/* ============================================
   QuickMem Design System
   Based on app's teal/cyan visual identity
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;500;600;700;800&display=swap');

:root {
  /* Brand Colors */
  --primary: #0097A7;
  --primary-light: #B2EBF2;
  --primary-lighter: #E0F7FA;
  --primary-dark: #00796B;
  --accent: #FF6D4A;
  --accent-hover: #E85A38;

  /* Neutral Colors */
  --bg: #F5F9FA;
  --card-bg: #FFFFFF;
  --text: #1A2B3C;
  --text-muted: #5A6B7C;
  --text-light: #8A9BAC;
  --border: #E0ECF0;

  /* Feature Card Colors (from app) */
  --card-learn: #80DEEA;
  --card-flashcard: #5C6BC0;
  --card-check: #FFD54F;
  --card-match: #FFAB91;

  /* Spacing */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 151, 167, 0.08);
  --shadow-md: 0 4px 16px rgba(0, 151, 167, 0.1);
  --shadow-lg: 0 8px 32px rgba(0, 151, 167, 0.12);
  --shadow-card: 0 2px 12px rgba(0, 0, 0, 0.06);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Nunito', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text);
  line-height: 1.6;
  background-color: var(--bg);
  -webkit-font-smoothing: antialiased;
}

@media (prefers-reduced-motion: reduce) {

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* ============================================
   Header
   ============================================ */
header {
  background-color: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  padding: 0 24px;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  height: 64px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}

.logo img {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
}

.logo span {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.02em;
}

nav {
  padding: 0;
}

nav ul {
  display: flex;
  list-style: none;
  align-items: center;
  gap: 8px;
}

nav ul li {
  margin: 0;
}

nav ul li a {
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  padding: 8px 14px;
  border-radius: var(--radius-full);
  transition: all 0.2s ease-out;
}

nav ul li a:hover,
nav ul li a:focus {
  color: var(--primary);
  background-color: var(--primary-lighter);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
  background: linear-gradient(180deg, var(--primary-lighter) 0%, var(--bg) 100%);
  padding: 80px 24px 60px;
  text-align: center;
  overflow: hidden;
}

.hero .content {
  max-width: 1200px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 16px;
  color: var(--text);
  letter-spacing: -0.03em;
  line-height: 1.2;
}

.hero p {
  font-size: 1.15rem;
  margin-bottom: 32px;
  line-height: 1.6;
  color: var(--text-muted);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero .btn {
  display: inline-block;
  background: var(--accent);
  color: white;
  padding: 14px 36px;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-full);
  text-decoration: none;
  transition: all 0.2s ease-out;
  box-shadow: 0 4px 16px rgba(255, 109, 74, 0.3);
  font-family: inherit;
  cursor: pointer;
}

.hero .btn:hover,
.hero .btn:focus {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(255, 109, 74, 0.4);
}

/* ============================================
   Feature Cards
   ============================================ */
.feature-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 56px;
  max-width: 1000px;
  margin-left: auto;
  margin-right: auto;
  padding: 0 20px;
}

.feature-card {
  border-radius: var(--radius-xl);
  height: 300px;
  box-shadow: var(--shadow-card);
  text-align: center;
  transition: transform 0.2s ease-out, box-shadow 0.2s ease-out;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  overflow: hidden;
  cursor: pointer;
}

.feature-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
}

.feature-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 0;
  padding: 16px 16px 8px;
  color: var(--text);
}

.feature-card img {
  width: 80px;
  margin-bottom: 20px;
}

.feature-card .imgcard {
  flex: 1;
  display: flex;
  align-items: flex-end;
  justify-content: flex-end;
}

.imgcard img {
  border-radius: var(--radius-lg) 0 var(--radius-xl) 0;
}

/* Card Colors */
#card-1 {
  background-color: var(--card-learn);
}

#card-1 img {
  width: 220px;
  height: 220px;
  background-color: #fff;
  padding: 20px 0 0 16px;
  border-radius: var(--radius-lg) 0 0 0;
}

#card-2 {
  background-color: var(--card-flashcard);
}

#card-2 h3 {
  color: #fff;
}

#card-2 img {
  width: 200px;
  height: 200px;
  padding: 8px;
  margin: auto;
}

#card-3 {
  background-color: var(--card-check);
}

#card-3 img {
  width: 220px;
  height: 220px;
  background-color: #fff;
  padding: 20px 0 0 16px;
  border-radius: var(--radius-lg) 0 0 0;
}

#card-4 {
  background-color: var(--card-match);
}

#card-4 img {
  width: 220px;
  height: 220px;
  background-color: #fff;
  padding: 20px 0 0 16px;
  border-radius: var(--radius-lg) 0 0 0;
}

/* ============================================
   About Section
   ============================================ */
.about {
  padding: 80px 24px;
}

.about-features {
  display: flex;
  flex-direction: column;
  max-width: 1000px;
  margin: 0 auto;
  gap: 64px;
}

.about-feature {
  display: flex;
  align-items: center;
  gap: 48px;
}

.about-feature-reverse {
  display: flex;
  flex-direction: row-reverse;
  align-items: center;
  gap: 48px;
}

.feature-text {
  flex: 1;
  padding: 0;
}

#feature-text-tab2 {
  padding: 0;
}

.feature-text h3 {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--text);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
  line-height: 1.3;
}

.feature-text p {
  font-size: 1.05rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.feature-image {
  flex: 1;
  text-align: center;
}

.feature-image img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

/* ============================================
   Team Section
   ============================================ */
.team {
  padding: 80px 24px;
  text-align: center;
  background-color: var(--card-bg);
}

.team h2 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 48px;
  color: var(--text);
  letter-spacing: -0.02em;
}

.team-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 32px;
  max-width: 1000px;
  margin: 0 auto;
}

.team-member {
  text-align: center;
  padding: 24px 16px;
  border-radius: var(--radius-lg);
  transition: all 0.2s ease-out;
}

.team-member:hover {
  background-color: var(--primary-lighter);
}

.team-member img {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  border: 3px solid var(--primary-light);
  transition: all 0.2s ease-out;
  object-fit: cover;
}

.team-member:hover img {
  border-color: var(--primary);
  transform: scale(1.05);
}

.team-member h3 {
  font-size: 1rem;
  margin-top: 8px;
  color: var(--text);
  font-weight: 700;
}

.team-member p {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
}

.github-username {
  font-size: 0.8rem;
  color: var(--text-light);
  margin-top: 8px;
  margin-bottom: 4px;
  font-weight: 600;
}

.github-username a,
.team-member h3 a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 700;
}

.github-username a:hover,
.team-member h3 a:hover {
  text-decoration: underline;
  color: var(--primary-dark);
}

/* ============================================
   Download Section
   ============================================ */
.download {
  text-align: center;
  padding: 48px 24px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
}

.download h2 {
  font-size: 2rem;
  font-weight: 800;
  color: #fff;
  margin-bottom: 24px;
  letter-spacing: -0.02em;
}

.download-buttons {
  display: flex;
  justify-content: center;
  gap: 20px;
}

.download-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4px;
  border-radius: var(--radius-md);
  transition: all 0.2s ease-out;
  cursor: pointer;
}

.download-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.google-play img,
.app-store img {
  height: 56px;
  width: auto;
  border-radius: var(--radius-sm);
}

/* ============================================
   Source Code Section
   ============================================ */
.source-code {
  text-align: center;
  padding: 48px 24px 64px;
  background: linear-gradient(135deg, var(--primary-dark) 0%, #004D40 100%);
}

.source-code h2 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 8px;
  color: #fff;
  letter-spacing: -0.02em;
}

.source-code p {
  margin-bottom: 24px;
  color: rgba(255, 255, 255, 0.8);
  font-weight: 500;
}

.github-logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: #fff;
  color: var(--text);
  padding: 12px 28px;
  text-decoration: none;
  border-radius: var(--radius-full);
  font-weight: 700;
  transition: all 0.2s ease-out;
  gap: 10px;
  cursor: pointer;
}

.github-logo img {
  width: 24px;
  height: 24px;
  border-radius: 50%;
}

.github-logo span {
  font-size: 0.95rem;
  font-weight: 700;
}

.github-logo:hover {
  background-color: var(--text);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

/* ============================================
   Footer
   ============================================ */
footer {
  background-color: var(--text);
  color: rgba(255, 255, 255, 0.7);
  padding: 24px;
  text-align: center;
  font-size: 0.9rem;
  font-weight: 500;
}

/* ============================================
   Language Dropdown
   ============================================ */
.language-dropdown {
  position: relative;
}

.language-dropdown a {
  display: flex;
  align-items: center;
  cursor: pointer;
  gap: 6px;
}

.language-dropdown img {
  width: 20px;
  height: 20px;
  border-radius: 4px;
}

.dropdown-menu {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  display: none;
  background-color: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  list-style: none;
  padding: 8px 0;
  box-shadow: var(--shadow-lg);
  z-index: 1000;
  min-width: 160px;
}

.dropdown-menu li {
  padding: 0;
}

.dropdown-menu li a {
  display: flex;
  align-items: center;
  text-decoration: none;
  color: var(--text);
  padding: 10px 16px;
  gap: 8px;
  font-size: 0.9rem;
  border-radius: 0;
}

.dropdown-menu li a:hover {
  background-color: var(--primary-lighter);
  color: var(--primary);
}

.dropdown-menu li img {
  width: 20px;
  height: 20px;
  margin: 0;
}

.language-dropdown:hover .dropdown-menu {
  display: block;
}

/* ============================================
   Hamburger Menu Button
   ============================================ */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--text);
  border-radius: var(--radius-sm);
  transition: background-color 0.2s ease;
  z-index: 101;
  -webkit-tap-highlight-color: transparent;
}

.menu-toggle:hover {
  background-color: var(--primary-lighter);
}

.menu-toggle svg line {
  transition: all 0.3s ease;
  transform-origin: center;
}

.menu-toggle.active .line-top {
  transform: translateY(6px) rotate(45deg);
}

.menu-toggle.active .line-mid {
  opacity: 0;
}

.menu-toggle.active .line-bot {
  transform: translateY(-6px) rotate(-45deg);
}

/* ============================================
   Responsive Design
   ============================================ */

/* --- Tablet landscape --- */
@media (max-width: 1024px) {
  .hero h1 {
    font-size: 2.4rem;
  }

  .feature-cards {
    grid-template-columns: repeat(2, 1fr);
    max-width: 500px;
  }

  .about-feature,
  .about-feature-reverse {
    flex-direction: column;
    gap: 24px;
  }

  .feature-text,
  .feature-image {
    width: 100%;
  }
}

/* --- Tablet portrait & mobile --- */
@media (max-width: 768px) {

  /* Show hamburger */
  .menu-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  /* Header layout */
  header {
    padding: 0 16px;
  }

  .container {
    height: 56px;
    position: relative;
  }

  /* Mobile nav - dropdown */
  nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    box-shadow: var(--shadow-md);
    padding: 8px 16px 16px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all 0.3s ease;
    z-index: 99;
  }

  nav.nav-open {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  nav ul {
    flex-direction: column;
    gap: 2px;
    width: 100%;
  }

  nav ul li {
    width: 100%;
  }

  nav ul li a {
    display: block;
    width: 100%;
    font-size: 0.95rem;
    padding: 12px 16px;
    border-radius: var(--radius-md);
    min-height: 44px;
    display: flex;
    align-items: center;
  }

  nav ul li a:hover,
  nav ul li a:focus {
    background-color: var(--primary-lighter);
  }

  /* Language dropdown mobile */
  .language-dropdown {
    border-top: 1px solid var(--border);
    margin-top: 4px;
    padding-top: 8px;
  }

  .dropdown-menu {
    position: static;
    display: none;
    box-shadow: none;
    border: none;
    background: var(--primary-lighter);
    border-radius: var(--radius-md);
    margin-top: 4px;
  }

  .language-dropdown:hover .dropdown-menu,
  .language-dropdown.active .dropdown-menu {
    display: block;
  }

  /* Hero */
  .hero {
    padding: 48px 20px 40px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1rem;

    br {
      display: none;
    }
  }

  .hero .btn {
    padding: 12px 28px;
    font-size: 0.95rem;
    min-height: 44px;
  }

  /* Feature cards */
  .feature-cards {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    max-width: 400px;
  }

  .feature-card {
    height: 220px;
  }

  .feature-card h3 {
    font-size: 1rem;
    padding: 12px 12px 4px;
  }

  #card-1 img,
  #card-3 img,
  #card-4 img {
    width: 160px;
    height: 160px;
  }

  #card-2 img {
    width: 140px;
    height: 140px;
  }

  /* About */
  .about {
    padding: 48px 20px;
  }

  .about-features {
    gap: 40px;
  }

  .feature-text h3 {
    font-size: 1.4rem;
  }

  .feature-text p {
    font-size: 0.95rem;
  }

  /* Team */
  .team {
    padding: 48px 20px;
  }

  .team h2 {
    font-size: 1.6rem;
    margin-bottom: 32px;
  }

  .team-container {
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
  }

  .team-member {
    padding: 16px 8px;
  }

  .team-member img {
    width: 72px;
    height: 72px;
  }

  .team-member h3 {
    font-size: 0.9rem;
  }

  .github-username {
    font-size: 0.72rem;
  }

  /* Download & Source */
  .download {
    padding: 40px 20px;
  }

  .source-code {
    padding: 40px 20px 48px;
  }
}

/* --- Mobile --- */
@media (max-width: 480px) {
  .hero {
    padding: 36px 16px 32px;
  }

  .hero h1 {
    font-size: 1.6rem;
  }

  .hero p {
    font-size: 0.9rem;
    margin-bottom: 24px;
  }

  .hero .btn {
    padding: 12px 24px;
    font-size: 0.9rem;
    width: 100%;
    max-width: 280px;
    justify-content: center;
    text-align: center;
  }

  .feature-cards {
    grid-template-columns: repeat(2, 1fr);
    max-width: 320px;
    margin-top: 36px;
  }

  .feature-card {
    height: 170px;
  }

  .feature-card h3 {
    font-size: 0.9rem;
    padding: 10px 10px 4px;
  }

  #card-1 img,
  #card-3 img,
  #card-4 img {
    width: 115px;
    height: 115px;
  }

  #card-2 img {
    width: 105px;
    height: 105px;
  }

  /* About */
  .about {
    padding: 36px 16px;
  }

  .about-features {
    gap: 32px;
  }

  .feature-text h3 {
    font-size: 1.25rem;
  }

  .feature-image img {
    border-radius: var(--radius-md);
  }

  /* Team */
  .team {
    padding: 36px 16px;
  }

  .team h2 {
    font-size: 1.4rem;
    margin-bottom: 24px;
  }

  .team-container {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .team-member img {
    width: 64px;
    height: 64px;
  }

  .team-member h3 {
    font-size: 0.85rem;
  }

  .team-member p {
    font-size: 0.78rem;
  }

  .github-username {
    font-size: 0.68rem;
  }

  /* Download & Source */
  .download h2,
  .source-code h2 {
    font-size: 1.5rem;
  }

  .source-code p {
    font-size: 0.9rem;
  }

  .github-logo {
    padding: 10px 24px;
  }

  .google-play img,
  .app-store img {
    height: 48px;
  }

  footer {
    font-size: 0.8rem;
    padding: 20px 16px;
  }
}

/* --- Small mobile --- */
@media (max-width: 360px) {
  .logo span {
    font-size: 1.2rem;
  }

  .hero h1 {
    font-size: 1.4rem;
  }

  .feature-cards {
    max-width: 280px;
    gap: 8px;
  }

  .feature-card {
    height: 150px;
  }

  #card-1 img,
  #card-3 img,
  #card-4 img {
    width: 100px;
    height: 100px;
  }

  #card-2 img {
    width: 90px;
    height: 90px;
  }

  .team-container {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }

  .team-member img {
    width: 56px;
    height: 56px;
  }
}