:root {
  --bg: #012530;
  --panel: rgba(7, 54, 66, 0.55);
  --panel-solid: #073642;
  --border: rgba(88, 110, 117, 0.3);
  --text: #fdf6e3;
  --text-dim: #93a1a1;
  --text-faint: #657b83;
  --teal: #2aa198;
  --teal-shadow: #1c766c;
  --violet: #6c71c4;
  --violet-shadow: #4b4f8c;
  --yellow: #b58900;
  --orange: #cb4b16;
  --red: #dc322f;
  --red-shadow: #961f1c;
  --green: #859900;
  --green-shadow: #5c6b00;
  --easy: #859900;
  --medium: #b58900;
  --hard: #cb4b16;
  --expert: #dc322f;
  --font-display: ui-rounded, "SF Pro Rounded", "Segoe UI", system-ui, sans-serif;
  --font-mono: "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

/* Belt-and-suspenders: several classes below (.btn-chunky, .node-btn, ...) set
   their own `display`, which ties the browser's default [hidden]{display:none}
   rule on specificity - and author styles win ties over the UA stylesheet, so
   without this, toggling the `hidden` property leaves the element visible. */
[hidden] { display: none !important; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
}

button { font-family: inherit; -webkit-tap-highlight-color: transparent; }
textarea:focus, button:focus { outline: none; }

a { color: var(--teal); text-decoration: none; }
a:hover { color: #3fc3b5; }

.app-shell { position: relative; min-height: 100vh; overflow-x: hidden; }

/* ---------- watercolor background ---------- */
.blob-bg { position: fixed; inset: 0; overflow: hidden; pointer-events: none; z-index: 0; }
.blob { position: absolute; border-radius: 50%; filter: blur(70px); opacity: 0.45; animation: drift 24s ease-in-out infinite; }
@keyframes drift {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  50% { transform: translate(18px, -14px) rotate(4deg); }
}
.blob-teal { left: -10%; top: -15%; width: 560px; height: 560px; background: radial-gradient(circle, var(--teal) 0%, transparent 68%); }
.blob-violet { right: -8%; top: 5%; width: 480px; height: 480px; background: radial-gradient(circle, var(--violet) 0%, transparent 68%); animation-direction: reverse; opacity: 0.5; }
.blob-diff { left: 10%; top: 38%; width: 420px; height: 420px; background: radial-gradient(circle, var(--medium) 0%, transparent 70%); opacity: 0.4; transition: background 0.4s ease; }
.blob-yellow { right: 6%; bottom: 0; width: 520px; height: 520px; background: radial-gradient(circle, var(--yellow) 0%, transparent 68%); opacity: 0.35; animation-direction: reverse; }
.blob-olive { left: 35%; bottom: -12%; width: 380px; height: 380px; background: radial-gradient(circle, var(--green) 0%, transparent 70%); opacity: 0.35; }

/* ---------- shell ---------- */
.shell-main { position: relative; z-index: 1; max-width: 640px; margin: 0 auto; padding: 26px 20px 70px; }

.topbar { display: flex; justify-content: space-between; align-items: center; gap: 14px; flex-wrap: wrap; margin-bottom: 6px; }
.brand { font-family: var(--font-display); font-weight: 800; font-size: 1.05rem; opacity: 0.85; }
.stats { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.stat-points, .stat-streak {
  display: flex; align-items: center; gap: 6px;
  font-weight: 800; font-size: 1.05rem; font-family: var(--font-display);
}
.flame-icon { transform-origin: 50% 90%; animation: flicker 2.1s ease-in-out infinite; }
@keyframes flicker {
  0%, 100% { transform: scaleY(1) scaleX(1) rotate(0deg); }
  25% { transform: scaleY(1.08) scaleX(0.95) rotate(-2deg); }
  50% { transform: scaleY(0.93) scaleX(1.05) rotate(1.5deg); }
  75% { transform: scaleY(1.04) scaleX(0.97) rotate(-1deg); }
}

/* ---------- track switcher ---------- */
.track-switcher { display: flex; gap: 8px; flex-wrap: wrap; margin: 14px 0 0; }
.track-pill {
  border: 1px solid var(--border); background: rgba(0, 0, 0, 0.15); color: var(--text-dim);
  padding: 7px 16px; border-radius: 999px; font-size: 0.82rem; font-weight: 700; cursor: pointer;
  transition: background 0.12s ease, color 0.12s ease, border-color 0.12s ease, transform 0.05s ease;
}
.track-pill:hover { color: var(--text); border-color: var(--text-faint); }
.track-pill:active { transform: scale(0.96); }
.track-pill.active { background: var(--teal); color: var(--bg); border-color: var(--teal); }

/* ---------- reset day ---------- */
.reset-day-btn {
  margin-left: auto; display: inline-flex; align-items: center; gap: 6px;
  background: transparent; border: 1px solid color-mix(in oklch, var(--red) 45%, transparent);
  color: color-mix(in oklch, var(--red) 80%, var(--text)); padding: 5px 12px; border-radius: 999px;
  font-size: 0.76rem; font-weight: 700; cursor: pointer;
}
.reset-day-btn:hover { background: rgba(220, 50, 47, 0.12); }
.reset-day-btn:active { transform: scale(0.96); }
.difficulty-row { display: flex; align-items: center; justify-content: center; flex-wrap: wrap; gap: 8px; position: relative; }

/* ---------- mascot ---------- */
.mascot-row { display: flex; align-items: flex-end; gap: 14px; margin: 22px 0 8px; }
.mascot-flame { flex: 0 0 auto; transform-origin: 50% 90%; animation: flicker 2.4s ease-in-out infinite; }
.mascot-bubble {
  position: relative; background: var(--panel-solid); border-radius: 20px 20px 20px 4px;
  padding: 12px 18px; font-size: 0.95rem; font-weight: 600; max-width: 420px;
}

/* ---------- difficulty badge ---------- */
.difficulty-row { text-align: center; margin: 20px 0 6px; }
.badge {
  display: inline-block; padding: 5px 16px; border-radius: 999px;
  font-size: 0.78rem; font-weight: 800; text-transform: uppercase; letter-spacing: 0.05em;
}
.badge-easy { background: rgba(133, 153, 0, 0.18); color: var(--easy); }
.badge-medium { background: rgba(181, 137, 0, 0.18); color: var(--medium); }
.badge-hard { background: rgba(203, 75, 22, 0.18); color: var(--hard); }
.badge-expert { background: rgba(220, 50, 47, 0.18); color: var(--expert); }
.badge-late { margin-left: 8px; background: rgba(220, 50, 47, 0.18); color: var(--red); }

/* ---------- node nav ---------- */
.node-nav {
  position: relative; display: flex; justify-content: space-around; align-items: center;
  margin: 26px 0 30px; padding: 0 10px;
}
.node-nav::before {
  content: ""; position: absolute; left: 15%; right: 15%; top: 32px;
  border-top: 3px dashed rgba(147, 161, 161, 0.3); z-index: 0;
}
.node-btn {
  position: relative; z-index: 1; display: flex; flex-direction: column; align-items: center;
  gap: 8px; background: none; border: none; cursor: pointer; padding: 0;
}
.node-circle {
  width: 64px; height: 64px; border-radius: 50%; display: flex; align-items: center; justify-content: center;
  position: relative; box-shadow: 0 4px 0 rgba(0, 0, 0, 0.3); background: #52717a;
  color: var(--text); font-weight: 800; font-size: 1.4rem; font-family: var(--font-mono);
  transition: background 0.2s ease;
}
.node-circle.current { animation: bounce 1.6s ease-in-out infinite; }
@keyframes bounce {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-8px) scale(1.05); }
}
.node-circle.done { background: var(--green) !important; box-shadow: 0 4px 0 var(--green-shadow) !important; }
.node-check { display: none; }
.node-circle.done .node-icon { display: none; }
.node-circle.done .node-check { display: block; }
.node-label { font-size: 0.78rem; font-weight: 700; color: var(--text-dim); }
.node-btn.current .node-label { color: var(--text); }

/* ---------- panels ---------- */
.blob-panel {
  position: relative; background: var(--panel); border: 1px solid var(--border);
  border-radius: 32px 32px 32px 8px; padding: 26px 24px; margin-bottom: 24px; backdrop-filter: blur(6px);
}

.prose { color: var(--text-dim); white-space: pre-wrap; margin: 0 0 8px; line-height: 1.6; }
.hint { color: var(--text-faint); font-size: 0.85rem; margin: 0 0 12px; }

/* ---------- quiz ---------- */
.question { margin-bottom: 20px; }
.question:last-child { margin-bottom: 0; }
.q-text { font-weight: 800; margin: 0 0 12px; font-family: var(--font-display); font-size: 1.02rem; }
.choice {
  display: flex; align-items: center; gap: 10px; width: 100%; text-align: left; margin-bottom: 8px; padding: 12px 16px;
  border-radius: 14px; cursor: pointer; background: rgba(0, 0, 0, 0.18); color: var(--text);
  border: none; font-size: 0.92rem; font-weight: 600; box-shadow: 0 3px 0 rgba(0, 0, 0, 0.35);
  transition: transform 0.05s ease, background 0.15s ease; min-height: 44px;
}
.choice:active:not(.locked) { transform: translateY(2px); box-shadow: 0 1px 0 rgba(0, 0, 0, 0.35); }
.choice-indicator {
  flex: 0 0 auto; width: 18px; height: 18px; border-radius: 50%; border: 2px solid var(--text-faint);
  position: relative; transition: background 0.12s ease, border-color 0.12s ease;
}
.choice-indicator::after {
  content: ""; position: absolute; inset: 3px; border-radius: 50%; background: var(--text);
  transform: scale(0); transition: transform 0.12s ease;
}
.choice.selected { background: var(--teal); color: var(--bg); box-shadow: 0 3px 0 var(--teal-shadow); }
.choice.selected .choice-indicator { border-color: var(--bg); }
.choice.selected .choice-indicator::after { transform: scale(1); background: var(--bg); }
.choice.correct { background: var(--green); color: var(--bg); box-shadow: 0 3px 0 var(--green-shadow); }
.choice.correct .choice-indicator { border-color: var(--bg); }
.choice.correct .choice-indicator::after { transform: scale(1); background: var(--bg); }
.choice.incorrect { background: var(--red); color: var(--bg); box-shadow: 0 3px 0 var(--red-shadow); }
.choice.incorrect .choice-indicator { border-color: var(--bg); }
.choice.incorrect .choice-indicator::after { transform: scale(1); background: var(--bg); }
.choice.locked { cursor: default; }

/* ---------- buttons ---------- */
.btn-row { display: flex; flex-direction: column; gap: 10px; margin: 4px 0; }
.btn-chunky {
  border: none; border-radius: 16px; padding: 13px 26px; font-weight: 800; font-size: 0.92rem;
  letter-spacing: 0.01em; cursor: pointer; transition: transform 0.05s ease, box-shadow 0.05s ease;
  display: flex; align-items: center; justify-content: center; gap: 8px; width: 100%;
}
/* compact icon/nav controls stay their natural size, not full-width */
#history-toggle, .cal-nav-btn { width: auto; display: inline-flex; }
.btn-chunky:active { transform: translateY(4px); }
.btn-chunky:disabled { cursor: not-allowed; opacity: 0.7; }
.btn-teal { background: var(--teal); color: var(--bg); box-shadow: 0 5px 0 var(--teal-shadow); }
.btn-teal:active { box-shadow: 0 1px 0 var(--teal-shadow); }
.btn-violet { background: var(--violet); color: var(--text); box-shadow: 0 5px 0 var(--violet-shadow); }
.btn-violet:active { box-shadow: 0 1px 0 var(--violet-shadow); }
.btn-green { background: var(--green); color: var(--bg); box-shadow: 0 5px 0 var(--green-shadow); }
.btn-green:active { box-shadow: 0 1px 0 var(--green-shadow); }
.btn-ghost { background: rgba(255, 255, 255, 0.08); color: var(--text); box-shadow: 0 5px 0 rgba(0, 0, 0, 0.3); }
.btn-ghost:active { box-shadow: 0 1px 0 rgba(0, 0, 0, 0.3); }
.btn-suggested { outline: 3px solid var(--text); outline-offset: 2px; }

/* ---------- code panel ---------- */
.docs-row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; margin: 0 0 16px; }
.docs-label { font-weight: 800; font-size: 0.8rem; color: var(--teal); }
.docs-link {
  padding: 5px 14px; border-radius: 999px; background: rgba(42, 161, 152, 0.16);
  color: var(--teal); font-size: 0.82rem; font-weight: 700;
}

textarea {
  width: 100%; min-height: 190px; background: #00161d; color: #dbe4ff; border: none;
  border-radius: 18px; font-family: var(--font-mono); font-size: 0.86rem; padding: 16px;
  resize: vertical; margin: 6px 0 16px; box-shadow: inset 0 0 0 1px var(--border);
}
#concept-notes { min-height: 100px; font-family: inherit; color: var(--text); font-size: 0.92rem; }

/* ---------- code editor (CodeMirror) ---------- */
.CodeMirror {
  height: auto; min-height: 190px; background: #00161d; color: #dbe4ff;
  border-radius: 18px; font-family: var(--font-mono); font-size: 0.86rem;
  padding: 8px 0; margin: 6px 0 16px; box-shadow: inset 0 0 0 1px var(--border);
}
.CodeMirror-gutters { background: #00161d; border-right: 1px solid var(--border); }
.CodeMirror-linenumber { color: var(--text-faint); }
.CodeMirror-cursor { border-left: 1px solid #dbe4ff; }
.cm-s-dailyptr.CodeMirror { background: #00161d; color: #dbe4ff; }
.cm-s-dailyptr .cm-keyword { color: var(--violet); }
.cm-s-dailyptr .cm-def, .cm-s-dailyptr .cm-variable-2 { color: var(--teal); }
.cm-s-dailyptr .cm-string { color: var(--green); }
.cm-s-dailyptr .cm-number { color: var(--yellow); }
.cm-s-dailyptr .cm-comment { color: var(--text-faint); font-style: italic; }
.cm-s-dailyptr .cm-atom, .cm-s-dailyptr .cm-tag { color: var(--orange); }
.cm-s-dailyptr .cm-attribute { color: var(--teal); }
.cm-s-dailyptr .cm-matchingbracket { color: var(--text); background: rgba(255, 255, 255, 0.15); }

.code-submit-btn { width: 100%; justify-content: center; }

/* ---------- block mode toggle ---------- */
.block-mode-toggle {
  display: flex; align-items: center; gap: 10px; cursor: pointer; margin: 4px 0 14px;
  -webkit-tap-highlight-color: transparent;
}
.block-mode-toggle input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.toggle-track {
  flex: 0 0 auto; width: 40px; height: 24px; border-radius: 999px; background: #33474d;
  position: relative; transition: background 0.15s ease; box-shadow: inset 0 0 0 1px var(--border);
}
.toggle-thumb {
  position: absolute; top: 3px; left: 3px; width: 18px; height: 18px; border-radius: 50%;
  background: var(--text-dim); transition: transform 0.15s ease, background 0.15s ease;
}
.block-mode-toggle input:checked + .toggle-track { background: var(--violet); }
.block-mode-toggle input:checked + .toggle-track .toggle-thumb { transform: translateX(16px); background: var(--text); }
.toggle-label { font-size: 0.82rem; color: var(--text-dim); font-weight: 600; }

/* ---------- block assembly (mobile "assemble the code" mode) ---------- */
.blocks-wrap { margin: 6px 0 16px; }
.blocks-assembly {
  min-height: 64px; border: 1px dashed color-mix(in oklch, var(--violet) 55%, transparent);
  border-radius: 14px; background: #00161d; padding: 10px; margin-bottom: 12px;
  display: flex; flex-direction: column; gap: 6px;
}
.blocks-empty-hint { color: var(--text-faint); font-size: 0.82rem; margin: 6px 4px; }
.blocks-bank { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 12px; }
.block-chip {
  font-family: var(--font-mono); font-size: 0.82rem; white-space: pre-wrap; word-break: break-word;
  color: var(--text);
  background: #33474d; border: none; border-radius: 10px; padding: 9px 12px; cursor: pointer;
  box-shadow: 0 3px 0 rgba(0, 0, 0, 0.3); transition: transform 0.05s ease;
  text-align: left; max-width: 100%;
}
.block-chip:active { transform: translateY(2px); box-shadow: 0 1px 0 rgba(0, 0, 0, 0.3); }
.block-chip.in-assembly { background: var(--violet); box-shadow: 0 3px 0 var(--violet-shadow); }
.blocks-clear-btn { font-size: 0.78rem; padding: 8px 16px; }

.panel-result {
  margin-top: 16px; font-weight: 700; font-size: 0.9rem; white-space: pre-wrap;
  font-family: var(--font-mono); color: var(--green);
}
.panel-result.fail { color: var(--red); }

/* ---------- concept AI feedback ---------- */
.ai-feedback { display: flex; align-items: flex-start; gap: 10px; margin-top: 16px; }
.ai-bubble {
  background: rgba(108, 113, 196, 0.16); border-radius: 16px 16px 16px 4px;
  padding: 12px 16px; font-size: 0.9rem; color: var(--text); font-weight: 600;
}
.model-answer-box {
  margin-top: 16px; padding: 14px 16px; border-radius: 16px; background: rgba(0, 0, 0, 0.18);
  font-size: 0.9rem; white-space: pre-wrap; color: var(--text-dim); font-family: inherit;
}
#code-reference { font-family: var(--font-mono); font-size: 0.82rem; white-space: pre-wrap; word-break: break-word; }

/* ---------- history ---------- */
.history-head { text-align: center; margin: 24px 0 28px; }
.history-head h1 { margin: 0 0 6px; font-family: var(--font-display); font-weight: 800; font-size: 1.6rem; }

.view-toggle { display: inline-flex; gap: 6px; margin-top: 14px; background: rgba(0, 0, 0, 0.18); border-radius: 999px; padding: 4px; }
.view-toggle-btn { border: none; background: transparent; color: var(--text-dim); padding: 7px 18px; border-radius: 999px; font-size: 0.82rem; font-weight: 700; cursor: pointer; }
.view-toggle-btn.active { background: var(--teal); color: var(--bg); }

/* ---------- calendar ---------- */
.calendar-nav { display: flex; align-items: center; justify-content: center; gap: 18px; margin-bottom: 14px; }
.cal-nav-btn { padding: 8px 16px; font-size: 1rem; line-height: 1; }
.calendar-month-label { font-family: var(--font-display); font-weight: 800; font-size: 1.1rem; min-width: 160px; text-align: center; }
.calendar-weekdays {
  display: grid; grid-template-columns: repeat(7, 1fr); gap: 6px; margin-bottom: 6px;
  text-align: center; color: var(--text-faint); font-size: 0.72rem; font-weight: 700; text-transform: uppercase;
}
.calendar-grid { display: grid; grid-template-columns: repeat(7, 1fr); gap: 6px; margin-bottom: 18px; }
.cal-cell {
  aspect-ratio: 1; border-radius: 12px; border: none; font-weight: 700; font-size: 0.85rem;
  display: flex; align-items: center; justify-content: center; cursor: pointer; color: var(--text);
  background: #33474d; transition: transform 0.05s ease;
}
.cal-cell:active:not(:disabled) { transform: scale(0.94); }
.cal-blank { visibility: hidden; cursor: default; }
.cal-future { background: transparent; color: var(--text-faint); opacity: 0.4; cursor: not-allowed; }
.cal-done { background: var(--green); color: var(--bg); }
.cal-late { background: var(--red); color: var(--bg); }
.cal-open { background: #52717a; }
.cal-today { outline: 2px solid var(--text); outline-offset: 2px; }
.calendar-legend { display: flex; justify-content: center; gap: 18px; flex-wrap: wrap; color: var(--text-dim); font-size: 0.78rem; margin-bottom: 8px; }
.legend-dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; margin-right: 6px; vertical-align: -1px; }
.legend-dot.done { background: var(--green); }
.legend-dot.late { background: var(--red); }
.legend-dot.open { background: #52717a; }

/* ---------- mobile ---------- */
@media (max-width: 600px) {
  .shell-main { padding: 16px 14px 50px; }
  .brand { font-size: 0.92rem; }
  .stats { gap: 10px; }
  .stat-points, .stat-streak { font-size: 0.92rem; }
  .btn-chunky { padding: 11px 18px; font-size: 0.86rem; }

  .track-switcher { gap: 8px; }
  .track-pill { flex: 1 1 auto; padding: 12px 14px; font-size: 0.86rem; min-height: 44px; text-align: center; }

  .difficulty-row { justify-content: center; }
  .reset-day-btn { margin-left: 0; padding: 8px 14px; font-size: 0.8rem; }

  .mascot-row { gap: 10px; margin: 16px 0 8px; }
  .mascot-flame { width: 38px; height: 38px; }
  .mascot-bubble { font-size: 0.86rem; padding: 10px 14px; max-width: none; }

  .node-nav { margin: 20px 0 24px; padding: 0; }
  .node-circle { width: 52px; height: 52px; font-size: 1.15rem; }
  .node-label { font-size: 0.7rem; }

  .blob-panel { padding: 18px 16px; border-radius: 24px 24px 24px 6px; }
  textarea { min-height: 150px; font-size: 0.8rem; padding: 12px; }
  .CodeMirror { min-height: 150px; font-size: 0.8rem; }

  .choice { padding: 11px 14px; font-size: 0.86rem; }

  .history-row, .history-row.align-right { justify-content: flex-start; }

  .calendar-month-label { min-width: 120px; font-size: 1rem; }
  .cal-cell { font-size: 0.78rem; border-radius: 8px; }
  .calendar-legend { gap: 12px; font-size: 0.72rem; }
}

@media (max-width: 380px) {
  .node-circle { width: 46px; height: 46px; font-size: 1rem; }
  .node-nav::before { left: 12%; right: 12%; top: 26px; }
  .stats { justify-content: flex-start; width: 100%; }
  .topbar { flex-direction: column; align-items: flex-start; }
}
.history-row { display: flex; align-items: center; gap: 14px; margin-bottom: 16px; cursor: pointer; }
.history-row.align-right { justify-content: flex-end; }
.history-circle {
  width: 52px; height: 52px; border-radius: 50%; border: none; display: flex; align-items: center;
  justify-content: center; cursor: pointer; flex: 0 0 auto; box-shadow: 0 3px 0 rgba(0, 0, 0, 0.3);
  background: #52717a;
}
.history-circle.done { background: var(--green); }
.history-circle.late { background: var(--red); }
.history-label { font-size: 0.92rem; font-weight: 700; }
.history-meta { font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.04em; }