/* ==========================================================================
   CSS STYLESHEET: Friend Study Buddy
   Beginner-friendly, Clean, Responsive Design with Dark Mode Support
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. CSS Variables (Colors, Spacing, Transitions)
   -------------------------------------------------------------------------- */
:root {
  --bg-primary: #f4f7fb;
  --bg-card: #ffffff;
  --bg-header: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --accent-color: #4f46e5;       /* Indigo */
  --accent-hover: #4338ca;
  --accent-light: #e0e7ff;
  --border-color: #e2e8f0;
  --result-bg: #f8fafc;
  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.08);
  --radius: 14px;
  --transition: all 0.25s ease-in-out;
}

/* Dark Mode Theme Variables */
body.dark-mode {
  --bg-primary: #0f172a;
  --bg-card: #1e293b;
  --bg-header: #1e293b;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --accent-color: #6366f1;
  --accent-hover: #4f46e5;
  --accent-light: #2e3856;
  --border-color: #334155;
  --result-bg: #0f172a;
  --shadow-sm: 0 2px 6px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
}

/* --------------------------------------------------------------------------
   2. Reset and Base Setup
   -------------------------------------------------------------------------- */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  scroll-behavior: smooth;
  font-family: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: var(--transition);
}

/* --------------------------------------------------------------------------
   3. Header & Navigation Bar
   -------------------------------------------------------------------------- */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg-header);
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.navbar {
  max-width: 1000px;
  margin: 0 auto;
  padding: 1rem 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--accent-color);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.5rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  transition: var(--transition);
}

.nav-links a:hover {
  color: var(--accent-color);
}

/* --------------------------------------------------------------------------
   4. Hero Section
   -------------------------------------------------------------------------- */
.hero-section {
  text-align: center;
  padding: 4rem 1.5rem 2.5rem;
  background: linear-gradient(180deg, var(--accent-light) 0%, var(--bg-primary) 100%);
  border-bottom: 1px solid var(--border-color);
}

.hero-content h1 {
  font-size: 2.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.hero-content .subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 1.75rem;
}

.hero-btn {
  display: inline-block;
  padding: 0.85rem 2rem;
  font-size: 1.05rem;
  text-decoration: none;
}

/* --------------------------------------------------------------------------
   5. Main Container & Card Layouts
   -------------------------------------------------------------------------- */
.container {
  max-width: 800px;
  margin: 2.5rem auto;
  padding: 0 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.card-header {
  margin-bottom: 1.5rem;
  border-bottom: 1px dashed var(--border-color);
  padding-bottom: 1rem;
}

.card-header h2 {
  font-size: 1.45rem;
  color: var(--text-primary);
  margin-bottom: 0.35rem;
}

.card-header p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* --------------------------------------------------------------------------
   6. Forms & Inputs
   -------------------------------------------------------------------------- */
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-group label {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--text-primary);
}

input[type="text"],
select {
  padding: 0.75rem 1rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-size: 0.95rem;
  outline: none;
  transition: var(--transition);
}

input[type="text"]:focus,
select:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px var(--accent-light);
}

/* --------------------------------------------------------------------------
   7. Buttons
   -------------------------------------------------------------------------- */
.btn {
  cursor: pointer;
  border: none;
  font-weight: 600;
  border-radius: 8px;
  padding: 0.75rem 1.4rem;
  font-size: 0.95rem;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.btn-primary {
  background-color: var(--accent-color);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--accent-light);
  color: var(--accent-color);
}

.btn-secondary:hover {
  background-color: var(--border-color);
}

.full-width {
  grid-column: 1 / -1;
  width: 100%;
  margin-top: 0.5rem;
}

.mt-3 {
  margin-top: 1.25rem;
}

/* --------------------------------------------------------------------------
   8. Dynamic Result Box
   -------------------------------------------------------------------------- */
.result-box {
  margin-top: 1.5rem;
  padding: 1.25rem;
  background-color: var(--result-bg);
  border-radius: 8px;
  border-left: 4px solid var(--accent-color);
  transition: var(--transition);
}

.result-box h3 {
  margin-bottom: 0.75rem;
  color: var(--accent-color);
  font-size: 1.15rem;
}

.result-box ul {
  list-style-type: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.result-box li {
  position: relative;
  padding-left: 1.5rem;
  color: var(--text-primary);
}

.result-box li::before {
  content: "•";
  position: absolute;
  left: 0.5rem;
  color: var(--accent-color);
  font-weight: bold;
}

.hidden {
  display: none;
}

.placeholder-text {
  color: var(--text-secondary);
  font-style: italic;
  font-size: 0.95rem;
}

/* --------------------------------------------------------------------------
   9. Quiz Specific Styling
   -------------------------------------------------------------------------- */
.quiz-questions {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.quiz-item {
  padding: 1.1rem;
  background-color: var(--result-bg);
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.quiz-question-title {
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.quiz-option-label {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  cursor: pointer;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  transition: var(--transition);
  font-size: 0.95rem;
}

.quiz-option-label:hover {
  border-color: var(--accent-color);
}

.score-badge {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent-color);
  margin-bottom: 0.5rem;
}

/* --------------------------------------------------------------------------
   10. Revision & Motivation Components
   -------------------------------------------------------------------------- */
.revision-control {
  margin-bottom: 1.25rem;
}

.select-row {
  display: flex;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

.select-row select {
  flex: 1;
}

.motivation-card {
  text-align: center;
}

.quote-display {
  padding: 1.75rem 1rem;
  margin-bottom: 1.25rem;
  background-color: var(--result-bg);
  border-radius: 8px;
  position: relative;
}

#quoteText {
  font-size: 1.2rem;
  font-weight: 500;
  color: var(--text-primary);
  font-style: italic;
}

.quote-icon {
  font-size: 1.75rem;
  color: var(--accent-color);
  opacity: 0.5;
}

/* --------------------------------------------------------------------------
   11. Footer
   -------------------------------------------------------------------------- */
footer {
  text-align: center;
  padding: 2.5rem 1.25rem;
  background-color: var(--bg-header);
  border-top: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-top: 3rem;
  transition: var(--transition);
}

.footer-small {
  font-size: 0.85rem;
  margin-top: 0.35rem;
  opacity: 0.8;
}

/* --------------------------------------------------------------------------
   12. Responsive Design (Mobile / Tablet)
   -------------------------------------------------------------------------- */
@media (max-width: 640px) {
  .navbar {
    flex-direction: column;
    align-items: center;
  }

  .nav-links {
    gap: 1rem;
    font-size: 0.9rem;
  }

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

  .form-grid {
    grid-template-columns: 1fr;
  }

  .select-row {
    flex-direction: column;
  }

  .card {
    padding: 1.25rem;
  }
}