/* Try it: the subnetting lesson (try.html). Loaded after styles.css. */
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
section.try-hero { padding: 150px 0 40px; background: radial-gradient(800px 420px at 80% 0%, rgba(142, 108, 255, 0.22), transparent 60%), var(--bg); }
.try-hero h1 { font-size: clamp(40px, 6.4vw, 78px); font-weight: 700; margin: 24px 0 20px; }
.try-skip { margin-top: 18px; font-size: 15px; }
.try-skip a { color: var(--muted); }

section.lesson { padding: 30px 0 80px; }
.lesson-wrap { max-width: 860px; }
.progress { list-style: none; margin: 0 0 18px; padding: 0; display: grid; grid-template-columns: repeat(8, 1fr); gap: 6px; }
.progress li { display: flex; flex-direction: column; align-items: center; gap: 6px; font-size: 12px; color: var(--muted); text-align: center; }
.p-num { width: 30px; height: 30px; border-radius: 50%; display: grid; place-items: center; border: 1px solid var(--line); background: var(--panel); font: 600 13px/1 var(--display); }
.progress li.done .p-num { background: var(--grad); color: #06101c; border-color: transparent; }
.progress li.current { color: var(--ink); }
.progress li.current .p-num { border-color: var(--cyan); box-shadow: 0 0 0 4px rgba(52, 231, 228, 0.15); }

.lesson-panel { border: 1px solid var(--line); border-radius: var(--radius); background: rgba(5, 8, 18, 0.75); box-shadow: 0 30px 80px -30px rgba(142, 108, 255, 0.45); overflow: hidden; }
.lesson-log { min-height: 260px; }
.msg-hint { border-style: dashed; }
.msg-hint .msg-who { color: var(--amber); }
.msg-list { margin: 8px 0 0; padding-left: 18px; }
.msg-list li + li { margin-top: 6px; }

.bench { border-top: 1px solid var(--line); background: rgba(255, 255, 255, 0.02); }
.bench:empty { display: none; }
.bench-form { padding: 20px 18px; }
.bench-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.btn-small { min-height: 44px; padding: 0 20px; font-size: 15px; }
.bench-note { margin-top: 10px; color: var(--amber); font-size: 14px; min-height: 1.4em; }
.w-number label, .w-field label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 6px; }
.w-row { display: flex; align-items: center; gap: 10px; }
.w-number input, .w-field input {
  font: 600 20px/1 var(--display); color: var(--ink); background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.2); border-radius: 10px; padding: 12px 14px; width: 9ch;
}
.w-field input { width: 100%; font-size: 18px; }
.w-number input:focus, .w-field input:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(52, 231, 228, 0.2); }
.w-field input.ok { border-color: rgba(52, 231, 228, 0.7); }
.w-field input[aria-invalid="true"] { border-color: rgba(255, 182, 72, 0.8); }
.w-suffix { color: var(--muted); }
.w-multi { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.w-note:empty { display: none; }

.w-bits { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.w-prefix { font: 600 22px/1 var(--display); color: var(--muted); }
.bits { display: grid; grid-template-columns: repeat(8, minmax(36px, 52px)); gap: 6px; }
.bit {
  display: flex; flex-direction: column; align-items: center; gap: 4px; padding: 8px 0 10px;
  border-radius: 10px; border: 1px solid rgba(255, 255, 255, 0.18); background: rgba(255, 255, 255, 0.04);
  color: var(--muted); cursor: pointer; font: inherit; transition: background 0.15s, border-color 0.15s, transform 0.1s;
}
.bit:hover:not(:disabled) { border-color: var(--cyan); transform: translateY(-1px); }
.bit-value { font-size: 11px; }
.bit-state { font: 700 22px/1 var(--display); }
.bit.on { background: linear-gradient(160deg, rgba(52, 231, 228, 0.35), rgba(142, 108, 255, 0.35)); border-color: var(--cyan); color: var(--ink); }
.bit-host { border-color: rgba(255, 182, 72, 0.55); }
.bit-host.on { background: linear-gradient(160deg, rgba(255, 182, 72, 0.4), rgba(142, 108, 255, 0.3)); border-color: var(--amber); }
.bit-locked { cursor: not-allowed; opacity: 0.55; border-style: dashed; }
.w-total { font: 700 26px/1 var(--display); color: var(--ink); min-width: 3.5ch; }

.bitbar { margin: 12px 0 4px; overflow-x: auto; }
.bitbar-row { display: flex; gap: 10px; }
.octet { display: flex; flex-direction: column; align-items: center; gap: 4px; }
.octet-bits { display: flex; gap: 2px; }
.cell { width: 18px; height: 24px; display: grid; place-items: center; border-radius: 4px; font: 600 13px/1 var(--display); }
.cell-net { background: rgba(52, 231, 228, 0.18); color: var(--cyan); }
.cell-host { background: rgba(255, 182, 72, 0.18); color: var(--amber); }
.octet-dec { font-size: 12px; color: var(--muted); }
.bitbar figcaption { margin-top: 8px; font-size: 12px; color: var(--muted); }
.key { display: inline-flex; align-items: center; gap: 6px; margin-right: 8px; }
.key::before { content: ""; width: 10px; height: 10px; border-radius: 3px; }
.key-net::before { background: var(--cyan); }
.key-host::before { background: var(--amber); }

section.calc-section { padding: 60px 0 110px; }
.locked { text-align: center; border: 1px dashed var(--line); border-radius: var(--radius); padding: 48px 24px; background: var(--panel); }
.locked h2 { font-size: clamp(26px, 3.6vw, 38px); }
.locked .sub { margin: 14px auto 0; }
.locked-icon { font-size: 34px; margin-bottom: 8px; }
.link-btn { font: inherit; color: var(--cyan); background: none; border: none; padding: 0; text-decoration: underline; cursor: pointer; }

.summary { margin-bottom: 64px; }
.skills { list-style: none; margin: 26px 0 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 12px; }
.skills li { display: flex; align-items: center; gap: 12px; padding: 14px 16px; border-radius: 12px; border: 1px solid var(--line); background: var(--panel); }
.skill-check { width: 26px; height: 26px; border-radius: 50%; display: grid; place-items: center; background: var(--grad); color: #06101c; font-weight: 700; flex-shrink: 0; }
.skills li.helped .skill-check { background: rgba(255, 182, 72, 0.85); }
.skills li > span:nth-child(2) { flex: 1; font-weight: 600; }
.skill-tag { font-size: 11px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--cyan); }
.skills li.helped .skill-tag { color: var(--amber); }

.calc-form { display: grid; grid-template-columns: 2fr 1fr; gap: 14px; margin-top: 28px; max-width: 640px; }
.calc-form input { width: 100%; font: 600 20px/1 var(--display); color: var(--ink); background: rgba(255, 255, 255, 0.05); border: 1px solid rgba(255, 255, 255, 0.18); border-radius: 10px; padding: 14px; }
.calc-form input:focus { outline: none; border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(52, 231, 228, 0.2); }
.calc-form input[aria-invalid="true"] { border-color: #ff8f9c; }
.calc-error { color: #ff8f9c; font-weight: 600; min-height: 1.4em; margin-top: 8px; }
.calc-results { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin: 10px 0 0; }
.calc-results div { border: 1px solid var(--line); border-radius: 12px; padding: 14px 16px; background: var(--panel); }
.calc-results dt { font-size: 12px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.calc-results dd { margin: 6px 0 0; font: 600 19px/1.25 var(--display); overflow-wrap: anywhere; }
.calc-h { font-size: 22px; margin: 34px 0 6px; }
.calc-working { margin: 16px 0 0; padding: 0; list-style: none; counter-reset: w; }
.calc-working li { counter-increment: w; display: grid; grid-template-columns: 34px 1fr; gap: 4px 12px; padding: 12px 0; border-top: 1px solid var(--line); }
.calc-working li::before { content: counter(w); grid-row: span 2; width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center; border: 1px solid var(--line); font: 600 13px/1 var(--display); color: var(--cyan); }
.try-cta { margin-top: 64px; padding: 32px; border-radius: var(--radius); border: 1px solid rgba(52, 231, 228, 0.3); background: linear-gradient(140deg, rgba(52, 231, 228, 0.08), rgba(142, 108, 255, 0.12)); display: flex; flex-wrap: wrap; gap: 20px; align-items: center; justify-content: space-between; }
.try-cta p { max-width: 56ch; color: var(--ink); font-size: 18px; }

@media (max-width: 760px) {
  .progress .p-label { display: none; }
  .w-multi { grid-template-columns: 1fr; }
  .calc-results { grid-template-columns: 1fr 1fr; }
  .calc-form { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .bits { grid-template-columns: repeat(8, 1fr); gap: 4px; width: 100%; }
  .bit-state { font-size: 18px; }
  .bit-value { font-size: 10px; }
  .calc-results { grid-template-columns: 1fr; }
  .cell { width: 13px; height: 20px; font-size: 11px; }
  .bitbar-row { gap: 6px; }
}
@media (prefers-reduced-motion: reduce) {
  .bit { transition: none; }
}