/* ================================================================
   GREAT KEZINO SCHOOLS — ONLINE CODING TUTOR
   style.css
   Linked from: index.html
================================================================ */

/* ── CUSTOM PROPERTIES ──────────────────────────────────────── */
:root {
  --bg:        #0b0d14;
  --bg2:       #11141f;
  --bg3:       #181c2b;
  --border:    #ffffff12;
  --accent1:   #00e5ff;   /* cyan   */
  --accent2:   #ff6b35;   /* orange */
  --accent3:   #a78bfa;   /* violet */
  --html-clr:  #ff6b35;
  --css-clr:   #00e5ff;
  --text:      #e2e8f0;
  --muted:     #8892a4;
  --card:      #141824;
  --sidebar-w: 300px;
  --radius:    12px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'DM Sans', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
}

/* ── NOISE TEXTURE OVERLAY ──────────────────────────────────── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
}

/* ════════════════════════════════════════════════════════════
   HEADER
════════════════════════════════════════════════════════════ */
header {
  position: relative;
  z-index: 10;
  background: linear-gradient(135deg, #0d1120 0%, #131a2e 60%, #0e1520 100%);
  border-bottom: 1px solid var(--border);
  padding: 0 2rem;
  overflow: hidden;
}

header::after {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background: radial-gradient(ellipse 60% 200% at 70% 50%, #00e5ff08 0%, transparent 70%);
  pointer-events: none;
}

.header-inner {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.4rem 0;
}

.logo-block {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.logo-icon {
  width: 52px;
  height: 52px;
  background: linear-gradient(135deg, var(--accent2), #ff9500);
  border-radius: 14px;
  display: grid;
  place-items: center;
  font-family: 'Bebas Neue', sans-serif;
  font-size: 1.5rem;
  color: #fff;
  box-shadow: 0 0 20px #ff6b3540;
  flex-shrink: 0;
  position: relative;
}

.logo-icon::after {
  content: '';
  position: absolute;
  inset: -2px;
  border-radius: 16px;
  background: linear-gradient(135deg, #ff6b35, #a78bfa);
  z-index: -1;
  filter: blur(6px);
  opacity: 0.5;
}

.logo-text h1 {
  font-family: 'Bebas Neue', sans-serif;
  font-size: 1.7rem;
  letter-spacing: 0.06em;
  line-height: 1;
  background: linear-gradient(90deg, #fff 40%, var(--accent1));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.logo-text p {
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin-top: 2px;
}

.badge {
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 0.35rem 0.75rem;
  border-radius: 20px;
  border: 1px solid var(--accent1);
  color: var(--accent1);
  background: #00e5ff0d;
}

/* ════════════════════════════════════════════════════════════
   HERO
════════════════════════════════════════════════════════════ */
.hero {
  position: relative;
  z-index: 5;
  text-align: center;
  padding: 4.5rem 2rem 3rem;
  background: radial-gradient(ellipse 80% 60% at 50% 0%, #00e5ff06 0%, transparent 70%);
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent1);
  margin-bottom: 1.2rem;
}

.hero-eyebrow span {
  display: inline-block;
  width: 24px;
  height: 1px;
  background: var(--accent1);
}

.hero h2 {
  font-family: 'Syne', sans-serif;
  font-size: clamp(2.2rem, 5vw, 3.8rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 1rem;
}

.hero h2 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--accent1), var(--accent3));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 560px;
  margin: 0 auto 2.8rem;
  line-height: 1.7;
}

/* ── BIG COURSE BUTTONS ─────────────────────────────────────── */
.course-buttons {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1rem;
}

.btn-course {
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding: 1.3rem 2.5rem;
  border: none;
  cursor: pointer;
  border-radius: 16px;
  font-family: 'Syne', sans-serif;
  font-size: 1.3rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1),
              box-shadow 0.25s ease;
  z-index: 1;
  min-width: 230px;
  justify-content: center;
}

.btn-course::before {
  content: '';
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 0.25s;
}

.btn-course:hover::before { opacity: 1; }
.btn-course:hover         { transform: translateY(-4px) scale(1.02); }
.btn-course:active        { transform: scale(0.97); }

.btn-course .btn-icon {
  font-size: 2rem;
  line-height: 1;
  filter: drop-shadow(0 0 8px currentColor);
}

.btn-course .btn-label { line-height: 1; }

.btn-course .btn-sub {
  display: block;
  font-size: 0.65rem;
  font-family: 'DM Sans', sans-serif;
  font-weight: 400;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  opacity: 0.75;
  margin-top: 2px;
}

/* HTML5 button */
.btn-html {
  background: linear-gradient(135deg, #ff6b35 0%, #ff9a3c 100%);
  color: #fff;
  box-shadow: 0 8px 32px #ff6b3540, 0 0 0 1px #ff6b3530;
}
.btn-html::before { background: linear-gradient(135deg, #ff7a46, #ffaf50); }
.btn-html:hover   { box-shadow: 0 14px 40px #ff6b3560, 0 0 0 2px #ff6b3550; }
.btn-html.active  {
  box-shadow: 0 0 0 3px #ff6b35, 0 8px 32px #ff6b3560;
  transform: translateY(-2px);
}

/* CSS3 button */
.btn-css {
  background: linear-gradient(135deg, #0a7ab8 0%, #00c8e8 100%);
  color: #fff;
  box-shadow: 0 8px 32px #00e5ff30, 0 0 0 1px #00e5ff20;
}
.btn-css::before { background: linear-gradient(135deg, #1488cc, #1ac8e8); }
.btn-css:hover   { box-shadow: 0 14px 40px #00e5ff55, 0 0 0 2px #00e5ff40; }
.btn-css.active  {
  box-shadow: 0 0 0 3px #00e5ff, 0 8px 32px #00e5ff55;
  transform: translateY(-2px);
}

/* ════════════════════════════════════════════════════════════
   APP LAYOUT
════════════════════════════════════════════════════════════ */
.app {
  display: none;
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 1.5rem 3rem;
  position: relative;
  z-index: 5;
}

.app.visible { display: flex; gap: 1.5rem; }

/* ── SIDEBAR ────────────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  position: sticky;
  top: 1.5rem;
  height: calc(100vh - 3rem);
  overflow-y: auto;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 0.75rem;
  scrollbar-width: thin;
  scrollbar-color: #ffffff18 transparent;
}

.sidebar::-webkit-scrollbar       { width: 4px; }
.sidebar::-webkit-scrollbar-thumb { background: #ffffff18; border-radius: 4px; }

.sidebar-header {
  padding: 0.25rem 0.5rem 1rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 0.75rem;
}

.sidebar-header h3 {
  font-family: 'Syne', sans-serif;
  font-weight: 700;
  font-size: 1rem;
}

.sidebar-header p {
  font-size: 0.72rem;
  color: var(--muted);
  margin-top: 0.25rem;
}

/* ── PROGRESS BAR ───────────────────────────────────────────── */
.progress-bar-wrap {
  height: 3px;
  background: var(--border);
  border-radius: 0 0 12px 12px;
  overflow: hidden;
  margin: 0 0.75rem 1.25rem;
}

.progress-bar-fill {
  height: 100%;
  border-radius: 2px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  background: var(--active-clr, var(--accent1));
}

/* ── TOPIC ITEMS ────────────────────────────────────────────── */
.topic-item {
  display: flex;
  align-items: flex-start;
  gap: 0.7rem;
  padding: 0.7rem 0.75rem;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  margin-bottom: 2px;
  border: 1px solid transparent;
}

.topic-item:hover {
  background: #ffffff08;
  border-color: var(--border);
}

.topic-item.active {
  background: #ffffff0e;
  border-color: var(--active-clr, var(--accent1));
}

.topic-num {
  font-size: 0.65rem;
  font-weight: 700;
  font-family: 'JetBrains Mono', monospace;
  color: var(--muted);
  min-width: 22px;
  padding-top: 2px;
}

.topic-item.active .topic-num  { color: var(--active-clr, var(--accent1)); }

.topic-name {
  font-size: 0.85rem;
  font-weight: 500;
  line-height: 1.35;
}

.topic-item.active .topic-name { color: var(--active-clr, var(--accent1)); }

/* ════════════════════════════════════════════════════════════
   MAIN CONTENT PANEL
════════════════════════════════════════════════════════════ */
.main-content {
  flex: 1;
  min-width: 0;
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2.5rem;
  min-height: 70vh;
  overflow: hidden;
}

/* ── WELCOME SCREEN ─────────────────────────────────────────── */
.welcome-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 400px;
  text-align: center;
  gap: 1.5rem;
}

.welcome-screen .big-icon {
  font-size: 4rem;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50%       { transform: translateY(-12px); }
}

.welcome-screen h3 {
  font-family: 'Syne', sans-serif;
  font-size: 1.6rem;
  font-weight: 700;
}

.welcome-screen p {
  color: var(--muted);
  max-width: 380px;
  line-height: 1.6;
}

/* ── TOPIC CONTENT ──────────────────────────────────────────── */
.topic-content        { display: none; animation: fadeUp 0.4s ease; }
.topic-content.visible { display: block; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(16px); }
  to   { opacity: 1; transform: translateY(0); }
}

.topic-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.65rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  padding: 0.3rem 0.7rem;
  border-radius: 20px;
  margin-bottom: 1rem;
  font-weight: 600;
}

.topic-content h2 {
  font-family: 'Syne', sans-serif;
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 0.75rem;
}

.topic-intro {
  font-size: 1.05rem;
  line-height: 1.75;
  color: var(--muted);
  max-width: 720px;
  margin-bottom: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

/* ── SECTION LABELS ─────────────────────────────────────────── */
.section-label {
  font-size: 0.68rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 600;
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.section-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* ── KEY POINTS ─────────────────────────────────────────────── */
.key-points {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 0.75rem;
  margin-bottom: 2.5rem;
}

.key-point {
  background: var(--bg3);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1rem 1.1rem;
  font-size: 0.88rem;
  line-height: 1.55;
  display: flex;
  gap: 0.75rem;
}

.key-point .kp-icon {
  font-size: 1.1rem;
  flex-shrink: 0;
  margin-top: 1px;
}

/* ── CODE BLOCK ─────────────────────────────────────────────── */
.code-block {
  background: #0a0c14;
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: 1.75rem;
  position: relative;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 1rem;
  background: #0d101c;
  border-bottom: 1px solid var(--border);
}

.code-block-header .dots {
  display: flex;
  gap: 5px;
}

.code-block-header .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.dot-r { background: #ff5f57; }
.dot-y { background: #febc2e; }
.dot-g { background: #28c840; }

.code-block-header .file-name {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.72rem;
  color: var(--muted);
  margin-left: 0.5rem;
}

.copy-btn {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.72rem;
  font-family: 'DM Sans', sans-serif;
  font-weight: 500;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 0.28rem 0.7rem;
  border-radius: 6px;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
  letter-spacing: 0.04em;
}

.copy-btn:hover  { border-color: var(--accent1); color: var(--accent1); }
.copy-btn.copied { border-color: #22c55e;         color: #22c55e; }

.code-block pre {
  padding: 1.4rem 1.5rem;
  overflow-x: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.83rem;
  line-height: 1.7;
  color: #c9d1d9;
}

/* ── SYNTAX HIGHLIGHT CLASSES ───────────────────────────────── */
.t   { color: #79c0ff; }                   /* tag       */
.a   { color: #ffb86c; }                   /* attribute */
.v   { color: #a8ff68; }                   /* value     */
.c   { color: #6e7681; font-style: italic; }/* comment  */
.k   { color: #ff79c6; }                   /* keyword   */
.s   { color: #f1fa8c; }                   /* string    */
.p   { color: #f8f8f2; }                   /* punctuation*/
.n   { color: #79c0ff; }                   /* number    */
.fn  { color: #50fa7b; }                   /* function  */
.pr  { color: #8be9fd; }                   /* property  */
.cm  { color: #bd93f9; }                   /* comment   */
.sel { color: #50fa7b; }                   /* selector  */
.val { color: #f1fa8c; }                   /* css value */
.un  { color: #ff79c6; }                   /* unit      */

/* ── REFERENCE TABLE ────────────────────────────────────────── */
.ref-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 2rem;
  font-size: 0.85rem;
}

.ref-table th {
  background: var(--bg3);
  padding: 0.65rem 1rem;
  text-align: left;
  font-family: 'Syne', sans-serif;
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
}

.ref-table td {
  padding: 0.65rem 1rem;
  border-bottom: 1px solid #ffffff08;
  vertical-align: middle;
  line-height: 1.5;
}

.ref-table tr:hover td { background: #ffffff04; }

.ref-table code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  background: var(--bg3);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  color: var(--accent1);
}

/* ── INFO BOXES ─────────────────────────────────────────────── */
.info-box {
  display: flex;
  gap: 1rem;
  padding: 1.1rem 1.25rem;
  border-radius: 10px;
  margin-bottom: 1.75rem;
  font-size: 0.88rem;
  line-height: 1.6;
}

.info-box.tip     { background: #00e5ff0c; border: 1px solid #00e5ff25; color: #c0f9ff; }
.info-box.note    { background: #a78bfa0c; border: 1px solid #a78bfa25; color: #ddd6fe; }
.info-box.warning { background: #ff6b350c; border: 1px solid #ff6b3525; color: #ffd0b5; }

.info-box .ib-icon {
  font-size: 1.2rem;
  flex-shrink: 0;
}

/* ── NAV BUTTONS (prev / next) ──────────────────────────────── */
.lesson-nav {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
  align-items: center;
}

.lesson-nav .spacer { flex: 1; }

.btn-prev,
.btn-next {
  padding: 0.65rem 1.3rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.88rem;
  font-family: 'DM Sans', sans-serif;
  font-weight: 600;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.btn-prev {
  background: var(--bg3);
  border: 1px solid var(--border);
  color: var(--text);
}

.btn-prev:hover { border-color: var(--active-clr, var(--accent1)); }

.btn-next {
  background: var(--active-clr, var(--accent1));
  border: none;
  color: #000;
}

.btn-next:hover { box-shadow: 0 4px 16px var(--active-clr, var(--accent1)); }

.course-complete {
  font-size: 0.88rem;
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* ════════════════════════════════════════════════════════════
   FOOTER
════════════════════════════════════════════════════════════ */
footer {
  position: relative;
  z-index: 5;
  text-align: center;
  padding: 1.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.75rem;
  color: var(--muted);
  letter-spacing: 0.05em;
}

footer strong { color: var(--accent1); }

/* ════════════════════════════════════════════════════════════
   RESPONSIVE
════════════════════════════════════════════════════════════ */
@media (max-width: 900px) {
  .app.visible {
    flex-direction: column;
  }
  .sidebar {
    width: 100%;
    height: auto;
    position: static;
    max-height: 320px;
  }
  .main-content {
    padding: 1.5rem;
  }
}

@media (max-width: 600px) {
  .header-inner { flex-direction: column; gap: 1rem; padding: 1rem 0; }
  .hero h2      { font-size: 1.8rem; }
  .btn-course   { min-width: 180px; padding: 1.1rem 1.6rem; font-size: 1.1rem; }
  .main-content { padding: 1.25rem; }
  .topic-content h2 { font-size: 1.5rem; }
}