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

:root {
    /* SmartHub Brand Colors */
    --primary-color: #2563eb;        /* Blue */
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #10b981;      /* Green for success */
    --accent-color: #f59e0b;         /* Orange for highlights */

    /* Neutral Colors */
    --background: #f8fafc;
    --surface: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #94a3b8;
    --border-color: #e2e8f0;

    /* Message Colors */
    --user-message-bg: #2563eb;
    --user-message-text: #ffffff;
    --ai-message-bg: #f1f5f9;
    --ai-message-text: #1e293b;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* ===========================
   Chat Container
   =========================== */
.chat-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    max-width: 1200px;
    margin: 0 auto;
    background: var(--surface);
    box-shadow: var(--shadow-lg);
}

/* ===========================
   Header
   =========================== */
.chat-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: var(--spacing-lg) var(--spacing-xl);
    box-shadow: var(--shadow-md);
    z-index: 10;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
}

.logo-section h1 {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.subtitle {
    font-size: 0.875rem;
    opacity: 0.9;
    font-weight: 400;
}

.grade-indicator {
    background: rgba(255, 255, 255, 0.2);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    backdrop-filter: blur(10px);
    font-size: 0.875rem;
    font-weight: 600;
    white-space: nowrap;
}

/* ===========================
   Chat Messages Area
   =========================== */
.chat-messages {
    flex: 1;
    overflow-y: auto;
    padding: var(--spacing-xl);
    background: var(--background);
    scroll-behavior: smooth;
}

.message {
    display: flex;
    margin-bottom: var(--spacing-lg);
    animation: messageSlideIn 0.3s ease-out;
}

@keyframes messageSlideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

.message-bubble {
    max-width: 75%;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    word-wrap: break-word;
    box-shadow: var(--shadow-sm);
}

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

.message.ai .message-bubble {
    background: var(--ai-message-bg);
    color: var(--ai-message-text);
    border-bottom-left-radius: var(--radius-sm);
    border-left: 3px solid var(--primary-color);
}

.message-content {
    font-size: 1rem;
    line-height: 1.5;
}

/* Message formatting */
.message-content p {
    margin-bottom: var(--spacing-sm);
}

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

.message-content ul,
.message-content ol {
    margin-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
}

.message-content li {
    margin-bottom: var(--spacing-xs);
}

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

.message-content em {
    font-style: italic;
}

.message-content code {
    background: rgba(0, 0, 0, 0.05);
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
}

/* Welcome message styling */
.message.welcome .message-bubble {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    border-left: none;
}

/* ===========================
   Typing Indicator
   =========================== */
.typing-indicator {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--background);
}

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

.typing-dots span {
    width: 8px;
    height: 8px;
    background: var(--primary-color);
    border-radius: 50%;
    animation: typingBounce 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 typingBounce {
    0%, 80%, 100% {
        transform: scale(0.8);
        opacity: 0.5;
    }
    40% {
        transform: scale(1);
        opacity: 1;
    }
}

.typing-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-style: italic;
}

/* ===========================
   Input Area
   =========================== */
.chat-input-container {
    background: var(--surface);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-lg) var(--spacing-xl);
    box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
}

.input-wrapper {
    display: flex;
    gap: var(--spacing-md);
    align-items: flex-end;
}

.message-input {
    flex: 1;
    min-height: 48px;
    max-height: 150px;
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: inherit;
    resize: none;
    transition: border-color var(--transition-fast);
    line-height: 1.5;
}

.message-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.message-input::placeholder {
    color: var(--text-light);
}

.send-button {
    min-width: 48px;
    height: 48px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.send-button:hover:not(:disabled) {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.send-button:active:not(:disabled) {
    transform: translateY(0);
}

.send-button:disabled {
    background: var(--text-light);
    cursor: not-allowed;
    opacity: 0.6;
}

.input-info {
    margin-top: var(--spacing-sm);
    text-align: right;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* ===========================
   Error Modal
   =========================== */
.error-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.2s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.error-content {
    background: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    max-width: 400px;
    text-align: center;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease-out;
}

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

.error-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.error-content h3 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    font-size: 1.25rem;
}

.error-content p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

.error-close-btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: var(--spacing-sm) var(--spacing-xl);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 600;
    transition: background var(--transition-fast);
}

.error-close-btn:hover {
    background: var(--primary-dark);
}

/* ===========================
   Scrollbar Styling
   =========================== */
.chat-messages::-webkit-scrollbar {
    width: 8px;
}

.chat-messages::-webkit-scrollbar-track {
    background: var(--background);
}

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

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

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .chat-header {
        padding: var(--spacing-md);
    }

    .header-content {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }

    .logo-section h1 {
        font-size: 1.25rem;
    }

    .grade-indicator {
        align-self: flex-end;
    }

    .chat-messages {
        padding: var(--spacing-md);
    }

    .message-bubble {
        max-width: 85%;
    }

    .chat-input-container {
        padding: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .logo-section h1 {
        font-size: 1.1rem;
    }

    .subtitle {
        font-size: 0.75rem;
    }

    .message-bubble {
        max-width: 90%;
        font-size: 0.9rem;
    }

    .message-input {
        font-size: 0.9rem;
    }
}

/* ===========================
   Utility Classes
   =========================== */
.hidden {
    display: none !important;
}

.text-center {
    text-align: center;
}

.mt-md {
    margin-top: var(--spacing-md);
}

.mb-md {
    margin-bottom: var(--spacing-md);
}