/* =============================================================================
   WebChat - Theme-Aware CSS Styling
   Responsive design with automatic dark/light theme detection
   ============================================================================= */

/* CSS Variables - Light Theme (Default) */
:root {
    /* Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-chat: #f5f5f5;
    --bg-user: #007bff;
    --bg-bot: #e9ecef;
    --bg-header: #343a40;
    --bg-footer: #495057;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-inverse: #ffffff;
    --text-muted: #868e96;
    --border-color: #dee2e6;
    --border-light: #e9ecef;
    --shadow-light: rgba(0, 0, 0, 0.1);
    --shadow-medium: rgba(0, 0, 0, 0.15);
    --shadow-heavy: rgba(0, 0, 0, 0.2);
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-xxl: 1.5rem;
    --line-height-tight: 1.25;
    --line-height-base: 1.5;
    --line-height-relaxed: 1.75;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-full: 50%;
    
    /* Transitions */
    --transition-fast: 0.15s ease-in-out;
    --transition-base: 0.3s ease-in-out;
    --transition-slow: 0.5s ease-in-out;
    
    /* Z-index */
    --z-dropdown: 1000;
    --z-sticky: 1020;
    --z-fixed: 1030;
    --z-modal: 1040;
    --z-popover: 1050;
    --z-tooltip: 1060;
}

/* Dark Theme */
@media (prefers-color-scheme: dark) {
    :root {
        --bg-primary: #1a1a1a;
        --bg-secondary: #2d2d2d;
        --bg-chat: #2d2d2d;
        --bg-user: #0056b3;
        --bg-bot: #495057;
        --bg-header: #212529;
        --bg-footer: #343a40;
        --text-primary: #ffffff;
        --text-secondary: #adb5bd;
        --text-inverse: #ffffff;
        --text-muted: #6c757d;
        --border-color: #495057;
        --border-light: #343a40;
        --shadow-light: rgba(0, 0, 0, 0.3);
        --shadow-medium: rgba(0, 0, 0, 0.4);
        --shadow-heavy: rgba(0, 0, 0, 0.5);
    }
}

/* Manual Dark Theme Override */
[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-chat: #2d2d2d;
    --bg-user: #0056b3;
    --bg-bot: #495057;
    --bg-header: #212529;
    --bg-footer: #343a40;
    --text-primary: #ffffff;
    --text-secondary: #adb5bd;
    --text-inverse: #ffffff;
    --text-muted: #6c757d;
    --border-color: #495057;
    --border-light: #343a40;
    --shadow-light: rgba(0, 0, 0, 0.3);
    --shadow-medium: rgba(0, 0, 0, 0.4);
    --shadow-heavy: rgba(0, 0, 0, 0.5);
}

/* Reset and Base Styles */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: var(--line-height-base);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* Main Chat Container */
.chat-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    max-width: 100%;
    margin: 0 auto;
    background-color: var(--bg-primary);
    transition: background-color var(--transition-base);
}

/* Header Styles */
.chat-header {
    background-color: var(--bg-header);
    color: var(--text-inverse);
    padding: var(--spacing-md);
    box-shadow: 0 2px 4px var(--shadow-light);
    z-index: var(--z-sticky);
    transition: background-color var(--transition-base);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.chat-header h1 {
    font-size: var(--font-size-xl);
    font-weight: 600;
    margin: 0;
}

.header-controls {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.theme-toggle,
.clear-btn {
    background: none;
    border: none;
    color: var(--text-inverse);
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    font-size: var(--font-size-lg);
}

.theme-toggle:hover,
.clear-btn:hover {
    background-color: var(--shadow-light);
    transform: scale(1.1);
}

.theme-toggle:active,
.clear-btn:active {
    transform: scale(0.95);
}

/* Main Chat Area */
.chat-main {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    background-color: var(--bg-chat);
    transition: background-color var(--transition-base);
}

.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-md);
    scroll-behavior: smooth;
}

/* Message Styles */
.welcome-message {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 200px;
    padding: var(--spacing-xl);
}

.user-message,
.bot-message {
    margin-bottom: var(--spacing-md);
    display: flex;
    animation: fadeInUp var(--transition-base) ease-out;
}

.user-message {
    justify-content: flex-end;
}

.bot-message {
    justify-content: flex-start;
}

.message-content {
    max-width: 70%;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    word-wrap: break-word;
    box-shadow: 0 1px 2px var(--shadow-light);
    transition: all var(--transition-fast);
}

.user-message .message-content {
    background-color: var(--bg-user);
    color: var(--text-inverse);
    border-bottom-right-radius: var(--radius-sm);
}

.bot-message .message-content {
    background-color: var(--bg-bot);
    color: var(--text-primary);
    border-bottom-left-radius: var(--radius-sm);
}

.message-content:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 4px var(--shadow-medium);
}

.message-time {
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    margin-top: var(--spacing-xs);
    opacity: 0.7;
    transition: opacity var(--transition-fast);
}

.user-message .message-time {
    text-align: right;
}

.bot-message .message-time {
    text-align: left;
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    align-items: center;
    padding: var(--spacing-md);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    gap: var(--spacing-sm);
}

.typing-dots {
    display: flex;
    gap: var(--spacing-xs);
}

.typing-dots span {
    width: 8px;
    height: 8px;
    background-color: var(--text-muted);
    border-radius: var(--radius-full);
    animation: typing 1.4s infinite ease-in-out;
}

.typing-dots span:nth-child(1) { animation-delay: -0.32s; }
.typing-dots span:nth-child(2) { animation-delay: -0.16s; }

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

/* Footer Styles */
.chat-footer {
    background-color: var(--bg-footer);
    padding: var(--spacing-md);
    box-shadow: 0 -2px 4px var(--shadow-light);
    transition: background-color var(--transition-base);
}

.message-form {
    max-width: 1200px;
    margin: 0 auto;
}

.input-container {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
    background-color: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-sm);
    box-shadow: inset 0 1px 3px var(--shadow-light);
    transition: all var(--transition-fast);
}

.input-container:focus-within {
    box-shadow: 0 0 0 2px var(--bg-user), inset 0 1px 3px var(--shadow-light);
}

#message-input {
    flex: 1;
    border: none;
    background: transparent;
    padding: var(--spacing-md);
    font-size: var(--font-size-base);
    color: var(--text-primary);
    outline: none;
    min-height: 44px;
    resize: none;
    font-family: inherit;
}

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

.send-button {
    background-color: var(--bg-user);
    color: var(--text-inverse);
    border: none;
    border-radius: var(--radius-full);
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.send-button:hover {
    background-color: var(--bg-user);
    transform: scale(1.05);
    box-shadow: 0 2px 4px var(--shadow-medium);
}

.send-button:active {
    transform: scale(0.95);
}

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

.footer-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: var(--spacing-sm);
    font-size: var(--font-size-xs);
    color: var(--text-muted);
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.session-info {
    font-family: monospace;
}

.char-count {
    font-family: monospace;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

/* Responsive Design - Mobile First */

/* Small devices (phones, 576px and up) */
@media (max-width: 575.98px) {
    .chat-container {
        height: 100vh;
        height: 100dvh; /* Dynamic viewport height for mobile browsers */
    }
    
    .chat-header {
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .header-content {
        gap: var(--spacing-sm);
    }
    
    .chat-header h1 {
        font-size: var(--font-size-lg);
    }
    
    .chat-messages {
        padding: var(--spacing-sm);
    }
    
    .message-content {
        max-width: 85%;
        padding: var(--spacing-sm) var(--spacing-md);
    }
    
    .user-message .message-content {
        border-bottom-right-radius: var(--radius-sm);
    }
    
    .bot-message .message-content {
        border-bottom-left-radius: var(--radius-sm);
    }
    
    .chat-footer {
        padding: var(--spacing-sm);
    }
    
    .input-container {
        padding: var(--spacing-xs);
    }
    
    #message-input {
        padding: var(--spacing-sm);
        font-size: 16px; /* Prevent zoom on iOS */
    }
    
    .send-button {
        width: 40px;
        height: 40px;
        font-size: var(--font-size-base);
    }
    
    .footer-info {
        flex-direction: column;
        gap: var(--spacing-xs);
        text-align: center;
    }
    
    .typing-indicator {
        padding: var(--spacing-sm);
        font-size: var(--font-size-xs);
    }
}

/* Medium devices (tablets, 768px and up) */
@media (min-width: 768px) {
    .chat-container {
        max-width: 100%;
        height: 100vh;
    }
    
    .message-content {
        max-width: 65%;
    }
    
    .chat-messages {
        padding: var(--spacing-lg);
    }
}

/* Large devices (desktops, 992px and up) */
@media (min-width: 992px) {
    .chat-container {
        max-width: 900px;
        margin: 0 auto;
        box-shadow: 0 0 20px var(--shadow-medium);
        border-radius: var(--radius-lg);
        overflow: hidden;
        margin: var(--spacing-lg) auto;
        height: calc(100vh - var(--spacing-xxl));
        max-height: 800px;
    }
    
    .message-content {
        max-width: 60%;
    }
}

/* Extra large devices (large desktops, 1200px and up) */
@media (min-width: 1200px) {
    .chat-container {
        max-width: 1000px;
    }
    
    .message-content {
        max-width: 55%;
    }
}

/* High DPI displays */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
    .theme-toggle,
    .clear-btn {
        -webkit-font-smoothing: antialiased;
        -moz-osx-font-smoothing: grayscale;
    }
}

/* Reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* Print styles */
@media print {
    .chat-header,
    .chat-footer,
    .theme-toggle,
    .clear-btn {
        display: none;
    }
    
    .chat-container {
        height: auto;
        box-shadow: none;
    }
    
    .message-content {
        box-shadow: none;
        border: 1px solid var(--border-color);
    }
}

/* Accessibility improvements */
@media (prefers-contrast: high) {
    :root {
        --border-color: #000000;
        --shadow-light: rgba(0, 0, 0, 0.5);
        --shadow-medium: rgba(0, 0, 0, 0.7);
        --shadow-heavy: rgba(0, 0, 0, 0.9);
    }
    
    [data-theme="dark"] {
        --border-color: #ffffff;
    }
}

/* Focus styles for better accessibility */
button:focus-visible,
input:focus-visible {
    outline: 2px solid var(--bg-user);
    outline-offset: 2px;
}

/* Loading state */
.loading {
    pointer-events: none;
    opacity: 0.6;
}

/* Error state */
.error {
    background-color: #dc3545;
    color: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin: var(--spacing-sm);
}

/* Success state */
.success {
    background-color: #28a745;
    color: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin: var(--spacing-sm);
}