/* =========================================================================
   BeamLab — vizuální identita „technický výkres / blueprint"
   ========================================================================= */
:root {
  --bp-bg: #0b1626;
  --bp-bg2: #0e1c30;
  --bp-panel: #10233c;
  --bp-panel2: #142a47;
  --bp-line: #1e3a5f;
  --bp-line2: #2a4d7a;
  --bp-ink: #d7e6f7;
  --bp-ink-dim: #8fa9c7;
  --bp-cyan: #53c8f0;
  --bp-amber: #ffb703;
  --bp-red: #ff6b6b;
  --bp-green: #3ddc97;
  --bp-violet: #b197fc;
  --mono: 'Cascadia Code', 'JetBrains Mono', Consolas, 'Courier New', monospace;
  --sans: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --radius: 10px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  color: var(--bp-ink);
  background-color: var(--bp-bg);
  background-image:
    linear-gradient(rgba(83, 200, 240, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(83, 200, 240, 0.045) 1px, transparent 1px),
    linear-gradient(rgba(83, 200, 240, 0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(83, 200, 240, 0.02) 1px, transparent 1px);
  background-size: 120px 120px, 120px 120px, 24px 24px, 24px 24px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ------------------------------- Header ------------------------------- */
.app-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(11, 22, 38, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--bp-line);
}
.header-inner {
  max-width: 1440px; margin: 0 auto; padding: 0.7rem 1.2rem;
  display: flex; align-items: center; gap: 1.1rem; flex-wrap: wrap;
}
.back-link {
  color: var(--bp-ink-dim); text-decoration: none; font-size: 1.3rem;
  width: 2.1rem; height: 2.1rem; display: grid; place-items: center;
  border: 1px solid var(--bp-line); border-radius: 8px; transition: 0.2s;
}
.back-link:hover { color: var(--bp-cyan); border-color: var(--bp-cyan); }
.brand { display: flex; align-items: center; gap: 0.6rem; }
.brand-mark { width: 44px; height: 27px; color: var(--bp-cyan); }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-name {
  font-family: var(--mono); font-weight: 700; font-size: 1.25rem;
  letter-spacing: 0.04em; color: var(--bp-ink);
}
.brand-name::after { content: '_'; color: var(--bp-amber); animation: blink 1.2s steps(1) infinite; }
@keyframes blink { 50% { opacity: 0; } }
.brand-sub { font-size: 0.72rem; color: var(--bp-ink-dim); letter-spacing: 0.08em; text-transform: uppercase; }

.main-tabs { display: flex; gap: 0.4rem; margin-left: auto; }
.main-tab {
  font-family: var(--mono); font-size: 0.92rem; padding: 0.5rem 1.1rem;
  background: transparent; color: var(--bp-ink-dim);
  border: 1px solid var(--bp-line); border-radius: 8px; cursor: pointer; transition: 0.2s;
}
.main-tab:hover { color: var(--bp-ink); border-color: var(--bp-line2); }
.main-tab.active { color: var(--bp-bg); background: var(--bp-cyan); border-color: var(--bp-cyan); font-weight: 600; }

.lang-toggle { display: flex; border: 1px solid var(--bp-line); border-radius: 8px; overflow: hidden; }
.lang-toggle button {
  font-family: var(--mono); font-size: 0.8rem; padding: 0.42rem 0.7rem;
  background: transparent; color: var(--bp-ink-dim); border: none; cursor: pointer; transition: 0.2s;
}
.lang-toggle button.active { background: var(--bp-panel2); color: var(--bp-amber); }

/* ------------------------------- Layout ------------------------------- */
main { flex: 1; }
.tab-panel { max-width: 1440px; margin: 0 auto; padding: 1.2rem; }
.calc-layout { display: grid; grid-template-columns: 390px 1fr; gap: 1.2rem; align-items: start; }

/* ------------------------------- Panely ------------------------------- */
.panel {
  background: linear-gradient(180deg, var(--bp-panel), var(--bp-bg2));
  border: 1px solid var(--bp-line);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  margin-bottom: 1.2rem;
  position: relative;
}
.panel::before {
  content: ''; position: absolute; inset: 6px; pointer-events: none;
  border: 1px dashed rgba(83, 200, 240, 0.12); border-radius: 6px;
}
.input-col .panel { margin-bottom: 1.2rem; }
.results-col .panel { margin-bottom: 1.2rem; }

.panel-title {
  font-size: 0.95rem; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase;
  display: flex; align-items: center; gap: 0.55rem; margin-bottom: 0.9rem; color: var(--bp-ink);
}
.panel-num {
  font-family: var(--mono); font-size: 0.75rem; color: var(--bp-amber);
  border: 1px solid var(--bp-amber); border-radius: 5px; padding: 0.1rem 0.35rem;
}

/* ------------------------------- Formuláře ------------------------------- */
.field-row {
  display: grid; grid-template-columns: 1fr 130px; gap: 0.6rem;
  align-items: center; margin-bottom: 0.55rem;
}
.field-row label { font-size: 0.85rem; color: var(--bp-ink-dim); }
input[type="number"], select {
  font-family: var(--mono); font-size: 0.9rem;
  background: var(--bp-bg); color: var(--bp-ink);
  border: 1px solid var(--bp-line2); border-radius: 7px;
  padding: 0.42rem 0.55rem; width: 100%;
  transition: border-color 0.2s;
}
input[type="number"]:focus, select:focus { outline: none; border-color: var(--bp-cyan); }
input[type="number"]::-webkit-inner-spin-button { opacity: 0.4; }
select { cursor: pointer; }
option { background: var(--bp-bg); }

.check-row {
  display: flex; align-items: center; gap: 0.55rem; font-size: 0.85rem;
  color: var(--bp-ink-dim); cursor: pointer; margin-top: 0.7rem;
}
.check-row input { accent-color: var(--bp-amber); width: 15px; height: 15px; cursor: pointer; }

/* Podpory (custom editor) */
.support-row {
  display: grid; grid-template-columns: 1fr 110px 92px 30px; gap: 0.45rem;
  align-items: center; margin-bottom: 0.45rem; font-size: 0.82rem;
}
.support-row .sup-label { color: var(--bp-ink-dim); font-family: var(--mono); }
.support-item { margin-bottom: 0.5rem; }
.support-item .support-row { margin-bottom: 0.25rem; }
.sup-tors-row { display: flex; align-items: center; gap: 0.4rem; font-size: 0.75rem; color: #2dd4bf; cursor: pointer; padding-left: 0.1rem; }
.sup-tors-row input { accent-color: #2dd4bf; width: 14px; height: 14px; cursor: pointer; }

/* Zatížení */
.load-card {
  border: 1px solid var(--bp-line); border-left: 3px solid var(--bp-red);
  border-radius: 8px; padding: 0.6rem 0.7rem; margin-bottom: 0.6rem;
  background: rgba(11, 22, 38, 0.5);
}
.load-card.udl { border-left-color: var(--bp-amber); }
.load-card.moment { border-left-color: var(--bp-violet); }
.load-card.torque { border-left-color: #2dd4bf; }
.load-head {
  display: flex; align-items: center; gap: 0.5rem; margin-bottom: 0.5rem;
  font-size: 0.82rem; font-weight: 600; letter-spacing: 0.03em;
}
.load-head .ltag { font-family: var(--mono); color: var(--bp-ink-dim); font-weight: 400; font-size: 0.75rem; }
.load-del {
  margin-left: auto; background: none; border: 1px solid var(--bp-line); color: var(--bp-ink-dim);
  border-radius: 6px; width: 24px; height: 24px; cursor: pointer; line-height: 1; transition: 0.2s;
}
.load-del:hover { color: var(--bp-red); border-color: var(--bp-red); }
.load-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.45rem; }
.load-grid.three { grid-template-columns: 1fr 1fr 1fr; }
.mini-field label { display: block; font-size: 0.68rem; color: var(--bp-ink-dim); margin-bottom: 0.15rem; font-family: var(--mono); }
.mini-field input { padding: 0.3rem 0.45rem; font-size: 0.85rem; }

.add-btns { display: flex; gap: 0.5rem; margin-top: 0.3rem; }
.btn-add {
  flex: 1; display: flex; align-items: center; justify-content: center; gap: 0.4rem;
  font-family: var(--mono); font-size: 0.8rem; padding: 0.5rem 0.3rem;
  background: transparent; color: var(--bp-cyan);
  border: 1px dashed var(--bp-line2); border-radius: 8px; cursor: pointer; transition: 0.2s;
}
.btn-add:hover { border-color: var(--bp-cyan); background: rgba(83, 200, 240, 0.07); }
.btn-add .ico { font-size: 1rem; }

/* Průřez */
.seg-toggle { display: flex; border: 1px solid var(--bp-line); border-radius: 8px; overflow: hidden; margin-bottom: 0.8rem; }
.seg-toggle button {
  flex: 1; font-size: 0.82rem; padding: 0.45rem; background: transparent;
  color: var(--bp-ink-dim); border: none; cursor: pointer; transition: 0.2s;
}
.seg-toggle button.active { background: var(--bp-panel2); color: var(--bp-cyan); font-weight: 600; }

.shape-grid { display: grid; grid-template-columns: repeat(6, 1fr); gap: 0.4rem; margin-bottom: 0.8rem; }
.shape-btn {
  aspect-ratio: 1; background: transparent; border: 1px solid var(--bp-line);
  border-radius: 8px; cursor: pointer; display: grid; place-items: center; transition: 0.2s; padding: 4px;
}
.shape-btn svg { width: 100%; height: 100%; stroke: var(--bp-ink-dim); fill: none; stroke-width: 6; }
.shape-btn:hover { border-color: var(--bp-line2); }
.shape-btn.active { border-color: var(--bp-amber); background: rgba(255, 183, 3, 0.08); }
.shape-btn.active svg { stroke: var(--bp-amber); }

.dims-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.45rem; }
.dims-grid .mini-field label { font-size: 0.72rem; }

.section-summary { display: grid; grid-template-columns: 158px 1fr; gap: 0.7rem; margin-top: 0.9rem; align-items: center; }
#sectionPreview { width: 158px; height: 140px; background: var(--bp-bg); border: 1px solid var(--bp-line); border-radius: 8px; }
.sec-props { font-family: var(--mono); font-size: 0.78rem; line-height: 1.75; color: var(--bp-ink-dim); }
.sec-props b { color: var(--bp-cyan); font-weight: 600; }
.sec-props .warn { color: var(--bp-red); }

.mat-props { font-family: var(--mono); font-size: 0.78rem; color: var(--bp-ink-dim); margin: 0.4rem 0 0.7rem; line-height: 1.7; }
.mat-props b { color: var(--bp-cyan); font-weight: 600; }

/* Skládaný průřez */
.comp-palette { grid-template-columns: repeat(7, 1fr); }
.comp-palette .shape-btn.armed { border-color: var(--bp-green); background: rgba(61, 220, 151, 0.1); }
.comp-palette .shape-btn.armed svg { stroke: var(--bp-green); }
.comp-profile-row { display: grid; grid-template-columns: 90px 1fr; gap: 0.45rem; margin-bottom: 0.5rem; }
.comp-hint { font-size: 0.75rem; color: var(--bp-ink-dim); margin-bottom: 0.55rem; line-height: 1.45; }
.comp-toolbar { display: flex; gap: 0.4rem; margin-bottom: 0.5rem; }
.comp-toolbar button {
  font-family: var(--mono); font-size: 0.75rem; padding: 0.35rem 0.6rem;
  background: transparent; color: var(--bp-cyan);
  border: 1px solid var(--bp-line2); border-radius: 7px; cursor: pointer; transition: 0.2s;
}
.comp-toolbar button:hover:not(:disabled) { border-color: var(--bp-cyan); background: rgba(83, 200, 240, 0.07); }
.comp-toolbar button:disabled { opacity: 0.35; cursor: default; }
.comp-toolbar #compDelBtn { margin-left: auto; color: var(--bp-red); }
.comp-toolbar #compDelBtn:hover:not(:disabled) { border-color: var(--bp-red); background: rgba(255, 107, 107, 0.07); }
#compCanvas {
  width: 100%; height: 285px; display: block;
  background: var(--bp-bg); border: 1px solid var(--bp-line2); border-radius: 8px;
  touch-action: none; cursor: default;
}
#compCanvas.armed { cursor: crosshair; border-color: var(--bp-green); }
.comp-note { font-size: 0.72rem; color: var(--bp-ink-dim); font-style: italic; margin-top: 0.5rem; line-height: 1.45; }
.comp-editor {
  border: 1px solid var(--bp-line); border-left: 3px solid var(--bp-amber);
  border-radius: 8px; padding: 0.6rem 0.7rem; margin-top: 0.6rem;
  background: rgba(11, 22, 38, 0.5);
}
.comp-editor .load-head { margin-bottom: 0.5rem; }
.comp-editor .dims-grid { grid-template-columns: 1fr 1fr; }

/* ------------------------------- Výsledky ------------------------------- */
.schematic-panel svg { width: 100%; height: auto; display: block; }
.solve-error {
  margin-top: 0.6rem; padding: 0.7rem 0.9rem; border: 1px solid var(--bp-red);
  border-radius: 8px; color: var(--bp-red); font-size: 0.88rem; background: rgba(255, 107, 107, 0.07);
}

.result-cards {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 0.8rem; margin-bottom: 1.2rem;
}
.rcard {
  background: linear-gradient(180deg, var(--bp-panel), var(--bp-bg2));
  border: 1px solid var(--bp-line); border-radius: var(--radius); padding: 0.75rem 0.9rem;
}
.rcard .rc-label {
  font-size: 0.68rem; text-transform: uppercase; letter-spacing: 0.09em;
  color: var(--bp-ink-dim); margin-bottom: 0.3rem; display: flex; justify-content: space-between;
}
.rcard .rc-value { font-family: var(--mono); font-size: 1.25rem; font-weight: 700; color: var(--bp-ink); }
.rcard .rc-value small { font-size: 0.75rem; color: var(--bp-ink-dim); font-weight: 400; }
.rcard .rc-sub { font-family: var(--mono); font-size: 0.72rem; color: var(--bp-ink-dim); margin-top: 0.2rem; }
.rcard.ok { border-left: 3px solid var(--bp-green); }
.rcard.bad { border-left: 3px solid var(--bp-red); }
.rcard.neutral { border-left: 3px solid var(--bp-cyan); }

.util-bar { height: 7px; background: var(--bp-bg); border-radius: 4px; margin-top: 0.45rem; overflow: hidden; border: 1px solid var(--bp-line); }
.util-fill { height: 100%; border-radius: 3px; background: var(--bp-green); transition: width 0.3s; }
.util-fill.bad { background: var(--bp-red); }
.util-fill.warn { background: var(--bp-amber); }

.chart-panel { padding-bottom: 0.6rem; }
.chart-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 0.4rem; }
.chart-head h3 { font-size: 0.88rem; font-weight: 600; letter-spacing: 0.04em; }
.chart-max { font-family: var(--mono); font-size: 0.78rem; color: var(--bp-amber); }
.chart-panel svg { width: 100%; height: 190px; display: block; }
.chart-note { font-size: 0.72rem; color: var(--bp-ink-dim); margin-top: 0.35rem; font-style: italic; }

/* ------------------------------- Učebnice ------------------------------- */
.learn-layout { display: grid; grid-template-columns: 280px 1fr; gap: 1.2rem; align-items: start; }
.learn-nav {
  position: sticky; top: 76px;
  background: linear-gradient(180deg, var(--bp-panel), var(--bp-bg2));
  border: 1px solid var(--bp-line); border-radius: var(--radius); padding: 0.7rem; overflow: hidden;
}
.learn-nav button {
  display: flex; align-items: center; gap: 0.6rem; width: 100%; text-align: left;
  background: none; border: none; color: var(--bp-ink-dim); cursor: pointer;
  padding: 0.6rem 0.7rem; border-radius: 8px; font-size: 0.88rem; transition: 0.15s; font-family: var(--sans);
}
.learn-nav button:hover { background: rgba(83, 200, 240, 0.07); color: var(--bp-ink); }
.learn-nav button.active { background: rgba(83, 200, 240, 0.12); color: var(--bp-cyan); font-weight: 600; }
.learn-nav .ch-num { font-family: var(--mono); font-size: 0.7rem; color: var(--bp-amber); min-width: 1.5rem; }

.learn-body {
  background: linear-gradient(180deg, var(--bp-panel), var(--bp-bg2));
  border: 1px solid var(--bp-line); border-radius: var(--radius); padding: 1.6rem 2rem;
  line-height: 1.75; font-size: 0.97rem;
}
.learn-body h2 { font-size: 1.45rem; margin-bottom: 1rem; color: var(--bp-ink); }
.learn-body h3 { font-size: 1.08rem; margin: 1.5rem 0 0.6rem; color: var(--bp-cyan); }
.learn-body p { margin-bottom: 0.8rem; color: var(--bp-ink); }
.learn-body ul, .learn-body ol { margin: 0 0 0.9rem 1.4rem; }
.learn-body li { margin-bottom: 0.35rem; }
.learn-body strong { color: var(--bp-amber); font-weight: 600; }
.learn-body em { color: var(--bp-ink-dim); }
.learn-body table { border-collapse: collapse; width: 100%; margin: 0.8rem 0 1.1rem; font-size: 0.88rem; }
.learn-body th, .learn-body td { border: 1px solid var(--bp-line2); padding: 0.5rem 0.65rem; text-align: left; }
.learn-body th { background: var(--bp-panel2); font-weight: 600; color: var(--bp-cyan); }
.learn-body .tbl-wrap { overflow-x: auto; }

/* Vzorce */
.formula {
  font-family: var(--mono); text-align: center; margin: 1rem auto; padding: 0.8rem 1rem;
  background: var(--bp-bg); border: 1px solid var(--bp-line2); border-radius: 8px;
  font-size: 1.05rem; color: var(--bp-ink); overflow-x: auto;
  display: flex; align-items: center; justify-content: center; gap: 0.4rem; flex-wrap: wrap;
}
.formula .hl { color: var(--bp-amber); }
.fx { font-family: var(--mono); color: var(--bp-cyan); white-space: nowrap; }
.frac { display: inline-flex; flex-direction: column; vertical-align: middle; text-align: center; margin: 0 0.25rem; }
.frac > span { display: block; padding: 0 0.35rem; }
.frac > span:first-child { border-bottom: 1.5px solid currentColor; }
sub, sup { font-size: 0.68em; }

.note-box {
  border-left: 3px solid var(--bp-amber); background: rgba(255, 183, 3, 0.06);
  border-radius: 0 8px 8px 0; padding: 0.7rem 1rem; margin: 0.9rem 0; font-size: 0.9rem;
}
.example-box {
  border: 1px solid var(--bp-green); border-radius: 8px; padding: 1rem 1.2rem; margin: 1rem 0;
}
.example-box .ex-title { font-weight: 700; color: var(--bp-green); margin-bottom: 0.5rem; font-size: 0.92rem; letter-spacing: 0.04em; text-transform: uppercase; }
.try-btn {
  display: inline-block; margin-top: 0.5rem; font-family: var(--mono); font-size: 0.82rem;
  color: var(--bp-bg); background: var(--bp-cyan); border: none; border-radius: 7px;
  padding: 0.45rem 0.9rem; cursor: pointer; transition: 0.2s; font-weight: 600;
}
.try-btn:hover { filter: brightness(1.15); }

.learn-fig { margin: 1rem auto; text-align: center; }
.learn-fig svg { max-width: 100%; height: auto; }
.learn-fig figcaption { font-size: 0.78rem; color: var(--bp-ink-dim); margin-top: 0.3rem; font-style: italic; }

/* ------------------------------- Footer ------------------------------- */
.app-footer {
  border-top: 1px solid var(--bp-line); padding: 1rem 1.2rem; text-align: center;
  font-size: 0.8rem; color: var(--bp-ink-dim);
}
.app-footer a { color: var(--bp-cyan); text-decoration: none; }
.app-footer a:hover { text-decoration: underline; }

/* ------------------------------- Responsive ------------------------------- */
@media (max-width: 1080px) {
  .calc-layout { grid-template-columns: 1fr; }
  .learn-layout { grid-template-columns: 1fr; }
  .learn-nav { position: static; display: flex; flex-wrap: wrap; gap: 0.3rem; }
  .learn-nav button { width: auto; }
}
@media (max-width: 640px) {
  .header-inner { gap: 0.6rem; }
  .brand-sub { display: none; }
  .main-tabs { order: 3; width: 100%; margin-left: 0; }
  .main-tab { flex: 1; }
  .learn-body { padding: 1.1rem 1rem; }
  .shape-grid { grid-template-columns: repeat(3, 1fr); }
  .shape-btn { aspect-ratio: auto; height: 52px; }
}