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

/* === BASE === */
body {
  font-family: 'Segoe UI', sans-serif;
  background: #0d1117;
  color: #e6edf3;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* === TOPBAR === */
#topbar {
  background: #161b22;
  border-bottom: 1px solid #30363d;
  padding: 0 12px;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 48px;
  flex-shrink: 0;
}

#home-link {
  color: #8b949e;
  font-size: 12px;
  text-decoration: none;
  border: 1px solid #30363d;
  padding: 3px 10px;
  border-radius: 6px;
  white-space: nowrap;
  transition: border-color .15s, color .15s;
}
#home-link:hover { border-color: #f7df1e; color: #f7df1e; }

#topbar h1 {
  font-size: 16px;
  font-weight: 700;
  background: linear-gradient(135deg, #f7df1e, #f0a500);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  white-space: nowrap;
}

.lang-btn {
  background: transparent;
  border: 1px solid #30363d;
  color: #8b949e;
  padding: 3px 8px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 11px;
}
.lang-btn.active { border-color: #f7df1e; color: #f7df1e; }

#progress-bar-wrap {
  flex: 1;
  height: 5px;
  background: #30363d;
  border-radius: 99px;
  overflow: hidden;
}
#progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #f7df1e, #f0a500);
  border-radius: 99px;
  transition: width .4s;
}
#progress-text { font-size: 11px; color: #8b949e; white-space: nowrap; }

#menu-btn {
  display: none;
  background: transparent;
  border: 1px solid #30363d;
  color: #8b949e;
  padding: 4px 8px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  line-height: 1;
}

/* === MAIN LAYOUT === */
#main { display: flex; flex: 1; overflow: hidden; position: relative; }

/* === SIDEBAR === */
#sidebar {
  width: 200px;
  background: #0d1117;
  border-right: 1px solid #30363d;
  overflow-y: auto;
  flex-shrink: 0;
  transition: transform .25s;
}
#sidebar h3 {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .8px;
  color: #8b949e;
  padding: 12px 14px 6px;
}

.lesson-item {
  padding: 9px 14px;
  cursor: pointer;
  font-size: 12px;
  color: #8b949e;
  border-left: 3px solid transparent;
  transition: all .15s;
  display: flex;
  align-items: center;
  gap: 6px;
}
.lesson-item:hover  { background: #161b22; color: #e6edf3; }
.lesson-item.active { background: #161b22; border-left-color: #f7df1e; color: #f7df1e; }
.lesson-item .check { color: #3fb950; font-size: 11px; margin-left: auto; }
.lesson-item .num   { font-size: 10px; color: #484f58; min-width: 16px; }

.section-header {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .8px;
  color: #484f58;
  padding: 10px 14px 4px;
  margin-top: 4px;
}

#sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.6);
  z-index: 49;
}

/* === CONTENT === */
#content { flex: 1; display: flex; flex-direction: column; overflow: hidden; }

/* === MOBILE TABS (hidden on desktop) === */
#tabs { display: none; background: #161b22; border-bottom: 1px solid #30363d; flex-shrink: 0; }
#tabs button {
  flex: 1;
  padding: 10px;
  background: transparent;
  border: none;
  color: #8b949e;
  font-size: 13px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  font-family: 'Segoe UI', sans-serif;
}
#tabs button.active { color: #f7df1e; border-bottom-color: #f7df1e; }

/* === SPLIT (lesson + editor side by side) === */
#split { flex: 1; display: flex; overflow: hidden; }

/* === LESSON PANEL === */
#lesson-panel {
  width: 44%;
  overflow-y: auto;
  padding: 20px 24px;
  border-right: 1px solid #30363d;
  flex-shrink: 0;
}
#lesson-panel h2 { font-size: 19px; font-weight: 700; margin-bottom: 4px; }
.lesson-meta     { font-size: 11px; color: #8b949e; margin-bottom: 14px; }
.lesson-body     { font-size: 15px; line-height: 1.75; color: #c9d1d9; }
.lesson-body p   { margin-bottom: 12px; }
.lesson-body pre {
  background: #161b22;
  border: 1px solid #30363d;
  border-radius: 8px;
  padding: 11px 13px;
  font-family: 'Courier New', monospace;
  font-size: 12px;
  overflow-x: auto;
  margin-bottom: 12px;
  color: #f0f6fc;
  line-height: 1.6;
}

.kw  { color: #ff7b72; }
.str { color: #a5d6ff; }
.fn  { color: #d2a8ff; }
.cm  { color: #6e7681; }
.num { color: #79c0ff; }
.bi  { color: #ffa657; }

.task-box {
  background: #161b22;
  border: 1px solid #30363d;
  border-left: 3px solid #f7df1e;
  border-radius: 8px;
  padding: 13px 15px;
  margin-top: 18px;
}
.task-box h4 {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: .5px;
  color: #f7df1e;
  margin-bottom: 6px;
}
.task-box p { font-size: 13px; color: #e6edf3; line-height: 1.6; }

#to-code-btn {
  display: none;
  margin-top: 16px;
  width: 100%;
  padding: 10px;
  background: linear-gradient(135deg, #f7df1e, #f0a500);
  border: none;
  border-radius: 8px;
  color: #0d1117;
  font-weight: 700;
  font-size: 14px;
  cursor: pointer;
  font-family: 'Segoe UI', sans-serif;
}

/* === EXERCISE PANEL === */
#exercise-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

#ex-header {
  padding: 9px 14px;
  border-bottom: 1px solid #30363d;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
  flex-wrap: wrap;
}
#ex-header h3 { font-size: 13px; font-weight: 600; }
#ex-nav { display: flex; gap: 5px; flex-wrap: wrap; }

.ex-dot {
  width: 24px; height: 24px;
  border-radius: 50%;
  border: 2px solid #30363d;
  background: transparent;
  color: #8b949e;
  font-size: 11px;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: all .15s;
}
.ex-dot.active { border-color: #f7df1e; color: #f7df1e; background: #f7df1e18; }
.ex-dot.done   { border-color: #3fb950; background: #3fb95022; color: #3fb950; }

#editor-wrap { flex: 3; overflow: hidden; position: relative; }
.CodeMirror  { height: 100% !important; font-size: 15px; font-family: 'Courier New', monospace; }

/* === OUTPUT BAR === */
#output-bar {
  flex: 2;
  min-height: 80px;
  border-top: 1px solid #30363d;
  display: flex;
  flex-direction: column;
}

#run-row {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 6px 10px;
  background: #161b22;
  border-bottom: 1px solid #30363d;
  flex-shrink: 0;
  flex-wrap: wrap;
}

#run-btn {
  background: linear-gradient(135deg, #f7df1e, #f0a500);
  border: none;
  color: #0d1117;
  padding: 6px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  font-weight: 700;
}
#reset-btn {
  background: transparent;
  border: 1px solid #30363d;
  color: #8b949e;
  padding: 6px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 11px;
}
#hint-btn {
  background: transparent;
  border: 1px solid #d2940022;
  color: #d29400;
  padding: 6px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 11px;
}

#feedback { font-size: 11px; display: flex; align-items: center; gap: 4px; margin-left: auto; }
.fb-pass { color: #3fb950; }
.fb-hint { color: #d29922; }

#output {
  flex: 1;
  overflow-y: auto;
  padding: 7px 11px;
  font-family: 'Courier New', monospace;
  font-size: 14px;
  background: #0d1117;
  line-height: 1.5;
}
.out-ok   { color: #e6edf3; }
.out-err  { color: #ff7b72; }
.out-info { color: #484f58; }

/* === RESPONSIVE — MOBILE ≤ 700px === */
@media (max-width: 700px) {
  body { height: 100dvh; }

  #menu-btn { display: block; }
  #progress-bar-wrap { max-width: 80px; }

  /* Sidebar: slides in as a drawer */
  #sidebar {
    position: fixed;
    top: 0; left: 0;
    height: 100%;
    width: 75%;
    max-width: 260px;
    z-index: 50;
    transform: translateX(-100%);
    border-right: 1px solid #30363d;
    background: #0d1117;
  }
  #sidebar.open { transform: translateX(0); }
  #sidebar-overlay.open { display: block; }

  /* Show tab bar */
  #tabs { display: flex; }

  /* Split becomes vertical column */
  #split { flex-direction: column; }

  /* Lesson panel fills its tab */
  #lesson-panel {
    width: 100%;
    border-right: none;
    padding: 16px;
    flex-shrink: 0;
    display: none;
  }
  #lesson-panel.tab-active { display: block; overflow-y: auto; flex: 1; }

  /* Show "Kodu yaz →" button in lesson panel */
  #to-code-btn { display: block; }

  /* Exercise panel fills its tab */
  #exercise-panel { display: none; }
  #exercise-panel.tab-active { display: flex; }

  #output-bar { height: 130px; }
  .CodeMirror  { font-size: 12px; }

  #ex-header { padding: 8px 12px; }
  #run-row   { padding: 5px 8px; gap: 6px; }
  #run-btn   { padding: 5px 12px; font-size: 11px; }
  #reset-btn, #hint-btn { padding: 5px 9px; font-size: 10px; }
  #feedback  { font-size: 11px; flex-basis: 100%; margin-left: 0; margin-top: 2px; }
}

@media (max-width: 400px) {
  #topbar h1 { font-size: 13px; }
  #home-link { padding: 2px 7px; font-size: 11px; }
  .lang-btn  { padding: 2px 6px; font-size: 10px; }
  #progress-bar-wrap { display: none; }
  .lesson-body pre { font-size: 11px; }
  #output { font-size: 11px; }
}