/* ========== 阶乘计算器 factorial-calculator ========== */

.fc-textarea {
    width: 100%;
    min-height: 84px;
    padding: 12px 14px;
    border: 1.5px solid var(--c-border);
    border-radius: 10px;
    background: var(--c-bg);
    color: var(--c-text);
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 18px;
    line-height: 1.6;
    resize: vertical;
    transition: border-color .15s, box-shadow .15s;
}
.fc-textarea:focus {
    outline: none;
    border-color: var(--c-primary);
    box-shadow: 0 0 0 3px color-mix(in srgb, var(--c-primary) 18%, transparent);
}

.fc-btn-row {
    display: flex;
    gap: 10px;
    margin-top: 10px;
}

.fc-error {
    margin-bottom: 14px;
    padding: 10px 14px;
    border-radius: 10px;
    background: #fdecef;
    border: 1px solid #f3c2cf;
    color: #c0396b;
    font-size: 14px;
}

/* ---------- 结果卡片 ---------- */
.fc-result { display: flex; flex-direction: column; gap: 14px; }

.fc-card {
    border: 1px solid var(--c-border);
    border-radius: 14px;
    background: var(--c-card-bg, #fff);
    padding: 18px;
    box-shadow: 0 2px 10px rgba(30, 41, 59, .05);
}

.fc-card-head {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-wrap: wrap;
    margin-bottom: 12px;
}
.fc-n-label {
    font-size: 20px;
    font-weight: 800;
    color: var(--c-primary);
    font-variant-numeric: tabular-nums;
}
.fc-tags { display: flex; gap: 6px; flex-wrap: wrap; flex: 1; }
.fc-tag {
    font-size: 12px;
    padding: 2px 9px;
    border-radius: 999px;
    background: #eef2ff;
    color: #4f46e5;
    white-space: nowrap;
}
.fc-tag-edge { background: #f1f5f9; color: #64748b; }
.fc-tag-zero { background: #e7f8ee; color: #16a34a; }
.fc-tag-big { background: #f3eefe; color: #7c5ad6; }

.fc-copy-one {
    border: 1px solid var(--c-border);
    background: var(--c-bg);
    color: var(--c-text-sub);
    border-radius: 8px;
    padding: 4px 10px;
    font-size: 12.5px;
    cursor: pointer;
    transition: all .15s;
}
.fc-copy-one:hover { border-color: var(--c-primary); color: var(--c-primary); }
.fc-copy-one.copied { border-color: #16a34a; color: #16a34a; background: #e7f8ee; }

/* ---------- 大数字 ---------- */
.fc-num {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 17px;
    line-height: 1.9;
    word-break: break-all;
    color: #0e7490;
    background: #f0f9fc;
    border: 1px solid #d4edf5;
    border-radius: 10px;
    padding: 12px 14px;
    font-variant-numeric: tabular-nums;
    user-select: all;
}
.fc-num-long { display: flex; flex-direction: column; gap: 8px; }
.fc-seg { word-break: break-all; }
.fc-omit {
    text-align: center;
    font-size: 12.5px;
    color: #b45309;
    background: #fef6e7;
    border-radius: 6px;
    padding: 3px 0;
    user-select: none;
}

/* ---------- 指标 ---------- */
.fc-metrics {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-top: 14px;
}
.fc-metric {
    text-align: center;
    border-radius: 10px;
    background: var(--c-bg-soft, #f6f7fb);
    border: 1px solid var(--c-border);
    padding: 10px 6px;
}
.fc-metric b {
    display: block;
    font-size: 17px;
    color: var(--c-text);
    font-variant-numeric: tabular-nums;
}
.fc-metric span { font-size: 12px; color: var(--c-text-muted); }

/* ---------- 折叠明细 ---------- */
.fc-detail {
    margin-top: 12px;
    border-top: 1px dashed var(--c-border);
    padding-top: 10px;
}
.fc-detail summary {
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    color: var(--c-text-sub);
    list-style: none;
}
.fc-detail summary::before { content: '▸ '; color: var(--c-primary); }
.fc-detail[open] summary::before { content: '▾ '; }
.fc-expr {
    margin-top: 10px;
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 14px;
    line-height: 2;
    color: var(--c-text);
    word-break: break-all;
}
.fc-expr sup { color: #db2777; font-weight: 700; }
.fc-note { font-size: 12.5px; color: var(--c-text-muted); margin: 8px 0 0; }

/* ---------- 黑夜模式 ---------- */
[data-theme="dark"] .fc-error {
    background: rgba(224, 68, 124, .13);
    border-color: rgba(224, 68, 124, .4);
    color: #ff7ab0;
}
[data-theme="dark"] .fc-num {
    background: rgba(14, 116, 144, .14);
    border-color: rgba(14, 116, 144, .4);
    color: #67d4ea;
}
[data-theme="dark"] .fc-omit { background: rgba(180, 83, 9, .18); color: #fbbf24; }
[data-theme="dark"] .fc-tag { background: rgba(79, 70, 229, .2); color: #a5b4fc; }
[data-theme="dark"] .fc-tag-edge { background: rgba(148, 163, 184, .16); color: #cbd5e1; }
[data-theme="dark"] .fc-tag-zero { background: rgba(22, 163, 74, .18); color: #4ede78; }
[data-theme="dark"] .fc-tag-big { background: rgba(124, 90, 214, .2); color: #b7a4f5; }
[data-theme="dark"] .fc-expr sup { color: #f472b6; }

@media (max-width: 620px) {
    .fc-num { font-size: 14.5px; }
    .fc-metrics { grid-template-columns: repeat(2, 1fr); }
    .fc-n-label { font-size: 18px; }
}