/* ===============================
   DESIGN SYSTEM & VARIABLES
   =============================== */

:root {
  /* Brand */
  --primary: #4F46E5;
  --primary-hover: #4338CA;
  --primary-light: #EEF2FF;

  /* Feedback */
  --success: #16A34A;
  --success-bg: #DCFCE7;
  --error: #DC2626;
  --error-bg: #FEE2E2;
  --warning: #D97706;
  --warning-bg: #FEF3C7;

  /* Text — crisp dark slate for light mode */
  --text: #0F172A;
  --text-sub: #475569;
  --text-muted: #94A3B8;

  /* Surfaces — pure white light mode */
  --surface: #FFFFFF;
  --card-bg: #FFFFFF;
  --bg: #F1F5F9;
  --border: #E2E8F0;
  --border-hover: #C7D2FE;

  /* Typography */
  --font-family: 'Nunito', 'Segoe UI', sans-serif;
  --font-size-xs: 12px;
  --font-size-sm: 14px;
  --font-size-base: 16px;
  --font-size-lg: 18px;
  --font-size-xl: 22px;
  --font-size-2xl: 28px;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;

  /* Radii */
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 20px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 32px rgba(0,0,0,0.12), 0 4px 8px rgba(0,0,0,0.06);

  /* Layout */
  --nav-height: 72px;
  --sidebar-width: 88px;
}

/* ===============================
   DARK MODE — dramatically different deep dark
   =============================== */

@media (prefers-color-scheme: dark) {
  :root {
    --primary: #818CF8;
    --primary-hover: #6366F1;
    --primary-light: #1E1B4B;
    --text: #F1F5F9;
    --text-sub: #94A3B8;
    --text-muted: #475569;
    --surface: #0F172A;
    --card-bg: #1E293B;
    --bg: #020617;
    --border: #1E293B;
    --border-hover: #334155;
    --success: #34D399;
    --success-bg: #064E3B;
    --error: #F87171;
    --error-bg: #450A0A;
    --warning-bg: #451A03;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.5);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.6);
    --shadow-lg: 0 10px 32px rgba(0,0,0,0.7);
  }
}

body.dark-mode {
  --primary: #818CF8;
  --primary-hover: #6366F1;
  --primary-light: #1E1B4B;
  --text: #F1F5F9;
  --text-sub: #94A3B8;
  --text-muted: #475569;
  --surface: #0F172A;
  --card-bg: #1E293B;
  --bg: #020617;
  --border: #1E293B;
  --border-hover: #334155;
  --success: #34D399;
  --success-bg: #064E3B;
  --error: #F87171;
  --error-bg: #450A0A;
  --warning-bg: #451A03;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.5);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.6);
  --shadow-lg: 0 10px 32px rgba(0,0,0,0.7);
}

/* ===============================
   GLOBAL RESET & BASE
   =============================== */

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

html {
  scroll-behavior: smooth;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  transition: background-color 0.3s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.3;
}

h1 { font-size: var(--font-size-xl); }
h2 { font-size: var(--font-size-lg); }
h3 { font-size: var(--font-size-base); margin-bottom: var(--space-sm); }

p {
  color: var(--text-sub);
  line-height: 1.6;
}

/* ===============================
   LAYOUT STRUCTURE
   =============================== */

.screen {
  display: none;
  width: 100%;
  min-height: 100vh;
  animation: screenIn 0.25s ease;
  overflow-x: hidden;
}

.screen.screen-active {
  display: flex;
  flex-direction: column;
}

@keyframes screenIn {
  from { opacity: 0; transform: translateY(5px); }
  to   { opacity: 1; transform: translateY(0); }
}

.app-main {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-lg) var(--space-md);
  padding-bottom: calc(var(--nav-height) + var(--space-lg));
}

.app-main::-webkit-scrollbar { width: 5px; }
.app-main::-webkit-scrollbar-track { background: transparent; }
.app-main::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ===============================
   APP HEADER (Home)
   =============================== */

/* Centered stacked header: logo on top, stats row below */
.app-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: var(--space-md) var(--space-md) var(--space-sm);
  position: sticky;
  top: 0;
  z-index: 10;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
}

.logo {
  width: 100%;
  text-align: center;
}

.logo h1 {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  margin: 0;
  background: linear-gradient(135deg, var(--primary) 0%, #9333EA 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -1px;
}

.header-right {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  flex-wrap: nowrap;
}

/* Compact XP / Streak chips */
.stat-chip {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--primary-light);
  border-radius: var(--radius-sm);
  padding: 4px 10px;
  min-width: 40px;
  text-align: center;
}

.stat-value {
  font-size: var(--font-size-sm);
  font-weight: 800;
  color: var(--primary);
  display: block;
  line-height: 1.2;
}

.stat-label {
  font-size: 10px;
  color: var(--text-sub);
  font-weight: 600;
  line-height: 1;
}

/* Difficulty picker button */
.difficulty-wrapper {
  position: relative;
}

.btn-difficulty {
  display: flex;
  align-items: center;
  gap: 5px;
  background: var(--primary-light);
  border: 1.5px solid var(--border-hover);
  border-radius: var(--radius-sm);
  padding: 6px 10px;
  cursor: pointer;
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--primary);
  transition: all 0.2s ease;
  white-space: nowrap;
}

.btn-difficulty:hover { border-color: var(--primary); }
.btn-difficulty:active { transform: scale(0.97); }

.diff-chevron {
  font-size: 10px;
  opacity: 0.6;
  transition: transform 0.2s ease;
  display: inline-block;
}

.btn-difficulty[aria-expanded="true"] .diff-chevron {
  transform: rotate(180deg);
}

/* Dropdown panel */
.difficulty-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  width: 230px;
  z-index: 200;
  overflow: hidden;
  animation: dropdownIn 0.15s cubic-bezier(0.4, 0, 0.2, 1);
}

.difficulty-dropdown[hidden] { display: none; }

@keyframes dropdownIn {
  from { opacity: 0; transform: translateY(-6px) scale(0.98); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

.diff-dropdown-title {
  font-size: var(--font-size-xs);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-muted);
  padding: 12px 16px 8px;
}

.diff-option {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  width: 100%;
  background: none;
  border: none;
  border-top: 1px solid var(--border);
  padding: 10px 16px;
  cursor: pointer;
  font-family: var(--font-family);
  text-align: left;
  transition: background 0.15s ease;
}

.diff-option:hover { background: var(--primary-light); }

.diff-option.active { background: var(--primary-light); }

.diff-option.active::after {
  content: '✓';
  margin-left: auto;
  color: var(--primary);
  font-weight: 800;
  font-size: var(--font-size-sm);
  flex-shrink: 0;
}

.diff-icon { font-size: 22px; flex-shrink: 0; }

.diff-info strong {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
}

.diff-info small {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  font-weight: 500;
}

/* ===============================
   LESSON HEADER
   =============================== */

.lesson-header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: var(--space-md);
  position: sticky;
  top: 0;
  z-index: 10;
  box-shadow: var(--shadow-sm);
}

.btn-back {
  background: var(--primary-light);
  border: none;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-lg);
  cursor: pointer;
  color: var(--primary);
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: all 0.2s ease;
}

.btn-back:active { transform: scale(0.9); }

.lesson-title {
  flex: 1;
  font-size: var(--font-size-base);
  font-weight: 700;
  margin: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.lesson-progress-bar {
  height: 4px;
  background: var(--border);
  overflow: hidden;
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
}

/* Lesson controls bar (shuffle + timer) */
.lesson-controls-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px var(--space-md);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  justify-content: center;
  flex-wrap: wrap;
}

.lesson-ctrl-btn {
  font-size: 12px;
  padding: 4px 12px;
  border-radius: 20px;
  border: 1.5px solid var(--border);
  background: var(--card-bg);
  color: var(--text-sub);
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}

.lesson-ctrl-btn.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

.lesson-timer-display {
  display: flex;
  align-items: center;
  gap: 3px;
  font-size: 14px;
  font-weight: 700;
  color: var(--primary);
  background: var(--primary-light);
  padding: 4px 12px;
  border-radius: 20px;
  transition: all 0.3s;
}

.lesson-timer-display.timer-urgent {
  color: var(--error);
  background: #FEE2E2;
  animation: pulse 0.5s infinite alternate;
}

@keyframes pulse { to { opacity: 0.6; } }

/* Submit + Prev + Next action row */
.lesson-action-row {
  display: flex;
  gap: 10px;
  margin-top: 20px;
}

.lesson-action-row .btn {
  flex: 1;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), #9333EA);
  width: 0%;
  transition: width 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Lesson screen: fixed viewport, no body scroll */
#screen-lesson.screen-active {
  height: 100dvh;
  min-height: unset;
  overflow: hidden;
}

#screen-lesson .lesson-main {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-sm) var(--space-md);
  padding-bottom: var(--space-md);
}

#screen-lesson .question-container {
  padding: var(--space-md);
  margin-bottom: var(--space-sm);
}

#screen-lesson .question-text {
  font-size: var(--font-size-base);
  margin-bottom: var(--space-md);
}

#screen-lesson .option-chip {
  padding: 10px var(--space-md);
  margin-bottom: 6px;
}

#screen-lesson .answer-buttons {
  gap: var(--space-sm);
}

#screen-lesson .answer-btn {
  min-height: 56px;
  padding: var(--space-md);
}

/* Concept card collapsible */
.concept-details {
  margin-bottom: var(--space-sm);
}

.concept-summary {
  cursor: pointer;
  font-size: 13px;
  font-weight: 700;
  color: var(--primary);
  padding: 5px 14px;
  background: var(--primary-light);
  border-radius: 20px;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  user-select: none;
  transition: opacity 0.2s;
}

.concept-summary::-webkit-details-marker { display: none; }
.concept-summary:hover { opacity: 0.8; }

.concept-details[open] .concept-summary {
  border-radius: 12px 12px 0 0;
}

.concept-details[open] .concept-card {
  border-radius: 0 0 12px 12px;
  margin-top: 0;
  margin-bottom: var(--space-sm);
}

/* ===============================
   SECTIONS
   =============================== */

.section-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-md);
}

.section-featured,
.section-topics,
.section-stats,
.section-level,
.section-achievements,
.section-preferences,
.section-about,
.section-history,
.section-tips {
  margin-bottom: var(--space-xl);
}

.section-topics h2,
.section-history h3,
.section-tips h3,
.section-achievements h3,
.section-preferences h3,
.section-stats h3,
.section-level h3 {
  margin-bottom: var(--space-md);
}

.btn-filter {
  background: transparent;
  border: 1.5px solid var(--border);
  color: var(--text-sub);
  border-radius: var(--radius-sm);
  padding: 6px var(--space-md);
  font-family: var(--font-family);
  font-size: var(--font-size-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-filter:hover { border-color: var(--primary); color: var(--primary); }

/* ===============================
   FILTER BAR
   =============================== */

.filter-bar {
  display: flex;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  padding-bottom: 2px;
}

.filter-bar::-webkit-scrollbar { display: none; }

.filter-pill {
  background: var(--card-bg);
  border: 1.5px solid var(--border);
  border-radius: 20px;
  padding: 6px 16px;
  font-family: var(--font-family);
  font-size: var(--font-size-xs);
  font-weight: 700;
  color: var(--text-sub);
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
  flex-shrink: 0;
  letter-spacing: 0.3px;
}

.filter-pill:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-light);
}

.filter-pill.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
  box-shadow: 0 2px 8px rgba(79, 70, 229, 0.28);
}

/* ===============================
   FEATURED / DAILY CARD
   =============================== */

.featured-card {
  background: linear-gradient(135deg, #4F46E5 0%, #7C3AED 55%, #9333EA 100%);
  color: white;
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-xl);
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.featured-card::before {
  content: '';
  position: absolute;
  top: -30px; right: -20px;
  width: 150px; height: 150px;
  background: rgba(255,255,255,0.07);
  border-radius: 50%;
}

.featured-card::after {
  content: '';
  position: absolute;
  bottom: -50px; right: 50px;
  width: 110px; height: 110px;
  background: rgba(255,255,255,0.05);
  border-radius: 50%;
}

.featured-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(255,255,255,0.2);
  padding: 4px var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.featured-card h3 {
  font-size: var(--font-size-xl);
  font-weight: 800;
  margin-bottom: 6px;
  color: white;
}

.featured-card p {
  color: rgba(255,255,255,0.85);
  margin-bottom: var(--space-lg);
  font-size: var(--font-size-sm);
}

/* ===============================
   TOPICS GRID — critical fix: .tree-title spans all columns
   =============================== */

.topics-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-sm);
}

/* CRITICAL: make category headings span the full grid */
.tree-title {
  grid-column: 1 / -1;
  font-size: var(--font-size-xs);
  font-weight: 800;
  color: var(--primary);
  text-transform: uppercase;
  letter-spacing: 1.2px;
  padding: var(--space-xs) 0 var(--space-xs);
  margin-top: var(--space-md);
  border-bottom: 2px solid var(--primary-light);
}

.tree-title:first-child { margin-top: 0; }

.tree-node {
  background: var(--card-bg);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-sm);
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--border);
  text-align: center;
  min-height: 88px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.tree-node:not(.locked):hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.tree-node:not(.locked):active {
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

.tree-node.locked {
  opacity: 0.45;
  cursor: not-allowed;
  background: var(--bg);
  border-color: var(--border);
}

.tree-node.mastered {
  border-color: var(--success);
  background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
}

body.dark-mode .tree-node.mastered {
  background: linear-gradient(135deg, #052e16 0%, #14532d 100%);
  border-color: var(--success);
}

@media (prefers-color-scheme: dark) {
  .tree-node.mastered {
    background: linear-gradient(135deg, #052e16 0%, #14532d 100%);
    border-color: var(--success);
  }
}

.tree-node h3 {
  margin: 0;
  font-size: 12px;
  font-weight: 700;
  color: var(--text);
  line-height: 1.3;
}

.tree-node .icon {
  font-size: 26px;
  margin-bottom: 5px;
  display: block;
}

.tree-node .progress-stars {
  margin-top: 4px;
  font-size: 10px;
  line-height: 1;
}

.tree-node.locked h3 { color: var(--text-sub); }

/* Topic card color accents — light mode */
.tree-node.color-1:not(.locked) { border-color: #C7D2FE; }
.tree-node.color-2:not(.locked) { border-color: #FBCFE8; }
.tree-node.color-3:not(.locked) { border-color: #A7F3D0; }
.tree-node.color-4:not(.locked) { border-color: #FDE68A; }
.tree-node.color-5:not(.locked) { border-color: #BAE6FD; }
.tree-node.color-6:not(.locked) { border-color: #DDD6FE; }

.tree-node.color-1:not(.locked):hover { background: #EEF2FF; border-color: #818CF8; }
.tree-node.color-2:not(.locked):hover { background: #FDF2F8; border-color: #EC4899; }
.tree-node.color-3:not(.locked):hover { background: #ECFDF5; border-color: #10B981; }
.tree-node.color-4:not(.locked):hover { background: #FFFBEB; border-color: #F59E0B; }
.tree-node.color-5:not(.locked):hover { background: #F0F9FF; border-color: #0EA5E9; }
.tree-node.color-6:not(.locked):hover { background: #F5F3FF; border-color: #8B5CF6; }

/* Dark mode — brighter borders, dark hover backgrounds */
body.dark-mode .tree-node.color-1:not(.locked) { border-color: #4F46E5; }
body.dark-mode .tree-node.color-2:not(.locked) { border-color: #BE185D; }
body.dark-mode .tree-node.color-3:not(.locked) { border-color: #059669; }
body.dark-mode .tree-node.color-4:not(.locked) { border-color: #D97706; }
body.dark-mode .tree-node.color-5:not(.locked) { border-color: #0284C7; }
body.dark-mode .tree-node.color-6:not(.locked) { border-color: #7C3AED; }

body.dark-mode .tree-node.color-1:not(.locked):hover { background: #1E1B4B; border-color: #818CF8; }
body.dark-mode .tree-node.color-2:not(.locked):hover { background: #4C0519; border-color: #F472B6; }
body.dark-mode .tree-node.color-3:not(.locked):hover { background: #052E16; border-color: #34D399; }
body.dark-mode .tree-node.color-4:not(.locked):hover { background: #451A03; border-color: #FCD34D; }
body.dark-mode .tree-node.color-5:not(.locked):hover { background: #082F49; border-color: #38BDF8; }
body.dark-mode .tree-node.color-6:not(.locked):hover { background: #2E1065; border-color: #A78BFA; }

@media (prefers-color-scheme: dark) {
  .tree-node.color-1:not(.locked) { border-color: #4F46E5; }
  .tree-node.color-2:not(.locked) { border-color: #BE185D; }
  .tree-node.color-3:not(.locked) { border-color: #059669; }
  .tree-node.color-4:not(.locked) { border-color: #D97706; }
  .tree-node.color-5:not(.locked) { border-color: #0284C7; }
  .tree-node.color-6:not(.locked) { border-color: #7C3AED; }

  .tree-node.color-1:not(.locked):hover { background: #1E1B4B; border-color: #818CF8; }
  .tree-node.color-2:not(.locked):hover { background: #4C0519; border-color: #F472B6; }
  .tree-node.color-3:not(.locked):hover { background: #052E16; border-color: #34D399; }
  .tree-node.color-4:not(.locked):hover { background: #451A03; border-color: #FCD34D; }
  .tree-node.color-5:not(.locked):hover { background: #082F49; border-color: #38BDF8; }
  .tree-node.color-6:not(.locked):hover { background: #2E1065; border-color: #A78BFA; }
}

/* ===============================
   STATS GRID
   =============================== */

.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.stat-large {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-align: center;
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--border);
}

.stat-large .stat-value {
  font-size: 36px;
  font-weight: 800;
  color: var(--primary);
  display: block;
  margin-bottom: 4px;
}

.stat-large .stat-label {
  color: var(--text-sub);
  font-size: var(--font-size-sm);
  font-weight: 600;
}

/* ===============================
   PROGRESS & LEVELS
   =============================== */

.progress-topics { display: grid; gap: var(--space-sm); }

.progress-topic-item {
  background: var(--card-bg);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  box-shadow: var(--shadow-sm);
  border: 1.5px solid var(--border);
}

.progress-topic-name {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-sm);
  font-weight: 700;
  font-size: var(--font-size-sm);
}

.progress-topic-bar {
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
}

.progress-topic-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), var(--success));
  width: 0%;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 4px;
}

.level-progress-bar {
  height: 14px;
  background: var(--border);
  border-radius: 7px;
  overflow: hidden;
  margin: var(--space-md) 0;
}

.level-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), #9333EA);
  width: 0%;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  border-radius: 7px;
}

.level-text-info {
  text-align: center;
  font-size: var(--font-size-sm);
  color: var(--text-sub);
  font-weight: 600;
}

.level-badge-large {
  font-size: 80px;
  text-align: center;
  margin-bottom: var(--space-lg);
  display: block;
}

/* ===============================
   LESSON COMPONENTS
   =============================== */

.concept-card {
  background: linear-gradient(135deg, var(--primary-light) 0%, rgba(147,51,234,0.06) 100%);
  border-left: 4px solid var(--primary);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
}

.concept-card p {
  margin-bottom: var(--space-sm);
  color: var(--text);
  font-size: var(--font-size-sm);
  font-weight: 600;
  line-height: 1.6;
}

.concept-card p:last-child { margin-bottom: 0; }

.question-container {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-md);
  border: 1.5px solid var(--border);
  margin-bottom: var(--space-lg);
}

.question-badge {
  display: inline-flex;
  align-items: center;
  background: var(--primary);
  color: white;
  padding: 3px var(--space-sm);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 800;
  margin-bottom: var(--space-md);
  letter-spacing: 0.6px;
  text-transform: uppercase;
}

.question-text {
  font-size: var(--font-size-lg);
  font-weight: 700;
  margin-bottom: var(--space-lg);
  margin-top: 0;
  line-height: 1.5;
  color: var(--text);
}

/* ===============================
   QUESTION OPTIONS
   =============================== */

.option-chip {
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  cursor: pointer;
  transition: all 0.18s ease;
  text-align: left;
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  font-weight: 600;
  min-height: 56px;
  display: flex;
  align-items: center;
  width: 100%;
  margin-bottom: var(--space-sm);
  color: var(--text);
}

.option-chip:last-child { margin-bottom: 0; }

.option-chip:hover {
  border-color: var(--primary);
  background: var(--primary-light);
  transform: translateX(3px);
}

.option-chip.selected {
  border-color: var(--primary);
  background: var(--primary-light);
  color: var(--primary);
}

.option-chip.correct {
  border-color: var(--success);
  background: var(--success-bg);
  color: var(--success);
}

.option-chip.incorrect {
  border-color: var(--error);
  background: var(--error-bg);
  color: var(--error);
}

/* ===============================
   INPUT & BUTTONS
   =============================== */

.input-answer {
  width: 100%;
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  font-size: var(--font-size-base);
  font-family: var(--font-family);
  font-weight: 600;
  color: var(--text);
  background: var(--bg);
  transition: all 0.2s ease;
  margin-bottom: var(--space-md);
}

.input-answer:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(79, 70, 229, 0.12);
  background: var(--card-bg);
}

.btn {
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  font-weight: 700;
  padding: var(--space-md) var(--space-lg);
  cursor: pointer;
  transition: all 0.2s ease;
  min-height: 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
}

.btn:active { transform: scale(0.97); }

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, #7C3AED 100%);
  color: white;
  box-shadow: 0 4px 14px rgba(79, 70, 229, 0.3);
}

.btn-primary:hover {
  box-shadow: 0 6px 18px rgba(79, 70, 229, 0.4);
  transform: translateY(-1px);
}

.btn-primary:active {
  transform: translateY(0) scale(0.97);
  box-shadow: 0 2px 8px rgba(79, 70, 229, 0.3);
}

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

.btn-secondary:active { opacity: 0.8; }
.btn-full { width: 100%; }

.btn-large {
  width: 100%;
  padding: var(--space-md) var(--space-xl);
  font-size: var(--font-size-lg);
  min-height: 56px;
}

.btn-submit {
  width: 100%;
  margin-top: var(--space-md);
}

.answer-buttons {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.answer-btn {
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: var(--font-family);
  font-size: var(--font-size-xl);
  font-weight: 800;
  min-height: 80px;
  color: var(--text);
}

.answer-btn:hover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.answer-btn:active { transform: scale(0.97); }

.answer-btn.correct {
  border-color: var(--success);
  background: var(--success-bg);
  color: var(--success);
}

.answer-btn.incorrect {
  border-color: var(--error);
  background: var(--error-bg);
  color: var(--error);
}

/* ===============================
   FEEDBACK
   =============================== */

.feedback-box {
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-md);
  display: none;
  animation: slideUp 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  font-weight: 600;
  font-size: var(--font-size-sm);
  line-height: 1.5;
}

.feedback-box.show { display: block; }

.feedback-box.correct {
  background: var(--success-bg);
  color: var(--success);
  border-left: 4px solid var(--success);
}

.feedback-box.incorrect {
  background: var(--error-bg);
  color: var(--error);
  border-left: 4px solid var(--error);
}

.feedback-box.info {
  background: var(--primary-light);
  color: var(--primary);
  border-left: 4px solid var(--primary);
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.lesson-stats {
  background: var(--card-bg);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  text-align: center;
  border: 1.5px solid var(--border);
}

.progress-text {
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--primary);
}

/* ===============================
   INJECTED QUESTION LABELS
   =============================== */

.injected-label {
  color: var(--text-sub);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: var(--space-md);
}

/* ===============================
   DAILY SCREEN
   =============================== */

.daily-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-xl);
  box-shadow: var(--shadow-md);
  border: 1.5px solid var(--border);
}

.daily-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-md);
}

.daily-bonus {
  background: linear-gradient(135deg, var(--success), #15803d);
  color: white;
  padding: 5px var(--space-md);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 800;
}

.daily-description {
  color: var(--text-sub);
  margin-bottom: var(--space-lg);
  font-size: var(--font-size-sm);
}

.daily-history { display: grid; gap: var(--space-sm); }

.daily-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--card-bg);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  border: 1.5px solid var(--border);
}

.daily-item-date { font-weight: 700; font-size: var(--font-size-sm); }
.daily-item-status { font-size: 20px; }

/* Daily history dots */
.daily-history {
  display: flex;
  gap: 8px;
  justify-content: space-between;
  padding: var(--space-sm) 0;
}

.daily-dot {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.daily-dot .dot-circle {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--border);
  font-size: 16px;
  color: var(--text-sub);
  transition: all 0.2s;
}

.daily-dot.done .dot-circle {
  background: var(--success);
  color: #fff;
}

.daily-dot small {
  font-size: 10px;
  color: var(--text-sub);
  font-weight: 600;
}

/* Tip card enhancements */
.tip-example {
  margin-top: 10px;
  font-size: 13px;
  font-style: italic;
  color: var(--text-sub);
  background: rgba(0,0,0,0.05);
  padding: 8px 12px;
  border-radius: 8px;
}

body.dark-mode .tip-example {
  background: rgba(255,255,255,0.06);
  color: #94A3B8;
}

.tip-card {
  background: linear-gradient(135deg, #FEF3C7, #FDE68A);
  border-left: 4px solid var(--warning);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  color: #92400E;
  font-weight: 600;
  font-size: var(--font-size-sm);
}

body.dark-mode .tip-card {
  background: linear-gradient(135deg, #451a03, #78350f);
  color: #FDE68A;
}

/* ===============================
   ACHIEVEMENTS
   =============================== */

.achievements-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

.achievement-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-align: center;
  border: 1.5px solid var(--border);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-sm);
}

.achievement-icon { font-size: 48px; }
.achievement-name { font-size: var(--font-size-sm); font-weight: 700; color: var(--primary); }
.achievement-card.locked { opacity: 0.4; }

/* ===============================
   PROFILE SCREEN
   =============================== */

.section-level { text-align: center; padding: var(--space-xl) 0; }

/* ===============================
   TOGGLE SWITCH
   =============================== */

.preference-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--card-bg);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-md);
  border: 1.5px solid var(--border);
  font-weight: 600;
}

.toggle { position: relative; display: inline-block; width: 52px; height: 30px; }
.toggle input { opacity: 0; width: 0; height: 0; }

.slider {
  position: absolute;
  cursor: pointer;
  top: 0; left: 0; right: 0; bottom: 0;
  background: var(--border);
  transition: 0.3s;
  border-radius: 15px;
}

.slider::before {
  position: absolute;
  content: "";
  height: 24px; width: 24px;
  left: 3px; bottom: 3px;
  background: white;
  transition: 0.3s;
  border-radius: 50%;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

input:checked + .slider { background: var(--primary); }
input:checked + .slider::before { transform: translateX(22px); }

/* ===============================
   ABOUT SECTION
   =============================== */

.about-text {
  text-align: center;
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  margin-top: var(--space-lg);
  font-weight: 500;
}

/* ===============================
   BOTTOM NAVIGATION (Mobile)
   =============================== */

.bottom-nav {
  position: fixed;
  bottom: 0; left: 0; right: 0;
  height: var(--nav-height);
  background: var(--surface);
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-around;
  align-items: center;
  z-index: 100;
  box-shadow: 0 -4px 20px rgba(79, 70, 229, 0.07);
  padding-bottom: env(safe-area-inset-bottom, 0px);
}

.nav-item {
  flex: 1;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-sm);
  font-family: var(--font-family);
  font-size: var(--font-size-xs);
  font-weight: 700;
  transition: all 0.2s ease;
  gap: 3px;
  height: 100%;
  position: relative;
}

.nav-icon {
  font-size: 22px;
  display: block;
  transition: transform 0.2s ease;
}

.nav-label { font-size: 10px; font-weight: 700; letter-spacing: 0.3px; }

.nav-item.nav-active { color: var(--primary); }

.nav-item.nav-active .nav-icon { transform: scale(1.15) translateY(-1px); }

/* pill indicator at top of active nav item */
.nav-item.nav-active::before {
  content: '';
  position: absolute;
  top: 0; left: 50%;
  transform: translateX(-50%);
  width: 28px; height: 3px;
  background: var(--primary);
  border-radius: 0 0 4px 4px;
}

/* ===============================
   RESPONSIVE: TABLET  640px+
   =============================== */

@media (min-width: 640px) {
  .app-main {
    padding: var(--space-xl);
    padding-bottom: calc(var(--nav-height) + var(--space-xl));
  }

  .topics-grid { grid-template-columns: repeat(3, 1fr); gap: var(--space-md); }
  .stats-grid { grid-template-columns: repeat(4, 1fr); }
  .achievements-grid { grid-template-columns: repeat(4, 1fr); }

  .tree-node { min-height: 100px; padding: var(--space-lg) var(--space-md); }
  .tree-node h3 { font-size: var(--font-size-sm); }
}

/* ===============================
   RESPONSIVE: DESKTOP  1024px+
   Desktop gets a LEFT SIDEBAR nav
   =============================== */

@media (min-width: 1024px) {

  /* Sidebar nav */
  .bottom-nav {
    top: 0; bottom: 0; left: 0; right: auto;
    width: var(--sidebar-width);
    height: 100vh;
    flex-direction: column;
    justify-content: flex-start;
    align-items: center;
    padding: var(--space-xl) 0;
    border-top: none;
    border-right: 1px solid var(--border);
    box-shadow: none;
    gap: var(--space-xs);
  }

  .nav-item {
    width: 100%;
    height: 64px;
    flex: none;
    border-radius: 0;
  }

  /* Active indicator on left side in sidebar */
  .nav-item.nav-active::before {
    top: 50%; left: 0;
    transform: translateY(-50%);
    width: 3px; height: 34px;
    border-radius: 0 4px 4px 0;
  }

  /* Screens pushed right of sidebar */
  .screen { margin-left: var(--sidebar-width); }

  .app-main {
    max-width: 1000px;
    margin-left: auto;
    margin-right: auto;
    width: 100%;
    padding-bottom: var(--space-2xl);
  }

  .topics-grid { grid-template-columns: repeat(4, 1fr); gap: var(--space-md); }

  .tree-node { min-height: 110px; padding: var(--space-lg) var(--space-md); }
  .tree-node h3 { font-size: var(--font-size-sm); }

  .lesson-main {
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
    width: 100%;
    padding-bottom: var(--space-2xl);
  }

  .question-container { padding: var(--space-xl); }
  .featured-card { padding: var(--space-xl); }
  .stats-grid { grid-template-columns: repeat(4, 1fr); }
  .achievements-grid { grid-template-columns: repeat(4, 1fr); }
}

@media (min-width: 1280px) {
  .topics-grid { grid-template-columns: repeat(5, 1fr); }
}

/* ===============================
   UTILITIES & ACCESSIBILITY
   =============================== */

.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border-width: 0;
}

.btn:focus-visible,
.nav-item:focus-visible,
.option-chip:focus-visible,
.tree-node:focus-visible {
  outline: 3px solid var(--primary);
  outline-offset: 3px;
}

/* ===============================
   LANDING PAGE
   =============================== */

#screen-landing {
  background: var(--bg);
  display: none;
  flex-direction: column;
}

#screen-landing.screen-active {
  display: flex;
}

/* Hide bottom nav on landing screen */
#screen-landing ~ .bottom-nav,
body.on-landing .bottom-nav {
  display: none;
}

.landing-wrapper {
  flex: 1;
  /* No overflow-y: auto — let the page/body scroll naturally */
}

/* Hero */
.landing-hero {
  min-height: 75vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  padding: var(--space-2xl) var(--space-lg);
  padding-top: 60px;
  position: relative;
  overflow: hidden;
  background: linear-gradient(160deg, #f8faff 0%, #eef2ff 50%, #f0fdf4 100%);
}

body.dark-mode .landing-hero {
  background: linear-gradient(160deg, #020617 0%, #0f172a 50%, #0f1a0f 100%);
}

@media (prefers-color-scheme: dark) {
  .landing-hero {
    background: linear-gradient(160deg, #020617 0%, #0f172a 50%, #0f1a0f 100%);
  }
}

/* decorative blobs */
.landing-hero::before {
  content: '';
  position: absolute;
  width: 300px; height: 300px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(79,70,229,0.18) 0%, transparent 70%);
  top: -80px; right: -80px;
  pointer-events: none;
}

.landing-hero::after {
  content: '';
  position: absolute;
  width: 200px; height: 200px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(16,185,129,0.15) 0%, transparent 70%);
  bottom: 20px; left: -40px;
  pointer-events: none;
}

.landing-badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--primary-light);
  border: 1.5px solid var(--border-hover);
  color: var(--primary);
  font-size: var(--font-size-xs);
  font-weight: 800;
  padding: 5px 14px;
  border-radius: 20px;
  margin-bottom: var(--space-lg);
  letter-spacing: 0.4px;
  text-transform: uppercase;
}

.landing-title {
  font-size: clamp(36px, 10vw, 64px);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -1.5px;
  margin-bottom: var(--space-md);
  color: var(--text);
}

.landing-title .accent {
  background: linear-gradient(135deg, var(--primary), #7C3AED, #059669);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.landing-subtitle {
  font-size: var(--font-size-lg);
  color: var(--text-sub);
  line-height: 1.6;
  max-width: 480px;
  margin-bottom: var(--space-xl);
  font-weight: 500;
}

.landing-cta-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  align-items: flex-start;
}

.btn-landing-start {
  padding: 16px 32px;
  font-size: var(--font-size-lg);
  font-weight: 800;
  border-radius: var(--radius-lg);
  letter-spacing: 0.2px;
  min-height: 56px;
  box-shadow: 0 8px 24px rgba(79,70,229,0.35);
}

.btn-landing-start:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 32px rgba(79,70,229,0.45);
}

.landing-meta {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  font-weight: 600;
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.landing-meta span::before {
  content: '✓ ';
  color: var(--success);
}

/* Features section */
.landing-section {
  padding: var(--space-2xl) var(--space-lg);
}

.landing-section-label {
  font-size: var(--font-size-xs);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--primary);
  margin-bottom: var(--space-sm);
}

.landing-section-title {
  font-size: clamp(24px, 5vw, 36px);
  font-weight: 800;
  color: var(--text);
  margin-bottom: var(--space-xl);
  line-height: 1.2;
  letter-spacing: -0.5px;
}

.features-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.feature-card {
  background: var(--surface);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  box-shadow: var(--shadow-sm);
  transition: all 0.2s ease;
}

.feature-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.feature-icon {
  font-size: 32px;
  margin-bottom: var(--space-sm);
  display: block;
}

.feature-card h3 {
  font-size: var(--font-size-base);
  font-weight: 800;
  color: var(--text);
  margin-bottom: 6px;
}

.feature-card p {
  font-size: var(--font-size-sm);
  color: var(--text-sub);
  line-height: 1.5;
}

/* Exam tags */
.landing-exams {
  padding: 0 var(--space-lg) var(--space-2xl);
}

.exam-category {
  margin-bottom: var(--space-lg);
}

.exam-cat-label {
  font-size: var(--font-size-xs);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-muted);
  margin-bottom: var(--space-sm);
}

.exam-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.exam-tag {
  background: var(--surface);
  border: 1.5px solid var(--border);
  color: var(--text-sub);
  font-size: var(--font-size-sm);
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 20px;
  transition: all 0.2s ease;
  cursor: default;
}

.exam-tag:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-light);
}

/* Scroll hint on hero */
.landing-scroll-hint {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  margin-top: var(--space-xl);
  color: var(--text-muted);
  font-size: var(--font-size-xs);
  font-weight: 600;
  animation: bounceDown 1.8s ease infinite;
}

.landing-scroll-hint span { font-size: 20px; }

@keyframes bounceDown {
  0%, 100% { transform: translateY(0); opacity: 0.6; }
  50%       { transform: translateY(6px); opacity: 1; }
}

/* Stats strip */
.landing-stats {
  padding: var(--space-xl) var(--space-lg);
  background: var(--primary);
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  text-align: center;
}

.landing-stat-value {
  font-size: 28px;
  font-weight: 800;
  color: white;
  display: block;
  line-height: 1;
  margin-bottom: 4px;
}

.landing-stat-label {
  font-size: 11px;
  font-weight: 700;
  color: rgba(255,255,255,0.75);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Bottom CTA */
.landing-bottom-cta {
  padding: var(--space-2xl) var(--space-lg);
  text-align: center;
  background: linear-gradient(160deg, var(--primary-light) 0%, var(--bg) 100%);
}

.landing-bottom-cta h2 {
  font-size: clamp(22px, 5vw, 32px);
  font-weight: 800;
  color: var(--text);
  margin-bottom: var(--space-md);
  letter-spacing: -0.5px;
}

.landing-bottom-cta p {
  color: var(--text-sub);
  margin-bottom: var(--space-xl);
  font-size: var(--font-size-sm);
}

/* Desktop landing */
@media (min-width: 640px) {
  .landing-hero {
    padding: var(--space-2xl) var(--space-2xl);
  }

  .features-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .landing-section {
    padding: var(--space-2xl);
  }

  .landing-exams {
    padding: 0 var(--space-2xl) var(--space-2xl);
  }

  .landing-bottom-cta {
    padding: var(--space-2xl);
  }
}

@media (min-width: 1024px) {
  /* On desktop, landing doesn't use sidebar */
  #screen-landing { margin-left: 0 !important; }

  .landing-hero {
    min-height: 100vh;
    padding: 80px 10%;
  }

  .landing-title {
    max-width: 700px;
  }
}