/* ================================================
   AI Learning Lab - Style
   Design: warm, literary, book-like
   Mobile-first, 375px baseline
   ================================================ */

/* ----- Tokens ----- */
:root {
  /* Palette */
  --color-bg:         #FFF8F0;
  --color-bg-warm:    #FFF3E4;
  --color-bg-chat-ai: #FDF5EB;
  --color-bg-chat-user: #F0E6D8;
  --color-bg-discovery: #FFF9F0;
  --color-text:       #3D2B1F;
  --color-text-soft:  #6B5344;
  --color-text-muted: #9C8578;
  --color-accent:     #C67B3C;
  --color-accent-hover: #B06A2F;
  --color-accent-light: #E8CEB0;
  --color-border:     #E8DDD3;
  --color-discovery-border: #D4A06A;
  --color-shadow:     rgba(61, 43, 31, 0.06);
  --color-overlay:    rgba(61, 43, 31, 0.3);

  /* Typography */
  --font-serif:  "Noto Serif SC", "Source Han Serif SC", Georgia, "Times New Roman", serif;
  --font-sans:   "Noto Sans SC", "Source Han Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;

  /* Spacing */
  --space-xs:  0.25rem;
  --space-sm:  0.5rem;
  --space-md:  1rem;
  --space-lg:  1.5rem;
  --space-xl:  2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Radii */
  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-lg: 1.25rem;
  --radius-full: 9999px;

  /* Transitions */
  --ease-gentle: cubic-bezier(0.4, 0, 0.2, 1);
  --duration-fast: 200ms;
  --duration-normal: 350ms;
  --duration-slow: 600ms;

  /* Layout */
  --chat-max-width: 680px;
  --input-max-height: 120px;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.7;
  overflow: hidden;
  height: 100dvh;
  width: 100%;
}

/* Screen-reader only utility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ----- Screen Transitions ----- */
.screen {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  opacity: 0;
  visibility: hidden;
  transition:
    opacity var(--duration-slow) var(--ease-gentle),
    visibility 0s linear var(--duration-slow);
  will-change: opacity;
}

.screen.active {
  opacity: 1;
  visibility: visible;
  transition:
    opacity var(--duration-slow) var(--ease-gentle),
    visibility 0s linear 0s;
}

/* ================================================
   SCREEN 0: AUTH
   ================================================ */
.screen--auth {
  justify-content: center;
  align-items: center;
  background:
    radial-gradient(ellipse at 50% 30%, #FFF8F0 0%, #FEF0DE 60%, #F9E4C8 100%);
  padding: var(--space-xl);
}

.auth__card {
  max-width: 380px;
  width: 100%;
  text-align: center;
  animation: fadeUp 0.8s var(--ease-gentle) both;
}

.auth__title {
  font-family: var(--font-serif);
  font-size: clamp(1.4rem, 4vw, 1.8rem);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
}

.auth__subtitle {
  font-family: var(--font-sans);
  font-size: 0.92rem;
  color: var(--color-text-soft);
  margin-bottom: var(--space-2xl);
  line-height: 1.6;
}

.auth__form {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.auth__field input {
  width: 100%;
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--color-text);
  background-color: var(--color-bg-warm);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 0.8rem 1rem;
  outline: none;
  transition: border-color var(--duration-fast) var(--ease-gentle);
}

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

.auth__field input:focus {
  border-color: var(--color-accent-light);
  box-shadow: 0 0 0 3px rgba(198, 123, 60, 0.1);
}

.auth__error {
  font-size: 0.85rem;
  color: #c0392b;
  text-align: left;
  padding: 0 var(--space-xs);
}

.auth__error[hidden] {
  display: none;
}

.auth__btn {
  font-family: var(--font-sans);
  font-size: 1.05rem;
  font-weight: 500;
  color: #FFF;
  background-color: var(--color-accent);
  border: none;
  border-radius: var(--radius-full);
  padding: 0.85rem;
  cursor: pointer;
  letter-spacing: 0.04em;
  margin-top: var(--space-sm);
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    transform var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
  box-shadow: 0 2px 12px rgba(198, 123, 60, 0.25);
}

.auth__btn:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(198, 123, 60, 0.35);
}

.auth__btn:active {
  transform: translateY(0);
}

.auth__btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.auth__switch {
  margin-top: var(--space-lg);
  font-size: 0.88rem;
  color: var(--color-text-muted);
}

.auth__switch-btn {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--color-accent);
  background: none;
  border: none;
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.auth__switch-btn:hover {
  color: var(--color-accent-hover);
}

/* Invite code status */
.auth__invite-status {
  display: block;
  font-size: 0.78rem;
  margin-top: var(--space-xs);
  min-height: 1.2em;
}

.auth__invite-status--valid {
  color: #27ae60;
}

.auth__invite-status--invalid {
  color: #c0392b;
}

/* ================================================
   SCREEN 1: LANDING
   ================================================ */
.screen--landing {
  justify-content: center;
  align-items: center;
  background:
    radial-gradient(ellipse at 50% 30%, #FFF8F0 0%, #FEF0DE 60%, #F9E4C8 100%);
  padding: var(--space-xl);
}

/* Landing header (greeting + logout) */
.landing__header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-xl);
  z-index: 10;
}

.landing__greeting {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  color: var(--color-text-soft);
}

.landing__pro-badge {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: #FFF;
  background: linear-gradient(135deg, #D4A06A, #C67B3C);
  border-radius: var(--radius-full);
  padding: 0.15rem 0.55rem;
  vertical-align: middle;
  margin-left: var(--space-xs);
  box-shadow: 0 1px 4px rgba(198, 123, 60, 0.3);
}

.landing__pro-badge[hidden] {
  display: none;
}

.landing__logout {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--color-text-muted);
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 0.3rem 0.9rem;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-gentle);
}

.landing__logout:hover {
  color: var(--color-text-soft);
  border-color: var(--color-text-muted);
  background-color: var(--color-bg-warm);
}

.landing__content {
  text-align: center;
  max-width: 520px;
  animation: fadeUp 0.8s var(--ease-gentle) both;
}

.landing__headline {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 5vw, 2.4rem);
  font-weight: 600;
  line-height: 1.5;
  color: var(--color-text);
  letter-spacing: 0.02em;
  margin-bottom: var(--space-lg);
}

.landing__subtitle {
  font-family: var(--font-sans);
  font-size: clamp(0.95rem, 2.5vw, 1.15rem);
  color: var(--color-text-soft);
  line-height: 1.8;
  margin-bottom: var(--space-2xl);
  animation: fadeUp 0.8s var(--ease-gentle) 0.2s both;
}

.landing__cta {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 1.05rem;
  font-weight: 500;
  color: #FFF;
  background-color: var(--color-accent);
  border: none;
  border-radius: var(--radius-full);
  padding: 0.85rem 2.8rem;
  cursor: pointer;
  letter-spacing: 0.06em;
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    transform var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
  animation: fadeUp 0.8s var(--ease-gentle) 0.4s both;
  box-shadow: 0 2px 12px rgba(198, 123, 60, 0.25);
}

.landing__cta:hover,
.landing__cta:focus-visible {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(198, 123, 60, 0.35);
}

.landing__cta:active {
  transform: translateY(0);
  box-shadow: 0 2px 8px rgba(198, 123, 60, 0.2);
}

.landing__cta:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.landing__watermark {
  position: fixed;
  bottom: var(--space-lg);
  left: var(--space-lg);
  font-family: var(--font-serif);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  opacity: 0.35;
  letter-spacing: 0.08em;
  user-select: none;
  animation: fadeUp 0.8s var(--ease-gentle) 0.6s both;
}

/* ================================================
   SIDEBAR
   ================================================ */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 40;
  width: 280px;
  height: 100dvh;
  background-color: var(--color-bg-warm);
  border-right: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  transform: translateX(-100%);
  transition: transform var(--duration-normal) var(--ease-gentle);
  will-change: transform;
}

/* Sidebar open state (mobile: JS toggled) */
.sidebar.open {
  transform: translateX(0);
}

/* Sidebar overlay (mobile backdrop) */
.sidebar-overlay {
  position: fixed;
  inset: 0;
  z-index: 35;
  background-color: var(--color-overlay);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-normal) var(--ease-gentle);
}

.sidebar-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

/* Sidebar header */
.sidebar__header {
  flex-shrink: 0;
  padding: var(--space-lg);
  border-bottom: 1px solid var(--color-border);
}

.sidebar__new-chat {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  width: 100%;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-accent);
  background-color: transparent;
  border: 1.5px solid var(--color-accent-light);
  border-radius: var(--radius-full);
  padding: 0.55rem var(--space-lg);
  cursor: pointer;
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    border-color var(--duration-fast) var(--ease-gentle);
}

.sidebar__new-chat:hover {
  background-color: var(--color-accent-light);
  border-color: var(--color-accent);
}

.sidebar__new-chat:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* Session list */
.sidebar__nav {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-sm) 0;
}

.sidebar__nav::-webkit-scrollbar {
  width: 3px;
}
.sidebar__nav::-webkit-scrollbar-thumb {
  background-color: var(--color-border);
  border-radius: 2px;
}

.sidebar__list {
  list-style: none;
  padding: 0 var(--space-sm);
}

.sidebar__empty {
  padding: var(--space-xl) var(--space-lg);
  font-size: 0.85rem;
  color: var(--color-text-muted);
  text-align: center;
}

.sidebar__item {
  padding: 0;
  margin-bottom: 2px;
}

.sidebar__item-btn {
  display: block;
  width: 100%;
  text-align: left;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--color-text-soft);
  background: none;
  border: none;
  border-radius: var(--radius-sm);
  padding: 0.55rem var(--space-md);
  cursor: pointer;
  transition: background-color var(--duration-fast) var(--ease-gentle);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sidebar__item-btn:hover {
  background-color: var(--color-bg-chat-ai);
  color: var(--color-text);
}

.sidebar__item-btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: -2px;
}

.sidebar__item--active .sidebar__item-btn {
  background-color: var(--color-bg-chat-user);
  color: var(--color-text);
  font-weight: 500;
}

.sidebar__item-date {
  display: block;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  margin-top: 1px;
}

/* Sidebar footer */
.sidebar__footer {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--color-border);
}

.sidebar__username {
  font-family: var(--font-sans);
  font-size: 0.82rem;
  color: var(--color-text-soft);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
}

.sidebar__logout {
  flex-shrink: 0;
  font-family: var(--font-sans);
  font-size: 0.78rem;
  color: var(--color-text-muted);
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  padding: 0.25rem 0.7rem;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-gentle);
}

.sidebar__logout:hover {
  color: var(--color-text-soft);
  border-color: var(--color-text-muted);
  background-color: var(--color-bg-chat-user);
}

/* ================================================
   SCREEN 2: CHAT
   ================================================ */
.screen--chat {
  background-color: var(--color-bg);
}

/* Hamburger toggle button (mobile) */
.chat__sidebar-toggle {
  position: fixed;
  top: var(--space-md);
  left: var(--space-md);
  z-index: 20;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg);
  color: var(--color-text-soft);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  box-shadow: 0 1px 4px var(--color-shadow);
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
}

.chat__sidebar-toggle:hover {
  background-color: var(--color-bg-warm);
  box-shadow: 0 2px 8px var(--color-shadow);
}

.chat__sidebar-toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

/* Empty state */
.chat__empty {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-3xl) var(--space-xl);
  animation: fadeUp 0.6s var(--ease-gentle) both;
}

.chat__empty[hidden] {
  display: none;
}

.chat__empty-title {
  font-family: var(--font-serif);
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

.chat__empty-subtitle {
  font-family: var(--font-sans);
  font-size: 1rem;
  color: var(--color-text-soft);
  margin-bottom: var(--space-2xl);
}

.chat__empty-cta {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 500;
  color: #FFF;
  background-color: var(--color-accent);
  border: none;
  border-radius: var(--radius-full);
  padding: 0.8rem 2.4rem;
  cursor: pointer;
  letter-spacing: 0.05em;
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    transform var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
  box-shadow: 0 2px 12px rgba(198, 123, 60, 0.25);
}

.chat__empty-cta:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(198, 123, 60, 0.35);
}

.chat__empty-cta:active {
  transform: translateY(0);
}

.chat__empty-cta:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

/* --- Messages --- */
.chat__messages {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-xl) var(--space-md) 0;
  scroll-behavior: smooth;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
}

.chat__messages::after {
  content: "";
  display: block;
  height: var(--space-lg);
}

/* Scrollbar styling */
.chat__messages::-webkit-scrollbar {
  width: 4px;
}
.chat__messages::-webkit-scrollbar-track {
  background: transparent;
}
.chat__messages::-webkit-scrollbar-thumb {
  background-color: var(--color-border);
  border-radius: 2px;
}

/* Message wrapper for max-width centering */
.msg-wrapper {
  max-width: var(--chat-max-width);
  margin: 0 auto var(--space-md);
  display: flex;
  animation: msgFadeIn var(--duration-normal) var(--ease-gentle) both;
}

.msg-wrapper--ai {
  justify-content: flex-start;
}

.msg-wrapper--user {
  justify-content: flex-end;
}

/* Bubbles */
.msg {
  max-width: 85%;
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-lg);
  word-break: break-word;
  overflow-wrap: break-word;
}

.msg--ai {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.85;
  background-color: var(--color-bg-chat-ai);
  color: var(--color-text);
  border-bottom-left-radius: var(--space-xs);
  box-shadow: 0 1px 4px var(--color-shadow);
}

.msg--user {
  font-family: var(--font-sans);
  font-size: 0.98rem;
  line-height: 1.75;
  background-color: var(--color-bg-chat-user);
  color: var(--color-text);
  border-bottom-right-radius: var(--space-xs);
}

/* Markdown-like formatting in messages */
.msg p {
  margin-bottom: 0.6em;
}
.msg p:last-child {
  margin-bottom: 0;
}
.msg strong {
  font-weight: 600;
}
.msg em {
  font-style: italic;
}

/* --- Discovery Card (inline) --- */
.msg--discovery {
  max-width: var(--chat-max-width);
  margin: var(--space-md) auto var(--space-lg);
  padding: var(--space-lg);
  background-color: var(--color-bg-discovery);
  border-left: 3px solid var(--color-discovery-border);
  border-radius: var(--radius-md);
  box-shadow: 0 2px 12px var(--color-shadow);
  animation: discoveryPop var(--duration-slow) var(--ease-gentle) both;
}

.msg--discovery__label {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--color-accent);
  letter-spacing: 0.04em;
  margin-bottom: var(--space-sm);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.msg--discovery__text {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--color-text);
}

/* --- Typing Indicator --- */
.chat__typing {
  max-width: var(--chat-max-width);
  margin: 0 auto;
  padding: 0 var(--space-md) var(--space-sm);
  display: flex;
  justify-content: flex-start;
}

.chat__typing[hidden] {
  display: none;
}

.chat__typing-bubble {
  display: flex;
  align-items: center;
  gap: 5px;
  background-color: var(--color-bg-chat-ai);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-lg);
  border-bottom-left-radius: var(--space-xs);
  box-shadow: 0 1px 4px var(--color-shadow);
}

.chat__typing-bubble .dot {
  width: 7px;
  height: 7px;
  background-color: var(--color-text-muted);
  border-radius: 50%;
  opacity: 0.4;
  animation: typingDot 1.4s ease-in-out infinite;
}

.chat__typing-bubble .dot:nth-child(2) {
  animation-delay: 0.2s;
}
.chat__typing-bubble .dot:nth-child(3) {
  animation-delay: 0.4s;
}

/* --- Input Area --- */
.chat__input-area {
  flex-shrink: 0;
  display: flex;
  align-items: flex-end;
  gap: var(--space-sm);
  max-width: var(--chat-max-width);
  margin: 0 auto;
  width: 100%;
  padding: var(--space-md);
  padding-bottom: max(var(--space-md), env(safe-area-inset-bottom, var(--space-md)));
  background-color: var(--color-bg);
}

.chat__input {
  flex: 1;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg-warm);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 0.7rem 1rem;
  resize: none;
  overflow-y: auto;
  max-height: var(--input-max-height);
  transition: border-color var(--duration-fast) var(--ease-gentle);
  outline: none;
}

.chat__input::placeholder {
  color: var(--color-text-muted);
}

.chat__input:focus {
  border-color: var(--color-accent-light);
  box-shadow: 0 0 0 3px rgba(198, 123, 60, 0.1);
}

.chat__send {
  flex-shrink: 0;
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-accent);
  color: #FFF;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    opacity var(--duration-fast) var(--ease-gentle),
    transform var(--duration-fast) var(--ease-gentle);
}

.chat__send:disabled {
  background-color: var(--color-border);
  cursor: not-allowed;
  opacity: 0.6;
}

.chat__send:not(:disabled):hover {
  background-color: var(--color-accent-hover);
  transform: scale(1.05);
}

.chat__send:not(:disabled):active {
  transform: scale(0.95);
}

.chat__send:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

/* --- Discoveries Toggle --- */
.chat__discoveries-toggle {
  position: fixed;
  top: var(--space-md);
  right: var(--space-md);
  z-index: 20;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg);
  color: var(--color-accent);
  border: 1.5px solid var(--color-border);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 2px 8px var(--color-shadow);
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
}

.chat__discoveries-toggle[hidden] {
  display: none;
}

.chat__discoveries-toggle:hover,
.chat__discoveries-toggle:focus-visible {
  background-color: var(--color-bg-warm);
  box-shadow: 0 4px 16px var(--color-shadow);
}

.chat__discoveries-toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

.chat__discovery-badge {
  position: absolute;
  top: -4px;
  right: -4px;
  min-width: 18px;
  height: 18px;
  font-size: 0.65rem;
  font-weight: 600;
  line-height: 18px;
  text-align: center;
  color: #FFF;
  background-color: var(--color-accent);
  border-radius: var(--radius-full);
  padding: 0 4px;
}

.chat__discovery-badge[hidden] {
  display: none;
}

/* --- Discoveries Panel --- */
.discoveries-panel {
  position: fixed;
  top: 0;
  right: 0;
  z-index: 30;
  width: min(360px, 85vw);
  height: 100%;
  background-color: var(--color-bg);
  border-left: 1px solid var(--color-border);
  box-shadow: -4px 0 24px var(--color-shadow);
  display: flex;
  flex-direction: column;
  transform: translateX(100%);
  transition: transform var(--duration-normal) var(--ease-gentle);
  overflow: hidden;
}

.discoveries-panel[hidden] {
  /* Keep in DOM for transition; hidden by transform */
}

.discoveries-panel.open {
  transform: translateX(0);
}

.discoveries-panel__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-lg);
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}

.discoveries-panel__title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text);
}

.discoveries-panel__close {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  color: var(--color-text-muted);
  background: none;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition: color var(--duration-fast), background-color var(--duration-fast);
}

.discoveries-panel__close:hover {
  color: var(--color-text);
  background-color: var(--color-bg-warm);
}

.discoveries-panel__list {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-md) var(--space-lg);
  list-style: none;
}

.discoveries-panel__item {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--color-text);
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--color-border);
  animation: msgFadeIn var(--duration-normal) var(--ease-gentle) both;
}

.discoveries-panel__item::before {
  content: "💡 ";
}

.discoveries-panel__item:last-child {
  border-bottom: none;
}

.discoveries-panel__empty {
  padding: var(--space-2xl) var(--space-lg);
  text-align: center;
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

/* Overlay for panel on mobile */
.discoveries-overlay {
  position: fixed;
  inset: 0;
  z-index: 25;
  background-color: var(--color-overlay);
  opacity: 0;
  transition: opacity var(--duration-normal) var(--ease-gentle);
  pointer-events: none;
}

.discoveries-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

/* ================================================
   SCREEN 3: SUMMARY
   ================================================ */
.screen--summary {
  justify-content: center;
  align-items: center;
  background:
    radial-gradient(ellipse at 50% 40%, #FFF8F0 0%, #FEF0DE 70%, #F9E4C8 100%);
  padding: var(--space-xl);
  overflow-y: auto;
}

.summary__card {
  max-width: 560px;
  width: 100%;
  background-color: rgba(255, 255, 255, 0.7);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  box-shadow: 0 4px 24px var(--color-shadow);
  animation: fadeUp 0.6s var(--ease-gentle) both;
}

.summary__title {
  font-family: var(--font-serif);
  font-size: clamp(1.4rem, 4vw, 1.8rem);
  font-weight: 600;
  color: var(--color-text);
  text-align: center;
  margin-bottom: var(--space-2xl);
}

.summary__section-title {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-text-muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: var(--space-md);
}

.summary__discoveries {
  margin-bottom: var(--space-2xl);
}

.summary__list {
  list-style: none;
  padding: 0;
}

.summary__list li {
  font-family: var(--font-serif);
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--color-text);
  padding: var(--space-sm) 0;
  padding-left: var(--space-lg);
  position: relative;
}

.summary__list li::before {
  content: "💡";
  position: absolute;
  left: 0;
  top: var(--space-sm);
}

.summary__next-steps {
  margin-bottom: var(--space-2xl);
}

.summary__next-content {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  line-height: 1.8;
  color: var(--color-text-soft);
}

.summary__next-content p {
  margin-bottom: 0.6em;
}

.summary__actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  align-items: center;
}

.summary__btn {
  font-family: var(--font-sans);
  font-size: 1rem;
  font-weight: 500;
  border: none;
  border-radius: var(--radius-full);
  padding: 0.8rem 2.4rem;
  cursor: pointer;
  letter-spacing: 0.04em;
  transition:
    background-color var(--duration-fast) var(--ease-gentle),
    transform var(--duration-fast) var(--ease-gentle),
    box-shadow var(--duration-fast) var(--ease-gentle);
  min-width: 180px;
}

.summary__btn:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 3px;
}

.summary__btn--primary {
  color: #FFF;
  background-color: var(--color-accent);
  box-shadow: 0 2px 12px rgba(198, 123, 60, 0.25);
}

.summary__btn--primary:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(198, 123, 60, 0.35);
}

.summary__btn--secondary {
  color: var(--color-accent);
  background-color: transparent;
  border: 1.5px solid var(--color-accent-light);
}

.summary__btn--secondary:hover {
  background-color: var(--color-bg-warm);
  transform: translateY(-1px);
}

/* ================================================
   TOAST NOTIFICATION
   ================================================ */
.toast {
  position: fixed;
  bottom: calc(env(safe-area-inset-bottom, 0px) + var(--space-2xl) + 60px);
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  color: #FFF;
  background-color: var(--color-text);
  padding: var(--space-sm) var(--space-lg);
  border-radius: var(--radius-full);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
  opacity: 0;
  transition:
    opacity var(--duration-normal) var(--ease-gentle),
    transform var(--duration-normal) var(--ease-gentle);
  z-index: 100;
  pointer-events: none;
}

.toast[hidden] {
  display: block; /* Keep in flow for transition */
}

.toast.visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ================================================
   ERROR MESSAGE
   ================================================ */
.msg--error {
  max-width: var(--chat-max-width);
  margin: var(--space-md) auto;
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.88rem;
  color: var(--color-text-muted);
  padding: var(--space-md);
  background-color: var(--color-bg-warm);
  border-radius: var(--radius-md);
  border: 1px dashed var(--color-border);
  animation: msgFadeIn var(--duration-normal) var(--ease-gentle) both;
}

.msg--search-indicator {
  max-width: var(--chat-max-width);
  margin: var(--space-sm) auto;
  text-align: center;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--color-accent);
  padding: var(--space-sm) var(--space-md);
  animation: msgFadeIn var(--duration-fast) var(--ease-gentle) both;
  transition: opacity var(--duration-normal) var(--ease-gentle);
}

.msg--search-indicator .search-icon {
  margin-right: var(--space-xs);
}

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

@keyframes msgFadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes discoveryPop {
  0% {
    opacity: 0;
    transform: scale(0.96) translateY(8px);
  }
  60% {
    opacity: 1;
    transform: scale(1.01) translateY(0);
  }
  100% {
    transform: scale(1) translateY(0);
  }
}

@keyframes typingDot {
  0%, 60%, 100% {
    opacity: 0.3;
    transform: translateY(0);
  }
  30% {
    opacity: 1;
    transform: translateY(-3px);
  }
}

/* ================================================
   RESPONSIVE
   ================================================ */

/* Small phones (< 375px) */
@media (max-width: 374px) {
  :root {
    font-size: 14px;
  }

  .landing__headline {
    font-size: 1.4rem;
  }

  .msg {
    max-width: 90%;
    padding: var(--space-sm) var(--space-md);
  }
}

/* Tablets and up */
@media (min-width: 768px) {
  /* Sidebar always visible on desktop — no transform needed */
  .sidebar {
    transform: translateX(0);
    width: 260px;
    z-index: 15; /* below discoveries panel */
  }

  /* On desktop, hamburger stays visible as collapse toggle */
  .chat__sidebar-toggle {
    left: calc(260px + var(--space-md));
    transition: left var(--duration-normal) var(--ease-gentle),
      background-color var(--duration-fast) var(--ease-gentle),
      box-shadow var(--duration-fast) var(--ease-gentle);
  }

  /* Hide mobile overlay on desktop */
  .sidebar-overlay {
    display: none;
  }

  /* Chat screen shifts right to make room for sidebar */
  .screen--chat {
    left: 260px;
    transition: left var(--duration-normal) var(--ease-gentle);
  }

  /* Collapsed state on desktop */
  body.sidebar-collapsed .sidebar {
    transform: translateX(-100%);
  }
  body.sidebar-collapsed .screen--chat {
    left: 0;
  }
  body.sidebar-collapsed .chat__sidebar-toggle {
    left: var(--space-md);
  }

  /* Discoveries toggle: account for sidebar offset */
  .chat__discoveries-toggle {
    right: var(--space-md);
  }

  .chat__messages {
    padding: var(--space-2xl) var(--space-xl) 0;
  }

  .chat__input-area {
    padding: var(--space-lg) var(--space-xl);
  }

  .msg {
    max-width: 75%;
  }

  .msg--ai {
    font-size: 1.05rem;
  }

  .summary__card {
    padding: var(--space-3xl);
  }

  .summary__actions {
    flex-direction: row;
    justify-content: center;
  }
}

/* Desktop */
@media (min-width: 1024px) {
  .msg {
    max-width: 70%;
  }

  .landing__content {
    max-width: 600px;
  }
}

/* Respect motion preferences */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* High contrast */
@media (prefers-contrast: high) {
  :root {
    --color-bg-chat-ai: #F5E8D4;
    --color-bg-chat-user: #E0D0BC;
    --color-border: #C4B5A3;
    --color-text-muted: #6B5344;
  }
}

/* Dark mode hint - subtle, keeps warm feel */
@media (prefers-color-scheme: dark) {
  /* Intentionally not implementing full dark mode.
     The warm, book-like aesthetic is central to the design.
     Users on dark mode still get a comfortable reading experience
     thanks to the warm cream tones. */
}