/* ==================== CSS Variables ==================== */
:root {
    /* Colors - Deep Sea Stars Theme */
    --bg-primary: #0a0f1a;
    --bg-secondary: #1a1f3a;
    --bg-tertiary: rgba(20, 30, 60, 0.6);
    --bg-card: rgba(26, 31, 58, 0.8);
    --bg-hover: rgba(59, 130, 246, 0.1);
    
    --accent-primary: #3b82f6;
    --accent-secondary: #8b5cf6;
    --accent-tertiary: #06b6d4;
    
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    
    --border-color: rgba(255, 255, 255, 0.1);
    --border-active: rgba(59, 130, 246, 0.5);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    --gradient-user: linear-gradient(135deg, #3b82f6, #1d4ed8);
    --gradient-glow: radial-gradient(circle at center, rgba(59, 130, 246, 0.3), transparent);
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.3);
    
    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    
    /* Z-Index */
    --z-particles: 0;
    --z-container: 10;
    --z-header: 100;
    --z-modal: 1000;
}

/* ==================== Reset & Base ==================== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100dvh;
    overflow: hidden;
}

/* ==================== Particle Background ==================== */
#particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: var(--z-particles);
    pointer-events: none;
}

/* ==================== App Container ==================== */
.app-container {
    position: relative;
    z-index: var(--z-container);
    display: flex;
    flex-direction: column;
    height: 100dvh;
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 var(--space-md);
}

/* ==================== Header ==================== */
.header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-md) 0;
    border-bottom: 1px solid var(--border-color);
    background: rgba(10, 15, 26, 0.8);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: var(--z-header);
}

.header-left {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.logo-icon {
    width: 36px;
    height: 36px;
    background: var(--gradient-primary);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-glow);
}

.logo-icon svg {
    width: 20px;
    height: 20px;
    color: white;
}

.logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-tabs {
    display: flex;
    gap: var(--space-xs);
    background: var(--bg-tertiary);
    padding: var(--space-xs);
    border-radius: var(--radius-lg);
}

.nav-tab {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
    padding: var(--space-sm) var(--space-md);
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition-fast);
}

.nav-tab svg {
    width: 16px;
    height: 16px;
}

.nav-tab:hover {
    color: var(--text-primary);
    background: var(--bg-hover);
}

.nav-tab.active {
    background: var(--accent-primary);
    color: white;
    box-shadow: var(--shadow-glow);
}

.header-right {
    display: flex;
    gap: var(--space-sm);
}

.icon-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition-fast);
}

.icon-btn svg {
    width: 20px;
    height: 20px;
}

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

/* ==================== Chat Area ==================== */
.chat-area {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
    padding: var(--space-lg) 0;
    scroll-behavior: smooth;
}

.chat-area::-webkit-scrollbar {
    width: 6px;
}

.chat-area::-webkit-scrollbar-track {
    background: transparent;
}

.chat-area::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: var(--radius-full);
}

.chat-area::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

/* ==================== Welcome Screen ==================== */
.welcome-screen {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    animation: fadeIn 0.5s ease;
}

.welcome-content {
    text-align: center;
    max-width: 600px;
    padding: var(--space-xl);
}

.welcome-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto var(--space-lg);
    background: var(--gradient-primary);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-glow);
    animation: float 3s ease-in-out infinite;
}

.welcome-icon svg {
    width: 40px;
    height: 40px;
    color: white;
}

.welcome-content h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--space-md);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-content p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--space-xl);
}

.suggestions {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-md);
}

.suggestion-card {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition-fast);
}

.suggestion-card:hover {
    background: var(--bg-hover);
    border-color: var(--border-active);
    transform: translateY(-2px);
}

.suggestion-icon {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-tertiary);
    border-radius: var(--radius-sm);
    flex-shrink: 0;
}

.suggestion-icon svg {
    width: 16px;
    height: 16px;
    color: var(--accent-primary);
}

.suggestion-card span:last-child {
    font-size: 0.875rem;
    color: var(--text-primary);
}

/* ==================== Messages ==================== */
.messages-container {
    display: flex;
    flex-direction: column;
    gap: var(--space-lg);
    padding-bottom: var(--space-xl);
}

.message {
    display: flex;
    gap: var(--space-md);
    animation: slideIn 0.3s ease;
}

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

.message-avatar {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.message.assistant .message-avatar {
    background: var(--gradient-primary);
    box-shadow: var(--shadow-glow);
}

.message.user .message-avatar {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
}

.message-avatar svg {
    width: 20px;
    height: 20px;
    color: white;
}

.message.user .message-avatar svg {
    color: var(--text-primary);
}

.message-content {
    max-width: 75%;
    padding: var(--space-md);
    border-radius: var(--radius-lg);
    line-height: 1.7;
}

.message.assistant .message-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-top-left-radius: var(--space-xs);
}

.message.user .message-content {
    background: var(--gradient-user);
    border-top-right-radius: var(--space-xs);
}

.message-content p {
    margin-bottom: var(--space-sm);
}

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

.message-content code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.875em;
    background: rgba(0, 0, 0, 0.3);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
}

.message-content pre {
    background: rgba(0, 0, 0, 0.4);
    border-radius: var(--radius-md);
    padding: var(--space-md);
    margin: var(--space-sm) 0;
    overflow-x: auto;
    position: relative;
}

.message-content pre code {
    background: transparent;
    padding: 0;
    font-size: 0.875rem;
    line-height: 1.5;
}

.code-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--space-sm) var(--space-md);
    background: rgba(0, 0, 0, 0.3);
    border-radius: var(--radius-md) var(--radius-md) 0 0;
    margin-bottom: var(--space-sm);
}

.code-header span {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.copy-btn {
    padding: var(--space-xs) var(--space-sm);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 0.75rem;
    cursor: pointer;
    transition: var(--transition-fast);
}

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

.message-time {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: var(--space-xs);
}

/* ==================== Loading Indicator ==================== */
.loading-indicator {
    display: flex;
    gap: var(--space-sm);
    padding: var(--space-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    border-top-left-radius: var(--space-xs);
    width: fit-content;
}

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

.loading-dot:nth-child(1) { animation-delay: 0s; }
.loading-dot:nth-child(2) { animation-delay: 0.2s; }
.loading-dot:nth-child(3) { animation-delay: 0.4s; }

/* ==================== Input Area ==================== */
.input-area {
    padding: var(--space-md) 0;
    border-top: 1px solid var(--border-color);
    background: rgba(10, 15, 26, 0.8);
    backdrop-filter: blur(10px);
}

.input-wrapper {
    display: flex;
    align-items: flex-end;
    gap: var(--space-sm);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--space-sm);
    transition: var(--transition-fast);
}

.input-wrapper:focus-within {
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-glow);
}

.input-wrapper textarea {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1.5;
    resize: none;
    outline: none;
    max-height: 150px;
    padding: var(--space-sm);
}

.input-wrapper textarea::placeholder {
    color: var(--text-muted);
}

.input-actions {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.char-count {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.send-btn {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--gradient-primary);
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition-fast);
}

.send-btn svg {
    width: 20px;
    height: 20px;
    color: white;
}

.send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.send-btn:not(:disabled):hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-glow);
}

.send-btn .loading-icon {
    display: none;
    animation: spin 1s linear infinite;
}

.send-btn.loading .send-icon {
    display: none;
}

.send-btn.loading .loading-icon {
    display: block;
}

.input-hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-align: center;
    margin-top: var(--space-sm);
}

/* ==================== Modal ==================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: var(--z-modal);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-normal);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow: hidden;
    transform: scale(0.9) translateY(20px);
    transition: var(--transition-normal);
}

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

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

.modal-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.close-btn {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition-fast);
}

.close-btn svg {
    width: 20px;
    height: 20px;
}

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

.modal-body {
    padding: var(--space-lg);
    max-height: 60vh;
    overflow-y: auto;
}

.setting-group {
    margin-bottom: var(--space-lg);
}

.setting-group:last-child {
    margin-bottom: 0;
}

.setting-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: var(--space-sm);
}

.setting-group input,
.setting-group select {
    width: 100%;
    padding: var(--space-sm) var(--space-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 1rem;
    outline: none;
    transition: var(--transition-fast);
}

.setting-group input:focus,
.setting-group select:focus {
    border-color: var(--accent-primary);
}

.setting-group input[type="range"] {
    -webkit-appearance: none;
    height: 6px;
    padding: 0;
    background: var(--bg-tertiary);
    border-radius: var(--radius-full);
}

.setting-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: var(--accent-primary);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-glow);
}

.range-value {
    display: inline-block;
    margin-left: var(--space-sm);
    font-size: 0.875rem;
    color: var(--accent-primary);
    font-weight: 500;
}

.modal-footer {
    padding: var(--space-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
}

.btn-secondary {
    padding: var(--space-sm) var(--space-lg);
    background: var(--accent-primary);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
}

.btn-secondary:hover {
    opacity: 0.9;
    transform: translateY(-1px);
}

/* ==================== Animations ==================== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

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

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ==================== Responsive ==================== */
@media (max-width: 768px) {
    .app-container {
        padding: 0 var(--space-sm);
    }
    
    .header {
        flex-wrap: wrap;
        gap: var(--space-md);
    }
    
    .nav-tabs {
        order: 3;
        width: 100%;
        overflow-x: auto;
        justify-content: flex-start;
        padding-bottom: var(--space-xs);
    }
    
    .nav-tab {
        white-space: nowrap;
        font-size: 0.75rem;
        padding: var(--space-sm);
    }
    
    .nav-tab span:not(.nav-tab svg) {
        display: none;
    }
    
    .suggestions {
        grid-template-columns: 1fr;
    }
    
    .message-content {
        max-width: 85%;
    }
    
    .logo-text {
        display: none;
    }
}

@media (max-width: 480px) {
    .welcome-icon {
        width: 60px;
        height: 60px;
    }
    
    .welcome-content h1 {
        font-size: 1.5rem;
    }
    
    .suggestion-card {
        padding: var(--space-sm);
    }
}

/* ==================== Accessibility ==================== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}


/* ==================== Setting Help ==================== */
.setting-help {
    margin-top: var(--space-lg);
    padding: var(--space-md);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.setting-help h4 {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
}

.setting-help ul {
    list-style: none;
}

.setting-help li {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: 0.75rem;
    color: var(--text-secondary);
    padding: var(--space-xs) 0;
}

.setting-help a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: var(--transition-fast);
}

.setting-help a:hover {
    text-decoration: underline;
}

/* ==================== Provider Select Styling ==================== */
select optgroup {
    font-weight: 600;
    color: var(--text-primary);
}

select option {
    padding: var(--space-sm);
    background: var(--bg-secondary);
}