.formulas-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem 4rem 1.5rem;
}

.vault-hero {
    text-align: center;
    margin-bottom: 2.5rem;
}

.vault-hero h1 {
    font-size: clamp(2rem, 6vw, 3.2rem);
    margin-bottom: 0.5rem;
}

.nav-btn-group {
    display: flex;
    gap: 10px;
}

.btn.small {
    padding: 8px 16px;
    font-size: 0.85rem;
}

/* Search Box */
.search-box-wrap {
    max-width: 620px;
    margin: 1.5rem auto 0 auto;
    position: relative;
    display: flex;
    align-items: center;
}

.search-box-wrap svg {
    position: absolute;
    left: 18px;
    color: var(--text-muted);
}

#formula-search-input {
    width: 100%;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border-light);
    border-radius: 999px;
    padding: 14px 90px 14px 50px;
    color: white;
    font-family: inherit;
    font-size: 1rem;
    backdrop-filter: blur(12px);
    transition: all 0.2s;
}

#formula-search-input:focus {
    outline: none;
    border-color: var(--cyan);
    box-shadow: 0 0 25px rgba(0, 229, 255, 0.25);
    background: rgba(0, 0, 0, 0.4);
}

.search-shortcut {
    position: absolute;
    right: 14px;
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid var(--border-light);
    border-radius: 6px;
    padding: 3px 8px;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--text-muted);
}

/* Category Filters */
.categories-bar {
    display: flex;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.cat-pill {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-light);
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.85rem;
    padding: 8px 16px;
    border-radius: 999px;
    cursor: pointer;
    transition: all 0.2s;
}

.cat-pill:hover {
    background: rgba(255, 255, 255, 0.08);
    color: white;
}

.cat-pill.active {
    background: rgba(0, 229, 255, 0.15);
    border-color: var(--cyan);
    color: var(--cyan);
}

/* Formulas Grid */
.formulas-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 20px;
}

.formula-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-light);
    border-radius: 18px;
    padding: 22px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    backdrop-filter: blur(14px);
    transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.formula-card:hover {
    transform: translateY(-2px);
    border-color: rgba(255, 255, 255, 0.2);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.card-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 14px;
}

.card-top h3 {
    font-size: 1.15rem;
    margin-bottom: 4px;
    color: var(--text-primary);
}

.subject-badge {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    padding: 3px 10px;
    border-radius: 999px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Subject Colors */
.subject-math { background: rgba(0, 229, 255, 0.15); color: var(--cyan); border: 1px solid rgba(0, 229, 255, 0.3); }
.subject-algo { background: rgba(16, 185, 129, 0.15); color: var(--emerald); border: 1px solid rgba(16, 185, 129, 0.3); }
.subject-os { background: rgba(179, 136, 255, 0.15); color: var(--purple); border: 1px solid rgba(179, 136, 255, 0.3); }
.subject-cn { background: rgba(245, 158, 11, 0.15); color: #f59e0b; border: 1px solid rgba(245, 158, 11, 0.3); }
.subject-toc { background: rgba(59, 130, 246, 0.15); color: #60a5fa; border: 1px solid rgba(59, 130, 246, 0.3); }
.subject-dbms { background: rgba(236, 72, 153, 0.15); color: #f472b6; border: 1px solid rgba(236, 72, 153, 0.3); }

/* Math Box */
.math-box {
    background: rgba(0, 0, 0, 0.35);
    border: 1px solid var(--border-light);
    border-radius: 12px;
    padding: 16px;
    margin-bottom: 14px;
    text-align: center;
    overflow-x: auto;
    font-size: 1.1rem;
    color: #ffffff;
}

.formula-notes {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.5;
    margin-bottom: 16px;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
    padding-top: 12px;
}

.card-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 0.8rem;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: color 0.15s;
}

.card-btn:hover {
    color: var(--text-primary);
}

.star-btn {
    font-size: 1.1rem;
    color: var(--text-muted);
}

.star-btn.starred {
    color: #facc15;
}

/* Modal */
.modal-overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
}

.modal-card {
    background: #11141c;
    border: 1px solid var(--border-light);
    border-radius: 20px;
    padding: 2rem;
    width: 100%;
    max-width: 460px;
}

.modal-card h3 {
    margin-bottom: 4px;
}

.modal-card p {
    font-size: 0.85rem;
    margin-bottom: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
    margin-bottom: 16px;
}

.form-group label {
    font-size: 0.85rem;
    font-weight: 600;
}

.text-input {
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--border-light);
    border-radius: 10px;
    padding: 10px 12px;
    color: white;
    font-family: inherit;
    font-size: 0.95rem;
}

.text-input:focus {
    outline: none;
    border-color: var(--cyan);
}

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
    margin-top: 20px;
}

/* Print Only Styles */
.print-header {
    display: none;
}

@media print {
    body {
        background: #ffffff !important;
        color: #000000 !important;
    }
    .no-print, .glow-orb, .card-footer {
        display: none !important;
    }
    .print-header {
        display: block !important;
        text-align: center;
        margin-bottom: 24px;
        color: #000;
    }
    .formulas-grid {
        display: block !important;
        column-count: 2;
        column-gap: 20px;
    }
    .formula-card {
        background: #ffffff !important;
        border: 1px solid #cccccc !important;
        color: #000000 !important;
        break-inside: avoid;
        margin-bottom: 16px;
        box-shadow: none !important;
        padding: 14px;
    }
    .card-top h3 {
        color: #000000 !important;
        font-size: 1rem;
    }
    .math-box {
        background: #f8f8f8 !important;
        border: 1px solid #eeeeee !important;
        color: #000000 !important;
        font-size: 0.95rem;
        padding: 8px;
    }
    .formula-notes {
        color: #444444 !important;
        font-size: 0.8rem;
    }
}

/* Mobile Responsiveness */
@media (max-width: 650px) {
    .formulas-container {
        padding: 0 1rem 3rem 1rem;
    }
    .formulas-grid {
        grid-template-columns: 1fr;
    }
    .categories-bar {
        gap: 6px;
    }
    .cat-pill {
        padding: 6px 12px;
        font-size: 0.8rem;
    }
    .search-shortcut {
        display: none;
    }
    #formula-search-input {
        padding-right: 20px;
    }
}