:root {
  --bg: #0f1117;
  --panel: #171a23;
  --panel-2: #1e222d;
  --border: #2a2f3c;
  --text: #e6e9ef;
  --muted: #9aa3b2;
  --accent: #6ea8fe;
  --accent-2: #4f8cff;
  --good: #3fb950;
  --warn: #d29922;
  --danger: #f85149;
  --radius: 12px;
  font-synthesis: none;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 22px;
  border-bottom: 1px solid var(--border);
  background: var(--panel);
}
.brand { display: flex; align-items: center; gap: 12px; }
.logo { font-size: 26px; }
.brand h1 { font-size: 17px; margin: 0; letter-spacing: 0.2px; }
.sub { margin: 2px 0 0; font-size: 12px; color: var(--muted); }

.score {
  display: flex; align-items: baseline; gap: 6px;
  background: var(--panel-2); padding: 8px 14px; border-radius: 999px;
  border: 1px solid var(--border);
}
.score-num { font-size: 20px; font-weight: 700; color: var(--good); }
.score-den { font-size: 12px; color: var(--muted); }

.tabs {
  display: flex; gap: 8px; padding: 12px 22px 0; flex-wrap: wrap;
  border-bottom: 1px solid var(--border); background: var(--panel);
}
.tab {
  border: 1px solid var(--border); background: var(--panel-2); color: var(--muted);
  padding: 8px 14px; border-radius: 10px 10px 0 0; cursor: pointer; font-size: 13px;
  display: flex; align-items: center; gap: 7px; transition: 0.15s;
}
.tab:hover { color: var(--text); }
.tab.active { color: var(--text); background: var(--bg); border-bottom-color: var(--bg); }
.tab .check { color: var(--good); font-weight: 700; }
.tab .num {
  background: var(--border); border-radius: 6px; width: 20px; height: 20px;
  display: grid; place-items: center; font-size: 12px;
}
.tab.solved .num { background: rgba(63,185,80,0.2); color: var(--good); }

.stage {
  flex: 1; max-width: 860px; width: 100%; margin: 0 auto;
  padding: 20px; display: flex; flex-direction: column; gap: 16px;
}

.level-info { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 18px; }
.owasp-tag {
  display: inline-block; font-size: 11px; letter-spacing: 0.4px; text-transform: uppercase;
  color: var(--accent); background: rgba(110,168,254,0.12); border: 1px solid rgba(110,168,254,0.3);
  padding: 3px 9px; border-radius: 999px; margin-bottom: 8px;
}
.level-info h2 { margin: 4px 0 8px; font-size: 18px; }
.hint summary { cursor: pointer; color: var(--muted); font-size: 13px; }
.hint p { margin: 8px 0 0; color: var(--muted); font-size: 13px; line-height: 1.5; }

.chat { display: flex; flex-direction: column; gap: 12px; flex: 1; }
.messages {
  flex: 1; min-height: 240px; display: flex; flex-direction: column; gap: 10px;
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px; overflow-y: auto; max-height: 52vh;
}
.msg { max-width: 78%; padding: 10px 14px; border-radius: 14px; font-size: 14px; line-height: 1.5; white-space: pre-wrap; word-wrap: break-word; }
.msg.user { align-self: flex-end; background: var(--accent-2); color: #fff; border-bottom-right-radius: 4px; }
.msg.bot { align-self: flex-start; background: var(--panel-2); border: 1px solid var(--border); border-bottom-left-radius: 4px; }
.msg.blocked { border-color: rgba(210,153,34,0.5); }
.empty-hint { color: var(--muted); font-size: 13px; text-align: center; margin: auto; }

.preview-wrap { border: 1px solid rgba(248,81,73,0.4); border-radius: var(--radius); overflow: hidden; }
.preview-label { background: rgba(248,81,73,0.12); color: var(--danger); font-size: 12px; padding: 7px 12px; }
.preview { width: 100%; height: 150px; border: 0; background: #fff; }

.composer { display: flex; gap: 10px; }
#input {
  flex: 1; resize: vertical; background: var(--panel); color: var(--text);
  border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; font-size: 14px;
  font-family: inherit;
}
#input:focus { outline: none; border-color: var(--accent); }
#send {
  background: var(--accent-2); color: #fff; border: 0; border-radius: 10px;
  padding: 0 22px; font-size: 14px; font-weight: 600; cursor: pointer; transition: 0.15s;
}
#send:hover { background: var(--accent); }
#send:disabled { opacity: 0.5; cursor: not-allowed; }

.toast {
  position: fixed; bottom: 26px; left: 50%; transform: translateX(-50%);
  background: var(--good); color: #06210d; font-weight: 600; font-size: 14px;
  padding: 12px 20px; border-radius: 10px; box-shadow: 0 8px 30px rgba(0,0,0,0.4);
  animation: pop 0.25s ease;
}
@keyframes pop { from { transform: translate(-50%, 12px); opacity: 0; } }

/* Teaching card ----------------------------------------------------------- */
/* The `hidden` HTML attribute must win over `display: grid` below, otherwise the
   overlay can never be dismissed (its default `display:none` is lower specificity). */
.teach-overlay[hidden] { display: none !important; }
.teach-overlay {
  position: fixed; inset: 0; z-index: 50;
  background: rgba(5, 7, 12, 0.72); backdrop-filter: blur(3px);
  display: grid; place-items: center; padding: 20px;
  animation: fade 0.2s ease;
}
@keyframes fade { from { opacity: 0; } }
.teach-card {
  width: min(560px, 100%); max-height: 90vh; overflow-y: auto;
  background: var(--panel); border: 1px solid var(--border);
  border-radius: 16px; padding: 26px 26px 22px;
  box-shadow: 0 24px 70px rgba(0,0,0,0.55);
  animation: rise 0.25s cubic-bezier(0.2, 0.8, 0.2, 1);
}
@keyframes rise { from { transform: translateY(16px); opacity: 0; } }
.teach-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 6px; }
.teach-badge {
  font-size: 11px; letter-spacing: 0.4px; text-transform: uppercase; font-weight: 700;
  color: var(--accent); background: rgba(110,168,254,0.12);
  border: 1px solid rgba(110,168,254,0.3); padding: 4px 10px; border-radius: 999px;
}
.teach-solved { font-size: 12px; color: var(--good); font-weight: 600; }
.teach-card h2 { margin: 8px 0 16px; font-size: 20px; }
.teach-row { margin-bottom: 14px; }
.teach-label { font-size: 12px; text-transform: uppercase; letter-spacing: 0.3px; color: var(--muted); margin-bottom: 4px; }
.teach-row p { margin: 0; font-size: 14px; line-height: 1.55; color: var(--text); }
.teach-fixrow {
  background: rgba(63,185,80,0.08); border: 1px solid rgba(63,185,80,0.25);
  border-radius: 10px; padding: 12px 14px; margin-top: 4px;
}
.teach-fixrow .teach-label { color: var(--good); }
.teach-close {
  margin-top: 18px; width: 100%; background: var(--accent-2); color: #fff;
  border: 0; border-radius: 10px; padding: 12px; font-size: 14px; font-weight: 600;
  cursor: pointer; transition: 0.15s;
}
.teach-close:hover { background: var(--accent); }

@media (max-width: 620px) {
  .stage { padding: 12px; }
  .msg { max-width: 90%; }
  .teach-card { padding: 20px 18px; }
}