/* ===========================
   DESIGN TOKENS
   =========================== */
:root {
  --bg: #0d0e11;
  --surface: #15171c;
  --surface-raised: #1c1f27;
  --surface-hover: #22262f;
  --border: rgba(255,255,255,0.07);
  --border-strong: rgba(255,255,255,0.13);

  --accent: #e8ff47;
  --accent-dim: rgba(232, 255, 71, 0.12);
  --accent-dim-hover: rgba(232, 255, 71, 0.2);

  --text-primary: #f0f1f3;
  --text-secondary: #8a8f9e;
  --text-muted: #4e535f;

  --danger: #ff5c5c;
  --danger-dim: rgba(255, 92, 92, 0.1);

  --success: #4dffa0;

  --font-display: 'Syne', sans-serif;
  --font-body: 'DM Sans', sans-serif;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;

  --sidebar-width: 260px;
  --transition: 200ms ease;
}

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

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

body {
  background: var(--bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.6;
  display: flex;
  min-height: 100vh;
  overflow-x: hidden;
}

button { cursor: pointer; font-family: inherit; border: none; background: none; }
input, textarea { font-family: inherit; }
ul { list-style: none; }
a { color: inherit; text-decoration: none; }

/* ===========================
   SIDEBAR
   =========================== */
#sidebar {
  width: var(--sidebar-width);
  min-height: 100vh;
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  padding: 24px 16px;
  gap: 20px;
  position: fixed;
  left: 0;
  top: 0;
  bottom: 0;
  z-index: 100;
  transition: transform var(--transition);
}

#logo {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 6px;
  margin-bottom: 4px;
}

#logo-mark {
  width: 32px;
  height: 32px;
  background: var(--accent);
  color: #000;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 16px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

#logo span {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  color: var(--text-primary);
}

/* Nav */
#sessions-nav {
  flex: 1;
  overflow-y: auto;
  scrollbar-width: none;
}
#sessions-nav::-webkit-scrollbar { display: none; }

.nav-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  padding: 0 8px;
  margin-bottom: 8px;
}

#sessions-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 10px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
  overflow: hidden;
}
#sessions-list li:hover { background: var(--surface-hover); }
#sessions-list li.active { background: var(--accent-dim); }
#sessions-list li.active .session-item-name { color: var(--accent); }

.session-item-icon {
  width: 26px;
  height: 26px;
  border-radius: 6px;
  background: var(--surface-raised);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 12px;
  color: var(--text-secondary);
}

.session-item-info {
  flex: 1;
  min-width: 0;
}

.session-item-name {
  font-size: 13px;
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  line-height: 1.3;
}

.session-item-meta {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 1px;
}

#sidebar-footer {
  padding-top: 8px;
  border-top: 1px solid var(--border);
}

/* ===========================
   BUTTONS
   =========================== */
.btn-primary {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px 16px;
  background: var(--accent);
  color: #000;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 13px;
  border-radius: var(--radius-sm);
  transition: opacity var(--transition), transform var(--transition);
}
.btn-primary:hover { opacity: 0.88; transform: translateY(-1px); }
.btn-primary:active { transform: translateY(0); }

.btn-ghost {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 8px 12px;
  background: transparent;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: background var(--transition), color var(--transition);
  border: 1px solid transparent;
}
.btn-ghost:hover {
  background: var(--surface-hover);
  color: var(--text-primary);
  border-color: var(--border);
}
.btn-ghost.danger { color: var(--danger); }
.btn-ghost.danger:hover { background: var(--danger-dim); color: var(--danger); border-color: transparent; }

/* ===========================
   MOBILE HEADER
   =========================== */
#mobile-header {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  z-index: 200;
}

#mobile-logo {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 16px;
}

#mobile-menu-btn, #mobile-new-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  transition: background var(--transition);
}
#mobile-menu-btn:hover, #mobile-new-btn:hover { background: var(--surface-hover); }

#sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 99;
}
#sidebar-overlay.visible { display: block; }

/* ===========================
   MAIN
   =========================== */
#main {
  margin-left: var(--sidebar-width);
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* ===========================
   VIEWS
   =========================== */
.view { display: none; }
.view.active { display: flex; flex-direction: column; }

/* ===========================
   HOME VIEW
   =========================== */
#view-home {
  align-items: center;
  padding: 64px 24px 80px;
}

#home-content {
  width: 100%;
  max-width: 720px;
  display: flex;
  flex-direction: column;
  gap: 40px;
}

#home-hero {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}

#hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  background: var(--accent-dim);
  border: 1px solid rgba(232,255,71,0.25);
  border-radius: 99px;
  font-size: 11px;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

#hero-title {
  font-family: var(--font-display);
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 800;
  line-height: 1.1;
  color: var(--text-primary);
}

#hero-title em {
  font-style: normal;
  color: var(--accent);
}

#hero-sub {
  font-size: 16px;
  color: var(--text-secondary);
  max-width: 500px;
  line-height: 1.65;
}

/* Input Card */
#input-card {
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-xl);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

#input-tabs {
  display: flex;
  gap: 4px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  padding: 4px;
}

.tab-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
  transition: background var(--transition), color var(--transition);
}
.tab-btn:hover { color: var(--text-secondary); }
.tab-btn.active {
  background: var(--surface-raised);
  color: var(--text-primary);
}

.tab-panel { display: none; flex-direction: column; gap: 10px; }
.tab-panel.active { display: flex; }

#session-name-input {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 9px 14px;
  font-size: 13px;
  color: var(--text-primary);
  outline: none;
  transition: border-color var(--transition);
  width: 100%;
}
#session-name-input::placeholder { color: var(--text-muted); }
#session-name-input:focus { border-color: var(--border-strong); }

#user-input {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px;
  font-size: 14px;
  color: var(--text-primary);
  resize: vertical;
  outline: none;
  transition: border-color var(--transition);
  min-height: 140px;
  line-height: 1.65;
}
#user-input::placeholder { color: var(--text-muted); }
#user-input:focus { border-color: var(--border-strong); }

#char-count {
  font-size: 11px;
  color: var(--text-muted);
  text-align: right;
}

/* PDF Drop Zone */
#pdf-drop-zone {
  border: 2px dashed var(--border-strong);
  border-radius: var(--radius-md);
  padding: 40px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);
  color: var(--text-muted);
  text-align: center;
}
#pdf-drop-zone:hover, #pdf-drop-zone.dragover {
  border-color: var(--accent);
  background: var(--accent-dim);
  color: var(--text-secondary);
}
#pdf-drop-zone p { font-size: 14px; font-weight: 500; color: var(--text-secondary); }
#pdf-drop-zone span { font-size: 13px; }
#pdf-browse { color: var(--accent); cursor: pointer; }
#pdf-browse:hover { text-decoration: underline; }

#pdf-info {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: var(--accent-dim);
  border: 1px solid rgba(232,255,71,0.2);
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--accent);
}
#pdf-info svg { flex-shrink: 0; color: var(--accent); }
#pdf-name { flex: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
#pdf-remove {
  width: 20px; height: 20px;
  border-radius: 50%;
  background: rgba(232,255,71,0.2);
  color: var(--accent);
  font-size: 14px;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
  transition: background var(--transition);
}
#pdf-remove:hover { background: rgba(232,255,71,0.4); }

#action-row {
  display: flex;
  gap: 8px;
}

.action-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 11px 14px;
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-family: var(--font-display);
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition);
}
.action-btn:hover {
  background: var(--accent-dim);
  border-color: rgba(232,255,71,0.3);
  color: var(--accent);
  transform: translateY(-1px);
}
.action-btn:active { transform: translateY(0); }

/* Recent Sessions */
#recent-sessions { display: flex; flex-direction: column; gap: 12px; }

.section-label {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

#recent-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 10px;
}

.recent-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition), transform var(--transition);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.recent-card:hover {
  border-color: var(--border-strong);
  background: var(--surface-raised);
  transform: translateY(-2px);
}

.recent-card-action {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: 4px;
  display: inline-block;
  align-self: flex-start;
}
.recent-card-action.explain { background: rgba(100,149,255,0.15); color: #6495ff; }
.recent-card-action.summarize { background: rgba(77,255,160,0.15); color: #4dffa0; }
.recent-card-action.keyconcepts { background: rgba(255,180,50,0.15); color: #ffb432; }

.recent-card-name {
  font-size: 14px;
  font-weight: 600;
  font-family: var(--font-display);
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.recent-card-preview {
  font-size: 12px;
  color: var(--text-muted);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.recent-card-date {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 4px;
}

#no-sessions-msg {
  font-size: 14px;
  color: var(--text-muted);
  text-align: center;
  padding: 24px;
}

/* ===========================
   RESULT VIEW
   =========================== */
#view-result {
  padding: 0;
  min-height: 100vh;
}

#result-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px 32px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  position: sticky;
  top: 0;
  z-index: 10;
}

#result-meta {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

#result-session-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

#result-action-badge {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 3px 9px;
  border-radius: 4px;
  flex-shrink: 0;
}
#result-action-badge.explain { background: rgba(100,149,255,0.15); color: #6495ff; }
#result-action-badge.summarize { background: rgba(77,255,160,0.15); color: #4dffa0; }
#result-action-badge.keyconcepts { background: rgba(255,180,50,0.15); color: #ffb432; }

#result-body {
  display: grid;
  grid-template-columns: 1fr 1.6fr;
  gap: 0;
  flex: 1;
  min-height: 0;
}

#result-source {
  padding: 28px 24px 28px 32px;
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
  max-height: calc(100vh - 200px);
}

.result-source-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

#result-source-text {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.7;
  white-space: pre-wrap;
  word-break: break-word;
}

#result-output {
  padding: 28px 32px 28px 24px;
  overflow-y: auto;
  max-height: calc(100vh - 200px);
}

#result-output-content {
  font-size: 15px;
  line-height: 1.75;
  color: var(--text-primary);
}

/* Markdown rendering */
#result-output-content h1,
#result-output-content h2,
#result-output-content h3 {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--text-primary);
  margin: 20px 0 10px;
}
#result-output-content h1 { font-size: 22px; }
#result-output-content h2 { font-size: 18px; color: var(--accent); }
#result-output-content h3 { font-size: 15px; }
#result-output-content p { margin-bottom: 12px; }
#result-output-content ul, #result-output-content ol {
  padding-left: 20px;
  margin-bottom: 12px;
}
#result-output-content li { margin-bottom: 6px; }
#result-output-content strong { color: var(--accent); font-weight: 600; }
#result-output-content code {
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 6px;
  font-size: 13px;
  font-family: 'Fira Code', monospace;
}
#result-output-content pre {
  background: var(--surface-raised);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px;
  overflow-x: auto;
  margin-bottom: 14px;
}
#result-output-content pre code { background: none; border: none; padding: 0; }

/* Follow-up Chat */
#followup-section {
  padding: 20px 32px 32px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 14px;
  background: var(--surface);
}

#chat-thread {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 320px;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

.chat-bubble {
  display: flex;
  gap: 10px;
  animation: bubbleIn 0.25s ease;
}
@keyframes bubbleIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.chat-bubble.user { flex-direction: row-reverse; }

.bubble-avatar {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  font-family: var(--font-display);
  flex-shrink: 0;
}
.chat-bubble.user .bubble-avatar {
  background: var(--accent);
  color: #000;
}
.chat-bubble.assistant .bubble-avatar {
  background: var(--surface-raised);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.bubble-content {
  max-width: 75%;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  font-size: 14px;
  line-height: 1.6;
}
.chat-bubble.user .bubble-content {
  background: var(--accent-dim);
  border: 1px solid rgba(232,255,71,0.15);
  color: var(--text-primary);
  border-bottom-right-radius: 4px;
}
.chat-bubble.assistant .bubble-content {
  background: var(--surface-raised);
  border: 1px solid var(--border);
  color: var(--text-primary);
  border-bottom-left-radius: 4px;
}

.typing-indicator {
  display: flex;
  gap: 4px;
  padding: 12px 14px;
  align-items: center;
}
.typing-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--text-muted);
  animation: typingPulse 1.2s ease-in-out infinite;
}
.typing-dot:nth-child(2) { animation-delay: 0.2s; }
.typing-dot:nth-child(3) { animation-delay: 0.4s; }
@keyframes typingPulse {
  0%, 60%, 100% { opacity: 0.3; transform: scale(1); }
  30% { opacity: 1; transform: scale(1.2); }
}

#chat-input-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

#chat-input {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 11px 16px;
  font-size: 14px;
  color: var(--text-primary);
  outline: none;
  transition: border-color var(--transition);
}
#chat-input::placeholder { color: var(--text-muted); }
#chat-input:focus { border-color: rgba(232,255,71,0.4); }

#chat-send-btn {
  width: 42px;
  height: 42px;
  background: var(--accent);
  color: #000;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: opacity var(--transition), transform var(--transition);
}
#chat-send-btn:hover { opacity: 0.85; transform: scale(1.05); }
#chat-send-btn:active { transform: scale(0.97); }
#chat-send-btn:disabled { opacity: 0.3; pointer-events: none; }

/* ===========================
   LOADING OVERLAY
   =========================== */
#loading-overlay {
  position: fixed;
  inset: 0;
  background: rgba(13,14,17,0.8);
  backdrop-filter: blur(4px);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
#loading-overlay.visible {
  opacity: 1;
  pointer-events: all;
}

#loading-card {
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-xl);
  padding: 36px 48px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
  box-shadow: 0 32px 80px rgba(0,0,0,0.5);
}

#loading-spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--border-strong);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

#loading-text {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 500;
}

/* ===========================
   TOAST
   =========================== */
#toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--surface-raised);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  padding: 10px 20px;
  font-size: 13px;
  color: var(--text-primary);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s, transform 0.2s;
  z-index: 9999;
  white-space: nowrap;
}
#toast.visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}
#toast.success { border-color: rgba(77,255,160,0.3); color: var(--success); }
#toast.error { border-color: rgba(255,92,92,0.3); color: var(--danger); }

/* ===========================
   RESPONSIVE
   =========================== */
@media (max-width: 900px) {
  #result-body {
    grid-template-columns: 1fr;
  }
  #result-source {
    border-right: none;
    border-bottom: 1px solid var(--border);
    max-height: 200px;
    padding: 20px 20px;
  }
  #result-output {
    max-height: none;
    padding: 20px 20px;
  }
  #followup-section { padding: 16px 20px 24px; }
  #result-header { padding: 12px 16px; }
}

@media (max-width: 768px) {
  #sidebar {
    transform: translateX(-100%);
  }
  #sidebar.open {
    transform: translateX(0);
    box-shadow: 20px 0 60px rgba(0,0,0,0.6);
  }

  #mobile-header { display: flex; }

  #main {
    margin-left: 0;
    padding-top: 56px;
  }

  #view-home {
    padding: 32px 16px 60px;
  }

  #action-row {
    flex-wrap: wrap;
  }

  .action-btn {
    flex: 1 1 40%;
  }

  #recent-cards {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  #hero-title { font-size: 30px; }
  #input-card { padding: 16px; }
}

/* ===========================
   SCROLLBAR
   =========================== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* ===========================
   ENTRY ANIMATIONS
   =========================== */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

#home-hero { animation: fadeUp 0.5s ease both; }
#input-card { animation: fadeUp 0.5s 0.1s ease both; }
#recent-sessions { animation: fadeUp 0.5s 0.2s ease both; }