/* ================================================================
   PDE Solver Pages — Luis Silvestre
   Shared navigation + page styling
   ================================================================ */

/* ---- Base ---- */

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

body {
  font-family: 'Poppins', system-ui, sans-serif;
  font-size: 15px;
  color: #1e1e1e;
  line-height: 1.6;
  margin: 0;
  padding: 0;
}

a {
  color: #800000;
}

a:hover {
  text-decoration: underline;
}

h3 {
  color: #800000;
  font-size: 1.05rem;
  margin-top: 0;
}

h4 {
  color: #800000;
  font-size: 0.9rem;
  margin: 12px 0 4px;
  padding-bottom: 0;
}

/* ---- Canvas ---- */

canvas {
  border: 1px solid #d0d0d0;
  border-radius: 2px;
}

/* ---- Buttons ---- */

button {
  font-family: 'Poppins', system-ui, sans-serif;
  cursor: pointer;
  background: #800000;
  color: #fff;
  border: none;
  border-radius: 3px;
  padding: 6px 18px;
  transition: background 0.15s;
}

button:hover {
  background: #5c0000;
}

/* ---- Inputs and selects ---- */

input[type="text"],
input[type="number"],
select,
textarea {
  font-family: 'Poppins', system-ui, sans-serif;
  font-size: 0.9rem;
  border: 1px solid #d0d0d0;
  border-radius: 3px;
  padding: 3px 6px;
  background: #fff;
}

input[type="text"]:focus,
select:focus {
  outline: 2px solid #800000;
  outline-offset: 1px;
}

/* ---- Navigation ---- */

.site-nav {
  background: #800000;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.25);
  font-family: 'Poppins', system-ui, sans-serif;
}

.nav-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}

.nav-brand {
  color: #fff;
  font-weight: 600;
  font-size: 1rem;
  padding: 14px 0;
  white-space: nowrap;
  text-decoration: none;
}

.nav-brand:hover {
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-menu a {
  color: rgba(255, 255, 255, 0.9);
  display: block;
  padding: 14px 12px;
  font-size: 0.85rem;
  text-decoration: none;
  transition: background 0.15s;
}

.nav-menu a:hover {
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
}

.nav-toggle {
  display: none;
  background: transparent;
  border: none;
  color: #fff;
  font-size: 1.4rem;
  cursor: pointer;
  padding: 10px;
  line-height: 1;
}

@media (max-width: 680px) {
  .nav-toggle {
    display: block;
  }

  .nav-menu {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: -24px;
    right: -24px;
    background: #5c0000;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
    z-index: 100;
  }

  .nav-menu.is-open {
    display: flex;
  }

  .nav-menu a {
    padding: 13px 24px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
  }
}