/* ═══════════════════════════════════════════════════════════
   Research Paper Analyzer - Modern UI Styles
   ═══════════════════════════════════════════════════════════ */

:root {
    /* Colors */
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-tertiary: #1a1a2e;
    --bg-card: #16162a;
    --bg-hover: #1e1e3a;
    --bg-input: #0d0d1a;

    --text-primary: #e8e8f0;
    --text-secondary: #9898b0;
    --text-muted: #5a5a7a;

    --accent-primary: #6c63ff;
    --accent-secondary: #4ecdc4;
    --accent-gradient: linear-gradient(135deg, #6c63ff, #4ecdc4);
    --accent-glow: rgba(108, 99, 255, 0.3);

    --border-color: rgba(255, 255, 255, 0.06);
    --border-active: rgba(108, 99, 255, 0.4);

    --success: #4ecdc4;
    --warning: #ffd93d;
    --error: #ff6b6b;

    /* Spacing */
    --sidebar-width: 300px;
    --header-height: 64px;
    --input-height: 80px;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);

    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 30px rgba(108, 99, 255, 0.15);
}

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

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow: hidden;
    height: 100vh;
}

/* ─── Animated Background ─── */
.bg-animation {
    position: fixed;
    inset: 0;
    z-index: 0;
    overflow: hidden;
    pointer-events: none;
}

.floating-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: 0.4;
    animation: float 20s infinite ease-in-out;
}

.orb-1 {
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(108, 99, 255, 0.3), transparent);
    top: -100px;
    right: -100px;
    animation-delay: 0s;
}

.orb-2 {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, rgba(78, 205, 196, 0.2), transparent);
    bottom: -50px;
    left: -50px;
    animation-delay: -7s;
}

.orb-3 {
    width: 250px;
    height: 250px;
    background: radial-gradient(circle, rgba(108, 99, 255, 0.15), transparent);
    top: 50%;
    left: 50%;
    animation-delay: -14s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -30px) scale(1.05); }
    50% { transform: translate(-20px, 20px) scale(0.95); }
    75% { transform: translate(15px, 15px) scale(1.02); }
}

.grid-overlay {
    position: absolute;
    inset: 0;
    background-image: 
        linear-gradient(rgba(255, 255, 255, 0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
    background-size: 60px 60px;
    animation: gridMove 30s linear infinite;
}

@keyframes gridMove {
    0% { transform: translate(0, 0); }
    100% { transform: translate(60px, 60px); }
}

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

/* ─── Sidebar ─── */
.sidebar {
    width: var(--sidebar-width);
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: transform var(--transition-slow);
    backdrop-filter: blur(20px);
}

.sidebar-header {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--accent-gradient);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    box-shadow: var(--shadow-glow);
}

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

/* ─── Upload Zone ─── */
.upload-section {
    padding: 1.25rem;
}

.upload-zone {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 1.5rem 1rem;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.upload-zone::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--accent-gradient);
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.upload-zone:hover {
    border-color: var(--accent-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

.upload-zone:hover::before {
    opacity: 0.05;
}

.upload-zone.drag-over {
    border-color: var(--accent-secondary);
    background: rgba(78, 205, 196, 0.05);
    transform: scale(1.02);
}

.upload-icon {
    color: var(--text-muted);
    margin-bottom: 0.5rem;
    transition: color var(--transition-normal), transform var(--transition-normal);
}

.upload-zone:hover .upload-icon {
    color: var(--accent-primary);
    transform: translateY(-3px);
}

.upload-text {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.upload-subtext {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

/* Upload Progress */
.upload-progress {
    margin-top: 1rem;
    animation: slideDown 0.3s ease;
}

.upload-progress.hidden {
    display: none;
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: 0.5rem;
    font-size: 0.8rem;
}

.progress-filename {
    color: var(--text-secondary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    max-width: 180px;
}

.progress-percent {
    color: var(--accent-primary);
    font-weight: 600;
}

.progress-bar {
    height: 4px;
    background: var(--bg-tertiary);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: 2px;
    width: 0%;
    transition: width 0.3s ease;
}

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

/* ─── Papers List ─── */
.papers-section {
    flex: 1;
    padding: 0 1.25rem;
    overflow-y: auto;
}

.section-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
}

.papers-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.paper-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition-fast);
    border: 1px solid transparent;
}

.paper-item:hover {
    background: var(--bg-hover);
    border-color: var(--border-color);
}

.paper-item.active {
    background: rgba(108, 99, 255, 0.1);
    border-color: var(--border-active);
}

.paper-icon {
    width: 32px;
    height: 32px;
    background: var(--bg-tertiary);
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent-primary);
    flex-shrink: 0;
}

.paper-info {
    overflow: hidden;
    flex: 1;
}

.paper-name {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-primary);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.paper-meta {
    font-size: 0.7rem;
    color: var(--text-muted);
}

.paper-delete {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.4rem;
    border-radius: 6px;
    opacity: 0.6;
    transition: all var(--transition-fast);
    flex-shrink: 0;
}

.paper-item:hover .paper-delete {
    opacity: 1;
}

.paper-delete:hover {
    background: rgba(255, 107, 107, 0.15);
    color: var(--error);
    opacity: 1;
}

.empty-state {
    text-align: center;
    padding: 2rem 1rem;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ─── Sidebar Footer ─── */
.sidebar-footer {
    padding: 1rem 1.25rem;
    border-top: 1px solid var(--border-color);
}

.model-badge {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.model-dot {
    width: 8px;
    height: 8px;
    background: var(--success);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(0.8); }
}

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

/* ─── Header ─── */
.main-header {
    height: var(--header-height);
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    border-bottom: 1px solid var(--border-color);
    backdrop-filter: blur(10px);
    background: rgba(10, 10, 15, 0.8);
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: background var(--transition-fast);
}

.menu-toggle:hover {
    background: var(--bg-hover);
}

.header-title h1 {
    font-size: 1.1rem;
    font-weight: 600;
}

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

.header-actions {
    margin-left: auto;
}

.btn-icon {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 6px;
    transition: all var(--transition-fast);
}

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

/* ─── Chat Area ─── */
.chat-area {
    flex: 1;
    overflow-y: auto;
    padding: 2rem;
    scroll-behavior: smooth;
}

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

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

.chat-area::-webkit-scrollbar-thumb {
    background: var(--bg-tertiary);
    border-radius: 3px;
}

/* ─── Welcome Screen ─── */
.welcome-screen {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 3rem 1rem;
    animation: fadeInUp 0.6s ease;
}

.welcome-screen.hidden {
    display: none;
}

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

.welcome-icon {
    position: relative;
    width: 80px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent-primary);
    margin-bottom: 1.5rem;
}

.pulse-ring {
    position: absolute;
    inset: 0;
    border: 2px solid var(--accent-primary);
    border-radius: 50%;
    animation: pulseRing 2s infinite;
}

@keyframes pulseRing {
    0% { transform: scale(0.8); opacity: 0.8; }
    100% { transform: scale(1.4); opacity: 0; }
}

.welcome-screen h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.welcome-screen p {
    color: var(--text-secondary);
    max-width: 500px;
    margin-bottom: 2rem;
    font-size: 0.95rem;
}

.suggestion-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    justify-content: center;
    max-width: 600px;
}

.chip {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 1rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--text-secondary);
    font-size: 0.8rem;
    cursor: pointer;
    transition: all var(--transition-normal);
    white-space: nowrap;
}

.chip:hover {
    background: var(--bg-hover);
    border-color: var(--accent-primary);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-glow);
}

/* ─── Messages ─── */
.messages-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.message {
    display: flex;
    gap: 1rem;
    animation: messageIn 0.4s ease;
    max-width: 800px;
}

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

.message-avatar {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 0.85rem;
    font-weight: 600;
}

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

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

.message-content {
    flex: 1;
    min-width: 0;
}

.message-text {
    padding: 1rem 1.25rem;
    border-radius: 12px;
    font-size: 0.9rem;
    line-height: 1.7;
    word-wrap: break-word;
}

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

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

.message-text p {
    margin-bottom: 0.75rem;
}

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

.message-text code {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    background: rgba(108, 99, 255, 0.1);
    padding: 0.15rem 0.4rem;
    border-radius: 4px;
    color: var(--accent-primary);
}

.message-text pre {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    overflow-x: auto;
    margin: 0.75rem 0;
}

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

.message-text ul, .message-text ol {
    padding-left: 1.5rem;
    margin: 0.5rem 0;
}

.message-text li {
    margin-bottom: 0.3rem;
}

/* Sources */
.message-sources {
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: rgba(78, 205, 196, 0.05);
    border: 1px solid rgba(78, 205, 196, 0.15);
    border-radius: 8px;
}

.sources-title {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--accent-secondary);
    margin-bottom: 0.5rem;
}

.source-item {
    font-size: 0.75rem;
    color: var(--text-muted);
    padding: 0.25rem 0;
}

/* Typing Indicator */
.typing-indicator {
    display: flex;
    gap: 4px;
    padding: 0.75rem 1.25rem;
}

.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; }

@keyframes typingBounce {
    0%, 60%, 100% { transform: translateY(0); opacity: 0.4; }
    30% { transform: translateY(-6px); opacity: 1; }
}

/* ─── Input Area ─── */
.input-area {
    padding: 1rem 2rem 1.5rem;
    border-top: 1px solid var(--border-color);
    background: rgba(10, 10, 15, 0.9);
    backdrop-filter: blur(10px);
}

.input-wrapper {
    max-width: 800px;
    margin: 0 auto;
}

.input-container {
    display: flex;
    align-items: flex-end;
    gap: 0.75rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    padding: 0.75rem 1rem;
    transition: border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.input-container:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(108, 99, 255, 0.1);
}

.input-container textarea {
    flex: 1;
    background: none;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9rem;
    line-height: 1.5;
    resize: none;
    max-height: 150px;
    padding: 0.25rem 0;
}

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

.input-actions {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* RAG Toggle */
.rag-toggle {
    display: flex;
    align-items: center;
}

.rag-toggle input[type="checkbox"] {
    display: none;
}

.toggle-label {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.3rem 0.6rem;
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    transition: all var(--transition-fast);
    background: var(--bg-tertiary);
    color: var(--text-muted);
    border: 1px solid var(--border-color);
}

.rag-toggle input:checked + .toggle-label {
    background: rgba(108, 99, 255, 0.15);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

/* Send Button */
.send-btn {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    border: none;
    background: var(--bg-tertiary);
    color: var(--text-muted);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-normal);
}

.send-btn:not(:disabled) {
    background: var(--accent-gradient);
    color: white;
    box-shadow: var(--shadow-glow);
}

.send-btn:not(:disabled):hover {
    transform: scale(1.05);
    box-shadow: 0 0 20px rgba(108, 99, 255, 0.4);
}

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

.input-hint {
    text-align: center;
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 0.5rem;
}

/* ─── Responsive ─── */
@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        bottom: 0;
        z-index: 100;
        transform: translateX(-100%);
        box-shadow: var(--shadow-lg);
    }

    .sidebar.open {
        transform: translateX(0);
    }

    .menu-toggle {
        display: block;
    }

    .chat-area {
        padding: 1rem;
    }

    .input-area {
        padding: 0.75rem 1rem 1rem;
    }

    .suggestion-chips {
        flex-direction: column;
        align-items: stretch;
    }
}

/* ─── Animations for dynamic elements ─── */
@keyframes shimmer {
    0% { background-position: -200% 0; }
    100% { background-position: 200% 0; }
}

.loading-shimmer {
    background: linear-gradient(
        90deg,
        var(--bg-tertiary) 25%,
        var(--bg-hover) 50%,
        var(--bg-tertiary) 75%
    );
    background-size: 200% 100%;
    animation: shimmer 1.5s infinite;
    border-radius: 8px;
}

/* Smooth scroll indicator */
.scroll-bottom {
    position: absolute;
    bottom: 100px;
    right: 2rem;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    transform: translateY(10px);
    transition: all var(--transition-normal);
    color: var(--text-secondary);
}

.scroll-bottom.visible {
    opacity: 1;
    transform: translateY(0);
}

.scroll-bottom:hover {
    background: var(--bg-hover);
    border-color: var(--accent-primary);
}