*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

/* ══════════════════════════════════════════════════════════
   LOADING SCREEN
══════════════════════════════════════════════════════════ */

#loader {
  position: fixed; inset: 0; z-index: 9999;
  background: #0f1117;
  display: flex; align-items: center; justify-content: center;
  transition: opacity 0.5s ease;
}
#loader.loader-out { opacity: 0; pointer-events: none; }

.loader-inner {
  width: min(420px, 92vw);
  display: flex; flex-direction: column; align-items: center;
}

/* Animated binary grid */
.packet-grid {
  display: grid;
  grid-template-columns: repeat(20, 1fr);
  gap: 2px;
  width: 100%;
  margin-bottom: 28px;
  opacity: 0.18;
  user-select: none;
}
.pgrid-cell {
  font-family: monospace; font-size: 11px; color: #4f8ef7; text-align: center;
  animation: blink-cell infinite alternate ease-in-out;
}
@keyframes blink-cell {
  0%   { opacity: 0.1; color: #4f8ef7; }
  50%  { opacity: 0.7; color: #3ecf8e; }
  100% { opacity: 0.15; color: #4f8ef7; }
}

/* Logo */
.loader-logo { display: flex; flex-direction: column; align-items: center; gap: 8px; margin-bottom: 28px; }
.loader-icon { animation: pulse-icon 2s ease-in-out infinite; }
@keyframes pulse-icon {
  0%, 100% { transform: scale(1);    opacity: 1; }
  50%       { transform: scale(1.06); opacity: 0.8; }
}
.loader-title { font-family: 'JetBrains Mono','Fira Code',monospace; font-size: 1.3rem; font-weight: 700; color: #e8eaf0; letter-spacing: -0.02em; }
.loader-sub   { font-family: 'JetBrains Mono','Fira Code',monospace; font-size: 0.72rem; color: #5a607a; letter-spacing: 0.04em; animation: fade-sub 1.5s ease-in-out infinite alternate; }
@keyframes fade-sub { from { opacity: 0.4; } to { opacity: 1; } }

/* Progress bar */
.loader-bar-wrap { width: 100%; height: 3px; background: rgba(255,255,255,0.06); border-radius: 2px; overflow: hidden; margin-bottom: 16px; }
.loader-bar { height: 100%; width: 0%; border-radius: 2px; background: linear-gradient(90deg,#4f8ef7,#3ecf8e); transition: width 0.15s ease; box-shadow: 0 0 8px rgba(79,142,247,0.6); }

/* Log lines */
.loader-log { width: 100%; height: 88px; overflow: hidden; font-family: 'JetBrains Mono','Fira Code',monospace; font-size: 0.72rem; display: flex; flex-direction: column; justify-content: flex-end; gap: 3px; }
.log-line { color: #5a607a; animation: slide-in 0.2s ease forwards; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.log-line:last-child { color: #9096b0; }
.log-arrow { color: #4f8ef7; margin-right: 6px; }
.log-ok    { color: #3ecf8e; margin-right: 6px; }
@keyframes slide-in { from { opacity:0; transform:translateY(6px); } to { opacity:1; transform:translateY(0); } }

/* ══════════════════════════════════════════════════════════
   END LOADING SCREEN
══════════════════════════════════════════════════════════ */


:root {
  --bg: #0f1117;
  --bg2: #1a1d27;
  --bg3: #22263a;
  --border: rgba(255,255,255,0.08);
  --border2: rgba(255,255,255,0.15);
  --text: #e8eaf0;
  --text2: #9096b0;
  --text3: #5a607a;
  --blue: #4f8ef7;
  --blue-bg: rgba(79,142,247,0.12);
  --blue-border: rgba(79,142,247,0.3);
  --green: #3ecf8e;
  --green-bg: rgba(62,207,142,0.1);
  --green-border: rgba(62,207,142,0.25);
  --red: #f56565;
  --red-bg: rgba(245,101,101,0.1);
  --amber: #f6ad55;
  --amber-bg: rgba(246,173,85,0.1);
  --purple: #a78bfa;
  --purple-bg: rgba(167,139,250,0.1);
  --radius: 10px;
  --radius-sm: 6px;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  min-height: 100vh;
  padding: 2rem 1rem;
}

h1 { font-size: 1.4rem; font-weight: 600; letter-spacing: -0.02em; color: var(--text); margin-bottom: 0.25rem; }
.subtitle { font-size: 0.8rem; color: var(--text3); margin-bottom: 1.75rem; letter-spacing: 0.03em; }
.container { max-width: 860px; margin: 0 auto; }

/* ── Tabs ── */
.tabs { display: flex; gap: 4px; margin-bottom: 1.5rem; background: var(--bg2); border-radius: var(--radius); padding: 4px; border: 1px solid var(--border); }
.tab { flex: 1; padding: 8px 10px; border-radius: var(--radius-sm); border: none; background: transparent; cursor: pointer; font-size: 0.72rem; font-family: inherit; color: var(--text2); transition: all .18s; letter-spacing: 0.02em; text-align: center; }
.tab:hover { color: var(--text); background: var(--bg3); }
.tab.active { background: var(--bg3); color: var(--blue); border: 1px solid var(--blue-border); }
.panel { display: none; }
.panel.active { display: block; }

/* ── Cards ── */
.card { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px 18px; margin-bottom: 10px; }
.card-label { font-size: 0.68rem; color: var(--text3); letter-spacing: 0.06em; text-transform: uppercase; margin-bottom: 6px; }
.card-value { font-size: 1rem; color: var(--text); font-weight: 500; }
.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin-bottom: 10px; }

/* ── Bit display ── */
.bit-row { display: flex; gap: 2px; flex-wrap: nowrap; overflow-x: auto; padding-bottom: 4px; }
.bit-row::-webkit-scrollbar { height: 3px; }
.bit-row::-webkit-scrollbar-track { background: var(--bg2); }
.bit-row::-webkit-scrollbar-thumb { background: var(--border2); border-radius: 2px; }
.bit { width: 24px; height: 30px; border-radius: 4px; display: flex; align-items: center; justify-content: center; font-size: 12px; font-weight: 600; flex-shrink: 0; transition: background .2s; }
.bit-net  { background: var(--blue-bg);  color: var(--blue);  border: 1px solid var(--blue-border); }
.bit-host { background: var(--green-bg); color: var(--green); border: 1px solid var(--green-border); }
.bit-sep  { width: 8px; flex-shrink: 0; }

.legend { display: flex; gap: 16px; margin-top: 8px; }
.legend-item { display: flex; align-items: center; gap: 6px; font-size: 0.72rem; color: var(--text2); }
.legend-dot  { width: 8px; height: 8px; border-radius: 2px; }

/* ── Subnet bar ── */
.subnet-bar { height: 36px; border-radius: 8px; overflow: hidden; display: flex; margin-bottom: 10px; border: 1px solid var(--border); }
.bar-net  { background: var(--blue-bg);  border-right: 1px solid var(--blue-border); display: flex; align-items: center; justify-content: center; font-size: 11px; color: var(--blue);  font-weight: 600; transition: width .3s ease; padding: 0 6px; overflow: hidden; }
.bar-host { background: var(--green-bg); display: flex; align-items: center; justify-content: center; font-size: 11px; color: var(--green); font-weight: 500; flex: 1; overflow: hidden; }

/* ── Slider ── */
.slider-wrap { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.slider-label { font-size: 0.8rem; color: var(--text2); min-width: 24px; }
input[type=range] { flex: 1; height: 4px; border-radius: 2px; appearance: none; background: var(--bg3); border: 1px solid var(--border2); cursor: pointer; outline: none; }
input[type=range]::-webkit-slider-thumb { appearance: none; width: 16px; height: 16px; border-radius: 50%; background: var(--blue); border: 2px solid var(--bg); cursor: pointer; }
.slider-val { font-size: 1.1rem; font-weight: 700; color: var(--blue); min-width: 28px; }

/* ── Text input ── */
input[type=text] { background: var(--bg2); border: 1px solid var(--border2); border-radius: var(--radius-sm); color: var(--text); font-family: inherit; font-size: 0.9rem; padding: 9px 12px; outline: none; transition: border-color .15s; width: 220px; }
input[type=text]:focus { border-color: var(--blue); }
.err { font-size: 0.72rem; color: var(--red); margin-top: 5px; min-height: 14px; }

/* ── IP Class Badge ── */
.class-badge { display: inline-block; padding: 2px 9px; border-radius: 20px; font-size: 0.72rem; font-weight: 600; letter-spacing: 0.03em; }
.auto-note { font-size: 0.7rem; color: var(--text3); }
.override-arrow { font-size: 0.7rem; color: var(--text3); }

/* ── Class selector buttons ── */
.class-selector { display: flex; gap: 5px; flex-wrap: wrap; margin: 10px 0 6px; }
.class-selector-label { font-size: 0.68rem; color: var(--text3); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 6px; }
.class-btn { padding: 5px 12px; border-radius: 20px; border: 1px solid var(--border2); background: transparent; cursor: pointer; font-size: 0.72rem; font-family: inherit; color: var(--text2); transition: all .15s; }
.class-btn:hover { border-color: var(--border2); background: var(--bg3); color: var(--text); }
.class-btn[data-cls="A"].active  { background: rgba(79,142,247,0.15);  color: #4f8ef7; border-color: rgba(79,142,247,0.4); }
.class-btn[data-cls="B"].active  { background: rgba(62,207,142,0.15);  color: #3ecf8e; border-color: rgba(62,207,142,0.4); }
.class-btn[data-cls="C"].active  { background: rgba(246,173,85,0.15);  color: #f6ad55; border-color: rgba(246,173,85,0.4); }
.class-btn[data-cls="D"].active  { background: rgba(167,139,250,0.15); color: #a78bfa; border-color: rgba(167,139,250,0.4); }
.class-btn[data-cls="E"].active  { background: rgba(245,101,101,0.15); color: #f56565; border-color: rgba(245,101,101,0.4); }
.class-btn .reset-hint { font-size: 0.6rem; color: var(--text3); }

/* ── Class info panel ── */
.class-info-panel { background: var(--bg3); border-left: 3px solid var(--blue); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; padding: 12px 14px; margin-top: 10px; transition: border-color .2s; }
.ci-row { display: flex; gap: 10px; margin-bottom: 5px; font-size: 0.78rem; align-items: baseline; }
.ci-row:last-child { margin-bottom: 0; }
.ci-label { color: var(--text3); min-width: 100px; flex-shrink: 0; }
.ci-val { color: var(--text2); }

/* ── Private / Public badge ── */
.badge-priv { font-size: 0.78rem; color: var(--amber); background: var(--amber-bg); border: 1px solid rgba(246,173,85,0.25); padding: 3px 10px; border-radius: 6px; }
.badge-pub  { font-size: 0.78rem; color: var(--green);  background: var(--green-bg);  border: 1px solid var(--green-border);  padding: 3px 10px; border-radius: 6px; }

/* ── Subnet Splitter ── */
select {
  background: var(--bg2); border: 1px solid var(--border2); border-radius: var(--radius-sm);
  color: var(--text); font-family: inherit; font-size: 0.82rem; padding: 7px 10px;
  outline: none; cursor: pointer; transition: border-color .15s;
}
select:focus { border-color: var(--blue); }

.split-header { font-size: 0.72rem; color: var(--text3); text-transform: uppercase; letter-spacing: 0.04em; margin-bottom: 8px; }
.split-row { display: grid; grid-template-columns: 28px 1fr 1fr auto; gap: 6px; padding: 6px 0; border-bottom: 1px solid var(--border); font-size: 0.78rem; align-items: center; }
.split-row:last-child { border-bottom: none; }
.split-num  { color: var(--text3); }
.split-net  { color: var(--blue); font-weight: 600; }
.split-range { color: var(--text2); }
.split-bc   { color: var(--text3); font-size: 0.72rem; }

/* ── Cheat sheet ── */
.cheat-header { display: grid; grid-template-columns: 60px 160px 90px 1fr; gap: 8px; padding: 8px 12px; font-size: 0.68rem; color: var(--text3); text-transform: uppercase; letter-spacing: 0.05em; border-bottom: 1px solid var(--border); }
.cheat-row    { display: grid; grid-template-columns: 60px 160px 90px 1fr; gap: 8px; padding: 8px 12px; font-size: 0.8rem; border-bottom: 1px solid var(--border); transition: background .12s; align-items: center; }
.cheat-row:last-child { border-bottom: none; }
.cheat-row:hover { background: var(--bg3); }
.cheat-cidr  { color: var(--blue); font-weight: 600; }
.cheat-mask  { color: var(--text2); }
.cheat-hosts { color: var(--green); }
.cheat-use   { color: var(--text3); font-size: 0.72rem; }

/* ── Quiz ── */
.quiz-q    { font-size: 0.9rem; font-weight: 500; color: var(--text); margin-bottom: 14px; line-height: 1.6; }
.quiz-meta { font-size: 0.7rem; color: var(--text3); margin-bottom: 12px; letter-spacing: 0.04em; }
.quiz-opt  { display: block; width: 100%; text-align: left; padding: 10px 14px; margin-bottom: 6px; background: var(--bg2); border: 1px solid var(--border2); border-radius: var(--radius-sm); color: var(--text2); font-family: inherit; font-size: 0.82rem; cursor: pointer; transition: all .15s; }
.quiz-opt:hover   { border-color: var(--blue); color: var(--text); background: var(--bg3); }
.quiz-opt.correct { background: var(--green-bg); border-color: var(--green-border); color: var(--green); }
.quiz-opt.wrong   { background: var(--red-bg);   border-color: rgba(245,101,101,0.3); color: var(--red); }
.feedback { font-size: 0.78rem; color: var(--text2); line-height: 1.65; margin-top: 10px; padding: 10px 12px; background: var(--bg3); border-radius: var(--radius-sm); border: 1px solid var(--border); display: none; }
.feedback.show { display: block; }

/* ── Buttons ── */
.btn         { padding: 8px 16px; border-radius: var(--radius-sm); border: 1px solid var(--border2); background: transparent; cursor: pointer; font-size: 0.78rem; font-family: inherit; color: var(--text2); transition: all .15s; }
.btn:hover   { border-color: var(--blue); color: var(--blue); background: var(--blue-bg); }
.btn-primary { background: var(--blue-bg); border-color: var(--blue-border); color: var(--blue); }
.btn-row     { display: flex; gap: 8px; margin-top: 12px; flex-wrap: wrap; }

/* ── Info box ── */
.info-box { background: var(--bg3); border-left: 3px solid var(--blue); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; padding: 12px 14px; font-size: 0.8rem; color: var(--text2); line-height: 1.65; margin-top: 10px; }
.info-box strong { color: var(--text); }

/* ── Section divider ── */
.section-divider { font-size: 0.68rem; color: var(--text3); text-transform: uppercase; letter-spacing: 0.06em; margin: 16px 0 8px; padding-bottom: 4px; border-bottom: 1px solid var(--border); }

/* ── Footer ── */
.site-footer { text-align: center; padding: 24px 16px; margin-top: 32px; border-top: 1px solid var(--border); }
.footer-content { display: flex; align-items: center; justify-content: center; gap: 8px; font-size: 0.8rem; color: var(--text3); }
.footer-name { color: var(--text2); font-weight: 500; }
.footer-divider { opacity: 0.5; }
.footer-year { color: var(--text3); }

@media (max-width: 600px) {
  .grid2 { grid-template-columns: 1fr; }
  .cheat-header, .cheat-row { grid-template-columns: 55px 140px 70px; }
  .cheat-use { display: none; }
  .tabs { flex-wrap: wrap; }
  .tab { flex: none; font-size: 0.68rem; }
  .split-row { grid-template-columns: 24px 1fr 1fr; }
  .split-bc { display: none; }
}