/* ============================================
   Formulas Page Styles
   ============================================ */

/* Hero */
.formulas-hero {
    padding: 140px 0 64px;
    background:
        radial-gradient(ellipse at 20% 20%, rgba(58, 138, 86, 0.08) 0%, transparent 55%),
        radial-gradient(ellipse at 80% 40%, rgba(167, 139, 250, 0.06) 0%, transparent 50%),
        linear-gradient(180deg, rgba(10, 15, 10, 0.4), rgba(10, 15, 10, 0.1));
    border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

.formulas-back {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 24px;
    transition: color 0.3s, gap 0.3s;
}

.formulas-back:hover {
    color: var(--green-400, #3a8a56);
    gap: 12px;
}

.formulas-eyebrow {
    display: inline-block;
    padding: 6px 14px;
    border: 1px solid rgba(58, 138, 86, 0.35);
    background: rgba(58, 138, 86, 0.08);
    border-radius: 100px;
    font-family: var(--font-mono, 'Exo 2', sans-serif);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.14em;
    color: var(--green-400, #3a8a56);
    margin-bottom: 20px;
    text-transform: uppercase;
}

.formulas-title {
    font-family: var(--font-display);
    font-size: clamp(30px, 4.5vw, 52px);
    font-weight: 800;
    line-height: 1.1;
    letter-spacing: -0.02em;
    margin-bottom: 22px;
    max-width: 920px;
}

.formulas-subtitle {
    font-size: clamp(14.5px, 1.3vw, 17px);
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 760px;
    margin-bottom: 32px;
}

/* Table of contents */
.formulas-toc {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
}

.formulas-toc a {
    display: inline-block;
    padding: 8px 14px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 100px;
    font-size: 12.5px;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all 0.25s;
}

.formulas-toc a:hover {
    background: rgba(58, 138, 86, 0.12);
    border-color: rgba(58, 138, 86, 0.4);
    color: var(--green-400, #3a8a56);
    transform: translateY(-1px);
}

/* Section */
.formulas-section {
    padding: 80px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.formulas-section:last-of-type {
    border-bottom: none;
}

.formulas-section-head {
    margin-bottom: 40px;
    max-width: 780px;
}

.formulas-section-head .section-num {
    display: inline-block;
    font-family: var(--font-mono, 'Exo 2', sans-serif);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.16em;
    padding: 4px 10px;
    border: 1px solid rgba(255, 255, 255, 0.12);
    border-radius: 5px;
    color: var(--text-secondary);
    margin-bottom: 14px;
}

.formulas-section-head h2 {
    font-family: var(--font-display);
    font-size: clamp(24px, 3vw, 32px);
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 10px;
    letter-spacing: -0.01em;
}

.formulas-section-head p {
    font-size: 14.5px;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Formula grid */
.formulas-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 18px;
}

.formulas-grid-tight {
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 14px;
}

/* Formula card */
.formula-card {
    --fc-accent: #3a8a56;
    padding: 24px 22px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    transition: all 0.35s var(--ease-out, ease-out);
    position: relative;
    overflow: hidden;
}

.formula-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 3px;
    height: 0;
    background: var(--fc-accent);
    transition: height 0.4s;
}

.formula-card:hover {
    border-color: color-mix(in srgb, var(--fc-accent) 40%, var(--border));
    transform: translateY(-2px);
    box-shadow: 0 18px 44px rgba(0, 0, 0, 0.25);
}

.formula-card:hover::before { height: 100%; }

.formula-card header {
    margin-bottom: 16px;
}

.fc-tag {
    display: inline-block;
    padding: 4px 10px;
    font-family: var(--font-mono, 'Exo 2', sans-serif);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.08em;
    color: var(--fc-accent);
    background: color-mix(in srgb, var(--fc-accent) 12%, transparent);
    border: 1px solid color-mix(in srgb, var(--fc-accent) 35%, transparent);
    border-radius: 5px;
    margin-bottom: 10px;
}

.formula-card h3 {
    font-family: var(--font-display);
    font-size: 16.5px;
    font-weight: 700;
    line-height: 1.3;
    color: var(--text-primary);
}

/* Equation block */
.fc-eq {
    padding: 14px 16px;
    background: rgba(10, 15, 10, 0.5);
    border: 1px solid color-mix(in srgb, var(--fc-accent) 25%, transparent);
    border-radius: 10px;
    margin-bottom: 12px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.fc-eq-sub {
    margin-top: -8px;
    background: rgba(10, 15, 10, 0.3);
    border-color: rgba(255, 255, 255, 0.06);
}

.fc-eq code {
    font-family: var(--font-mono, 'Exo 2', sans-serif);
    font-size: 13.5px;
    font-weight: 500;
    color: #fff;
    letter-spacing: 0.01em;
    white-space: nowrap;
    display: block;
}

.fc-eq-sub code {
    color: var(--text-secondary);
    font-size: 12.5px;
}

.fc-desc {
    font-size: 13.5px;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 12px;
}

.fc-note {
    font-size: 12px;
    color: rgba(255, 255, 255, 0.45);
    line-height: 1.6;
    padding-top: 12px;
    border-top: 1px dashed rgba(255, 255, 255, 0.08);
    font-style: italic;
}

/* Standards block */
.formula-standards {
    margin-top: 36px;
    padding: 28px 28px 24px;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid rgba(255, 255, 255, 0.06);
    border-radius: 16px;
}

.formula-standards + .formula-standards {
    margin-top: 16px;
}

.formula-standards h3 {
    font-family: var(--font-display);
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 18px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 12px;
}

.formula-standards h3::before {
    content: '';
    width: 4px;
    height: 16px;
    background: linear-gradient(180deg, var(--green-400, #3a8a56), transparent);
    border-radius: 2px;
}

.fs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 10px;
}

.fs-item {
    display: flex;
    flex-direction: column;
    gap: 6px;
    padding: 12px 14px;
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.04);
    border-radius: 10px;
}

.fs-label {
    font-size: 11px;
    font-weight: 600;
    color: var(--text-secondary);
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

.fs-item code {
    font-family: var(--font-mono, 'Exo 2', sans-serif);
    font-size: 12.5px;
    color: #fff;
    font-weight: 500;
}

/* Responsive */
@media (max-width: 900px) {
    .formulas-hero { padding: 112px 0 48px; }
    .formulas-section { padding: 56px 0; }
    .formulas-section-head { margin-bottom: 28px; }
    .fs-grid { grid-template-columns: 1fr; }
    .formula-standards { padding: 22px 20px 20px; }
}

@media (max-width: 600px) {
    .formulas-grid, .formulas-grid-tight { grid-template-columns: 1fr; }
    .formulas-title { font-size: 28px; }
    .fc-eq code { font-size: 12px; }
}