/*
Theme Name: EngViet Learn
Theme URI: https://example.com/eng-viet-learn
Author: Antigravity AI
Author URI: https://example.com
Description: Theme học tiếng Anh chuyên sâu dành cho người Việt Nam - Tích hợp luyện phát âm IPA, từ vựng song ngữ, ngữ pháp ứng dụng và bài tập trắc nghiệm tương tác.
Version: 1.0.0
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Text Domain: eng-viet-learn
Tags: education, e-learning, language-learning, english, vietnamese, responsive
*/

:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --primary-light: #eff6ff;
  --secondary: #059669;
  --accent: #f59e0b;
  --danger: #ef4444;
  --dark: #0f172a;
  --gray-900: #1e293b;
  --gray-700: #334155;
  --gray-500: #64748b;
  --gray-300: #cbd5e1;
  --gray-100: #f1f5f9;
  --white: #ffffff;
  --font-family: 'Plus Jakarta Sans', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 9999px;
  --shadow-sm: 0 2px 4px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 10px 25px -5px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 20px 35px -10px rgba(15, 23, 42, 0.12);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-family);
  background-color: #f8fafc;
  color: var(--gray-700);
  line-height: 1.6;
  font-size: 16px;
  overflow-x: hidden;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: var(--transition);
}

a:hover {
  color: var(--primary-dark);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header & Navigation */
.site-header {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid #e2e8f0;
  box-shadow: var(--shadow-sm);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--dark);
}

.logo-badge {
  background: linear-gradient(135deg, var(--primary), #4f46e5);
  color: var(--white);
  padding: 8px 12px;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 700;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

.main-nav ul {
  display: flex;
  list-style: none;
  gap: 28px;
  align-items: center;
}

.main-nav a {
  font-weight: 600;
  color: var(--gray-700);
  font-size: 0.98rem;
  padding: 8px 0;
  position: relative;
}

.main-nav a:hover,
.main-nav a.active {
  color: var(--primary);
}

.header-cta {
  display: flex;
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--white);
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.45);
  color: var(--white);
}

.btn-outline {
  border: 1.5px solid var(--primary);
  color: var(--primary);
  background: transparent;
}

.btn-outline:hover {
  background: var(--primary-light);
}

/* Hero Section */
.hero {
  padding: 70px 0 60px;
  background: radial-gradient(circle at 10% 20%, rgba(37, 99, 235, 0.08) 0%, transparent 40%),
              radial-gradient(circle at 90% 80%, rgba(5, 150, 105, 0.08) 0%, transparent 40%);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 50px;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: #dbeafe;
  color: var(--primary-dark);
  font-size: 0.85rem;
  font-weight: 700;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  margin-bottom: 20px;
}

.hero-title {
  font-size: 3rem;
  line-height: 1.2;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 20px;
}

.hero-title span {
  background: linear-gradient(135deg, var(--primary), #8b5cf6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-desc {
  font-size: 1.15rem;
  color: var(--gray-500);
  margin-bottom: 30px;
  max-width: 540px;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  margin-bottom: 35px;
}

.hero-stats {
  display: flex;
  gap: 32px;
  padding-top: 25px;
  border-top: 1px solid #e2e8f0;
}

.stat-num {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--dark);
}

.stat-label {
  font-size: 0.85rem;
  color: var(--gray-500);
}

/* Interactive Demo Card in Hero */
.demo-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 28px;
  box-shadow: var(--shadow-lg);
  border: 1px solid #e2e8f0;
  position: relative;
}

.demo-card::before {
  content: '';
  position: absolute;
  top: -2px;
  left: -2px;
  right: -2px;
  bottom: -2px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  z-index: -1;
  border-radius: calc(var(--radius-lg) + 2px);
  opacity: 0.2;
}

.demo-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 18px;
  padding-bottom: 12px;
  border-bottom: 1px solid #f1f5f9;
}

.demo-tag {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  background: #fef3c7;
  color: #92400e;
  padding: 4px 10px;
  border-radius: var(--radius-full);
}

.ipa-card {
  background: #f8fafc;
  border-radius: var(--radius-md);
  padding: 20px;
  text-align: center;
  margin-bottom: 20px;
  border: 1px dashed var(--gray-300);
}

.ipa-symbol {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: 2px;
}

.ipa-word {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--dark);
  margin-top: 4px;
}

.ipa-viet-hint {
  font-size: 0.9rem;
  color: var(--gray-500);
  margin-top: 6px;
}

/* Audio Player Interactive */
.audio-btn {
  background: var(--primary);
  color: var(--white);
  border: none;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
  transition: var(--transition);
}

.audio-btn:hover {
  transform: scale(1.08);
}

/* Learning Paths Section */
.section {
  padding: 80px 0;
}

.section-title-wrap {
  text-align: center;
  max-width: 650px;
  margin: 0 auto 50px;
}

.section-subtitle {
  color: var(--primary);
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 8px;
}

.section-title {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--dark);
}

.path-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
}

.path-card {
  background: var(--white);
  border-radius: var(--radius-md);
  padding: 30px 24px;
  box-shadow: var(--shadow-sm);
  border: 1px solid #e2e8f0;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.path-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary-light);
}

.path-icon {
  width: 54px;
  height: 54px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
}

.path-icon.ipa { background: #dbeafe; color: #1e40af; }
.path-icon.vocab { background: #d1fae5; color: #065f46; }
.path-icon.grammar { background: #fef3c7; color: #92400e; }
.path-icon.listening { background: #ede9fe; color: #5b21b6; }

.path-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--dark);
  margin-bottom: 10px;
}

.path-card p {
  font-size: 0.93rem;
  color: var(--gray-500);
  margin-bottom: 18px;
}

.path-tag {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  background: var(--gray-100);
  color: var(--gray-700);
}

/* Flashcard & Interactive Section */
.flashcard-wrapper {
  perspective: 1000px;
  cursor: pointer;
  height: 220px;
  margin-bottom: 20px;
}

.flashcard {
  width: 100%;
  height: 100%;
  position: relative;
  transition: transform 0.6s;
  transform-style: preserve-3d;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
}

.flashcard.flipped {
  transform: rotateY(180deg);
}

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: var(--radius-md);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 20px;
  text-align: center;
}

.card-front {
  background: linear-gradient(135deg, #ffffff, #f1f5f9);
  border: 2px solid #e2e8f0;
}

.card-back {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--white);
  transform: rotateY(180deg);
}

/* Quiz Component */
.quiz-box {
  background: var(--white);
  border-radius: var(--radius-md);
  padding: 24px;
  border: 1px solid #e2e8f0;
  box-shadow: var(--shadow-sm);
}

.quiz-question {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--dark);
  margin-bottom: 16px;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.quiz-option {
  padding: 12px 18px;
  background: #f8fafc;
  border: 1.5px solid #e2e8f0;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  gap: 12px;
}

.quiz-option:hover {
  background: var(--primary-light);
  border-color: var(--primary);
}

.quiz-option.correct {
  background: #dcfce7 !important;
  border-color: var(--secondary) !important;
  color: #166534 !important;
  font-weight: 600;
}

.quiz-option.wrong {
  background: #fee2e2 !important;
  border-color: var(--danger) !important;
  color: #991b1b !important;
}

.quiz-feedback {
  margin-top: 14px;
  font-size: 0.92rem;
  display: none;
}

/* Footer */
.site-footer {
  background: var(--dark);
  color: #94a3b8;
  padding: 60px 0 30px;
  font-size: 0.92rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-col h4 {
  color: var(--white);
  font-size: 1.05rem;
  margin-bottom: 18px;
}

.footer-col ul {
  list-style: none;
}

.footer-col li {
  margin-bottom: 10px;
}

.footer-col a {
  color: #94a3b8;
}

.footer-col a:hover {
  color: var(--white);
}

.footer-bottom {
  padding-top: 30px;
  border-top: 1px solid #334155;
  text-align: center;
}

/* Auth Forms (Login & Register) */
.auth-page-wrapper {
  background: radial-gradient(circle at 10% 20%, rgba(37, 99, 235, 0.05) 0%, transparent 40%),
              radial-gradient(circle at 90% 80%, rgba(5, 150, 105, 0.05) 0%, transparent 40%);
  min-height: 80vh;
  display: flex;
  align-items: center;
}

.auth-container {
  max-width: 460px;
  margin: 0 auto;
  background: var(--white);
  border-radius: 24px;
  padding: 40px 36px;
  box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.18), 0 0 0 1px rgba(226, 232, 240, 0.8);
  border: 1px solid #e2e8f0;
  position: relative;
}

.auth-tabs {
  display: flex;
  background: #f1f5f9;
  border-radius: var(--radius-full);
  padding: 5px;
  margin-bottom: 28px;
  gap: 4px;
}

.auth-tab-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  background: transparent;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.92rem;
  color: var(--gray-500);
  cursor: pointer;
  transition: var(--transition);
  font-family: inherit;
}

.auth-tab-btn.active {
  background: var(--white);
  color: var(--primary);
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.08);
}

.auth-tab-content {
  display: none !important;
}

.auth-tab-content.active {
  display: block !important;
}

.auth-box-header {
  text-align: center;
  margin-bottom: 24px;
}

.auth-box-header h2 {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--dark);
  margin-bottom: 6px;
  letter-spacing: -0.02em;
}

.auth-box-header p {
  font-size: 0.9rem;
  color: var(--gray-500);
  line-height: 1.5;
}

.form-group {
  margin-bottom: 18px;
  text-align: left;
}

.form-group label {
  display: block;
  font-size: 0.86rem;
  font-weight: 600;
  color: #334155;
  margin-bottom: 6px;
}

.form-control {
  width: 100%;
  height: 46px;
  padding: 0 16px;
  border: 1.5px solid #cbd5e1;
  border-radius: 10px;
  font-size: 0.95rem;
  font-family: inherit;
  color: var(--dark);
  background-color: #f8fafc;
  box-sizing: border-box;
  transition: var(--transition);
  outline: none;
}

.form-control:focus {
  border-color: var(--primary);
  background-color: var(--white);
  box-shadow: 0 0 0 3.5px rgba(37, 99, 235, 0.15);
}

.form-check {
  display: flex;
  align-items: center;
  margin: 14px 0 20px;
  font-size: 0.88rem;
  color: var(--gray-500);
}

.form-check input {
  margin-right: 8px;
  width: 16px;
  height: 16px;
  accent-color: var(--primary);
  cursor: pointer;
}

.forgot-link {
  font-size: 0.82rem;
  color: var(--primary);
  font-weight: 600;
  text-decoration: none;
}

.forgot-link:hover {
  text-decoration: underline;
}

.btn-block {
  width: 100%;
  height: 48px;
  font-size: 1rem;
  font-weight: 700;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.auth-alert {
  padding: 12px 16px;
  border-radius: 10px;
  font-size: 0.88rem;
  margin-bottom: 20px;
}

.auth-alert.error {
  background: #fee2e2;
  color: #991b1b;
  border: 1px solid #fca5a5;
}

.user-menu-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  background: var(--primary-light);
  color: var(--primary);
  padding: 6px 14px;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.9rem;
}

/* Responsive */
@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .main-nav {
    display: none;
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}