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

:root {
  --kv-bg:      #0f172a;
  --kv-card:    #1e293b;
  --kv-card-2:  #263248;
  --kv-text:    #f1f5f9;
  --kv-muted:   #94a3b8;
  --kv-border:  #334155;
  --kv-accent:  #38bdf8;
  --kv-pass:    #22c55e;
  --kv-fail:    #ef4444;
  --kv-warn:    #f59e0b;
}

body {
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--kv-bg);
  color: var(--kv-text);
  min-height: 100vh;
  font-size: 15px;
  line-height: 1.5;
}

/* ── Header ── */

.app-header {
  padding: 20px 16px 14px;
  border-bottom: 1px solid var(--kv-border);
  position: relative;
  text-align: center;
}

.home-logo {
  position: absolute;
  top: 12px;
  left: 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  text-decoration: none;
}

.home-logo img { width: 32px; height: 32px; opacity: 0.9; display: block; transition: opacity 0.15s; }
.home-logo:hover img { opacity: 1; }

.home-logo-label {
  font-size: 0.6rem;
  font-weight: 500;
  letter-spacing: 0.03em;
  color: var(--kv-muted);
  transition: color 0.15s;
  white-space: nowrap;
}
.home-logo:hover .home-logo-label { color: var(--kv-accent); }

.app-header h1 { font-size: 1.5rem; font-weight: 700; letter-spacing: -0.02em; padding: 0 52px; }
.app-header-center > p { color: var(--kv-muted); font-size: 0.88rem; margin-top: 4px; padding: 0 52px; }

/* ── Theme toggle ── */

.theme-toggle {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 1px solid var(--kv-border);
  background: var(--kv-card);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--kv-muted);
  font-size: 0.9rem;
  transition: background 0.15s, border-color 0.15s;
}
.theme-toggle:hover {
  background: var(--kv-card-2);
  border-color: var(--kv-accent);
  color: var(--kv-text);
}

/* ── Mobile header ── */

@media (max-width: 800px) {
  input, select, textarea { font-size: 16px; }
  .app-header { display: flex; align-items: flex-start; gap: 8px; padding: 12px 16px; }
  .home-logo { position: static; flex: 0 0 auto; order: 1; padding-top: 6px; }
  .app-header-center { flex: 1; min-width: 0; order: 2; text-align: center; }
  .theme-toggle { position: static; flex: 0 0 auto; order: 3; width: 44px; height: 44px; }
  .app-header h1 { font-size: 1.1rem; padding: 0; }
  .app-header-center > p { padding: 0; font-size: 0.82rem; }
}

/* ── Contact card ── */

.contact-wrap {
  max-width: 540px;
  margin: 40px auto;
  padding: 0 16px;
}

.contact-card {
  background: var(--kv-card);
  border: 1px solid var(--kv-border);
  border-radius: 14px;
  padding: 32px;
}

.contact-label {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--kv-muted);
  margin-bottom: 10px;
}

.contact-email {
  display: block;
  text-align: center;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--kv-accent);
  text-decoration: none;
  padding: 14px 16px;
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: 10px;
  letter-spacing: 0.01em;
  transition: background 0.15s, border-color 0.15s;
}
.contact-email:hover {
  background: rgba(56, 189, 248, 0.14);
  border-color: rgba(56, 189, 248, 0.5);
}

/* ── Divider ── */

.divider {
  text-align: center;
  color: var(--kv-muted);
  font-size: 0.82rem;
  margin: 24px 0;
  position: relative;
}
.divider::before,
.divider::after {
  content: '';
  position: absolute;
  top: 50%;
  width: 28%;
  height: 1px;
  background: var(--kv-border);
}
.divider::before { left: 0; }
.divider::after { right: 0; }

/* ── Form ── */

.form-group {
  margin-bottom: 16px;
}
.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--kv-muted);
  margin-bottom: 6px;
}
.form-group input,
.form-group textarea {
  width: 100%;
  background: var(--kv-card-2);
  border: 1px solid var(--kv-border);
  border-radius: 8px;
  padding: 10px 12px;
  color: var(--kv-text);
  font-size: 0.95rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.15s;
}
.form-group input:focus,
.form-group textarea:focus {
  border-color: var(--kv-accent);
}
.form-group textarea {
  resize: vertical;
  min-height: 120px;
  line-height: 1.5;
}
.form-group input::placeholder,
.form-group textarea::placeholder {
  color: var(--kv-muted);
  opacity: 0.7;
}

/* ── Send button ── */

.btn-send {
  width: 100%;
  padding: 12px;
  background: var(--kv-accent);
  color: #0f172a;
  font-weight: 700;
  font-size: 0.95rem;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  min-height: 44px;
  transition: background 0.15s;
  font-family: inherit;
}
.btn-send:hover { background: #0ea5e9; }

/* ── Helper note ── */

.helper-note {
  text-align: center;
  font-size: 0.78rem;
  color: var(--kv-muted);
  margin-top: 12px;
  line-height: 1.5;
}

/* ── Footer ── */

footer {
  text-align: center;
  padding: 32px 20px;
  color: var(--kv-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--kv-border);
  margin-top: 48px;
}
footer a { color: var(--kv-accent); text-decoration: none; }
footer a:hover { text-decoration: underline; }
footer p + p { margin-top: 8px; }

/* ── Light mode ── */

html:not(.dark) {
  --kv-bg:     #edf2f7;
  --kv-card:   #d4dce8;
  --kv-card-2: #c5cfe0;
  --kv-text:   #0f172a;
  --kv-muted:  #475569;
  --kv-border: #e2e8f0;
  --kv-accent: #0369a1;
  --kv-warn:   #d97706;
}

/* ── Tool info & FAQ ── */

.tool-info {
  max-width: 900px;
  margin: 48px auto 0;
  padding: 0 20px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
}
@media (max-width: 680px) { .tool-info { grid-template-columns: 1fr; } }

.tool-info h2 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--kv-text);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--kv-border);
}
.tool-about p { font-size: 0.9rem; color: var(--kv-muted); line-height: 1.6; margin-bottom: 8px; }
.faq-item { border-bottom: 1px solid var(--kv-border); padding: 10px 0; }
.faq-item summary {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--kv-text);
  cursor: pointer;
  list-style: none;
  padding-right: 20px;
  position: relative;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: '+'; position: absolute; right: 0; color: var(--kv-muted); }
.faq-item[open] summary::after { content: '−'; }
.faq-item p { font-size: 0.85rem; color: var(--kv-muted); line-height: 1.6; margin-top: 8px; }

/* ── Tool navigation bar ── */

.kv-tool-nav{display:flex;justify-content:center;overflow-x:auto;border-bottom:1px solid var(--kv-border);background:var(--kv-bg);padding:0 16px;scrollbar-width:none;}
.kv-tool-nav::-webkit-scrollbar{display:none;}
.kv-tool-nav a{flex-shrink:0;padding:10px 14px;font-size:0.82rem;font-weight:500;color:var(--kv-muted);text-decoration:none;border-bottom:2px solid transparent;white-space:nowrap;transition:color 0.15s;}
.kv-tool-nav a:hover{color:var(--kv-text);}
.kv-tool-nav a.kv-nav-active{color:var(--kv-accent);border-bottom-color:var(--kv-accent);}
html:not(.dark) .kv-tool-nav{background:#edf2f7;border-color:#e2e8f0;}
html:not(.dark) .kv-tool-nav a{color:#475569;}
html:not(.dark) .kv-tool-nav a:hover{color:#0f172a;}
html:not(.dark) .kv-tool-nav a.kv-nav-active{color:#0369a1;border-bottom-color:#0369a1;}
@media(max-width:800px){.kv-tool-nav{justify-content:flex-start;}}