/* StudyGuard — page structure: header, hero, sections, grids, footer. */

/* Header ------------------------------------------------------------------ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--white);
  border-bottom: var(--border-hairline);
}

/* Frosted header where the browser can blur, plain white everywhere else. */
@supports ((backdrop-filter: blur(1px)) or (-webkit-backdrop-filter: blur(1px))) {
  .site-header {
    background-color: rgba(255, 255, 255, 0.82);
    -webkit-backdrop-filter: blur(12px) saturate(150%);
    backdrop-filter: blur(12px) saturate(150%);
  }
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  min-height: var(--header-height);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--navy-800);
  text-decoration: none;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  background-color: var(--navy-800);
  color: var(--white);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.04em;
  transition:
    transform var(--duration) var(--ease-out),
    box-shadow var(--duration) var(--ease-out);
}

@media (hover: hover) and (pointer: fine) {
  .brand:hover .brand__mark {
    transform: scale(1.06) rotate(-2deg);
    box-shadow: var(--shadow-md);
  }
}

.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 700;
}

.brand__tagline {
  color: var(--color-text-muted);
  font-size: var(--text-xs);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--space-5);
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  margin: 0;
  padding: 0;
  list-style: none;
}

.site-nav__list a {
  position: relative;
  display: inline-block;
  padding: var(--space-1) 0;
  color: var(--navy-800);
  font-size: var(--text-sm);
  font-weight: 500;
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease-out);
}

/* Underline grows out of the middle instead of switching on abruptly. */
.site-nav__list a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  border-radius: var(--radius-pill);
  background-color: var(--color-accent);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--duration) var(--ease-out);
}

.site-nav__list a:hover {
  color: var(--color-accent-strong);
}

@media (hover: hover) and (pointer: fine) {
  .site-nav__list a:hover::after {
    transform: scaleX(1);
  }
}

.site-nav__list a:focus-visible::after {
  transform: scaleX(1);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-2);
  /* Comfortable thumb target on a phone (at least 44px tall). */
  min-height: 44px;
  padding: var(--space-2) var(--space-4);
  border: var(--border-hairline);
  border-radius: var(--radius-sm);
  background-color: var(--white);
  color: var(--navy-800);
  font-size: var(--text-sm);
  font-weight: 600;
  cursor: pointer;
  transition:
    border-color var(--duration-fast) var(--ease-out),
    background-color var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out);
}

.nav-toggle:active {
  transform: scale(0.97);
}

.nav-toggle[aria-expanded="true"] {
  border-color: var(--navy-700);
  background-color: var(--grey-050);
}

.nav-toggle__bars,
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  display: block;
  width: 16px;
  height: 2px;
  background-color: var(--navy-800);
  transition:
    transform var(--duration) var(--ease-out),
    top var(--duration) var(--ease-out),
    background-color var(--duration-fast) linear;
}

.nav-toggle__bars {
  position: relative;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
}

.nav-toggle__bars::before {
  top: -5px;
}

.nav-toggle__bars::after {
  top: 5px;
}

/* Open menu: the three bars fold into a cross. */
.nav-toggle[aria-expanded="true"] .nav-toggle__bars {
  background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before {
  top: 0;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after {
  top: 0;
  transform: rotate(-45deg);
}

/* Hero -------------------------------------------------------------------- */

.hero {
  position: relative;
  overflow: hidden;
  padding: var(--space-9) 0 var(--space-8);
  background-color: var(--navy-800);
  background-image: linear-gradient(180deg, var(--navy-800), var(--navy-900));
  color: var(--white);
}

/* Two soft pools of light so the navy block does not read as flat paint. */
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    radial-gradient(60% 55% at 12% 0%, rgba(63, 107, 82, 0.4), transparent 60%),
    radial-gradient(45% 45% at 92% 12%, rgba(169, 133, 63, 0.22), transparent 55%);
}

.hero > .container {
  position: relative;
  z-index: 1;
}

.hero h1,
.hero__lead {
  /* Keep the reading line short without narrowing the container, so the hero
     stays flush with the sections below it. */
  max-width: 820px;
}

.hero h1 {
  color: var(--white);
  margin-bottom: var(--space-4);
}

.hero .eyebrow {
  color: var(--green-200);
}

.hero__lead {
  margin-bottom: var(--space-6);
  color: var(--grey-200);
  font-size: var(--text-lg);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-bottom: var(--space-8);
}

.hero__stats {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-7);
  margin: 0;
  padding-top: var(--space-5);
  border-top: 1px solid rgba(255, 255, 255, 0.18);
}

.hero__stat dt {
  color: var(--grey-300);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero__stat dd {
  margin: var(--space-1) 0 0;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: 700;
}

/* Sections ---------------------------------------------------------------- */

.section {
  padding: var(--space-9) 0;
  border-bottom: var(--border-hairline);
}

.section--muted {
  background-color: var(--color-surface-muted);
}

.section--oxbridge {
  background-color: var(--gold-050);
  border-bottom-color: var(--gold-200);
}

.section__head {
  max-width: 760px;
  margin-bottom: var(--space-7);
}

.section__lead {
  color: var(--color-text-muted);
  font-size: var(--text-lg);
}

.split {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-6);
}

.split--wide {
  gap: var(--space-8);
  align-items: start;
}

.grid {
  display: grid;
  gap: var(--space-5);
}

.grid--three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid--cards {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.steps {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-5);
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

/* Footer ------------------------------------------------------------------ */

.site-footer {
  padding: var(--space-8) 0 var(--space-5);
  background-color: var(--navy-900);
  color: var(--grey-200);
  font-size: var(--text-sm);
}

.site-footer__inner {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: var(--space-6);
}

.site-footer a {
  color: var(--white);
  text-decoration: none;
}

.site-footer a:hover {
  color: var(--green-200);
  text-decoration: underline;
}

.site-footer__brand {
  margin-bottom: var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--white);
}

.site-footer__note {
  color: var(--grey-300);
}

.site-footer__nav,
.site-footer__contacts {
  display: grid;
  gap: var(--space-2);
}

.site-footer__legal {
  margin-top: var(--space-7);
  padding-top: var(--space-4);
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--grey-300);
  font-size: var(--text-xs);
}

/* Responsive -------------------------------------------------------------- */

@media (max-width: 1024px) {
  .grid--cards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 860px) {
  .nav-toggle {
    display: flex;
  }

  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: var(--header-height);
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-2);
    padding: var(--space-4) var(--container-gutter) var(--space-5);
    background-color: var(--white);
    border-bottom: var(--border-hairline);
    box-shadow: var(--shadow-lg);
    /* On a short screen (or landscape) the menu scrolls instead of overflowing. */
    max-height: calc(100vh - var(--header-height));
    overflow-y: auto;
  }

  .site-nav.is-open {
    display: flex;
    animation: sg-nav-in var(--duration) var(--ease-out) both;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  /* Full-width rows: easier to hit with a thumb than inline links. */
  .site-nav__list a {
    padding: var(--space-3) var(--space-1);
    border-bottom: var(--border-hairline);
    font-size: var(--text-base);
  }

  .site-nav__list li:last-child a {
    border-bottom: 0;
  }

  .site-nav__list a::after {
    display: none;
  }

  .site-nav .button {
    margin-top: var(--space-3);
    width: 100%;
  }

  .site-header__inner {
    position: relative;
  }

  .split,
  .grid--three,
  .grid--cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .site-footer__inner {
    grid-template-columns: 1fr 1fr;
  }

  .section,
  .hero {
    padding-top: var(--space-8);
    padding-bottom: var(--space-8);
  }
}

@keyframes sg-nav-in {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }

  to {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 620px) {
  :root {
    --container-gutter: var(--space-4);
    --header-height: 62px;
  }

  .split,
  .grid--three,
  .steps,
  .site-footer__inner {
    grid-template-columns: minmax(0, 1fr);
  }

  /*
   * One mentor per row on a phone. The card itself turns into a compact
   * horizontal strip (see .mentor in components.css): a full-width square
   * photo with the text underneath wastes the screen, and two narrow columns
   * squeeze the credentials into three-word lines.
   */
  .grid--cards {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-3);
  }

  /* Figures read as a row of three, not a ragged wrapped line. */
  .hero__stats {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: var(--space-4);
  }

  .brand__tagline {
    display: none;
  }

  .brand__mark {
    width: 36px;
    height: 36px;
  }

  .section,
  .hero {
    padding-top: var(--space-7);
    padding-bottom: var(--space-7);
  }

  .section__head {
    margin-bottom: var(--space-6);
  }

  .hero__actions {
    margin-bottom: var(--space-7);
  }

  /* Both hero buttons side by side, each wide enough to read. */
  .hero__actions .button {
    flex: 1 1 auto;
    min-width: 46%;
  }

  .site-footer__inner {
    gap: var(--space-7);
  }
}

/* Very narrow phones: three figures side by side become too tight. */
@media (max-width: 380px) {
  .hero__stats {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}