/* =========================================================================
   Quantum Mechanics Visualizer — shared styles
   ========================================================================= */
:root {
  --bg:        #0e1116;
  --bg-soft:   #161b22;
  --bg-card:   #1b222c;
  --border:    #2a3340;
  --text:      #e6edf3;
  --text-dim:  #9aa7b4;
  --accent:    #6ea8fe;
  --accent-2:  #f78fb3;
  --pos:       #4f8cff;   /* positive lobe / Re */
  --neg:       #ff6b6b;   /* negative lobe / Im */
  --shadow:    0 8px 28px rgba(0,0,0,.35);
  --radius:    14px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  background: radial-gradient(1200px 600px at 80% -10%, #1a2433 0%, var(--bg) 55%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.5;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---- Top navigation ---- */
.nav {
  display: flex; align-items: center; gap: 1.4rem;
  padding: .85rem 1.6rem;
  background: rgba(13,17,23,.75);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 50;
}
.nav .brand { font-weight: 700; letter-spacing: .2px; margin-right: .4rem; }
.nav .brand .psi { color: var(--accent-2); }
.nav a { color: var(--text-dim); font-size: .95rem; }
.nav a.active, .nav a:hover { color: var(--text); text-decoration: none; }

/* ---- Layout containers ---- */
.wrap { max-width: 1280px; margin: 0 auto; padding: 1.4rem 1.6rem 3rem; }
.page-title { margin: .4rem 0 .2rem; font-size: 1.6rem; }
.page-sub { color: var(--text-dim); margin: 0 0 1.2rem; max-width: 70ch; }

/* ---- Quantum-number control bar ---- */
.controls {
  display: flex; flex-wrap: wrap; align-items: center; gap: 1.1rem;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: .9rem 1.2rem; box-shadow: var(--shadow);
  margin-bottom: 1.2rem;
}
.qn { display: flex; align-items: center; gap: .55rem; }
.qn label { color: var(--text-dim); font-size: .92rem; }
.qn .var { font-style: italic; font-weight: 700; color: var(--text); }
.seg { display: inline-flex; gap: .28rem; flex-wrap: wrap; }
.seg button {
  min-width: 2.1rem; padding: .32rem .55rem;
  background: var(--bg-soft); color: var(--text);
  border: 1px solid var(--border); border-radius: 8px;
  font: inherit; font-size: .92rem; cursor: pointer; transition: all .12s ease;
}
.seg button:hover { border-color: var(--accent); }
.seg button.sel { background: var(--accent); border-color: var(--accent); color: #08111f; font-weight: 700; }
.toggle { margin-left: auto; }
.qn input[type=range] { accent-color: var(--accent); width: 150px; cursor: pointer; }
.qn .var.lvl { min-width: 6.5rem; font-style: normal; color: var(--text-dim); font-size: .88rem; }

/* ---- Cards / panels ---- */
.grid { display: grid; gap: 1.2rem; }
.grid.cols-2 { grid-template-columns: 1fr 1fr; }
@media (max-width: 920px) { .grid.cols-2 { grid-template-columns: 1fr; } }

.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.1rem 1.2rem; box-shadow: var(--shadow);
}
.card h2 { margin: 0 0 .2rem; font-size: 1.15rem; }
.sub-h { font-weight: 400; color: var(--text-dim); font-size: .9rem; }
.card .hint { color: var(--text-dim); font-size: .86rem; margin: 0 0 .7rem; }

/* Equation box */
.eq {
  background: var(--bg-soft); border: 1px solid var(--border);
  border-radius: 10px; padding: .7rem .8rem; margin: .2rem 0 .9rem;
  overflow-x: auto; font-size: 1.02rem;
}
.eq .katex { color: var(--text); }
.eq-note { color: var(--text-dim); font-size: .85rem; margin: -.5rem 0 .8rem; }

.plot { width: 100%; height: 320px; }
.plot.tall { height: 380px; }
.plot.cloud { height: 460px; }

/* ---- Landing page cards ---- */
.hero { padding: 2.2rem 0 1rem; }
.hero h1 { font-size: 2.1rem; margin: 0 0 .4rem; }
.hero h1 .psi { color: var(--accent-2); }
.hero p { color: var(--text-dim); max-width: 65ch; font-size: 1.05rem; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 1.2rem; margin-top: 1.4rem; }
@media (max-width: 920px) { .cards { grid-template-columns: 1fr; } }
.app-card {
  display: block; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.3rem; box-shadow: var(--shadow);
  transition: transform .14s ease, border-color .14s ease; color: var(--text);
}
.app-card:hover { transform: translateY(-4px); border-color: var(--accent); text-decoration: none; }
.app-card .tag { color: var(--accent); font-size: .8rem; text-transform: uppercase; letter-spacing: .08em; }
.app-card h3 { margin: .3rem 0 .5rem; font-size: 1.25rem; }
.app-card .eq { margin: .6rem 0 .3rem; background: var(--bg-soft); }
.app-card p { color: var(--text-dim); font-size: .92rem; margin: .6rem 0 0; }

.footer { color: var(--text-dim); font-size: .85rem; text-align: center; padding: 2rem 0 .5rem; }