/* ===========================================================
   Professor Madison — Design System
   =========================================================== */

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@600;700;800&family=Inter:wght@400;500;600;700&display=swap');

:root{
  --bg:            #081420;
  --bg-alt:        #0c1c2c;
  --card:          #10263a;
  --card-hover:    #143050;
  --border:        #1d3d56;
  --border-soft:   #16324a;
  --teal:          #18e3ac;
  --teal-2:        #10b3c4;
  --teal-soft:     rgba(24,227,172,.12);
  --text:          #eef4f8;
  --text-dim:      #9fb6c8;
  --text-faint:    #6f8ba0;
  --physics:       #18e3ac;
  --physics-2:     #10b3c4;
  --radius:        16px;
  --radius-sm:     10px;
  --maxw:          1180px;
  --shadow:        0 10px 30px rgba(0,0,0,.35);
  --font-head:     'Poppins', system-ui, sans-serif;
  --font-body:     'Inter', system-ui, sans-serif;
}

*,*::before,*::after{ box-sizing:border-box; }
html{ scroll-behavior:smooth; }
body{
  margin:0;
  background:
    radial-gradient(1100px 600px at 85% -10%, rgba(24,227,172,.08), transparent 60%),
    radial-gradient(900px 500px at -10% 20%, rgba(16,179,196,.07), transparent 55%),
    var(--bg);
  color:var(--text);
  font-family:var(--font-body);
  line-height:1.6;
  min-height:100vh;
  display:flex;
  flex-direction:column;
}
main{ flex:1; }
img{ max-width:100%; display:block; }
a{ color:inherit; text-decoration:none; }
h1,h2,h3,h4{ font-family:var(--font-head); margin:0 0 .5em; line-height:1.2; }
p{ margin:0 0 1em; color:var(--text-dim); }
ul{ margin:0; padding:0; list-style:none; }
.container{ max-width:var(--maxw); margin:0 auto; padding:0 24px; }

/* ---------- Header ---------- */
.site-header{
  position:sticky; top:0; z-index:50;
  background:rgba(8,20,32,.85);
  backdrop-filter:blur(10px);
  border-bottom:1px solid var(--border-soft);
}
.site-header .container{
  display:flex; align-items:center; justify-content:space-between;
  gap:16px; padding-top:14px; padding-bottom:14px;
}
.brand{ display:flex; align-items:center; gap:12px; }
.brand-logo{ width:38px; height:38px; flex:none; }
.brand-text{ display:flex; flex-direction:column; line-height:1.05; }
.brand-text .p{ font-size:.62rem; letter-spacing:.28em; color:var(--text-faint); font-weight:600; }
.brand-text .m{ font-family:var(--font-head); font-weight:800; font-size:1.15rem; letter-spacing:.02em; }

.main-nav{ display:flex; align-items:center; gap:6px; flex-wrap:wrap; }
.main-nav a{
  font-size:.9rem; font-weight:600; color:var(--text-dim);
  padding:8px 14px; border-radius:999px; transition:.15s;
  white-space:nowrap;
}
.main-nav a:hover{ color:var(--text); background:var(--teal-soft); }
.main-nav a.active{ color:var(--bg); background:var(--teal); }

.nav-toggle{
  display:none; background:none; border:1px solid var(--border); color:var(--text);
  border-radius:8px; padding:8px 10px; font-size:1.1rem; cursor:pointer;
}

/* ---------- Hero ---------- */
.hero{ padding:64px 0 40px; text-align:center; }
.hero .eyebrow{
  display:inline-block; font-size:.78rem; font-weight:700; letter-spacing:.18em;
  color:var(--teal); text-transform:uppercase; margin-bottom:14px;
}
.hero h1{ font-size:clamp(1.9rem,4vw,3rem); font-weight:800; }
.hero h1 span{ background:linear-gradient(120deg,var(--teal),var(--teal-2)); -webkit-background-clip:text; background-clip:text; color:transparent; }
.hero p.lead{ font-size:1.05rem; max-width:620px; margin:0 auto 8px; }
.hero .tagline{ font-style:italic; color:var(--teal); font-weight:600; margin-top:8px; }

/* ---------- Buttons ---------- */
.btn{
  display:inline-flex; align-items:center; gap:8px; font-weight:700; font-size:.92rem;
  padding:12px 22px; border-radius:999px; border:1px solid transparent; cursor:pointer;
  transition:.15s; font-family:var(--font-body);
}
.btn-primary{ background:linear-gradient(120deg,var(--teal),var(--teal-2)); color:#04231b; }
.btn-primary:hover{ filter:brightness(1.08); transform:translateY(-1px); }
.btn-outline{ border-color:var(--border); color:var(--text); background:transparent; }
.btn-outline:hover{ border-color:var(--teal); color:var(--teal); }

/* ---------- Card grid (section hubs) ---------- */
.grid{ display:grid; grid-template-columns:repeat(auto-fit,minmax(240px,1fr)); gap:22px; margin:36px 0; }
.card{
  background:var(--card); border:1px solid var(--border); border-radius:var(--radius);
  padding:26px; transition:.18s; display:flex; flex-direction:column; height:100%;
}
.card:hover{ border-color:var(--teal); background:var(--card-hover); transform:translateY(-2px); }
.card .icon{ font-size:1.8rem; margin-bottom:12px; }
.card h3{ font-size:1.1rem; }
.card p{ flex:1; font-size:.92rem; }
.card .go{ font-size:.85rem; font-weight:700; color:var(--teal); }

/* ---------- Content list cards (videos, files, blog...) ---------- */
.item-grid{ display:grid; grid-template-columns:repeat(auto-fit,minmax(280px,1fr)); gap:22px; }
.item-card{
  background:var(--card); border:1px solid var(--border); border-radius:var(--radius);
  overflow:hidden; display:flex; flex-direction:column;
}
.item-card .thumb{
  aspect-ratio:16/9; background:var(--bg-alt); position:relative; overflow:hidden;
}
.item-card .thumb iframe{ width:100%; height:100%; border:0; }
.item-card .body{ padding:18px 20px 20px; display:flex; flex-direction:column; gap:8px; flex:1; }
.item-card .tag{
  align-self:flex-start; font-size:.7rem; font-weight:700; letter-spacing:.05em; text-transform:uppercase;
  color:var(--teal); background:var(--teal-soft); padding:4px 10px; border-radius:999px;
}
.item-card h3{ font-size:1.02rem; margin:0; }
.item-card .meta{ font-size:.78rem; color:var(--text-faint); }
.item-card .actions{ margin-top:auto; padding-top:6px; }

/* ---------- Empty state ---------- */
.empty-state{
  text-align:center; padding:60px 24px; border:1px dashed var(--border); border-radius:var(--radius);
  color:var(--text-faint);
}
.empty-state .icon{ font-size:2.2rem; margin-bottom:10px; }
.empty-state-sm{
  text-align:center; padding:28px 20px; border:1px dashed var(--border); border-radius:var(--radius-sm);
  color:var(--text-faint); font-size:.88rem;
}
.empty-state-sm .icon{ font-size:1.5rem; margin-bottom:6px; }

/* ---------- Seções por série (Física) ---------- */
.serie-section{ margin-bottom:44px; }
.serie-section:last-child{ margin-bottom:0; }
.serie-title{
  font-size:1.05rem; font-weight:700; color:var(--teal);
  border-bottom:1px solid var(--border-soft); padding-bottom:10px; margin-bottom:20px;
}
.tema-group{ margin-bottom:28px; }
.tema-group:last-child{ margin-bottom:0; }
.tema-title{
  font-size:.85rem; font-weight:700; color:var(--text-dim);
  text-transform:uppercase; letter-spacing:.05em; margin-bottom:14px;
}

/* ---------- Footer ---------- */
.site-footer{ border-top:1px solid var(--border-soft); margin-top:60px; padding:40px 0 28px; }
.footer-grid{ display:flex; justify-content:space-between; align-items:center; flex-wrap:wrap; gap:20px; }
.footer-brand{ display:flex; align-items:center; gap:10px; }
.footer-brand .brand-logo{ width:28px; height:28px; }
.footer-brand span{ font-family:var(--font-head); font-weight:700; }
.social-links{ display:flex; gap:12px; }
.social-links a{
  width:40px; height:40px; border-radius:50%; border:1px solid var(--border);
  display:flex; align-items:center; justify-content:center; transition:.15s;
}
.social-links a:hover{ border-color:var(--teal); background:var(--teal-soft); }
.social-links svg{ width:18px; height:18px; fill:var(--text-dim); }
.social-links a:hover svg{ fill:var(--teal); }
.footer-copy{ text-align:center; color:var(--text-faint); font-size:.8rem; margin-top:24px; }

/* ---------- Responsive nav ---------- */
@media (max-width:900px){
  .nav-toggle{ display:inline-flex; }
  .main-nav{
    position:absolute; top:100%; left:0; right:0; background:var(--bg-alt);
    border-bottom:1px solid var(--border-soft); flex-direction:column; align-items:stretch;
    padding:10px 16px; display:none;
  }
  .main-nav.open{ display:flex; }
  .main-nav a{ padding:12px 10px; border-radius:8px; }
  .site-header .container{ position:relative; flex-wrap:wrap; }
}