/* ==========================================================
   11 容斥问题计算器 · 靛蓝 + 薄荷
   ----------------------------------------------------------
   版式：首屏左文右求解台，结果区左韦恩图右公式代入
   配色：主色靛蓝 #3454d1，辅色薄荷 #0f9d8a，提示橙 #e8590c
   ========================================================== */

.tsk.iec {
    --tsk-bg: #f2f6fc;
    --tsk-card: #ffffff;
    --tsk-card-2: #f6f9ff;
    --tsk-ink: #1b2740;
    --tsk-sub: #55627d;
    --tsk-faint: #8b97ad;
    --tsk-line: #dfe7f4;
    --tsk-line-2: #edf2fa;
    --tsk-brand: #3454d1;
    --tsk-brand-2: #0f9d8a;
    --tsk-brand-soft: #e8edfd;
    --tsk-brand-ink: #2643b8;
    --tsk-accent: #e8590c;
    --tsk-accent-soft: #fdefe6;
    background:
        radial-gradient(700px 320px at 96% -10%, rgba(15, 157, 138, .10), transparent 62%),
        radial-gradient(520px 280px at -4% 8%, rgba(52, 84, 209, .09), transparent 60%),
        var(--tsk-bg);
}

:root[data-theme="dark"] .tsk.iec {
    --tsk-bg: #0b1120;
    --tsk-card: #141c2e;
    --tsk-card-2: #182136;
    --tsk-ink: #e8edf9;
    --tsk-sub: #a6b2cb;
    --tsk-faint: #78869f;
    --tsk-line: #263149;
    --tsk-line-2: #1e283d;
    --tsk-brand: #7d97ff;
    --tsk-brand-2: #3ad0b6;
    --tsk-brand-soft: rgba(125, 151, 255, .14);
    --tsk-brand-ink: #9db0ff;
    --tsk-accent: #ff9560;
    --tsk-accent-soft: rgba(255, 149, 96, .12);
}

/* ---------- 首屏 ---------- */
.iec-hero {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 394px;
    gap: 30px;
    padding: 30px 0 24px;
    align-items: stretch;
}

.iec-hero-l {
    display: flex;
    flex-direction: column;
}

.iec-hero-l > .tsk-hs {
    flex: 1 1 auto;
}

.iec-hero-l .tsk-h1 b {
    color: var(--tsk-brand-ink);
}

.iec-hero-l .tsk-lead b {
    background: linear-gradient(180deg, transparent 62%, var(--tsk-brand-soft) 62%);
    padding: 0 2px;
}

/* ---------- 求解台 ---------- */
.iec-board {
    background: var(--tsk-card);
    border: 1px solid var(--tsk-line);
    border-radius: 16px;
    box-shadow: var(--tsk-shadow);
    overflow: hidden;
}

.iec-board-hd {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    background: linear-gradient(135deg, var(--tsk-brand), #4a6ae8);
    color: #fff;
}

.iec-board-hd span {
    font-size: 13.5px;
    font-weight: 800;
    letter-spacing: .03em;
}

.iec-board-hd i {
    font-style: normal;
    font: 700 10.5px/1 var(--tsk-num);
    letter-spacing: .1em;
    opacity: .82;
}

.iec-modes {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 6px;
    padding: 12px 14px 0;
}

.iec-mode {
    border: 1.5px solid var(--tsk-line);
    background: var(--tsk-card-2);
    color: var(--tsk-sub);
    font: 700 12.5px/1.4 var(--tsk-font);
    padding: 9px 6px;
    border-radius: 9px;
    cursor: pointer;
    transition: .15s;
}

.iec-mode:hover {
    border-color: var(--tsk-brand);
    color: var(--tsk-brand-ink);
}

.iec-mode.on {
    background: var(--tsk-brand);
    border-color: var(--tsk-brand);
    color: #fff;
    box-shadow: 0 6px 14px rgba(52, 84, 209, .24);
}

:root[data-theme="dark"] .iec-mode.on {
    color: #0b1120;
}

.iec-panel {
    padding: 14px 16px 0;
}

.iec-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 9px 12px;
}

.iec-grid label {
    display: block;
    margin-bottom: 4px;
    font-size: 11.5px;
    font-weight: 700;
    color: var(--tsk-sub);
}

.iec-grid input {
    width: 100%;
    height: 36px;
    padding: 0 10px;
    border: 1.5px solid var(--tsk-line);
    border-radius: 8px;
    background: var(--tsk-card-2);
    color: var(--tsk-ink);
    font: 700 13.5px/34px var(--tsk-num);
    outline: none;
    transition: .15s;
}

.iec-grid input:focus {
    border-color: var(--tsk-brand);
    background: var(--tsk-card);
    box-shadow: 0 0 0 3px var(--tsk-brand-soft);
}

.iec-grid input.bad {
    border-color: var(--tsk-bad);
    box-shadow: 0 0 0 3px var(--tsk-bad-soft);
}

.iec-err {
    margin: 10px 16px 0;
    padding: 8px 11px;
    border-radius: 8px;
    background: var(--tsk-bad-soft);
    color: var(--tsk-bad);
    font-size: 12px;
    line-height: 1.7;
    display: none;
}

.iec-err.show {
    display: block;
}

.iec-acts {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
}

.iec-board .iec-acts {
    padding: 14px 16px 6px;
}

.iec-board .tsk-btn-main {
    flex: 1;
    min-width: 120px;
}

.iec-board-foot {
    padding: 4px 16px 16px;
    font-size: 10.5px;
    line-height: 1.7;
    color: var(--tsk-faint);
}

/* ---------- 结果区 ---------- */
.iec-result {
    margin: 4px 0 26px;
    background: var(--tsk-card);
    border: 1px solid var(--tsk-line);
    border-radius: 16px;
    box-shadow: var(--tsk-shadow);
    padding: 20px 22px 22px;
    animation: iecIn .32s ease both;
}

@keyframes iecIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: none; }
}

.iec-res-hd {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 13px;
}

.iec-res-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
}

.iec-res-card {
    background: var(--tsk-card-2);
    border: 1px solid var(--tsk-line-2);
    border-radius: 11px;
    padding: 14px 16px;
}

.iec-res-card b {
    display: block;
    font: 800 26px/1.15 var(--tsk-num);
    color: var(--tsk-ink);
    font-variant-numeric: tabular-nums;
}

.iec-res-card span {
    display: block;
    margin-top: 4px;
    font-size: 11.5px;
    font-weight: 700;
    color: var(--tsk-faint);
}

.iec-res-card i {
    display: block;
    margin-top: 3px;
    font-style: normal;
    font-size: 10.5px;
    color: var(--tsk-sub);
}

.iec-res-card.iec-main {
    background: var(--tsk-brand-soft);
    border-color: rgba(52, 84, 209, .26);
}

.iec-res-card.iec-main b {
    color: var(--tsk-brand-ink);
}

.iec-res-card.iec-none {
    background: var(--tsk-accent-soft);
    border-color: rgba(232, 89, 12, .2);
}

.iec-res-card.iec-none b {
    color: var(--tsk-accent);
}

.iec-res-body {
    display: grid;
    grid-template-columns: 320px minmax(0, 1fr);
    gap: 18px;
    margin-top: 16px;
    align-items: start;
}

.iec-venn-wrap {
    background: var(--tsk-card-2);
    border: 1px solid var(--tsk-line);
    border-radius: 12px;
    padding: 12px 10px 8px;
}

.iec-venn {
    width: 100%;
    height: auto;
    display: block;
}

.iec-circle {
    fill: var(--tsk-brand);
    fill-opacity: .09;
    stroke: var(--tsk-brand);
    stroke-width: 1.6;
}

.iec-circle.a {
    fill: rgba(52, 84, 209, .10);
}

.iec-circle.b {
    fill: rgba(15, 157, 138, .12);
    stroke: var(--tsk-brand-2);
}

.iec-circle.c {
    fill: rgba(232, 89, 12, .10);
    stroke: var(--tsk-accent);
}

.iec-vt {
    font: 800 13px/1 var(--tsk-num);
    fill: var(--tsk-ink);
    text-anchor: middle;
    dominant-baseline: middle;
}

.iec-vt-abc {
    fill: var(--tsk-accent);
}

.iec-vl {
    font: 800 12px/1 var(--tsk-font);
    fill: var(--tsk-faint);
    text-anchor: middle;
}

.iec-venn-cap {
    margin: 6px 4px 0;
    font-size: 10.5px;
    color: var(--tsk-faint);
    text-align: center;
    line-height: 1.6;
}

.iec-steps-wrap {
    min-width: 0;
}

.iec-table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 8px;
    border: 1px solid var(--tsk-line);
    border-radius: 10px;
    overflow: hidden;
    display: table;
}

.iec-table th,
.iec-table td {
    padding: 8px 11px;
    font-size: 11.5px;
    line-height: 1.6;
    text-align: left;
    border-bottom: 1px solid var(--tsk-line-2);
    vertical-align: top;
}

.iec-table thead th {
    background: var(--tsk-card-2);
    font-size: 10.5px;
    font-weight: 800;
    color: var(--tsk-brand-ink);
    letter-spacing: .04em;
}

.iec-table tbody tr:last-child td {
    border-bottom: 0;
}

.iec-table td:last-child {
    font-family: var(--tsk-num);
    font-weight: 800;
    color: var(--tsk-brand-ink);
    white-space: nowrap;
}

.iec-note {
    margin-top: 10px;
    padding: 11px 13px;
    border-radius: 9px;
    background: var(--tsk-brand-soft);
    border-left: 3px solid var(--tsk-brand);
    font-size: 12px;
    line-height: 1.8;
    color: var(--tsk-sub);
}

.iec-note.warn {
    background: var(--tsk-accent-soft);
    border-left-color: var(--tsk-accent);
}

.iec-note b {
    color: var(--tsk-brand-ink);
}

/* ---------- 公式卡 ---------- */
.iec-formula-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(268px, 1fr));
    gap: 11px;
}

.iec-formula {
    background: var(--tsk-card);
    border: 1px solid var(--tsk-line);
    border-radius: 12px;
    padding: 17px 18px;
    box-shadow: var(--tsk-shadow-sm);
}

.iec-f-tag {
    display: inline-block;
    padding: 2px 9px;
    border-radius: 99px;
    background: var(--tsk-brand-soft);
    color: var(--tsk-brand-ink);
    font: 800 10.5px/1.7 var(--tsk-num);
    letter-spacing: .04em;
}

.iec-formula h3 {
    margin: 9px 0 0;
    font: 800 15px/1.6 var(--tsk-num);
    color: var(--tsk-ink);
    letter-spacing: .01em;
}

.iec-formula p {
    margin: 7px 0 0;
    font-size: 12px;
    line-height: 1.8;
    color: var(--tsk-sub);
}

/* ---------- 变式练习 ---------- */
.iec-variant {
    background: var(--tsk-card);
    border: 1.5px dashed var(--tsk-line);
    border-radius: 14px;
    padding: 18px 20px;
}

.iec-v-q {
    margin: 0 0 12px;
    font-size: 13.5px;
    line-height: 1.9;
    color: var(--tsk-ink);
    font-weight: 600;
}

.iec-v-q em {
    font-style: normal;
    color: var(--tsk-brand-ink);
    font-weight: 800;
}

.iec-v-ans {
    margin-top: 12px;
    padding: 12px 14px;
    border-radius: 9px;
    background: var(--tsk-card-2);
    border-left: 3px solid var(--tsk-brand-2);
    font-size: 12.5px;
    line-height: 1.85;
    color: var(--tsk-sub);
    white-space: pre-line;
}

.iec-v-ans b {
    color: var(--tsk-brand-ink);
}

/* ---------- 原理 ---------- */
.iec-why {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 10px;
}

.iec-why-item {
    padding: 15px 17px;
    background: var(--tsk-card);
    border: 1px solid var(--tsk-line);
    border-radius: 11px;
}

.iec-why-item b {
    display: block;
    font-size: 13px;
    color: var(--tsk-ink);
}

.iec-why-item p {
    margin: 5px 0 0;
    font-size: 12px;
    line-height: 1.8;
    color: var(--tsk-sub);
}

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
    .iec-hero {
        grid-template-columns: 1fr;
        gap: 22px;
    }
    .iec-res-body {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 560px) {
    .iec-grid {
        grid-template-columns: 1fr 1fr;
    }
    .iec-mode {
        font-size: 11.5px;
        padding: 8px 3px;
    }
    .iec-res-card b {
        font-size: 22px;
    }
}

/* ---------- 打印 ---------- */
@media print {
    .iec-board,
    .iec-acts,
    .iec-variant,
    .iec-hero,
    .tsk-crumb-bar,
    .tskb-tabs,
    .tskb-related {
        display: none !important;
    }
    .iec-result {
        box-shadow: none;
        border-color: #bbb;
    }
    .iec-table th,
    .iec-table td {
        border-color: #ccc;
    }
}