;
    border: 1px solid var(--border-subtle);
    border-radius: 12px;
    padding: 14px 16px;
    display: flex;
    align-items: center;
    gap: 12px;
    text-align: left;
    cursor: pointer;
    transition: background-color 0.2s, border-color 0.2s;
    font-family: var(--font-inter);
    color: var(--text-secondary);
}

.prompt-chip:hover {
    background-color: var(--bg-surface);
    border-color: var(--border-focus);
    color: var(--text-primary);
}

.chip-icon {
    font-size: 1.2rem;
}

.chip-text {
    font-size: 0.875rem;
}

/* Chat Messages Nodes */
.message {
    width: 100%;
    padding: 24px;
    display: flex;
    justify-content: center;
}

.message-inner {
    width: 100%;
    max-width: var(--max-chat-width);
    display: flex;
    gap: 16px;
}

.message.user .message-inner {
    flex-direction: row-reverse;
}

.avatar {
    width: 30px;
    height: 30px;
    border-radius: 4px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 1rem;
}

.user .avatar {
    background-color: var(--bg-surface);
}

.assistant .avatar {
    background-color: var(--action-primary);
    color: var(--bg-main);
}

.message-content {
    flex: 1;
    font-size: 1rem;
    line-height: 1.6;
    word-wrap: break-word;
    color: var(--text-primary);
}

/* User Message styling variant */
.user .message-content {
    background-color: var(--bg-surface);
    padding: 12px 18px;
    border-radius: var(--radius-lg);
    border-top-right-radius: 4px;
    max-width: fit-content;
}

/* Bot Markdown Styles */
.assistant .message-content p {
    margin-bottom: 1rem;
}

.assistant .message-content p:last-child {
    margin-bottom: 0;
}

.assistant .message-content h1, 
.assistant .message-content h2, 
.assistant .message-content h3 {
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    font-weight: 600;
}

.assistant .message-content ul,
.assistant .message-content ol {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.assistant .message-content li {
    margin-bottom: 0.25rem;
}

/* Inline Code */
.message-content p code, .message-content li code {
    background-color: var(--border-subtle);
    padding: 0.2em 0.4em;
    border-radius: 4px;
    font-family: inherit;
    font-size: 0.9em;
    color: #fca5a5;
}

/* Block Code */
.message-content pre {
    background-color: transparent;
    margin: 1rem 0;
    border-radius: 8px;
    border: 1px solid var(--border-subtle);
    overflow: hidden;
    font-family: 'Menlo', monospace;
}

.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--bg-sidebar);
    padding: 8px 16px;
    font-size: 0.75rem;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-subtle);
}

.copy-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 6px;
    transition: color 0.2s;
}

.copy-btn:hover {
    color: var(--text-primary);
}

.message-content pre code {
    display: block;
    padding: 16px;
    overflow-x: auto;
    background: #0d1117 !important; /* GitHub dark bg */
    font-size: 0.875rem;
    line-height: 1.5;
}

/* Composer / Input Area */
.composer-container {
    padding: 24px;
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    background: linear-gradient(0deg, var(--bg-main) 60%, transparent);
}

.composer-box {
    width: 100%;
    max-width: var(--max-chat-width);
    position: relative;
    background-color: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    display: flex;
    overflow: hidden;
    transition: border-color 0.2s;
}

.composer-box:focus-within {
    border-color: var(--border-focus);
}

#message-input {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    padding: 16px 54px 16px 20px;
    font-family: var(--font-inter);
    font-size: 1rem;
    resize: none;
    max-height: 200px;
    outline: none;
}

#message-input::placeholder {
    color: var(--text-secondary);
}

.composer-actions {
    position: absolute;
    right: 8px;
    bottom: 8px;
}

.btn-send {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background-color: var(--action-primary);
    color: var(--text-inverse);
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.2s;
}

.btn-send:hover {
    opacity: 0.9;
    transform: scale(1.05);
}

.composer-footer p {
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-top: 12px;
    text-align: center;
}

/* Model Badge & Indicators */
.model-badge {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px;
    margin-top: 16px;
    padding-top: 12px;
    border-top: 1px solid var(--border-subtle);
    user-select: none;
}

.badge-tag {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.70rem;
    color: var(--text-secondary);
    background-color: var(--bg-main);
    padding: 4px 8px;
    border-radius: 6px;
    border: 1px solid var(--border-subtle);
}

.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 12px 18px;
}
.typing-dot {
    width: 6px;
    height: 6px;
    background-color: var(--text-secondary);
    border-radius: 50%;
    animation: bounce 1.4s infinite;
}
.typing-dot:nth-child(2) { animation-delay: 0.2s; }
.typing-dot:nth-child(3) { animation-delay: 0.4s; }

/* Utilities & Mobile */
.sidebar-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 40;
}

.mobile-only {
    display: none;
}

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

@keyframes fadeScale {
    from { opacity: 0; transform: scale(0.95); }
    to { opacity: 1; transform: scale(1); }
}

@media (max-width: 768px) {
    .mobile-only {
        display: flex;
    }
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        transform: translateX(-100%);
    }
    .sidebar.open {
        transform: translateX(0);
    }
    .sidebar.open ~ .sidebar-overlay,
    .app-container:has(.sidebar.open) .sidebar-overlay {
        display: block;
    }
    .quick-prompts {
        grid-template-columns: 1fr;
    }
    .message {
        padding: 16px;
    }
    .message-inner {
        gap: 12px;
    }
    .message-content {
        font-size: 0.95rem;
    }
    .composer-container {
        padding: 16px;
    }
}