:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --bg-color: #f5f5f7;
    --card-bg: #ffffff;
    --text-primary: #1d1d1f;
    --text-secondary: #6e6e73;
    --border-color: #d2d2d7;
    --accent-color: #667eea;
    --accent-hover: #5568d3;
    --error-color: #ff3b30;
    --success-color: #34c759;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 4px 20px rgba(0, 0, 0, 0.12);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.app-container {
    max-width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background: var(--card-bg);
}

/* Header */
.header {
    background: var(--primary-gradient);
    color: white;
    padding: 1.5rem 1rem;
    text-align: center;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-bottom: 0.25rem;
}

.logo-icon {
    font-size: 1.75rem;
}

.header h1 {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
}

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

/* Expert Selector */
.expert-selector {
    display: flex;
    gap: 0.5rem;
    padding: 1rem;
    background: var(--card-bg);
    border-bottom: 1px solid var(--border-color);
}

.expert-dropdown {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background: var(--card-bg);
    color: var(--text-primary);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%236e6e73' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    padding-right: 2.5rem;
}

.clear-btn-bottom {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    width: 100%;
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: #ff6b6b;
    color: white;
    border: none;
    border-radius: 12px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.clear-btn-bottom:hover {
    background: #ff5252;
}

.clear-btn-bottom:active {
    transform: scale(0.98);
}

.btn-icon {
    font-size: 1rem;
}

/* Chat Container */
.chat-container {
    flex: 1;
    overflow-y: auto;
    padding: 1rem;
    background: var(--bg-color);
    min-height: 50vh;
}

/* Welcome Screen */
.welcome-screen {
    text-align: center;
    padding: 2rem 1rem;
    max-width: 500px;
    margin: 0 auto;
}

.welcome-title {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.welcome-subtitle {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.starter-prompts {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.prompt-btn {
    padding: 1rem;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    font-size: 0.9rem;
    color: var(--text-primary);
    text-align: left;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: var(--shadow);
}

.prompt-btn:hover {
    border-color: var(--accent-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.prompt-btn:active {
    transform: translateY(0);
}

/* Messages */
.messages {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.message {
    display: flex;
    gap: 0.75rem;
    max-width: 85%;
    animation: fadeIn 0.3s ease;
}

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

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

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    flex-shrink: 0;
}

.message.user .message-avatar {
    background: var(--primary-gradient);
}

.message.assistant .message-avatar {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.message-content {
    padding: 1rem 1.125rem;
    border-radius: 16px;
    font-size: 0.95rem;
    line-height: 1.5;
    word-wrap: break-word;
    transition: all 0.2s ease;
}

.message.user .message-content {
    background: var(--accent-color);
    color: white;
    border-bottom-right-radius: 4px;
    box-shadow: 0 2px 8px rgba(102, 126, 234, 0.3);
}

.message.assistant .message-content {
    background: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    border-bottom-left-radius: 4px;
    box-shadow: var(--shadow);
}

/* Action Buttons */
.action-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
    padding: 0.75rem 1rem;
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
}

.action-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.25rem;
    padding: 0.75rem 0.5rem;
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.action-btn:hover {
    background: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
}

.action-btn:active {
    transform: scale(0.95);
}

/* Input Container */
.input-container {
    padding: 1rem;
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
}

.input-wrapper {
    display: flex;
    gap: 0.5rem;
    align-items: flex-end;
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 24px;
    padding: 0.5rem;
    transition: border-color 0.2s ease;
}

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

#userInput {
    flex: 1;
    border: none;
    background: transparent;
    font-size: 0.95rem;
    font-family: inherit;
    resize: none;
    outline: none;
    padding: 0.5rem;
    max-height: 120px;
    color: var(--text-primary);
}

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

.send-btn {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--accent-color);
    border: none;
    color: white;
    font-size: 1.25rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s ease;
    flex-shrink: 0;
}

.send-btn:hover {
    background: var(--accent-hover);
    transform: scale(1.05);
}

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

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

.send-icon {
    display: block;
    transform: translateX(1px);
}

/* Loading Indicator */
.loading-indicator {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: rgba(255, 255, 255, 0.95);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
}

.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-color);
    border-top-color: var(--accent-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

/* Uploaded Content */
.uploaded-content {
    margin-top: 0.5rem;
    padding: 0.75rem;
    background: rgba(0, 0, 0, 0.05);
    border-radius: 8px;
    font-size: 0.85rem;
}

.uploaded-image {
    max-width: 100%;
    border-radius: 8px;
    margin-top: 0.5rem;
}

/* Markdown Styling */
.message-content p {
    margin: 0.5rem 0;
    line-height: 1.6;
}

.message-content p:first-child {
    margin-top: 0;
}

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

.message-content h1,
.message-content h2,
.message-content h3 {
    font-weight: 600;
    line-height: 1.3;
    margin: 1.25rem 0 0.75rem 0;
}

.message-content h1:first-child,
.message-content h2:first-child,
.message-content h3:first-child {
    margin-top: 0;
}

.message-content h1 {
    font-size: 1.25rem;
    color: var(--accent-color);
    border-bottom: 2px solid var(--accent-color);
    padding-bottom: 0.5rem;
}

.message-content h2 {
    font-size: 1.15rem;
    color: var(--text-primary);
}

.message-content h3 {
    font-size: 1.05rem;
    color: var(--text-primary);
}

.message-content ul,
.message-content ol {
    margin: 0.75rem 0;
    padding-left: 1.75rem;
}

.message-content li {
    margin: 0.5rem 0;
    line-height: 1.5;
}

.message-content ul li {
    list-style-type: disc;
}

.message-content ol li {
    list-style-type: decimal;
}

.message-content li::marker {
    color: var(--accent-color);
    font-weight: 600;
}

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

.message-content em {
    font-style: italic;
    color: var(--text-secondary);
}

.message-content code {
    background: rgba(102, 126, 234, 0.1);
    color: var(--accent-color);
    padding: 0.125rem 0.375rem;
    border-radius: 4px;
    font-size: 0.9em;
    font-family: 'SF Mono', 'Monaco', 'Consolas', 'Courier New', monospace;
    font-weight: 500;
}

.message-content pre {
    background: rgba(0, 0, 0, 0.05);
    padding: 0.75rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 0.75rem 0;
    border-left: 3px solid var(--accent-color);
}

.message-content pre code {
    background: none;
    padding: 0;
    color: var(--text-primary);
}

.message-content blockquote {
    border-left: 4px solid var(--accent-color);
    padding-left: 1rem;
    margin: 0.75rem 0;
    color: var(--text-secondary);
    font-style: italic;
    background: rgba(102, 126, 234, 0.05);
    padding: 0.75rem 1rem;
    border-radius: 0 8px 8px 0;
}

.message-content hr {
    border: none;
    border-top: 2px solid var(--border-color);
    margin: 1rem 0;
}

.message-content a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s ease;
}

.message-content a:hover {
    border-bottom-color: var(--accent-color);
}

/* Special styling for user messages */
.message.user .message-content h1,
.message.user .message-content h2,
.message.user .message-content h3 {
    color: white;
}

.message.user .message-content h1 {
    border-bottom-color: rgba(255, 255, 255, 0.3);
}

.message.user .message-content code {
    background: rgba(255, 255, 255, 0.2);
    color: white;
}

.message.user .message-content blockquote {
    background: rgba(255, 255, 255, 0.1);
    border-left-color: rgba(255, 255, 255, 0.5);
    color: rgba(255, 255, 255, 0.9);
}

.message.user .message-content strong {
    color: white;
}

.message.user .message-content li::marker {
    color: rgba(255, 255, 255, 0.8);
}

/* Export Modal Styles */
.export-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.6);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    animation: fadeIn 0.2s ease;
}

.export-modal-content {
    background: white;
    padding: 2rem;
    border-radius: 16px;
    max-width: 400px;
    width: 90%;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
    animation: slideUp 0.3s ease;
}

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

.export-modal-content h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 700;
}

.export-hint {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.export-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.export-option-btn {
    padding: 0.875rem 1rem;
    background: var(--bg-color);
    border: 2px solid var(--border-color);
    border-radius: 12px;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: left;
    font-family: inherit;
}

.export-option-btn:hover {
    background: var(--accent-color);
    color: white;
    border-color: var(--accent-color);
    transform: translateX(5px);
}

.export-option-btn:active {
    transform: translateX(3px);
}

.close-modal-btn {
    width: 100%;
    padding: 0.75rem;
    background: transparent;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: inherit;
    font-weight: 500;
}

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

.close-modal-btn:active {
    transform: scale(0.98);
}

/* Responsive */
@media (min-width: 768px) {
    .app-container {
        max-width: 600px;
        margin: 0 auto;
        box-shadow: var(--shadow-lg);
    }

    .message {
        max-width: 75%;
    }
}

/* Scrollbar Styling */
.chat-container::-webkit-scrollbar {
    width: 6px;
}

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

.chat-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

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

/* Typing Indicator */
.typing-indicator {
    display: flex;
    align-items: center;
    gap: 4px;
    padding: 8px 0;
}

.typing-indicator span {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--accent-color);
    animation: typing 1.4s infinite;
    opacity: 0.6;
}

.typing-indicator span:nth-child(1) {
    animation-delay: 0s;
}

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

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

@keyframes typing {
    0%, 60%, 100% {
        transform: translateY(0);
        opacity: 0.6;
    }
    30% {
        transform: translateY(-10px);
        opacity: 1;
    }
}

/* Restoration Notice */
.restoration-notice {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--success-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    font-size: 0.9rem;
    font-weight: 500;
    z-index: 1001;
    animation: slideDown 0.3s ease;
}

.restoration-notice.fade-out {
    animation: fadeOut 0.5s ease;
    opacity: 0;
}

@keyframes slideDown {
    from {
        transform: translateX(-50%) translateY(-20px);
        opacity: 0;
    }
    to {
        transform: translateX(-50%) translateY(0);
        opacity: 1;
    }
}

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