/* ============================================================
   Justido - TutorHub  |  styles.css
   ============================================================ */

/* ---------- RESET & BASE ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue-50: #eff6ff; --blue-100: #dbeafe; --blue-500: #3b82f6; --blue-600: #2563eb; --blue-700: #1d4ed8;
  --green-50: #f0fdf4; --green-100: #dcfce7; --green-500: #22c55e; --green-600: #16a34a; --green-700: #15803d;
  --purple-50: #faf5ff; --purple-100: #f3e8ff; --purple-500: #a855f7; --purple-600: #9333ea;
  --amber-500: #f59e0b;
  --gray-50: #f9fafb; --gray-100: #f3f4f6; --gray-200: #e5e7eb; --gray-300: #d1d5db;
  --gray-400: #9ca3af; --gray-500: #6b7280; --gray-600: #4b5563; --gray-700: #374151; --gray-800: #1f2937;
  --indigo-500: #6366f1; --indigo-600: #4f46e5;
  --red-500: #ef4444;
  --radius: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
  --shadow: 0 1px 3px rgba(0,0,0,.1), 0 1px 2px rgba(0,0,0,.06);
  --shadow-lg: 0 10px 15px rgba(0,0,0,.1), 0 4px 6px rgba(0,0,0,.05);
  --transition: .2s ease;
}

html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--gray-800); background: var(--gray-50);
  line-height: 1.6; min-height: 100vh; display: flex; flex-direction: column;
  -webkit-font-smoothing: antialiased;
}
a { text-decoration: none; color: inherit; }
img { max-width: 100%; display: block; }
button, input, select, textarea { font: inherit; }

/* ---------- LAYOUT ---------- */
.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }
.container-narrow { max-width: 720px; }
.page-padding { padding-top: 40px; padding-bottom: 60px; }
.page { display: none; }
.page.active { display: block; }
main { flex: 1; }

/* ---------- BUTTONS ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 24px; border-radius: var(--radius); font-weight: 600; font-size: .9375rem;
  border: none; cursor: pointer; transition: var(--transition); text-align: center; justify-content: center;
}
.btn svg { width: 16px; height: 16px; }
.btn-primary { background: var(--blue-500); color: #fff; }
.btn-primary:hover { background: var(--blue-600); }
.btn-primary:disabled { background: var(--gray-300); cursor: default; }
.btn-green { background: var(--green-600); color: #fff; }
.btn-green:hover { background: var(--green-700); }
.btn-white { background: #fff; color: var(--indigo-600); }
.btn-white:hover { background: var(--blue-50); }
.btn-outline-white { background: transparent; color: #fff; border: 2px solid #fff; }
.btn-outline-white:hover { background: rgba(255,255,255,.1); }
.btn-full { width: 100%; }

/* ---------- NAVBAR ---------- */
.navbar {
  background: #fff; border-bottom: 1px solid var(--gray-100);
  position: sticky; top: 0; z-index: 100; box-shadow: var(--shadow-sm);
}
.nav-container {
  max-width: 1100px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; justify-content: space-between; height: 60px;
}
.nav-logo {
  display: flex; align-items: center; gap: 10px; transition: opacity var(--transition);
}
.nav-logo:hover { opacity: .8; }
.logo-icon {
  background: linear-gradient(135deg, var(--blue-500), var(--indigo-600));
  padding: 7px; border-radius: 10px; display: flex; color: #fff;
}
.logo-icon svg { width: 20px; height: 20px; }
.logo-text { font-weight: 700; font-size: 1.2rem; color: var(--gray-800); }
.logo-accent { color: var(--blue-600); }

.nav-links { display: flex; gap: 4px; }
.nav-link {
  padding: 8px 16px; border-radius: 10px; font-size: .875rem; font-weight: 500;
  color: var(--gray-600); transition: var(--transition);
}
.nav-link:hover { background: var(--gray-50); color: var(--gray-800); }
.nav-link.active { background: var(--blue-50); color: var(--blue-600); }

.nav-toggle {
  display: none; background: none; border: none; padding: 8px;
  color: var(--gray-600); cursor: pointer;
}
.nav-toggle svg { width: 22px; height: 22px; }
.nav-mobile { display: none; padding: 8px 20px 12px; border-top: 1px solid var(--gray-100); }
.nav-mobile.open { display: block; }
.nav-mobile-link {
  display: block; padding: 12px 16px; border-radius: 10px; font-size: .875rem;
  font-weight: 500; color: var(--gray-600);
}
.nav-mobile-link:hover, .nav-mobile-link.active { background: var(--blue-50); color: var(--blue-600); }

@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-toggle { display: block; }
}

/* ---------- HERO ---------- */
.hero {
  background: linear-gradient(135deg, var(--blue-500), var(--indigo-500), var(--purple-500));
  color: #fff; text-align: center;
}
.hero-inner { max-width: 680px; margin: 0 auto; padding: 80px 20px; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: rgba(255,255,255,.2); border-radius: 50px;
  padding: 6px 16px; font-size: .8125rem; font-weight: 600; margin-bottom: 24px;
}
.hero-badge svg { width: 14px; height: 14px; }
.hero-title { font-size: 2.75rem; font-weight: 800; line-height: 1.15; margin-bottom: 16px; }
.hero-subtitle { font-size: 1.125rem; color: rgba(255,255,255,.8); margin-bottom: 32px; line-height: 1.7; }
.hero-actions { display: flex; flex-wrap: wrap; justify-content: center; gap: 12px; }

@media (max-width: 600px) {
  .hero-inner { padding: 50px 20px; }
  .hero-title { font-size: 2rem; }
  .hero-subtitle { font-size: 1rem; }
}

/* ---------- SECTIONS ---------- */
.section { padding: 64px 0; }
.section-gray { background: var(--gray-50); border-top: 1px solid var(--gray-100); }
.section-title { text-align: center; font-size: 1.5rem; font-weight: 700; margin-bottom: 6px; }
.section-subtitle { text-align: center; color: var(--gray-500); margin-bottom: 48px; }

/* ---------- PAGE HEADERS ---------- */
.page-header { margin-bottom: 32px; }
.page-header h1 { font-size: 1.875rem; font-weight: 700; margin-bottom: 6px; }
.page-header p { color: var(--gray-500); font-size: .9375rem; }

/* ---------- FEATURE CARDS ---------- */
.features-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.feature-card {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius-xl);
  padding: 28px; transition: var(--transition); display: block;
}
.feature-card:hover { box-shadow: var(--shadow-lg); border-color: var(--gray-300); }
.feature-icon {
  width: 48px; height: 48px; border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center; margin-bottom: 16px;
}
.feature-icon svg { width: 24px; height: 24px; }
.feature-icon.blue  { background: var(--blue-50);   color: var(--blue-600); }
.feature-icon.green { background: var(--green-50);  color: var(--green-600); }
.feature-icon.purple{ background: var(--purple-50); color: var(--purple-600); }
.feature-card h3 { font-size: 1.0625rem; font-weight: 600; margin-bottom: 8px; }
.feature-card p { color: var(--gray-500); font-size: .875rem; margin-bottom: 16px; line-height: 1.6; }
.feature-link {
  font-size: .875rem; font-weight: 600; color: var(--blue-600);
  display: inline-flex; align-items: center; gap: 4px; transition: gap var(--transition);
}
.feature-card:hover .feature-link { gap: 8px; }
.feature-link svg { width: 14px; height: 14px; }

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

/* ---------- STATS ---------- */
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.stat-card {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius);
  padding: 20px; text-align: center;
}
.stat-card svg { width: 24px; height: 24px; color: var(--indigo-500); margin: 0 auto 8px; }
.stat-value { font-size: 1.5rem; font-weight: 700; }
.stat-label { font-size: .8125rem; color: var(--gray-500); }

@media (max-width: 600px) { .stats-grid { grid-template-columns: repeat(2, 1fr); } }

/* ---------- CHAT (ASK PAGE) ---------- */
.chat-container {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius-xl); overflow: hidden;
}
.chat-messages { min-height: 320px; max-height: 420px; overflow-y: auto; padding: 20px; }
.chat-empty {
  text-align: center; padding: 48px 0; color: var(--gray-400);
}
.chat-empty svg { width: 48px; height: 48px; margin: 0 auto 12px; opacity: .5; }
.chat-empty p { font-size: .875rem; margin-bottom: 16px; }
.chat-suggestions { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }
.suggestion-chip {
  background: var(--gray-100); color: var(--gray-600); border: none; padding: 6px 14px;
  border-radius: 50px; font-size: .75rem; cursor: pointer; transition: var(--transition);
}
.suggestion-chip:hover { background: var(--blue-50); color: var(--blue-600); }

.chat-bubble {
  max-width: 75%; padding: 12px 16px; border-radius: 16px; font-size: .875rem;
  line-height: 1.6; margin-bottom: 12px; word-wrap: break-word;
}
.chat-bubble.user {
  background: var(--blue-500); color: #fff; margin-left: auto;
  border-bottom-right-radius: 6px;
}
.chat-bubble.tutor {
  background: var(--gray-100); color: var(--gray-800);
  border-bottom-left-radius: 6px;
}
.chat-bubble .tutor-label { font-size: .7rem; font-weight: 700; color: var(--indigo-600); margin-bottom: 4px; }

.chat-typing { display: flex; gap: 5px; padding: 12px 16px; }
.chat-typing span {
  width: 8px; height: 8px; background: var(--gray-400); border-radius: 50%;
  animation: bounce .6s infinite alternate;
}
.chat-typing span:nth-child(2) { animation-delay: .15s; }
.chat-typing span:nth-child(3) { animation-delay: .3s; }
@keyframes bounce { to { transform: translateY(-6px); opacity: .4; } }

.chat-input-area {
  border-top: 1px solid var(--gray-100); padding: 12px; display: flex; gap: 8px;
}
.chat-input-area input {
  flex: 1; padding: 10px 16px; background: var(--gray-50); border: 1px solid var(--gray-200);
  border-radius: var(--radius); font-size: .875rem; outline: none; transition: var(--transition);
}
.chat-input-area input:focus { border-color: var(--blue-500); box-shadow: 0 0 0 3px rgba(59,130,246,.15); }
.chat-send {
  background: var(--blue-500); color: #fff; border: none; padding: 10px;
  border-radius: var(--radius); cursor: pointer; transition: var(--transition);
  display: flex; align-items: center;
}
.chat-send:hover { background: var(--blue-600); }
.chat-send:disabled { background: var(--gray-300); cursor: default; }
.chat-send svg { width: 16px; height: 16px; }

/* ---------- WORKSHEET PAGE ---------- */
.form-card {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius-xl); padding: 28px;
}
.form-group { margin-bottom: 24px; }
.form-group label { display: block; font-size: .875rem; font-weight: 600; color: var(--gray-700); margin-bottom: 6px; }
.form-group select, .form-group textarea {
  width: 100%; padding: 10px 16px; background: var(--gray-50); border: 1px solid var(--gray-200);
  border-radius: var(--radius); font-size: .875rem; outline: none; transition: var(--transition);
  resize: none;
}
.form-group select:focus, .form-group textarea:focus {
  border-color: var(--blue-500); box-shadow: 0 0 0 3px rgba(59,130,246,.15);
}

.upload-zone {
  border: 2px dashed var(--gray-300); border-radius: var(--radius); padding: 40px 20px;
  text-align: center; cursor: pointer; transition: var(--transition);
}
.upload-zone:hover { border-color: var(--blue-500); background: var(--blue-50); }
.upload-zone svg { width: 32px; height: 32px; color: var(--gray-400); margin: 0 auto 8px; }
.upload-zone p { font-size: .875rem; color: var(--gray-500); margin-bottom: 4px; }
.upload-zone span { font-size: .75rem; color: var(--gray-400); }

.file-list { margin-top: 12px; }
.file-item {
  display: flex; align-items: center; justify-content: space-between;
  background: var(--gray-50); border-radius: 10px; padding: 8px 12px; margin-bottom: 8px;
}
.file-item-info { display: flex; align-items: center; gap: 8px; min-width: 0; }
.file-item-info svg { width: 16px; height: 16px; color: var(--gray-400); flex-shrink: 0; }
.file-item-name { font-size: .875rem; color: var(--gray-700); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-item-size { font-size: .75rem; color: var(--gray-400); flex-shrink: 0; }
.file-remove {
  background: none; border: none; color: var(--gray-400); cursor: pointer; padding: 4px;
  transition: var(--transition); display: flex;
}
.file-remove:hover { color: var(--red-500); }
.file-remove svg { width: 16px; height: 16px; }

.success-card {
  background: var(--green-50); border: 1px solid var(--green-100); border-radius: var(--radius-xl);
  padding: 48px 28px; text-align: center;
}
.success-icon {
  width: 64px; height: 64px; background: var(--green-100); border-radius: 50%;
  display: flex; align-items: center; justify-content: center; margin: 0 auto 16px;
}
.success-icon svg { width: 32px; height: 32px; color: var(--green-600); }
.success-card h2 { font-size: 1.5rem; margin-bottom: 8px; }
.success-card p { color: var(--gray-500); margin-bottom: 4px; }
.success-detail { display: block; font-size: .8125rem; color: var(--gray-400); margin-bottom: 24px; }

/* ---------- RESOURCES PAGE ---------- */
.subjects-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px; }
.subject-card {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius-xl);
  padding: 28px; cursor: pointer; transition: var(--transition); display: block;
}
.subject-card:hover { box-shadow: var(--shadow-lg); border-color: var(--gray-300); }
.subject-card .emoji { font-size: 2.5rem; margin-bottom: 16px; display: block; }
.subject-card h3 { font-size: 1.25rem; font-weight: 700; margin-bottom: 4px; }
.subject-card p { font-size: .875rem; color: var(--gray-500); margin-bottom: 12px; }

.back-btn {
  background: none; border: none; display: inline-flex; align-items: center; gap: 6px;
  font-size: .875rem; color: var(--gray-500); cursor: pointer; margin-bottom: 24px;
  transition: var(--transition);
}
.back-btn:hover { color: var(--blue-600); }
.back-btn svg { width: 16px; height: 16px; }

.subject-header { display: flex; align-items: center; gap: 16px; margin-bottom: 32px; }
.subject-header .emoji { font-size: 3rem; }
.subject-header h1 { font-size: 1.875rem; font-weight: 700; }
.subject-header p { font-size: .875rem; color: var(--gray-500); }

.topic-card {
  background: #fff; border: 1px solid var(--gray-200); border-radius: var(--radius-xl);
  overflow: hidden; margin-bottom: 12px;
}
.topic-header {
  width: 100%; background: none; border: none; text-align: left;
  padding: 20px 24px; display: flex; align-items: center; justify-content: space-between;
  cursor: pointer; transition: var(--transition);
}
.topic-header:hover { background: var(--gray-50); }
.topic-header h3 { font-weight: 600; margin-bottom: 2px; }
.topic-header p { font-size: .875rem; color: var(--gray-500); }
.topic-header svg { width: 20px; height: 20px; color: var(--gray-400); flex-shrink: 0; transition: transform var(--transition); }
.topic-header.open svg { transform: rotate(90deg); }

.topic-body {
  display: none; padding: 0 24px 20px; border-top: 1px solid var(--gray-100);
}
.topic-body.open { display: block; }
.topic-body .tips-label {
  font-size: .7rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em;
  color: var(--gray-400); margin: 16px 0 12px;
}
.tip-item {
  display: flex; align-items: flex-start; gap: 10px; font-size: .875rem;
  color: var(--gray-700); margin-bottom: 10px; line-height: 1.6;
}
.tip-item svg { width: 16px; height: 16px; color: var(--amber-500); flex-shrink: 0; margin-top: 3px; }

@media (max-width: 600px) { .subjects-grid { grid-template-columns: 1fr; } }

/* ---------- FOOTER ---------- */
.footer {
  background: var(--gray-50); border-top: 1px solid var(--gray-200); margin-top: auto;
}
.footer-inner { padding: 28px 0; text-align: center; }
.footer-brand {
  display: inline-flex; align-items: center; gap: 8px; margin-bottom: 6px;
  font-size: .875rem; font-weight: 600; color: var(--gray-500);
}
.footer-brand svg { width: 16px; height: 16px; }
.footer p { font-size: .75rem; color: var(--gray-400); }
.footer-contact { margin-top: 4px; }
.footer-contact a { color: var(--blue-600); text-decoration: underline; }