/* ============================================================
   STUDY BUDDY – style.css
   Theme: Cute, minimalist, and friendly with light blue palette
   ============================================================ */

/* ── CSS Custom Properties (Design Tokens) ─────────────────── */
:root {
  /* Primary palette */
  --clr-primary:        #3B82F6;   /* Blue 500 */
  --clr-primary-light:  #BFDBFE;   /* Blue 200 */
  --clr-primary-xlight: #EFF6FF;   /* Blue 50  */
  --clr-primary-dark:   #1D4ED8;   /* Blue 700 */
  --clr-accent:         #60A5FA;   /* Blue 400 */

  /* Neutrals */
  --clr-white:          #FFFFFF;
  --clr-bg:             #F0F7FF;   /* Very light blue-tinted page bg */
  --clr-sidebar-bg:     #FFFFFF;
  --clr-bubble-bot:     #FFFFFF;
  --clr-bubble-user:    #BFDBFE;
  --clr-text:           #1E3A5F;   /* Deep navy for body text */
  --clr-text-soft:      #5A7FA8;
  --clr-text-muted:     #93B4D0;
  --clr-border:         #DBEAFE;   /* Blue 100 */
  --clr-shadow:         rgba(59,130,246,.12);

  /* Sizing */
  --sidebar-width:      260px;
  --header-height:      64px;
  --input-area-height:  80px;
  --border-radius:      16px;
  --border-radius-sm:   10px;
  --border-radius-xs:   6px;

  /* Typography */
  --font-main:          'Nunito', sans-serif;

  /* Transitions */
  --transition:         .2s ease;
  --transition-slow:    .35s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-main);
  background-color: var(--clr-bg);
  color: var(--clr-text);
  line-height: 1.6;
  min-height: 100dvh;
  overflow: hidden; /* prevent body scroll; inner areas scroll */
  -webkit-font-smoothing: antialiased;
}

button {
  font-family: var(--font-main);
  cursor: pointer;
  border: none;
  background: none;
}

textarea {
  font-family: var(--font-main);
  resize: none;
}

a {
  color: var(--clr-primary);
}

/* ── Scrollbar (Webkit) ─────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: var(--clr-primary-light);
  border-radius: 99px;
}

/* ============================================================
   LAYOUT
   ============================================================ */
.app-wrapper {
  display: flex;
  height: 100dvh;
  width: 100vw;
  overflow: hidden;
}

/* ── Sidebar ────────────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
  background: var(--clr-sidebar-bg);
  border-right: 1.5px solid var(--clr-border);
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-slow), width var(--transition-slow);
  z-index: 200;
  overflow: hidden;
}

.sidebar-header {
  padding: 20px 18px 16px;
  border-bottom: 1.5px solid var(--clr-border);
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-icon {
  font-size: 1.6rem;
  line-height: 1;
}

.logo-text {
  font-size: 1.25rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-dark));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -.3px;
}

.sidebar-body {
  flex: 1;
  overflow-y: auto;
  padding: 18px 12px;
}

.sidebar-label {
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--clr-text-muted);
  padding: 0 6px;
  margin-bottom: 10px;
}

.topic-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.topic-btn {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  text-align: left;
  padding: 10px 12px;
  border-radius: var(--border-radius-sm);
  font-size: .88rem;
  font-weight: 600;
  color: var(--clr-text-soft);
  transition: background var(--transition), color var(--transition), transform var(--transition);
}

.topic-btn:hover {
  background: var(--clr-primary-xlight);
  color: var(--clr-primary-dark);
  transform: translateX(3px);
}

.topic-icon {
  font-size: 1rem;
  flex-shrink: 0;
}

.sidebar-footer {
  padding: 16px 12px;
  border-top: 1.5px solid var(--clr-border);
}

.new-chat-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 12px;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-dark));
  color: #fff;
  border-radius: var(--border-radius-sm);
  font-size: .9rem;
  font-weight: 700;
  transition: opacity var(--transition), transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 14px var(--clr-shadow);
}

.new-chat-btn:hover {
  opacity: .9;
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(59,130,246,.25);
}

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

/* ── Chat Container ─────────────────────────────────────────── */
.chat-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100dvh;
  overflow: hidden;
  position: relative;
}

/* ── Chat Header ────────────────────────────────────────────── */
.chat-header {
  height: var(--header-height);
  min-height: var(--header-height);
  background: rgba(255,255,255,.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1.5px solid var(--clr-border);
  display: flex;
  align-items: center;
  padding: 0 20px;
  gap: 14px;
  z-index: 100;
  position: sticky;
  top: 0;
}

.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 6px;
  border-radius: var(--border-radius-xs);
  transition: background var(--transition);
}

.menu-toggle:hover { background: var(--clr-primary-xlight); }

.menu-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--clr-primary);
  border-radius: 99px;
  transition: transform var(--transition), opacity var(--transition);
}

.header-info {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
}

.buddy-avatar-sm {
  width: 38px;
  height: 38px;
  background: linear-gradient(135deg, var(--clr-primary-light), var(--clr-accent));
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  flex-shrink: 0;
}

.header-title {
  font-size: 1rem;
  font-weight: 800;
  color: var(--clr-text);
  line-height: 1.2;
}

.header-status {
  font-size: .75rem;
  color: var(--clr-text-soft);
  display: flex;
  align-items: center;
  gap: 5px;
  font-weight: 600;
}

.status-dot {
  width: 7px;
  height: 7px;
  background: #22c55e;
  border-radius: 50%;
  display: inline-block;
  animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50%       { opacity: .4; }
}

.new-chat-btn-mobile {
  display: none;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--clr-primary-xlight);
  font-size: 1rem;
  transition: background var(--transition);
}

.new-chat-btn-mobile:hover { background: var(--clr-primary-light); }

/* ── Messages Area ──────────────────────────────────────────── */
.messages-area {
  flex: 1;
  overflow-y: auto;
  padding: 28px 20px 16px;
  display: flex;
  flex-direction: column;
  gap: 18px;
  scroll-behavior: smooth;
}

/* ── Welcome State ──────────────────────────────────────────── */
.welcome-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  margin: auto;
  padding: 20px 10px;
  max-width: 560px;
  animation: fade-up .5s ease both;
}

.welcome-avatar {
  font-size: 4rem;
  line-height: 1;
  margin-bottom: 16px;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(-10px); }
}

.welcome-title {
  font-size: 1.55rem;
  font-weight: 800;
  color: var(--clr-text);
  margin-bottom: 8px;
  line-height: 1.3;
}

.welcome-subtitle {
  font-size: .95rem;
  color: var(--clr-text-soft);
  margin-bottom: 28px;
  font-weight: 500;
  line-height: 1.7;
}

.suggestion-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
}

.chip {
  background: var(--clr-white);
  border: 1.5px solid var(--clr-border);
  color: var(--clr-text);
  padding: 9px 16px;
  border-radius: 99px;
  font-size: .85rem;
  font-weight: 700;
  transition: background var(--transition), border-color var(--transition), transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 2px 8px var(--clr-shadow);
}

.chip:hover {
  background: var(--clr-primary-light);
  border-color: var(--clr-primary);
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(59,130,246,.2);
}

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

/* ── Message Bubbles ────────────────────────────────────────── */
.message-row {
  display: flex;
  gap: 10px;
  animation: fade-up .3s ease both;
  max-width: 100%;
}

@keyframes fade-up {
  from { opacity: 0; transform: translateY(14px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* User message – right aligned */
.message-row.user {
  flex-direction: row-reverse;
}

/* Avatar */
.msg-avatar {
  width: 34px;
  height: 34px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .95rem;
  flex-shrink: 0;
  align-self: flex-end;
  box-shadow: 0 2px 8px var(--clr-shadow);
}

.msg-avatar.bot-avatar {
  background: linear-gradient(135deg, var(--clr-primary-light), var(--clr-accent));
}

.msg-avatar.user-avatar {
  background: linear-gradient(135deg, #a78bfa, #7c3aed);
}

/* Bubble */
.msg-bubble {
  max-width: min(68%, 560px);
  padding: 13px 16px;
  border-radius: var(--border-radius);
  font-size: .93rem;
  font-weight: 500;
  line-height: 1.7;
  position: relative;
  word-break: break-word;
}

.message-row.bot .msg-bubble {
  background: var(--clr-bubble-bot);
  color: var(--clr-text);
  border-bottom-left-radius: 4px;
  box-shadow: 0 2px 12px var(--clr-shadow);
  border: 1.5px solid var(--clr-border);
}

.message-row.user .msg-bubble {
  background: var(--clr-bubble-user);
  color: var(--clr-primary-dark);
  border-bottom-right-radius: 4px;
  box-shadow: 0 2px 12px rgba(59,130,246,.15);
}

/* Timestamp */
.msg-time {
  font-size: .68rem;
  color: var(--clr-text-muted);
  margin-top: 5px;
  font-weight: 600;
  display: block;
  text-align: right;
}

.message-row.bot .msg-time { text-align: left; }

/* ── Markdown Rendered Styles ───────────────────────────────── */
.msg-bubble p { margin-bottom: .5em; }
.msg-bubble p:last-child { margin-bottom: 0; }

.msg-bubble strong { font-weight: 800; color: var(--clr-primary-dark); }
.message-row.user .msg-bubble strong { color: var(--clr-primary-dark); }

.msg-bubble em { font-style: italic; }

.msg-bubble ul, .msg-bubble ol {
  padding-left: 1.4em;
  margin: .5em 0;
}

.msg-bubble li { margin-bottom: .25em; }

.msg-bubble code {
  background: var(--clr-primary-xlight);
  color: var(--clr-primary-dark);
  padding: 2px 6px;
  border-radius: var(--border-radius-xs);
  font-family: 'Courier New', monospace;
  font-size: .85em;
}

.msg-bubble pre {
  background: #1e2a3a;
  color: #e2e8f0;
  padding: 14px;
  border-radius: var(--border-radius-sm);
  overflow-x: auto;
  margin: .75em 0;
  font-size: .83em;
  line-height: 1.6;
}

.msg-bubble pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: 1em;
}

.msg-bubble h1, .msg-bubble h2, .msg-bubble h3 {
  font-weight: 800;
  margin: .6em 0 .3em;
  color: var(--clr-primary-dark);
}

.msg-bubble blockquote {
  border-left: 3px solid var(--clr-primary);
  padding-left: 12px;
  color: var(--clr-text-soft);
  margin: .5em 0;
  font-style: italic;
}

/* ── Error Bubble ───────────────────────────────────────────── */
.msg-bubble.error {
  background: #FEF2F2;
  border-color: #FCA5A5;
  color: #991B1B;
}

/* ── Typing Indicator ───────────────────────────────────────── */
.typing-indicator {
  padding: 0 20px 12px;
}

.typing-bubble {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--clr-white);
  border: 1.5px solid var(--clr-border);
  border-radius: var(--border-radius);
  border-bottom-left-radius: 4px;
  padding: 10px 14px;
  box-shadow: 0 2px 12px var(--clr-shadow);
  animation: fade-up .25s ease both;
}

.buddy-avatar-xs {
  font-size: .9rem;
}

.typing-dots {
  display: flex;
  gap: 4px;
  align-items: center;
}

.typing-dots span {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--clr-primary);
  animation: bounce-dot .9s ease infinite;
}

.typing-dots span:nth-child(2) { animation-delay: .15s; }
.typing-dots span:nth-child(3) { animation-delay: .3s;  }

@keyframes bounce-dot {
  0%, 80%, 100% { transform: translateY(0);   opacity: .5; }
  40%            { transform: translateY(-7px); opacity: 1;  }
}

.typing-text {
  font-size: .8rem;
  color: var(--clr-text-muted);
  font-weight: 600;
}

/* ── Input Area ─────────────────────────────────────────────── */
.input-area {
  background: rgba(255,255,255,.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1.5px solid var(--clr-border);
  padding: 12px 20px 14px;
  flex-shrink: 0;
}

.input-wrapper {
  display: flex;
  gap: 10px;
  align-items: flex-end;
  background: var(--clr-white);
  border: 2px solid var(--clr-border);
  border-radius: var(--border-radius);
  padding: 8px 8px 8px 16px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.input-wrapper:focus-within {
  border-color: var(--clr-primary);
  box-shadow: 0 0 0 3px rgba(59,130,246,.15);
}

.message-input {
  flex: 1;
  border: none;
  outline: none;
  font-size: .95rem;
  font-weight: 600;
  color: var(--clr-text);
  background: transparent;
  max-height: 140px;
  overflow-y: auto;
  padding: 4px 0;
  line-height: 1.5;
}

.message-input::placeholder {
  color: var(--clr-text-muted);
  font-weight: 500;
}

.send-btn {
  width: 40px;
  height: 40px;
  min-width: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-dark));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity var(--transition), transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 3px 10px rgba(59,130,246,.3);
  flex-shrink: 0;
}

.send-btn:hover:not(:disabled) {
  transform: scale(1.08);
  box-shadow: 0 5px 16px rgba(59,130,246,.4);
}

.send-btn:active:not(:disabled) { transform: scale(.97); }

.send-btn:disabled {
  opacity: .4;
  cursor: not-allowed;
  box-shadow: none;
}

.input-hint {
  font-size: .7rem;
  color: var(--clr-text-muted);
  text-align: center;
  margin-top: 6px;
  font-weight: 600;
}

.input-hint kbd {
  background: var(--clr-primary-xlight);
  border: 1px solid var(--clr-border);
  border-radius: 4px;
  padding: 1px 5px;
  font-size: .68rem;
  font-family: var(--font-main);
}

/* ── Modal ──────────────────────────────────────────────────── */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15,30,60,.45);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 999;
  padding: 16px;
}

.modal-backdrop[hidden] { display: none; }

.modal-card {
  background: var(--clr-white);
  border-radius: 24px;
  padding: 36px 32px;
  max-width: 440px;
  width: 100%;
  text-align: center;
  box-shadow: 0 20px 60px rgba(59,130,246,.2);
  animation: fade-up .3s ease both;
}

.modal-icon {
  font-size: 3rem;
  margin-bottom: 12px;
}

.modal-title {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--clr-text);
  margin-bottom: 14px;
}

.modal-body {
  font-size: .92rem;
  color: var(--clr-text-soft);
  line-height: 1.7;
  font-weight: 500;
  margin-bottom: 24px;
}

.modal-body code {
  background: var(--clr-primary-xlight);
  color: var(--clr-primary-dark);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: .88em;
}

.modal-close-btn {
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-primary-dark));
  color: #fff;
  padding: 12px 32px;
  border-radius: 99px;
  font-size: .95rem;
  font-weight: 700;
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 14px rgba(59,130,246,.3);
}

.modal-close-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(59,130,246,.4);
}

/* ============================================================
   RESPONSIVE – Mobile (≤ 768px)
   ============================================================ */
@media (max-width: 768px) {
  :root {
    --sidebar-width: 100vw;
  }

  .sidebar {
    position: fixed;
    top: 0;
    left: 0;
    height: 100dvh;
    transform: translateX(-100%);
    box-shadow: 4px 0 24px rgba(59,130,246,.2);
  }

  /* When sidebar is open on mobile */
  .sidebar.open {
    transform: translateX(0);
  }

  /* Overlay behind sidebar on mobile */
  .sidebar-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15,30,60,.35);
    z-index: 199;
    display: none;
  }
  .sidebar-overlay.visible { display: block; }

  .menu-toggle {
    display: flex;
  }

  .new-chat-btn-mobile {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .messages-area {
    padding: 20px 14px 10px;
  }

  .msg-bubble {
    max-width: 85%;
    font-size: .9rem;
  }

  .input-area {
    padding: 10px 14px 12px;
  }

  .welcome-title { font-size: 1.3rem; }
  .welcome-subtitle { font-size: .88rem; }
  .chip { font-size: .8rem; padding: 8px 14px; }
}

/* ── Very small screens ──────────────────────────────────────── */
@media (max-width: 380px) {
  .msg-bubble { max-width: 92%; }
  .welcome-title { font-size: 1.15rem; }
}

/* ── Large screens (≥ 1200px) ───────────────────────────────── */
@media (min-width: 1200px) {
  .messages-area {
    padding: 32px 60px 16px;
  }
  .input-area {
    padding: 14px 60px 16px;
  }
  .typing-indicator {
    padding: 0 60px 14px;
  }
  .msg-bubble {
    max-width: 56%;
  }
}