:root {
    --sky: #38bdf8;
    --green: #16a34a;
}

* {
    box-sizing: border-box;
    text-decoration: none;
}

.footer .footer-col a{
    color: #fff;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: Inter, system-ui, Segoe UI, Arial;
    color: #eef2ff;
    background: linear-gradient(180deg, #0a0f1d 0%, #0e1831 50%, #0a0f1d 100%);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 16px;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    backdrop-filter: saturate(150%) blur(10px);
    background: rgba(10, 15, 29, .5);
    border-bottom: 1px solid rgba(255, 255, 255, .06);
}

.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    color: #fff;
    text-decoration: none;
    font-weight: 700;
}

.nav {
    display: flex;
    gap: 20px;
}

.nav a {
    color: #e5e7eb;
    text-decoration: none;
    font-weight: 500;
    padding: 6px 8px;
    border-radius: 10px;
}

.nav a:hover {
    background: rgba(255, 255, 255, .07);
    color: #fff;
}

.nav-toggle {
    display: none;
    background: none;
    border: 1px solid rgba(255, 255, 255, .15);
    color: #fff;
    padding: 6px 10px;
    border-radius: 8px;
}

.hero {
    position: relative;
    min-height: 78vh;
    display: grid;
    place-items: center;
    overflow: hidden;
}

#scene {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
}

.hero-overlay {
    position: relative;
    z-index: 1;
    text-align: center;
}

.hero-overlay h1 {
    font-size: clamp(28px, 5vw, 48px);
    line-height: 1.1;
    margin: 0;
}

.hero-overlay h1 span {
    color: var(--sky);
}

.hero-overlay p {
    color: #c7d2fe;
    margin-top: 8px;
}

.search {
    margin: 18px auto 0;
    display: flex;
    gap: 8px;
    max-width: 620px;
    background: rgba(255, 255, 255, .08);
    padding: 8px;
    border-radius: 14px;
    border: 1px solid rgba(255, 255, 255, .1);
}

.search input {
    flex: 1;
    padding: 12px 14px;
    background: transparent;
    border: none;
    outline: none;
   color: #fff;
}

.search button {
    padding: 12px 16px;
    background: var(--sky);
    border: none;
    color: #001122;
    font-weight: 700;
    border-radius: 10px;
    cursor: pointer;
    box-shadow: 0 8px 20px rgba(56, 189, 248, .35);
}

.hero-quick {
    margin-top: 14px;
    display: flex;
    gap: 10px;
    justify-content: center;
}

.btn {
    padding: 10px 14px;
    border-radius: 10px;
    border: 1px solid rgba(255, 255, 255, .15);
    color: #e5e7eb;
    text-decoration: none;
    backdrop-filter: blur(6px);
}

.btn.primary {
    background: var(--green);
    border-color: transparent;
    color: #04120a;
}

.section {
    padding: 64px 0;
}

.section-title {
    font-size: clamp(22px, 3vw, 32px);
    margin: 0 0 22px 0;
}

.grid {
    display: grid;
    gap: 14px;
}

.grid-classes {
    grid-template-columns: repeat(6, 1fr);
}

.card {
    background: linear-gradient(180deg, #0b1221, #0a1327);
    border: 1px solid rgba(255, 255, 255, .06);
    border-radius: 16px;
    padding: 16px;
    text-align: center;
    color: #e5e7eb;
    text-decoration: none;
    font-weight: 600;
    box-shadow: inset 0 1px 0 rgba(255, 255, 255, .03), 0 10px 30px rgba(0, 0, 0, .25);
    transform-style: preserve-3d;
    transition: transform .25s, box-shadow .25s;
}

.card:hover {
    box-shadow: 0 18px 40px rgba(56, 189, 248, .1);
}

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

.tile {
    background: linear-gradient(180deg, #0b1221, #0b1428);
    border: 1px solid rgba(255, 255, 255, .06);
    border-radius: 18px;
    padding: 18px;
    text-decoration: none;
    color: #eef2ff;
    display: flex;
    gap: 12px;
    align-items: center;
    box-shadow: 0 10px 30px rgba(0, 0, 0, .25);
    transform-style: preserve-3d;
    transition: transform .25s, box-shadow .25s;
}

.tile-3dicon {
    font-size: 28px;
    filter: drop-shadow(0 6px 12px rgba(56, 189, 248, .35));
}

.footer {
    padding: 40px 0;
    border-top: 1px solid rgba(255, 255, 255, .08);
    background: rgba(10, 15, 29, .5);
    backdrop-filter: blur(6px);
}

.footer-inner {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 18px;
}

.legal {
    margin-top: 18px;
    text-align: center;
    color: #9ca3af;
}

.tilt {
    perspective: 800px;
}

.think-box {
  position: relative;
  background: linear-gradient(180deg, #0b1221, #0a1327);
  border: 1px solid rgba(255, 255, 255, .08);
  border-radius: 14px;
  padding: 24px 20px;
  margin: 20px 0;
}

.think-label {
  position: absolute;
  left: 1.5rem;
  top: -0.8rem;
  background: #0a1327;
  padding: 4px 10px;
  border-radius: 8px;
  color: #38bdf8;
  font-size: 14px;
}

.think-question {
  margin-top: 10px;
  font-size: 16px;
}

.think-answer {
  margin-top: 14px;
}

.think-answer span {
  display: inline-block;
  margin-left: 12px; /* GAP BETWEEN 'Answer:' AND TEXT */
  color: #c7d2fe;
}

/* Chapter images */
.chapter-img {
  width: 100%;
  max-width: 220px;   /* perfect for Class 1 */
  height: auto;
  display: block;
  margin: 12px auto;
  border-radius: 12px;
}

/* Image card container */
.card {
  background: #0f172a;
  padding: 16px;
  border-radius: 14px;
  margin: 20px 0;
  text-align: center;
}

/* Image caption */
.img-caption {
  font-size: 14px;
  color: #cbd5e1;
  margin-top: 8px;
}


@media (max-width: 1100px) {
    .grid-classes {
        grid-template-columns: repeat(4, 1fr);
    }
    .grid-subjects {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 700px) {
    .nav {
        display: none;
    }
    .nav.open {
        display: flex;
        position: absolute;
        top: 64px;
        right: 16px;
        background: #0b1221;
        padding: 10px;
        border-radius: 10px;
        border: 1px solid rgba(255, 255, 255, .1);
        flex-direction: column;
    }
    .nav-toggle {
        display: inline-flex;
    }
    .grid-classes {
        grid-template-columns: repeat(3, 1fr);
    }
    .grid-subjects {
        grid-template-columns: repeat(2, 1fr);
    }
    .footer-inner {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 420px) {
    .grid-classes {
        grid-template-columns: repeat(2, 1fr);
    }
    .grid-subjects {
        grid-template-columns: repeat(2, 1fr);
    }
}