/* Study tools — reuses the site's design tokens (see app.css :root). */

.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 16px; }
.tool-card {
    display: block;
    padding: 18px;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius-sm, 8px);
    text-decoration: none;
    color: inherit;
    transition: border-color .15s ease, transform .15s ease;
}
.tool-card:hover { border-color: var(--teal); transform: translateY(-1px); }
.tool-card h3 { margin: 0 0 6px; }
.tool-card p { margin: 0 0 10px; color: var(--ink-soft); font-size: .92rem; }
.tool-card-cta { color: var(--teal-deep); font-weight: 600; font-size: .9rem; }

.tool-hint, .tool-intro p { color: var(--ink-soft); margin: 0 0 16px; }

.tool-panel {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius-sm, 8px);
    padding: 18px;
    max-width: 760px;
}

.tool-table { width: 100%; border-collapse: collapse; }
.tool-table th, .tool-table td { padding: 8px 8px; border-bottom: 1px solid var(--line-soft); text-align: left; }
.tool-table th { color: var(--ink-soft); font-size: .85rem; font-weight: 600; }
.tool-table tr:last-child td { border-bottom: 0; }
.tool-table .w-grade { width: 110px; }
.tool-table .w-credits { width: 110px; }
.tool-table-result td:first-child { color: var(--ink-soft); }
.tool-table-result strong { font-size: 1.05rem; }

.inp {
    width: 100%;
    padding: 8px 10px;
    border: 1px solid var(--line);
    border-radius: 6px;
    background: var(--paper, #fff);
    font: inherit;
    color: inherit;
}
.inp:focus { outline: 2px solid var(--teal); outline-offset: -1px; }
.inp-lg { max-width: 220px; font-size: 1.1rem; }

.tool-field { margin-bottom: 18px; }
.tool-field label { display: block; margin-bottom: 6px; color: var(--ink-soft); font-size: .9rem; }

.tool-actions { display: flex; gap: 8px; margin: 14px 0 4px; flex-wrap: wrap; }
.btn {
    padding: 8px 14px;
    border: 1px solid var(--teal);
    border-radius: 6px;
    background: var(--teal-tint);
    color: var(--teal-deep);
    font: inherit; font-weight: 600;
    cursor: pointer;
}
.btn:hover { background: var(--teal); color: #fff; }
.btn-ghost { background: transparent; border-color: var(--line); color: var(--ink-soft); }
.btn-ghost:hover { background: var(--paper-deep); color: inherit; }
.btn-icon {
    border: 0; background: transparent; cursor: pointer;
    color: var(--ink-faint); font-size: 1.2rem; line-height: 1; padding: 4px 8px;
}
.btn-icon:hover { color: var(--brick); }

.tool-result {
    margin-top: 18px; padding-top: 16px;
    border-top: 1px solid var(--line);
    display: flex; align-items: baseline; justify-content: space-between; gap: 12px; flex-wrap: wrap;
}
.tool-result-label { color: var(--ink-soft); margin-right: 10px; }
.tool-result-value { font-size: 2rem; font-weight: 700; color: var(--teal-deep); }
.tool-result-sub { color: var(--ink-faint); font-size: .9rem; }

@media (max-width: 640px) {
    .tool-table .w-grade, .tool-table .w-credits { width: 84px; }
    .tool-table th, .tool-table td { padding: 6px 4px; }
}

/* Math tool engine: fields laid out in a responsive grid */
.math-fields {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 14px;
    margin-bottom: 6px;
}
.math-fields .tool-field { margin-bottom: 0; }
.math-fields .inp { max-width: none; }
.math-results { margin-top: 18px; border-top: 1px solid var(--line); }
.math-results td { padding: 9px 8px; }
.math-results strong { color: var(--teal-deep); font-size: 1.05rem; }

@media (max-width: 480px) {
    .math-fields { grid-template-columns: 1fr 1fr; }
}