/* ── Two's Complement Calculator ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --accent:    #06b6d4;
  --accent2:   #0891b2;
  --accent-bg: rgba(6,182,212,.1);
  --surface:   #0f172a;
  --card:      #111827;
  --card2:     #1e293b;
  --border:    #1e293b;
  --border2:   #334155;
  --text:      #f1f5f9;
  --text2:     #94a3b8;
  --text3:     #64748b;
  --radius:    14px;
  --mono:      'Courier New', Courier, monospace;
}

body { background: var(--surface); color: var(--text); font-family: system-ui, sans-serif; line-height: 1.6; }

/* ── header ── */
.site-header { position: sticky; top: 0; z-index: 200; background: rgba(15,23,42,.95); backdrop-filter: blur(12px); border-bottom: 1px solid var(--border); }
.header-inner { max-width: 1200px; margin: 0 auto; padding: 0 24px; height: 60px; display: flex; align-items: center; justify-content: space-between; }
.logo { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.logo-icon { width: 32px; height: 32px; }
.logo-text { font-size: 1.05rem; font-weight: 700; color: var(--text); }
.nav-links { display: flex; gap: 24px; }
.nav-links a { color: var(--text2); text-decoration: none; font-size: .875rem; transition: color .15s; }
.nav-links a:hover { color: var(--text); }
@media(max-width:640px) { .nav-links { display: none; } }

/* ── hero ── */
.hero { padding: 52px 24px 36px; text-align: center; max-width: 660px; margin: 0 auto; }
.hero-badge { display: inline-flex; align-items: center; gap: 6px; padding: 5px 14px; background: var(--accent-bg); border: 1px solid rgba(6,182,212,.3); border-radius: 999px; font-size: .78rem; font-weight: 600; color: var(--accent); margin-bottom: 18px; }
.hero h1 { font-size: clamp(1.6rem,4vw,2.4rem); font-weight: 800; line-height: 1.2; margin-bottom: 12px; }
.hero h1 span { background: linear-gradient(135deg,#06b6d4,#67e8f9); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.hero p { color: var(--text2); font-size: 1rem; }

/* ── tool wrap ── */
.tool-wrap { max-width: 820px; margin: 0 auto; padding: 0 20px 80px; }

/* ── mode + bits bar ── */
.ctrl-bar { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; margin-bottom: 22px; }
.mode-group, .bits-group { display: flex; background: var(--card); border: 1px solid var(--border2); border-radius: var(--radius); padding: 5px; gap: 4px; }
.ctrl-btn { padding: 8px 16px; border: none; border-radius: 9px; font-size: .82rem; font-weight: 600; cursor: pointer; transition: background .14s, color .14s; background: transparent; color: var(--text2); white-space: nowrap; }
.ctrl-btn.active { background: var(--accent); color: #fff; }
.bits-group .ctrl-btn { padding: 7px 13px; }

/* ── main card ── */
.tc-card { background: var(--card); border: 1px solid var(--border2); border-radius: var(--radius); padding: 28px; }
.tc-label { font-size: .78rem; font-weight: 700; color: var(--text2); margin-bottom: 8px; letter-spacing: .04em; }
.tc-input-row { display: flex; gap: 10px; margin-bottom: 6px; }
.tc-input { flex: 1; background: var(--card2); border: 1px solid var(--border2); border-radius: 10px; color: var(--text); font-size: 1rem; padding: 11px 16px; outline: none; font-family: var(--mono); transition: border-color .18s, box-shadow .18s; }
.tc-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(6,182,212,.15); }
.tc-input::placeholder { color: var(--text3); font-family: system-ui; font-size: .9rem; }
.tc-hint { font-size: .77rem; color: var(--text3); margin-bottom: 16px; }

.calc-btn { padding: 11px 28px; background: linear-gradient(135deg, var(--accent), #67e8f9); border: none; border-radius: 10px; color: #0f172a; font-size: .875rem; font-weight: 800; cursor: pointer; display: flex; align-items: center; gap: 8px; transition: opacity .18s, transform .15s; flex-shrink: 0; }
.calc-btn:hover { opacity: .9; transform: translateY(-1px); }
.calc-btn svg { width: 16px; height: 16px; }
.clear-btn { padding: 11px 18px; background: var(--card2); border: 1px solid var(--border2); border-radius: 10px; color: var(--text3); font-size: .82rem; font-weight: 600; cursor: pointer; transition: color .15s, border-color .15s; }
.clear-btn:hover { color: #f87171; border-color: rgba(248,113,113,.3); }

.tc-err { margin-top: 12px; padding: 10px 16px; background: rgba(248,113,113,.1); border: 1px solid rgba(248,113,113,.3); border-radius: 9px; color: #f87171; font-size: .84rem; }

/* ── result ── */
.tc-result { margin-top: 24px; }
.tc-result-grid { display: grid; grid-template-columns: repeat(2,1fr); gap: 12px; margin-bottom: 20px; }
@media(max-width:440px) { .tc-result-grid { grid-template-columns: 1fr; } }
.tc-res-item { background: var(--card2); border: 1px solid var(--border2); border-radius: 10px; padding: 14px 16px; display: flex; justify-content: space-between; align-items: flex-start; gap: 10px; }
.tc-res-item label { font-size: .72rem; font-weight: 700; color: var(--text3); text-transform: uppercase; letter-spacing: .06em; display: block; margin-bottom: 5px; }
.tc-res-item .val { font-size: .95rem; font-weight: 800; color: var(--text); font-family: var(--mono); word-break: break-all; }
.tc-res-item .val.accent { color: var(--accent); }
.copy-btn { width: 30px; height: 30px; flex-shrink: 0; background: var(--card); border: 1px solid var(--border2); border-radius: 7px; display: flex; align-items: center; justify-content: center; cursor: pointer; color: var(--text3); transition: all .14s; }
.copy-btn:hover, .copy-btn.ok { background: var(--accent-bg); color: var(--accent); border-color: rgba(6,182,212,.3); }
.copy-btn svg { width: 13px; height: 13px; }

/* ── bit visualization ── */
.bit-viz { background: var(--card2); border: 1px solid var(--border2); border-radius: 12px; padding: 20px; }
.bit-viz-title { font-size: .78rem; font-weight: 700; color: var(--text2); margin-bottom: 14px; display: flex; align-items: center; gap: 8px; }
.bit-viz-title svg { width: 14px; height: 14px; color: var(--accent); }
.bit-row { display: flex; flex-wrap: wrap; gap: 3px; }
.bit-cell { min-width: 24px; height: 28px; display: flex; align-items: center; justify-content: center; border-radius: 5px; font-size: .78rem; font-family: var(--mono); font-weight: 800; border: 1px solid var(--border2); padding: 0 4px; transition: background .15s; }
.bit-cell.sign-1 { background: rgba(239,68,68,.18); border-color: rgba(239,68,68,.35); color: #f87171; }
.bit-cell.sign-0 { background: rgba(6,182,212,.12); border-color: rgba(6,182,212,.25); color: var(--accent); }
.bit-cell.one    { background: rgba(6,182,212,.1); border-color: rgba(6,182,212,.22); color: var(--accent); }
.bit-cell.zero   { background: var(--card); color: var(--text3); }
.bit-legend { display: flex; gap: 14px; flex-wrap: wrap; font-size: .74rem; margin-top: 10px; }
.bit-dot { width: 10px; height: 10px; border-radius: 3px; display: inline-block; margin-right: 5px; vertical-align: middle; }

/* ── steps ── */
.steps-block { margin-top: 16px; background: var(--card2); border: 1px solid var(--border2); border-radius: 12px; padding: 20px; }
.steps-title { font-size: .82rem; font-weight: 700; color: var(--text2); margin-bottom: 16px; display: flex; align-items: center; gap: 8px; }
.steps-title svg { width: 14px; height: 14px; color: var(--accent); }
.step-row { display: flex; align-items: center; gap: 14px; margin-bottom: 12px; flex-wrap: wrap; }
.step-row:last-child { margin-bottom: 0; border-top: 1px solid var(--border); padding-top: 12px; margin-top: 4px; }
.step-label { font-size: .75rem; font-weight: 700; color: var(--text3); min-width: 130px; flex-shrink: 0; }
.step-bits { font-size: .88rem; font-family: var(--mono); font-weight: 700; color: var(--text); letter-spacing: .08em; word-break: break-all; }
.step-bits.inv { color: #fbbf24; }
.step-bits.res { color: var(--accent); }
.step-sep { width: 100%; height: 1px; background: var(--border); margin: 4px 0; }

/* ── info sections ── */
.info-section { border-top: 1px solid var(--border); padding: 40px 0; }
.info-section:first-of-type { border-top: none; padding-top: 0; margin-top: 56px; }
.info-icon-row { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.info-icon { width: 44px; height: 44px; border-radius: 12px; background: var(--accent-bg); border: 1px solid rgba(6,182,212,.2); display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.info-icon svg { width: 20px; height: 20px; color: var(--accent); }
.info-section h2 { font-size: 1.25rem; font-weight: 800; color: var(--text); }
.info-body { color: var(--text2); font-size: .9rem; line-height: 1.8; }
.info-body p { margin-bottom: 12px; }
.info-body p:last-child { margin-bottom: 0; }
.info-body ol, .info-body ul { padding-left: 20px; }
.info-body li { margin-bottom: 8px; }
.info-body strong { color: var(--text); }
.info-body code { background: var(--card2); padding: 2px 7px; border-radius: 5px; font-family: var(--mono); font-size: .84em; color: var(--accent); }
.info-example { background: var(--card2); border: 1px solid var(--border2); border-radius: 10px; padding: 16px 20px; margin-top: 14px; font-family: var(--mono); font-size: .85rem; color: var(--text2); line-height: 2; }
.info-example .hl { color: var(--accent); font-weight: 700; }
.info-example .hl-warn { color: #fbbf24; font-weight: 700; }
.info-example .hl-err { color: #f87171; font-weight: 700; }

/* ── FAQ ── */
.faq-section { margin-top: 0; padding-top: 40px; border-top: 1px solid var(--border); }
.faq-section h2 { font-size: 1.25rem; font-weight: 800; margin-bottom: 18px; }
.faq-item { border-bottom: 1px solid var(--border); padding: 15px 0; }
.faq-item:last-child { border-bottom: none; }
.faq-q { font-size: .9rem; font-weight: 700; color: var(--text); cursor: pointer; display: flex; justify-content: space-between; align-items: center; gap: 16px; }
.faq-q svg { width: 16px; height: 16px; color: var(--text3); flex-shrink: 0; transition: transform .2s; }
.faq-q.open svg { transform: rotate(180deg); }
.faq-a { font-size: .855rem; color: var(--text2); line-height: 1.75; margin-top: 10px; }
.faq-a code { background: var(--card2); padding: 1px 6px; border-radius: 4px; font-family: var(--mono); font-size: .82em; color: var(--accent); }

/* ── related ── */
.related-section { padding: clamp(24px,4vw,40px) 0; border-top: 1px solid var(--border); }
.related-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 20px; flex-wrap: wrap; gap: 10px; }
.related-title { font-size: 1.2rem; font-weight: 800; color: var(--text); }
.btn-view-all { display: inline-flex; align-items: center; gap: 5px; padding: 7px 16px; border-radius: 999px; font-size: .83rem; font-weight: 600; border: 1px solid var(--border2); color: var(--text2); transition: border-color .15s, color .15s; text-decoration: none; }
.btn-view-all:hover { border-color: var(--accent); color: var(--accent); }
.related-grid { display: grid; grid-template-columns: repeat(auto-fill,minmax(200px,1fr)); gap: 14px; }
.related-tool-card { background: var(--card); border: 1px solid var(--border2); border-radius: var(--radius); padding: 18px; display: flex; flex-direction: column; gap: 10px; text-decoration: none; transition: border-color .18s, transform .18s, box-shadow .18s; }
.related-tool-card:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,.3); }
.related-tool-icon { width: 40px; height: 40px; border-radius: 10px; display: flex; align-items: center; justify-content: center; }
.related-tool-icon svg { width: 20px; height: 20px; color: #fff; }
.related-tool-name { font-size: .92rem; font-weight: 700; color: var(--text); }
.related-tool-desc { font-size: .8rem; color: var(--text2); line-height: 1.5; flex: 1; }
.related-tool-link { display: inline-flex; align-items: center; gap: 5px; font-size: .8rem; font-weight: 600; color: var(--accent); margin-top: 4px; }
.related-tool-link svg { width: 13px; height: 13px; }
.blog-cards-grid { display: grid; grid-template-columns: repeat(auto-fill,minmax(240px,1fr)); gap: 14px; }
.blog-card-sm { background: var(--card); border: 1px solid var(--border2); border-radius: var(--radius); padding: 20px; display: flex; flex-direction: column; gap: 8px; text-decoration: none; transition: border-color .18s, transform .18s, box-shadow .18s; }
.blog-card-sm:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,.3); }
.blog-cat-badge { display: inline-flex; padding: 2px 9px; border-radius: 999px; font-size: .7rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; width: fit-content; }
.blog-card-title { font-size: .92rem; font-weight: 700; line-height: 1.4; color: var(--text); }
.blog-card-excerpt { font-size: .8rem; color: var(--text2); line-height: 1.6; flex: 1; }
.blog-card-meta { font-size: .73rem; color: var(--text3); }
.blog-read-link { display: inline-flex; align-items: center; gap: 4px; font-size: .8rem; font-weight: 600; color: var(--accent); margin-top: 4px; }
.blog-read-link svg { width: 12px; height: 12px; }

[x-cloak] { display: none !important; }