:root {
    --ink: #101828;
    --muted: #5f6475;
    --blue: #004aad;
    --blue-dark: #082d73;
    --lavender: #e9ddff;
    --lavender-2: #f6f0ff;
    --violet: #7b61d1;
    --gold: #f4bd4f;
    --paper: #ffffff;
    --line: #ded8ee;
    --shadow: 0 18px 45px rgba(24, 35, 84, .12);
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    color: var(--ink);
    background:
        radial-gradient(circle at top left, rgba(233,221,255,.95), transparent 32rem),
        radial-gradient(circle at top right, rgba(198,217,255,.75), transparent 30rem),
        linear-gradient(180deg, #fbf8ff 0%, #f7f9ff 48%, #ffffff 100%);
    line-height: 1.65;
}

header {
    position: relative;
    overflow: hidden;
    padding: 2rem max(1.25rem, 5vw) 1rem;
    color: var(--blue-dark);
}

header::before {
    content: "∇  Δ  ∂  Σ  λ";
    position: absolute;
    inset: 0 0 auto auto;
    transform: translate(3rem, -2rem);
    font-family: Georgia, serif;
    font-size: clamp(4rem, 12vw, 10rem);
    color: rgba(0, 74, 173, .07);
    pointer-events: none;
}

h1 {
    max-width: 1050px;
    margin: 0 auto 1.25rem;
    font-family: Georgia, "Times New Roman", serif;
    font-size: clamp(2.4rem, 7vw, 5.4rem);
    line-height: .95;
    letter-spacing: -.04em;
    color: var(--blue);
}

nav {
    max-width: 1050px;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    gap: .55rem;
    padding: .55rem;
    border: 1px solid rgba(123, 97, 209, .22);
    border-radius: 999px;
    background: rgba(255, 255, 255, .72);
    backdrop-filter: blur(12px);
    box-shadow: 0 10px 30px rgba(0, 74, 173, .08);
}

nav a {
    color: var(--blue-dark);
    padding: .72rem 1rem;
    border-radius: 999px;
    text-decoration: none;
    font-weight: 750;
    transition: transform .18s ease, background .18s ease, color .18s ease;
}

nav a:hover,
nav a.active {
    background: var(--blue);
    color: #fff;
    transform: translateY(-1px);
}

main {
    width: min(1050px, calc(100% - 2rem));
    margin: 1.4rem auto 3rem;
}

section,
.content-card {
    margin-bottom: 1.4rem;
    padding: clamp(1.25rem, 3vw, 2.2rem);
    background: rgba(255,255,255,.88);
    border: 1px solid rgba(123, 97, 209, .18);
    border-radius: 28px;
    box-shadow: var(--shadow);
}

.hero-panel {
    display: grid;
    grid-template-columns: minmax(0, 1.15fr) minmax(280px, .85fr);
    gap: 1.5rem;
    align-items: center;
    background: linear-gradient(135deg, #ffffff 0%, var(--lavender-2) 100%);
}

.hero-panel img,
.math-card img {
    width: 100%;
    display: block;
    border-radius: 22px;
    box-shadow: 0 15px 35px rgba(0, 74, 173, .12);
}

.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: .45rem;
    margin: 0 0 .75rem;
    padding: .3rem .75rem;
    border-radius: 999px;
    background: var(--lavender);
    color: var(--blue-dark);
    font-size: .84rem;
    font-weight: 800;
    letter-spacing: .04em;
    text-transform: uppercase;
}

h2 {
    margin: 0 0 .85rem;
    font-family: Georgia, "Times New Roman", serif;
    font-size: clamp(1.85rem, 3vw, 2.6rem);
    line-height: 1.1;
    color: var(--blue-dark);
}

h3 {
    margin: 1.5rem 0 .75rem;
    color: var(--blue-dark);
    font-size: 1.1rem;
}

p { margin: 0 0 1rem; }
a { color: var(--blue); }

.math-grid,
.organizer-grid,
.info-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1rem;
}

.math-card,
.organizer-card,
.info-card {
    padding: 1rem;
    border-radius: 22px;
    background: linear-gradient(180deg, #fff, #fbf8ff);
    border: 1px solid var(--line);
}

.math-card h3,
.organizer-card h3,
.info-card h3 { margin-top: .25rem; }

ul { padding-left: 1.25rem; }
li + li { margin-top: .35rem; }

table {
    width: 100%;
    border-collapse: collapse;
    overflow: hidden;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: #fff;
}

th, td {
    padding: .95rem 1rem;
    border-bottom: 1px solid var(--line);
    text-align: left;
    vertical-align: top;
}

th {
    background: var(--blue-dark);
    color: #fff;
    font-size: .9rem;
    text-transform: uppercase;
    letter-spacing: .04em;
}

tr:nth-child(even) td { background: #faf7ff; }
tr:last-child td { border-bottom: 0; }

a.button,
button,
form button {
    display: inline-block;
    border: 0;
    border-radius: 999px;
    padding: .8rem 1.25rem;
    background: var(--blue);
    color: #fff;
    font-weight: 800;
    text-decoration: none;
    cursor: pointer;
}

a.button:hover,
button:hover,
form button:hover { background: var(--blue-dark); }

form label { display: block; margin-top: 1rem; font-weight: 700; }
form input,
form textarea {
    width: 100%;
    padding: .75rem .85rem;
    margin-top: .35rem;
    border-radius: 14px;
    border: 1px solid var(--line);
    font-size: 1rem;
}

iframe {
    border-radius: 22px;
    border: 1px solid var(--line) !important;
    box-shadow: var(--shadow);
}

alert, .highlight {
    color: var(--blue-dark);
    font-weight: 850;
}

footer {
    margin-top: 3rem;
    min-height: 170px;
    background-image: url("images/SpinM-Logo.png");
    background-size: auto 82%;
    background-position: center;
    background-repeat: no-repeat;
    opacity: .18;
}

@media (max-width: 850px) {
    .hero-panel,
    .math-grid,
    .organizer-grid,
    .info-grid { grid-template-columns: 1fr; }
    nav { border-radius: 24px; }
}

@media (max-width: 600px) {
    header { padding-top: 1.25rem; }
    nav { align-items: stretch; }
    nav a { flex: 1 1 100%; text-align: center; }
    th, td { padding: .75rem; }
}