:root {
  --bg:       #0d1117;
  --bg-alt:   #161b22;
  --bg-code:  #1c2128;
  --border:   #21262d;
  --text:     #e6edf3;
  --dim:      #8b949e;
  --green:    #3fb950;
  --amber:    #d29922;
  --blue:     #58a6ff;
  --purple:   #bc8cff;
  --red:      #f85149;
  --font:     'Courier New', Consolas, 'Lucida Console', monospace;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
.hidden { display: none !important; }

html, body {
  height: 100%;
  height: 100dvh;
  overflow: hidden;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.6;
  display: flex;
  flex-direction: column;
}

/* ── Header ────────────────────────────────────────────── */

#header {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 0 20px;
  height: 46px;
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.logo {
  color: var(--purple);
  font-weight: bold;
  font-size: 15px;
  white-space: nowrap;
  letter-spacing: 0.02em;
}

.version {
  color: var(--dim);
  font-size: 11px;
  margin-left: auto;
  white-space: nowrap;
}

.header-mid {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 12px;
  max-width: 480px;
}

#level-label {
  color: var(--dim);
  font-size: 12px;
  white-space: nowrap;
}

#progress-bar {
  flex: 1;
  height: 3px;
  background: var(--border);
  border-radius: 2px;
}

#progress-fill {
  height: 100%;
  background: var(--green);
  border-radius: 2px;
  width: 0%;
  transition: width 0.5s ease;
}

#tier-btn {
  color: var(--amber);
  font-size: 12px;
  white-space: nowrap;
  background: rgba(210, 153, 34, 0.1);
  border: 1px solid rgba(210, 153, 34, 0.3);
  padding: 2px 10px;
  border-radius: 10px;
  font-family: var(--font);
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
}

#tier-btn:hover {
  border-color: var(--amber);
  color: var(--text);
}

/* ── Welcome Screen ────────────────────────────────────── */

#welcome-screen {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 20px;
}

.welcome-question {
  color: var(--text);
  font-size: 16px;
  margin-bottom: 24px;
}

.welcome-options {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: center;
}

.welcome-btn {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 20px 24px;
  width: 260px;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.2s, transform 0.15s;
  font-family: var(--font);
  color: var(--text);
}

.welcome-btn:hover {
  border-color: var(--green);
  transform: translateY(-2px);
}

.welcome-btn-label {
  font-size: 15px;
  font-weight: bold;
  margin-bottom: 8px;
}

.welcome-btn-desc {
  color: var(--dim);
  font-size: 11px;
  line-height: 1.5;
}

/* ── Tier Selection Screen ──────────────────────────────── */

#tier-select {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 20px;
}


.tier-heading {
  color: var(--text);
  font-size: 22px;
  font-weight: bold;
  margin-bottom: 8px;
}

.tier-sub {
  color: var(--dim);
  font-size: 13px;
  margin-bottom: 32px;
  text-align: center;
  max-width: 500px;
}

.tier-cards {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  justify-content: center;
}

.tier-card {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 24px 28px;
  width: 220px;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.2s, transform 0.15s;
  font-family: var(--font);
  color: var(--text);
}

.tier-card:hover {
  border-color: var(--green);
  transform: translateY(-2px);
}

.tier-card-name {
  font-size: 16px;
  font-weight: bold;
  margin-bottom: 8px;
}

.tier-card-count {
  color: var(--dim);
  font-size: 12px;
  margin-bottom: 6px;
}

.tier-card-bar {
  height: 3px;
  background: var(--border);
  border-radius: 2px;
  margin-bottom: 12px;
}

.tier-card-fill {
  height: 100%;
  background: var(--green);
  border-radius: 2px;
  width: 0%;
  transition: width 0.5s ease;
}

.tier-card-desc {
  color: var(--dim);
  font-size: 11px;
  line-height: 1.5;
}

/* ── Challenge Panel ────────────────────────────────────── */

#challenge-panel {
  padding: 14px 20px 12px;
  background: var(--bg-alt);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

#challenge-title {
  color: var(--text);
  font-size: 15px;
  font-weight: bold;
  margin-bottom: 6px;
}

#challenge-scenario {
  color: var(--dim);
  font-size: 12px;
  margin-bottom: 4px;
  white-space: pre-wrap;
}

#challenge-task {
  color: var(--text);
  font-size: 13px;
}

#challenge-task::before {
  content: '→ ';
  color: var(--green);
}

#challenge-concept {
  color: var(--dim);
  font-size: 12px;
  line-height: 1.6;
  padding: 7px 12px;
  background: rgba(88, 166, 255, 0.06);
  border-left: 2px solid var(--blue);
  border-radius: 0 4px 4px 0;
  margin-bottom: 10px;
}

#hint-row {
  margin-top: 10px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}

#hint-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--dim);
  font-family: var(--font);
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 3px;
  cursor: pointer;
  flex-shrink: 0;
  transition: border-color 0.15s, color 0.15s;
}

#hint-toggle:hover {
  border-color: var(--amber);
  color: var(--amber);
}

#hint-text {
  color: var(--amber);
  font-size: 12px;
  display: none;
}

#hint-text.visible {
  display: inline;
}

/* ── Terminal ───────────────────────────────────────────── */

#terminal {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

#terminal-output {
  flex: 1;
  overflow-y: auto;
  padding: 18px 22px;
  scroll-behavior: smooth;
}

#terminal-output::-webkit-scrollbar { width: 5px; }
#terminal-output::-webkit-scrollbar-track { background: var(--bg); }
#terminal-output::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ── Session Header ─────────────────────────────────────── */

.session-header {
  color: var(--dim);
  font-size: 12px;
  margin-bottom: 18px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.session-header .model {
  color: var(--purple);
}

/* ── Messages ───────────────────────────────────────────── */

.msg-user {
  display: flex;
  gap: 10px;
  margin-bottom: 16px;
}

.msg-user .prompt-sym {
  color: var(--green);
  flex-shrink: 0;
  font-size: 15px;
  line-height: 1.5;
}

.msg-user .content {
  color: var(--text);
  word-break: break-word;
}

.msg-claude {
  margin-left: 6px;
  margin-bottom: 20px;
  padding-left: 14px;
  border-left: 2px solid var(--border);
}

/* ── Tool calls ─────────────────────────────────────────── */

.tool-call {
  margin-bottom: 6px;
}

.tool-header {
  color: var(--dim);
  font-size: 13px;
}

.tool-dot {
  color: var(--text);
}

.tool-name {
  color: var(--purple);
  font-weight: bold;
}

.tool-args {
  color: var(--dim);
}

.tool-result {
  color: var(--dim);
  font-size: 12px;
  padding-left: 14px;
  margin-top: 1px;
}

/* ── Response text ──────────────────────────────────────── */

.response-text {
  color: var(--text);
  white-space: pre-wrap;
  word-break: break-word;
}

/* ── Code blocks ────────────────────────────────────────── */

.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 12px 14px;
  margin: 8px 0;
  overflow-x: auto;
}

.code-block .lang-label {
  color: var(--dim);
  font-size: 11px;
  margin-bottom: 6px;
  text-transform: lowercase;
}

.code-block pre {
  color: var(--text);
  white-space: pre;
  font-family: var(--font);
  font-size: 13px;
  line-height: 1.55;
}

/* diff coloring */
.code-block pre .diff-add { color: var(--green); }
.code-block pre .diff-del { color: var(--red); }

/* ── Thinking ───────────────────────────────────────────── */

.thinking {
  color: var(--dim);
  font-size: 13px;
  margin-bottom: 8px;
  font-style: italic;
}

/* ── Extended Thinking Block ────────────────────────────── */

.thinking-block {
  background: rgba(88, 166, 255, 0.04);
  border: 1px solid rgba(88, 166, 255, 0.15);
  border-radius: 6px;
  padding: 10px 14px;
  margin-bottom: 10px;
}

.thinking-block-header {
  color: var(--blue);
  font-size: 12px;
  margin-bottom: 6px;
}

.thinking-block-body {
  color: var(--dim);
  font-size: 12px;
  line-height: 1.6;
  white-space: pre-wrap;
}

/* ── Help output ────────────────────────────────────────── */

.help-output .response-text {
  white-space: pre;
}

/* ── Cursor ─────────────────────────────────────────────── */

.cursor {
  display: inline-block;
  width: 7px;
  height: 13px;
  background: var(--green);
  vertical-align: text-bottom;
  animation: blink 1s step-end infinite;
  margin-left: 1px;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0; }
}

/* ── Input line ─────────────────────────────────────────── */

#input-line {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 22px;
  border-top: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
}

.prompt-sym {
  color: var(--green);
  font-size: 15px;
  flex-shrink: 0;
}

#user-input {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  caret-color: var(--green);
}

#user-input::placeholder { color: var(--dim); }
#user-input:disabled      { opacity: 0.4; }

/* ── Completion screen ──────────────────────────────────── */

#completion-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
  padding: 40px;
}

#completion-screen .comp-icon  { color: var(--green); font-size: 44px; margin-bottom: 14px; }
#completion-screen .comp-title { color: var(--green); font-size: 26px; font-weight: bold; margin-bottom: 20px; }
#completion-screen .comp-body  { color: var(--dim); line-height: 1.9; max-width: 520px; }
#completion-screen .comp-body .hi { color: var(--text); }

#restart-btn {
  margin-top: 32px;
  background: none;
  border: 1px solid var(--border);
  color: var(--dim);
  font-family: var(--font);
  font-size: 13px;
  padding: 8px 18px;
  border-radius: 4px;
  cursor: pointer;
  transition: border-color 0.15s, color 0.15s;
}

#restart-btn:hover {
  border-color: var(--dim);
  color: var(--text);
}

/* ── Continue banner ────────────────────────────────────── */

.continue-banner {
  margin-top: 16px;
  padding: 14px 16px;
  background: rgba(63, 185, 80, 0.06);
  border: 1px solid rgba(63, 185, 80, 0.25);
  border-radius: 6px;
  font-size: 13px;
}

.continue-top {
  color: var(--green);
  font-weight: bold;
  margin-bottom: 6px;
}

.continue-check {
  font-size: 15px;
}

.continue-message {
  color: var(--dim);
  font-size: 12px;
  line-height: 1.6;
  margin-bottom: 10px;
}

.continue-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.continue-btn {
  background: var(--green);
  color: var(--bg);
  border: none;
  font-family: var(--font);
  font-size: 13px;
  font-weight: bold;
  padding: 4px 14px;
  border-radius: 3px;
  cursor: pointer;
  margin-left: 4px;
  transition: opacity 0.15s;
}

.continue-btn:hover { opacity: 0.85; }

.continue-hint {
  color: var(--dim);
  font-size: 11px;
}

/* ── Retry hint ─────────────────────────────────────────── */

.retry-hint {
  color: var(--amber);
  font-size: 12px;
  margin-top: 6px;
  padding-left: 14px;
  border-left: 2px solid rgba(210, 153, 34, 0.4);
}

/* ── Keyboard open ─────────────────────────────────────── */

.keyboard-open #header {
  height: 30px;
}

.keyboard-open .logo {
  display: none;
}

.keyboard-open #challenge-panel {
  padding: 6px 14px 6px;
}

.keyboard-open #challenge-title {
  font-size: 13px;
  margin-bottom: 2px;
}

.keyboard-open #challenge-concept {
  display: none;
}

.keyboard-open #hint-row {
  display: none;
}

.keyboard-open #terminal-output {
  padding: 8px 14px;
}

.keyboard-open #input-line {
  padding: 6px 14px;
}

/* ── Mobile ────────────────────────────────────────────── */

@media (max-width: 600px) {
  html {
    height: 100%;
    overflow: hidden;
  }

  body {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
  }

  #header {
    gap: 8px;
    padding: 0 12px;
    height: 40px;
  }

  .logo {
    font-size: 13px;
  }

  .header-mid {
    gap: 6px;
  }

  #level-label {
    font-size: 11px;
  }

  #tier-btn {
    font-size: 11px;
    padding: 2px 8px;
  }

  /* Welcome screen */
  #welcome-screen {
    padding: 24px 16px;
  }

  .welcome-question {
    font-size: 14px;
  }

  .welcome-options {
    flex-direction: column;
    width: 100%;
    gap: 12px;
  }

  .welcome-btn {
    width: 100%;
    padding: 16px 18px;
    min-height: 44px;
  }

  /* Tier selection */
  #tier-select {
    padding: 24px 16px;
    overflow-y: auto;
  }

  .tier-heading {
    font-size: 18px;
  }

  .tier-sub {
    font-size: 12px;
    margin-bottom: 20px;
  }

  .tier-cards {
    flex-direction: column;
    width: 100%;
    gap: 12px;
  }

  .tier-card {
    width: 100%;
    padding: 16px 18px;
    min-height: 44px;
  }

  /* Challenge panel */
  #challenge-panel {
    padding: 10px 14px 8px;
    max-height: 35vh;
    overflow-y: auto;
  }

  #challenge-title {
    font-size: 14px;
    margin-bottom: 4px;
  }

  #challenge-concept {
    font-size: 11px;
    padding: 5px 10px;
    margin-bottom: 6px;
  }

  #challenge-scenario {
    font-size: 11px;
  }

  #challenge-task {
    font-size: 12px;
  }

  #hint-row {
    margin-top: 6px;
  }

  /* Terminal */
  #terminal-output {
    padding: 12px 14px;
  }

  .msg-claude {
    padding-left: 10px;
  }

  .code-block {
    padding: 8px 10px;
    font-size: 12px;
  }

  .code-block pre {
    font-size: 11px;
  }

  .tool-header {
    font-size: 12px;
  }

  .tool-result {
    font-size: 11px;
  }

  .session-header {
    font-size: 11px;
    margin-bottom: 12px;
    padding-bottom: 8px;
  }

  /* Input */
  #input-line {
    padding: 8px 14px;
    gap: 8px;
  }

  #user-input {
    font-size: 16px; /* prevents iOS zoom on focus */
  }

  /* Continue banner */
  .continue-banner {
    padding: 10px 12px;
  }

  .continue-btn {
    padding: 6px 16px;
    min-height: 36px;
  }

  /* Completion screen */
  #completion-screen {
    padding: 24px 16px;
  }

  #completion-screen .comp-title {
    font-size: 20px;
  }

  #completion-screen .comp-body {
    font-size: 12px;
  }

  #restart-btn {
    min-height: 44px;
    padding: 10px 20px;
  }

  /* Thinking blocks */
  .thinking-block {
    padding: 8px 10px;
  }

  .thinking-block-header {
    font-size: 11px;
  }

  .thinking-block-body {
    font-size: 11px;
  }
}