:root {
    /* Dark Theme (Default) */
    --bg-primary: #0a0e1a;
    --bg-secondary: #141929;
    --bg-tertiary: #1e2538;
    --bg-glass: rgba(255, 255, 255, 0.05);

    --text-primary: #e4e7f0;
    --text-secondary: #9ba3ba;
    --text-muted: #6b7280;

    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);

    --border-color: rgba(255, 255, 255, 0.1);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.15);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.3);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;

    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

[data-theme="light"] {
    --bg-primary: #f8fafc;
    --bg-secondary: #ffffff;
    --bg-tertiary: #f1f5f9;
    --bg-glass: rgba(0, 0, 0, 0.03);

    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #94a3b8;

    --border-color: rgba(0, 0, 0, 0.08);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
}

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

body {
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow: hidden;
    position: relative;
}

/* Background Canvas */
#particle-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
}

/* App Container */
.app-container {
    position: relative;
    z-index: 1;
    width: 100vw;
    height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    height: 64px;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
}

.header-left {
    display: flex;
    align-items: center;
    gap: 16px;
}

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

.logo-icon {
    font-size: 32px;
    animation: float 3s ease-in-out infinite;
}

.logo h1 {
    font-size: 20px;
    font-weight: 600;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.header-right {
    display: flex;
    gap: 8px;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    overflow: hidden;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    padding: 20px;
}

.sidebar-header {
    margin-bottom: 16px;
}

.sidebar-header h2 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-secondary);
}

.chat-list {
    flex: 1;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.chat-item {
    padding: 12px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
}

.chat-item:hover {
    background: var(--bg-secondary);
    border-color: var(--accent-primary);
    transform: translateX(4px);
}

.chat-item.active {
    background: var(--accent-gradient);
    border-color: var(--accent-primary);
}

.chat-item-title {
    font-size: 14px;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    margin-bottom: 4px;
}

.chat-item-time {
    font-size: 12px;
    color: var(--text-muted);
}

/* Chat Area */
.chat-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-secondary);
}

.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

/* Welcome Message */
.welcome-message {
    text-align: center;
    padding: 48px 24px;
    max-width: 500px;
    margin: auto;
}

.welcome-icon {
    font-size: 64px;
    margin-bottom: 16px;
    animation: pulse 2s ease-in-out infinite;
}

.welcome-message h2 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 8px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-message p {
    font-size: 16px;
    color: var(--text-secondary);
}

/* Message Bubble */
.message {
    display: flex;
    gap: 12px;
    max-width: 80%;
    animation: slideUp 0.3s ease;
}

.message.user {
    align-self: flex-end;
    flex-direction: row-reverse;
}

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--accent-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 18px;
    flex-shrink: 0;
}

.message-content {
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 12px 16px;
    box-shadow: var(--shadow-sm);
}

.message.user .message-content {
    background: var(--accent-gradient);
    color: white;
}

.message-content p {
    line-height: 1.6;
    margin: 0;
}

.message-content pre {
    margin: 8px 0;
    border-radius: var(--radius-sm);
    overflow-x: auto;
}

.message-content code {
    font-family: 'Monaco', 'Consolas', monospace;
    font-size: 14px;
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 8px;
}

.typing-dot {
    width: 8px;
    height: 8px;
    background: var(--text-muted);
    border-radius: 50%;
    animation: typingBounce 1.4s infinite;
}

.typing-dot:nth-child(2) {
    animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
    animation-delay: 0.4s;
}

/* Input Area */
.input-area {
    padding: 20px 24px;
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-top: 1px solid var(--border-color);
}

.input-wrapper {
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 12px;
    display: flex;
    gap: 12px;
    transition: all 0.2s ease;
}

.input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

#user-input {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 15px;
    font-family: var(--font-family);
    resize: none;
    max-height: 120px;
}

.input-actions {
    display: flex;
    gap: 8px;
    align-items: flex-end;
}

/* Buttons */
.icon-button {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    border: none;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-button:hover {
    background: var(--bg-secondary);
    transform: scale(1.05);
}

.primary-button {
    width: 100%;
    padding: 12px 20px;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-sm);
    color: white;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.primary-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.send-button {
    padding: 10px 24px;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-sm);
    color: white;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 8px;
}

.send-button:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-sm);
}

/* LLM Selector */
.llm-selector {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 12px;
    font-size: 14px;
}

.llm-selector label {
    color: var(--text-secondary);
    font-weight: 500;
}

.llm-selector select {
    padding: 8px 12px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-family);
    cursor: pointer;
    transition: all 0.2s ease;
}

.llm-selector select:hover {
    border-color: var(--accent-primary);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(8px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.modal-header {
    padding: 24px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 {
    font-size: 20px;
    font-weight: 600;
}

.close-button {
    width: 32px;
    height: 32px;
    border: none;
    background: var(--bg-tertiary);
    border-radius: 50%;
    cursor: pointer;
    font-size: 20px;
    color: var(--text-primary);
}

.modal-body {
    padding: 24px;
}

.setting-group {
    margin-bottom: 24px;
}

.setting-group h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 12px;
}

.setting-group p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    margin-bottom: 8px;
}

.provider-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
}

.provider-card {
    padding: 16px;
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
}

.provider-card:hover {
    border-color: var(--accent-primary);
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.provider-card.active {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.1);
}

/* API Keys Management */
.api-key-item {
    margin-bottom: 16px;
    padding: 12px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
}

.api-key-item label {
    display: block;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-secondary);
}

.api-key-input-wrapper {
    display: flex;
    gap: 8px;
}

.api-key-input-wrapper input {
    flex: 1;
    padding: 8px 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-family);
    font-size: 14px;
}

.api-key-input-wrapper button {
    padding: 8px 16px;
    border: none;
    border-radius: var(--radius-sm);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.test-key-btn {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.test-key-btn:hover {
    background: var(--bg-secondary);
    border-color: var(--accent-primary);
}

.save-key-btn {
    background: var(--accent-gradient);
    color: white;
}

.save-key-btn:hover {
    opacity: 0.9;
    transform: scale(1.02);
}

.key-status {
    display: block;
    font-size: 12px;
    margin-top: 6px;
    padding: 4px 8px;
    border-radius: 4px;
}

.key-status.valid {
    color: #22c55e;
    background: rgba(34, 197, 94, 0.1);
}

.key-status.invalid {
    color: #ef4444;
    background: rgba(239, 68, 68, 0.1);
}

.key-status.configured {
    color: #22c55e;
    background: rgba(34, 197, 94, 0.1);
}

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

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-glass);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-primary);
}

/* Responsive */
@media (max-width: 768px) {
    .sidebar {
        position: absolute;
        left: -280px;
        height: 100%;
        z-index: 10;
        transition: left 0.3s ease;
    }

    .sidebar.active {
        left: 0;
    }

    .message {
        max-width: 95%;
    }
}