/* ASME VIII-1-2023 — Steel/iron theme */
:root {
  --primary: #4a90d9;
  --primary-light: #6cb0f5;
  --primary-dark: #2c5f8a;
  --bg: #1a1d24;
  --surface: #232733;
  --surface-2: #2c3140;
  --text: #e6e9ef;
  --text-dim: #9aa3b2;
  --border: #3a4050;
  --gold: #ffb946;
  --ok: #4caf50;
  --warn: #ff7043;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { background: var(--bg); color: var(--text); font-family: 'Segoe UI', 'Helvetica Neue', Arial, sans-serif; min-height: 100vh; }

/* TOPBAR */
.topbar {
  display: flex; justify-content: space-between; align-items: center;
  padding: 0.75rem 1.5rem;
  background: linear-gradient(135deg, #2c3140 0%, #1f2330 100%);
  border-bottom: 2px solid var(--primary);
  position: sticky; top: 0; z-index: 100;
}
.topbar-left, .topbar-right { display: flex; align-items: center; gap: 0.75rem; }
.btn-top {
  color: var(--text); text-decoration: none; padding: 0.4rem 0.9rem;
  border-radius: 4px; font-size: 0.9rem; transition: background 0.2s;
}
.btn-top:hover { background: rgba(74,144,217,0.2); color: var(--primary-light); }
#lang-select {
  background: var(--surface-2); color: var(--text); border: 1px solid var(--border);
  padding: 0.4rem 0.8rem; border-radius: 4px; font-size: 0.85rem; cursor: pointer;
}

/* HERO */
.hero {
  text-align: center; padding: 3rem 1rem 1.5rem;
  background: radial-gradient(ellipse at center, rgba(74,144,217,0.12) 0%, transparent 70%);
}
.hero-title {
  font-size: 2.4rem; font-weight: 700; letter-spacing: 1px;
  color: var(--primary-light); text-shadow: 0 0 24px rgba(74,144,217,0.4);
}
.hero-subtitle { font-size: 1.25rem; color: var(--gold); margin-top: 0.3rem; }
.hero-tagline { color: var(--text-dim); margin-top: 0.4rem; font-size: 0.95rem; }

/* TAB BAR */
.tab-bar {
  display: flex; justify-content: center; gap: 4px; flex-wrap: wrap;
  padding: 0.75rem 1rem; background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.tab-btn {
  background: transparent; color: var(--text-dim); border: 1px solid transparent;
  padding: 0.55rem 1.1rem; border-radius: 4px 4px 0 0; cursor: pointer;
  font-size: 0.9rem; font-weight: 500; transition: all 0.2s;
}
.tab-btn:hover { color: var(--text); background: rgba(74,144,217,0.08); }
.tab-btn.active { color: var(--primary-light); border-bottom: 2px solid var(--primary); background: var(--surface-2); }

/* WRAPPER */
.wrapper { max-width: 960px; margin: 0 auto; padding: 1.5rem 1rem 3rem; }

.tab-panel { display: none; }
.tab-panel.active { display: block; animation: fadein 0.25s; }
@keyframes fadein { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }

.panel-title {
  font-size: 1.5rem; font-weight: 700; color: var(--primary-light);
  margin-bottom: 0.3rem;
}
.panel-intro { color: var(--text-dim); margin-bottom: 1.2rem; font-size: 0.92rem; line-height: 1.5; }

/* CALC CARD */
.calc-card {
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px;
  padding: 1.5rem; margin-bottom: 1.5rem;
}
.calc-card h3 {
  margin-top: 1rem; margin-bottom: 0.5rem; color: var(--gold);
  font-size: 0.95rem; font-weight: 600;
}
.calc-card h3:first-child { margin-top: 0; }

/* FORM */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.85rem; margin-top: 1rem; }
.form-col label { display: block; font-size: 0.82rem; color: var(--text-dim); margin-bottom: 0.25rem; }
.form-col input, .form-col select {
  width: 100%; padding: 0.55rem 0.7rem; background: var(--surface-2);
  border: 1px solid var(--border); border-radius: 4px; color: var(--text);
  font-size: 0.9rem;
}
.form-col input:focus, .form-col select:focus { outline: none; border-color: var(--primary); }

.form-row { margin-top: 0.85rem; }
.form-row label { display: block; font-size: 0.82rem; color: var(--text-dim); margin-bottom: 0.25rem; }
.form-row input, .form-row select {
  width: 100%; max-width: 320px; padding: 0.55rem 0.7rem; background: var(--surface-2);
  border: 1px solid var(--border); border-radius: 4px; color: var(--text); font-size: 0.9rem;
}

/* RADIO */
.radio-group { display: flex; flex-wrap: wrap; gap: 0.75rem 1.25rem; margin-top: 0.5rem; }
.radio-label {
  display: flex; align-items: center; gap: 0.4rem; cursor: pointer;
  font-size: 0.88rem; color: var(--text);
}
.radio-label input[type=radio] { accent-color: var(--primary); }

/* BUTTONS */
.btn-calc, .btn-reset {
  padding: 0.65rem 1.6rem; border: none; border-radius: 4px; cursor: pointer;
  font-size: 0.95rem; font-weight: 600; margin-top: 1.2rem; margin-right: 0.6rem;
  transition: all 0.2s;
}
.btn-calc { background: var(--primary); color: #fff; }
.btn-calc:hover { background: var(--primary-dark); }
.btn-reset { background: transparent; color: var(--text-dim); border: 1px solid var(--border); }
.btn-reset:hover { color: var(--text); border-color: var(--text-dim); }

/* RESULT */
.result-box { margin-top: 1.2rem; }
.result-box.info { background: var(--surface-2); border-radius: 6px; padding: 1rem; border-left: 4px solid var(--primary); }
.result-box.ok { border-left-color: var(--ok); }
.result-box.warn { border-left-color: var(--warn); }

.res-row { display: flex; justify-content: space-between; padding: 0.35rem 0; border-bottom: 1px solid rgba(255,255,255,0.06); }
.res-row:last-child { border-bottom: none; }
.res-label { color: var(--text-dim); font-size: 0.85rem; }
.res-val { color: var(--text); font-weight: 600; font-size: 0.9rem; }
.res-status { padding: 0.5rem 0.8rem; border-radius: 4px; font-weight: 700; font-size: 0.95rem; margin-top: 0.6rem; text-align: center; }
.res-status.ok { background: rgba(76,175,80,0.15); color: var(--ok); }
.res-status.warn { background: rgba(255,112,67,0.15); color: var(--warn); }

/* NOTES */
.note-box {
  background: rgba(74,144,217,0.06); border-left: 3px solid var(--primary);
  padding: 0.6rem 0.9rem; border-radius: 0 4px 4px 0; margin-top: 0.8rem;
  font-size: 0.85rem; color: var(--text-dim); line-height: 1.5;
}
.note-box strong { color: var(--gold); margin-right: 0.3rem; }

/* FOOTER */
.footer { text-align: center; padding: 1.5rem; color: var(--text-dim); font-size: 0.82rem; border-top: 1px solid var(--border); margin-top: 2rem; }

/* RESPONSIVE */
@media (max-width: 700px) {
  .topbar { flex-direction: column; gap: 0.5rem; align-items: stretch; }
  .topbar-left, .topbar-right { justify-content: center; }
  .hero-title { font-size: 1.7rem; }
  .hero-subtitle { font-size: 1rem; }
  .tab-bar { gap: 2px; padding: 0.5rem; }
  .tab-btn { padding: 0.45rem 0.7rem; font-size: 0.8rem; }
  .form-grid { grid-template-columns: 1fr; }
  .calc-card { padding: 1rem; }
  .radio-group { flex-direction: column; gap: 0.4rem; }
}