/* ═══════════════════════════════════════════════════════
   EXAM GUIDE — Premium Design System
   ═══════════════════════════════════════════════════════ */

:root {
  --sky: #0369a1;
  --sky-light: #38bdf8;
  --indigo: #4f46e5;
  --ink: #0f172a;
  --surface: rgba(255, 255, 255, 0.82);
  --surface-border: rgba(255, 255, 255, 0.7);
  --shadow-soft: 0 20px 60px rgba(15, 23, 42, 0.08);
  --shadow-card: 0 8px 32px rgba(15, 23, 42, 0.07);
  --shadow-elevated: 0 24px 70px rgba(15, 23, 42, 0.12);
  --radius-card: 1.5rem;
  --radius-pill: 999px;
  --transition-fast: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 380ms cubic-bezier(0.4, 0, 0.2, 1);
  --gradient-brand: linear-gradient(135deg, #0369a1 0%, #2563eb 50%, #4f46e5 100%);
  --gradient-hero: linear-gradient(135deg, #055B93 0%, #047DD8 100%);
}

/* ── Reset & Base ──────────────────────────────────── */
* {
  letter-spacing: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Tiro Bangla", "Inter", Arial, Helvetica, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

img {
  display: block;
  max-width: 100%;
}

/* ══════════════════════════════════════════════════════
   PAGE LOADER — 4-dot spinner (same as Next.js version)
   ══════════════════════════════════════════════════════ */
.page-loader {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #f8fbff 0%, #eef7ff 48%, #fff6fb 100%);
  transition: opacity 500ms ease, visibility 500ms ease;
}

.page-loader.is-hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.loader-dots {
  position: relative;
  width: 6.25em;
  height: 6.25em;
}

.loader-dot {
  position: absolute;
  width: 2.4em;
  height: 2.4em;
  border-radius: 50%;
  margin: auto;
}

/* White pulsing center dot */
.loader-dot--center {
  inset: 0;
  background: white;
  animation: loaderPulse 1.2s ease-in-out infinite;
}

/* Top dot (gold) */
.loader-dot:nth-child(2) {
  background: #FFBB33;
  top: 0;
  left: 0;
  right: 0;
  animation: loaderTop 1.2s ease-in-out infinite;
}

/* Right dot (green) */
.loader-dot:nth-child(3) {
  background: #99CC00;
  top: 0;
  bottom: 0;
  right: 0;
  animation: loaderRight 1.2s ease-in-out infinite;
}

/* Bottom dot (blue) */
.loader-dot:nth-child(4) {
  background: #33B5E5;
  bottom: 0;
  left: 0;
  right: 0;
  animation: loaderBottom 1.2s ease-in-out infinite;
}

/* Left dot (red) */
.loader-dot:nth-child(5) {
  background: #FF4444;
  top: 0;
  bottom: 0;
  left: 0;
  animation: loaderLeft 1.2s ease-in-out infinite;
}

@keyframes loaderPulse {
  0%, 100% { transform: scale(0.6); opacity: 0; }
  50% { transform: scale(1); opacity: 1; }
}

@keyframes loaderTop {
  0% { transform: scale(1); top: 0; }
  25% { transform: scale(0.4); }
  50% { top: calc(50% - 1.2em); transform: scale(1); }
  75% { transform: scale(0.4); }
  100% { transform: scale(1); top: 0; }
}

@keyframes loaderRight {
  0% { transform: scale(1); right: 0; }
  25% { transform: scale(0.4); }
  50% { right: calc(50% - 1.2em); transform: scale(1); }
  75% { transform: scale(0.4); }
  100% { transform: scale(1); right: 0; }
}

@keyframes loaderBottom {
  0% { transform: scale(1); bottom: 0; }
  25% { transform: scale(0.4); }
  50% { bottom: calc(50% - 1.2em); transform: scale(1); }
  75% { transform: scale(0.4); }
  100% { transform: scale(1); bottom: 0; }
}

@keyframes loaderLeft {
  0% { transform: scale(1); left: 0; }
  25% { transform: scale(0.4); }
  50% { left: calc(50% - 1.2em); transform: scale(1); }
  75% { transform: scale(0.4); }
  100% { transform: scale(1); left: 0; }
}

/* ── Background ────────────────────────────────────── */
.modern-bg {
  background:
    radial-gradient(ellipse 80% 60% at 10% 0%, rgba(14, 165, 233, 0.15), transparent),
    radial-gradient(ellipse 60% 50% at 90% 10%, rgba(79, 70, 229, 0.12), transparent),
    radial-gradient(ellipse 50% 40% at 50% 100%, rgba(236, 72, 153, 0.06), transparent),
    linear-gradient(135deg, #f8fbff 0%, #eef7ff 48%, #fff6fb 100%);
  min-height: 100vh;
}

/* ══════════════════════════════════════════════════════
   HEADER & NAVIGATION
   ══════════════════════════════════════════════════════ */
.site-header {
  animation: slideDown 520ms cubic-bezier(0.4, 0, 0.2, 1) both;
  transition: background var(--transition-fast), box-shadow var(--transition-fast);
}

.site-header.is-scrolled {
  background: rgba(255, 255, 255, 0.95) !important;
  box-shadow: 0 4px 30px rgba(15, 23, 42, 0.08);
  border-bottom-color: transparent;
}

.brand-lockup span:first-child {
  animation: brandPulse 3s ease-in-out infinite;
}

/* Nav Links */
.nav-link {
  position: relative;
  transition: color var(--transition-fast), background var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
}

.nav-link:hover {
  transform: translateY(-2px);
}

.nav-link.active {
  box-shadow: 0 4px 16px rgba(3, 105, 161, 0.25);
}

/* Icon Buttons */
.icon-button {
  display: grid;
  height: 2.65rem;
  width: 2.65rem;
  place-items: center;
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.8);
  color: var(--sky);
  box-shadow: var(--shadow-card);
  cursor: pointer;
  border: 1px solid rgba(255, 255, 255, 0.6);
  transition: transform var(--transition-fast), background var(--transition-fast), box-shadow var(--transition-fast);
}

.icon-button:hover {
  transform: translateY(-2px) scale(1.05);
  background: white;
  box-shadow: 0 12px 28px rgba(3, 105, 161, 0.15);
}

.icon-button:active {
  transform: scale(0.92);
}

/* Mobile Panel */
.mobile-panel {
  animation: mobileSlide 300ms cubic-bezier(0.4, 0, 0.2, 1) both;
}

.mobile-panel a {
  transition: background var(--transition-fast), transform var(--transition-fast);
}

.mobile-panel a:hover {
  transform: translateX(4px);
}

/* ── CTA / Modern Button ──────────────────────────── */
.btn-modern {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
  background: var(--gradient-brand);
  color: #fff;
  font-weight: 800;
  border: none;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.28);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), filter var(--transition-fast);
}

.btn-modern:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 36px rgba(37, 99, 235, 0.35);
  filter: brightness(1.06);
}

.btn-modern:active {
  transform: translateY(0) scale(0.97);
}

/* ── Social Buttons ───────────────────────────────── */
.social-button {
  display: grid;
  height: 2.5rem;
  width: 2.5rem;
  place-items: center;
  border-radius: 0.85rem;
  background: #f1f5f9;
  color: #334155;
  cursor: pointer;
  transition: transform var(--transition-fast), background var(--transition-fast), color var(--transition-fast), box-shadow var(--transition-fast);
}

.social-button:hover {
  transform: translateY(-3px) scale(1.08);
  background: var(--sky);
  color: white;
  box-shadow: 0 8px 20px rgba(3, 105, 161, 0.3);
}

/* ══════════════════════════════════════════════════════
   SEARCH MODAL
   ══════════════════════════════════════════════════════ */
.search-modal.flex {
  animation: fadeIn 200ms ease both;
}

.search-panel {
  animation: searchPop 280ms cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

/* ══════════════════════════════════════════════════════
   HERO SECTION
   ══════════════════════════════════════════════════════ */
.hero-shell {
  box-shadow: 0 30px 80px rgba(15, 23, 42, 0.2);
  position: relative;
}

.hero-shell::after {
  content: "";
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.15), rgba(79, 70, 229, 0.1));
  pointer-events: none;
  z-index: 0;
}

.hero-content {
  animation: riseIn 650ms cubic-bezier(0.4, 0, 0.2, 1) both;
  animation-delay: 200ms;
}

.hero-slide-enter {
  animation: heroFade 450ms ease both;
}

/* Hero slide dots / indicators */
.hero-indicators {
  position: absolute;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 0.5rem;
  z-index: 20;
}

.hero-dot {
  width: 0.5rem;
  height: 0.5rem;
  border-radius: var(--radius-pill);
  background: rgba(255, 255, 255, 0.45);
  border: none;
  cursor: pointer;
  transition: width var(--transition-fast), background var(--transition-fast);
}

.hero-dot.active {
  width: 1.5rem;
  background: white;
}

/* ══════════════════════════════════════════════════════
   SECTION HEADINGS
   ══════════════════════════════════════════════════════ */
.section-heading {
  position: relative;
}

.section-heading::after {
  content: "";
  display: block;
  width: 4rem;
  height: 0.25rem;
  margin-top: 0.6rem;
  border-radius: var(--radius-pill);
  background: var(--gradient-brand);
  animation: underlineGrow 600ms ease both;
}

/* ══════════════════════════════════════════════════════
   REVEAL ANIMATIONS (Scroll-triggered)
   ══════════════════════════════════════════════════════ */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 600ms cubic-bezier(0.4, 0, 0.2, 1), transform 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger delay classes for cards */
.reveal-delay-1 { transition-delay: 80ms; }
.reveal-delay-2 { transition-delay: 160ms; }
.reveal-delay-3 { transition-delay: 240ms; }
.reveal-delay-4 { transition-delay: 320ms; }
.reveal-delay-5 { transition-delay: 400ms; }

/* ══════════════════════════════════════════════════════
   ARTICLE CARDS — Premium hover effects
   ══════════════════════════════════════════════════════ */
.article-card {
  color: inherit;
  text-decoration: none;
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth), border-color var(--transition-smooth);
  will-change: transform;
}

.article-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 50px rgba(15, 23, 42, 0.12);
  border-color: rgba(56, 189, 248, 0.3);
}

.article-card img {
  background: #e2e8f0;
  transition: transform 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

.article-card:hover img {
  transform: scale(1.06);
}

/* Category badge on cards */
.article-card .category-badge {
  transition: transform var(--transition-fast);
}

.article-card:hover .category-badge {
  transform: translateY(-2px);
}

/* ══════════════════════════════════════════════════════
   GLASSMORPHISM SURFACES
   ══════════════════════════════════════════════════════ */
.form-surface,
.info-surface {
  border: 1px solid var(--surface-border);
  background: var(--surface);
  box-shadow: var(--shadow-elevated);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  transition: box-shadow var(--transition-smooth), transform var(--transition-smooth);
}

.form-surface:hover,
.info-surface:hover {
  box-shadow: 0 28px 80px rgba(15, 23, 42, 0.14);
}

/* ══════════════════════════════════════════════════════
   PAGE BANNER (List, About, Contact pages)
   ══════════════════════════════════════════════════════ */
.page-banner {
  position: relative;
  overflow: hidden;
}

.page-banner::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--gradient-hero);
}

.page-banner::after {
  content: "";
  position: absolute;
  width: 300px;
  height: 300px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.06);
  top: -80px;
  right: -60px;
  animation: floatBlob 8s ease-in-out infinite;
}

/* ══════════════════════════════════════════════════════
   SCROLL PROGRESS BAR
   ══════════════════════════════════════════════════════ */
.js-progress {
  transition: width 100ms linear;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.4);
}

/* ══════════════════════════════════════════════════════
   ARTICLE VIEW (Content)
   ══════════════════════════════════════════════════════ */
.article-view {
  color: #1f2937;
  line-height: 1.85;
  font-size: 1.08rem;
}

.article-view h1,
.article-view h2,
.article-view h3 {
  color: var(--ink);
  font-weight: 800;
  line-height: 1.25;
  margin: 1.75rem 0 0.75rem;
}

.article-view h1 { font-size: 2rem; }
.article-view h2 { font-size: 1.6rem; }
.article-view h3 { font-size: 1.35rem; }

.article-view p,
.article-view ul,
.article-view ol {
  margin: 1rem 0;
}

.article-view a {
  color: var(--sky);
  font-weight: 600;
  transition: color var(--transition-fast);
}

.article-view a:hover {
  color: var(--indigo);
}

.article-view img {
  border-radius: 1rem;
  margin: 1.5rem auto;
  max-width: 100%;
  box-shadow: var(--shadow-card);
}

.article-view table {
  display: block;
  max-width: 100%;
  overflow-x: auto;
  border-collapse: collapse;
}

.article-view th,
.article-view td {
  border: 1px solid #cbd5e1;
  padding: 0.625rem 0.85rem;
}

.article-view th {
  background: #f1f5f9;
  font-weight: 700;
}

.article-view blockquote {
  border-left: 4px solid var(--sky);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: rgba(3, 105, 161, 0.04);
  border-radius: 0 var(--radius-card) var(--radius-card) 0;
  font-style: italic;
}

/* ══════════════════════════════════════════════════════
   LINE CLAMP
   ══════════════════════════════════════════════════════ */
.line-clamp-2 {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* ══════════════════════════════════════════════════════
   BACK TO TOP
   ══════════════════════════════════════════════════════ */
.js-back-to-top {
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
  box-shadow: 0 8px 24px rgba(3, 105, 161, 0.3);
}

.js-back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: 0 14px 36px rgba(3, 105, 161, 0.4);
}

/* ══════════════════════════════════════════════════════
   SKELETON SHIMMER (loading states)
   ══════════════════════════════════════════════════════ */
.skeleton {
  background: linear-gradient(90deg, #e2e8f0 25%, #f1f5f9 37%, #e2e8f0 63%);
  background-size: 400% 100%;
  animation: shimmer 1.4s ease infinite;
  border-radius: 0.75rem;
}

/* ══════════════════════════════════════════════════════
   CATEGORY FILTER PILLS
   ══════════════════════════════════════════════════════ */
.js-category-filter {
  cursor: pointer;
  border: none;
  transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast), box-shadow var(--transition-fast);
  white-space: nowrap;
}

.js-category-filter:hover {
  transform: translateY(-1px);
}

.js-category-filter:active {
  transform: scale(0.95);
}

/* ══════════════════════════════════════════════════════
   FORM INPUTS (focus ring effect)
   ══════════════════════════════════════════════════════ */
input:focus,
textarea:focus {
  border-color: var(--sky) !important;
  box-shadow: 0 0 0 4px rgba(3, 105, 161, 0.1) !important;
  outline: none;
}

/* ══════════════════════════════════════════════════════
   TOAST NOTIFICATION
   ══════════════════════════════════════════════════════ */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%) translateY(120%);
  padding: 0.85rem 1.5rem;
  border-radius: var(--radius-pill);
  font-size: 0.9rem;
  font-weight: 700;
  color: white;
  box-shadow: 0 12px 36px rgba(0,0,0,0.18);
  z-index: 9999;
  transition: transform 400ms cubic-bezier(0.34, 1.56, 0.64, 1);
  pointer-events: none;
}

.toast.show {
  transform: translateX(-50%) translateY(0);
}

.toast.success { background: #059669; }
.toast.error   { background: #dc2626; }

/* ══════════════════════════════════════════════════════
   KEYFRAME ANIMATIONS
   ══════════════════════════════════════════════════════ */
@keyframes slideDown {
  from { opacity: 0; transform: translateY(-20px); }
  to { opacity: 1; transform: translateY(0); }
}

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

@keyframes searchPop {
  from { opacity: 0; transform: translateY(16px) scale(0.96); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes mobileSlide {
  from { opacity: 0; transform: translateY(-12px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes riseIn {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes heroFade {
  from { opacity: 0; transform: scale(1.02); }
  to { opacity: 1; transform: scale(1); }
}

@keyframes brandPulse {
  0%, 100% { box-shadow: 0 12px 28px rgba(3, 105, 161, 0.22); }
  50% { box-shadow: 0 16px 40px rgba(79, 70, 229, 0.28); }
}

@keyframes underlineGrow {
  from { width: 0; }
  to { width: 4rem; }
}

@keyframes shimmer {
  0% { background-position: -400% 0; }
  100% { background-position: 400% 0; }
}

@keyframes floatBlob {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(20px, -20px) scale(1.1); }
  66% { transform: translate(-10px, 10px) scale(0.95); }
}

@keyframes bounceIn {
  0% { opacity: 0; transform: scale(0.3); }
  50% { opacity: 1; transform: scale(1.05); }
  70% { transform: scale(0.95); }
  100% { transform: scale(1); }
}

/* ══════════════════════════════════════════════════════
   REDUCED MOTION
   ══════════════════════════════════════════════════════ */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 1ms !important;
    scroll-behavior: auto !important;
    transition-duration: 1ms !important;
  }
  .page-loader { display: none !important; }
}

/* ══════════════════════════════════════════════════════
   QUESTION STYLES (Dynamic Content)
   ══════════════════════════════════════════════════════ */
.article-view .header {
  background: white;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  padding: 24px;
  margin-bottom: 24px;
  border: 1px solid #e0e0e0;
}

.article-view .header h1 {
  font-size: 28px;
  font-weight: 700;
  color: #424242;
  text-align: center;
  margin: 0;
}

.questions-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .questions-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.question-card {
  background: white;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  padding: 24px;
  border: 1px solid #e0e0e0;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.question-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.question-header {
  background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
  padding: 20px;
  border-radius: 12px;
  border: 1px solid #bbdefb;
  margin-bottom: 20px;
}

.article-view .question-header h2 {
  font-size: 18px;
  font-weight: 700;
  color: #424242;
  line-height: 1.4;
  margin: 0;
}

.options-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 20px;
}

.option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 16px;
  background: #f5f5f5;
  border-radius: 12px;
  border: 1px solid #e0e0e0;
  cursor: pointer;
  transition: all 0.2s ease;
}

.option:not(.disabled):hover {
  background: #e3f2fd;
  border-color: #64b5f6;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.05);
}

.option.correct {
  background: #e8f5e9;
  border-color: #4caf50;
}

.option.correct .option-letter {
  background: #4caf50;
  color: white;
  border-color: #388e3c;
}

.option.wrong {
  background: #ffebee;
  border-color: #f44336;
}

.option.wrong .option-letter {
  background: #f44336;
  color: white;
  border-color: #d32f2f;
}

.option.disabled {
  cursor: default;
  pointer-events: none;
}

.option-letter {
  height: 32px;
  width: 32px;
  background: #e0e0e0;
  color: #424242;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-weight: 700;
  font-size: 14px;
  border: 1px solid #bdbdbd;
}

.option-text {
  font-size: 14px;
  font-weight: 500;
  color: #424242;
}

.answer-section {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
  padding-top: 0;
  border-top: 1px solid transparent;
}

.answer-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.answer-info {
  display: flex;
  align-items: center;
  gap: 8px;
}

.answer-label {
  font-size: 14px;
  font-weight: 700;
  color: #424242;
}

.correct-answer {
  height: 24px;
  width: 24px;
  background: #43a047;
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-weight: 700;
  font-size: 12px;
}

.answer-text {
  font-size: 14px;
  font-weight: 500;
  color: #424242;
}

.check-icon {
  color: #43a047;
  font-size: 20px;
}

.toggle-btn {
  background: #1976d2;
  color: white;
  border: none;
  padding: 12px 20px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0 auto;
}

.toggle-btn:hover {
  background: #1565c0;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(25, 118, 210, 0.3);
}

/* Hide checkbox */
.answer-toggle {
  display: none !important;
}

/* Show answer when checkbox is checked */
.answer-toggle:checked ~ .answer-section {
  max-height: 200px;
  padding-top: 20px;
  border-top: 1px solid #e0e0e0;
}

/* Change button text when checkbox is checked */
.answer-toggle:checked + .toggle-btn .show-text {
  display: none;
}

.answer-toggle:checked + .toggle-btn .hide-text {
  display: inline;
}

.toggle-btn .hide-text {
  display: none;
}

.toggle-btn .show-text {
  display: inline;
}

/* Rotate icon when expanded */
.answer-toggle:checked + .toggle-btn .fa-chevron-down {
  transform: rotate(180deg);
}

.toggle-btn .fa-chevron-down {
  transition: transform 0.3s ease;
}