/* ===== BASE ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --primary: #4f46e5;
    --primary-dark: #4338ca;
    --secondary: #7c3aed;
    --accent: #0891b2;
    --success: #059669;
    --danger: #dc2626;
    --warning: #d97706;
    --bg: #f1f5ff;
    --bg2: #e8eeff;
    --surface: #ffffff;
    --surface2: #f5f7ff;
    --border: rgba(99,102,241,0.14);
    --border2: rgba(99,102,241,0.25);
    --text: #1e293b;
    --text-muted: #64748b;
    --text-dim: #475569;
    --radius: 14px;
    --shadow: 0 4px 24px rgba(99,102,241,0.10);
    --shadow-lg: 0 8px 48px rgba(99,102,241,0.16);
}

html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
}

.mono { font-family: 'JetBrains Mono', monospace; }

/* ===== BACKGROUND ===== */
.bg-grid {
    position: fixed; inset: 0; z-index: 0;
    background-image:
        linear-gradient(rgba(99,102,241,0.08) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99,102,241,0.08) 1px, transparent 1px);
    background-size: 40px 40px;
    pointer-events: none;
}

.bg-glow {
    position: fixed;
    width: 800px; height: 800px;
    background: radial-gradient(circle, rgba(99,102,241,0.18) 0%, transparent 70%);
    top: -200px; left: 50%; transform: translateX(-50%);
    pointer-events: none; z-index: 0;
}

/* ===== LAYOUT ===== */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; position: relative; z-index: 1; }

/* ===== HEADER ===== */
.header {
    position: sticky; top: 0; z-index: 100;
    background: rgba(255,255,255,0.88);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border2);
    padding: 16px 0;
    box-shadow: 0 2px 16px rgba(99,102,241,0.08);
}

.header .container { display: flex; align-items: center; justify-content: space-between; gap: 16px; }

.logo {
    display: flex; align-items: center; gap: 12px;
    font-size: 1.25rem; letter-spacing: -0.02em; color: var(--text);
    text-decoration: none;
}
.logo strong { color: var(--primary); }

.nav { display: flex; gap: 4px; }
.nav-link {
    padding: 8px 16px; border-radius: 8px;
    color: var(--text-dim); text-decoration: none;
    font-size: 0.875rem; font-weight: 500;
    transition: all 0.2s;
}
.nav-link:hover { background: var(--bg2); color: var(--text); }
.nav-link.active { background: rgba(79,70,229,0.12); color: var(--primary); }
.nav-link.nav-home {
    display: flex; align-items: center; gap: 6px;
    border: 1px solid var(--border2); margin-right: 6px;
}
.nav-link.nav-home:hover { border-color: var(--primary); color: var(--primary); background: rgba(79,70,229,0.08); }

/* ===== MAIN ===== */
.main { padding: 48px 0 80px; }

/* ===== HERO ===== */
.hero { text-align: center; margin-bottom: 48px; }
.hero-title {
    font-size: clamp(2rem, 5vw, 3.25rem);
    font-weight: 700; letter-spacing: -0.03em;
    line-height: 1.1; margin-bottom: 16px;
}
.gradient-text {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 50%, var(--accent) 100%);
    -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.hero-desc { color: var(--text-dim); font-size: 1.1rem; max-width: 560px; margin: 0 auto; }

/* ===== CARD ===== */
.card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
    box-shadow: var(--shadow);
    transition: border-color 0.2s;
}
.card:hover { border-color: var(--border2); }
.card-header {
    display: flex; align-items: center; justify-content: space-between;
    margin-bottom: 24px; padding-bottom: 20px;
    border-bottom: 1px solid var(--border);
}
.card-header h2 { font-size: 1.125rem; font-weight: 600; }

/* ===== FORM ===== */
.calc-card { margin-bottom: 32px; }
.form-grid { display: grid; grid-template-columns: 1fr auto; gap: 16px; margin-bottom: 20px; }
.cidr-group { min-width: 140px; }

.form-label {
    display: flex; align-items: center; gap: 8px;
    font-size: 0.8125rem; font-weight: 500; color: var(--text-dim);
    margin-bottom: 10px; text-transform: uppercase; letter-spacing: 0.06em;
}

.input-wrap { position: relative; }

.form-input {
    width: 100%; padding: 14px 18px;
    background: #fff; border: 1.5px solid var(--border2);
    border-radius: 10px; color: var(--text);
    font-size: 1rem; outline: none;
    transition: all 0.2s;
}
.form-input::placeholder { color: var(--text-muted); }
.form-input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79,70,229,0.15); }
.form-input.is-error { border-color: var(--danger); }
.form-input.has-prefix { padding-left: 36px; }

.input-prefix {
    position: absolute; left: 14px; top: 50%; transform: translateY(-50%);
    color: var(--primary); font-family: 'JetBrains Mono', monospace; font-weight: 600;
    font-size: 1.1rem;
}

.input-hint {
    display: block; margin-top: 6px; font-size: 0.75rem; color: var(--text-muted);
}

.alert {
    display: flex; align-items: center; gap: 10px;
    padding: 14px 18px; border-radius: 10px;
    font-size: 0.875rem; margin-bottom: 20px;
}
.alert-error { background: rgba(220,38,38,0.08); border: 1px solid rgba(220,38,38,0.3); color: #b91c1c; }

.form-actions { display: flex; gap: 12px; }

.btn {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 13px 24px; border-radius: 10px;
    font-size: 0.9375rem; font-weight: 600; cursor: pointer;
    border: none; text-decoration: none; transition: all 0.2s;
}
.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: #fff; box-shadow: 0 4px 16px rgba(99,102,241,0.4);
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 6px 24px rgba(99,102,241,0.5); }
.btn-primary:active { transform: translateY(0); }
.btn-ghost {
    background: transparent; color: var(--text-dim);
    border: 1px solid var(--border2);
}
.btn-ghost:hover { background: var(--surface2); color: var(--text); }

/* ===== RESULTS ===== */
.results-grid {
    display: grid; grid-template-columns: 1fr 360px; gap: 24px;
    margin-bottom: 24px; animation: fadeUp 0.4s ease;
}

@keyframes fadeUp {
    from { opacity: 0; transform: translateY(20px); }
    to   { opacity: 1; transform: translateY(0); }
}

.result-main .info-grid {
    display: grid; grid-template-columns: 1fr 1fr; gap: 1px;
    background: var(--border); border-radius: 10px; overflow: hidden;
}
.info-item {
    background: #fff; padding: 16px 20px;
    transition: background 0.15s;
}
.info-item:hover { background: var(--surface2); }
.info-item.highlight { background: rgba(79,70,229,0.07); }
.info-item.highlight:hover { background: rgba(79,70,229,0.12); }
.info-item.highlight-red { background: rgba(220,38,38,0.06); }
.info-item.highlight-red:hover { background: rgba(220,38,38,0.1); }

.info-label { display: block; font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 6px; }
.info-value { display: block; font-size: 1rem; font-weight: 600; color: var(--text); }
.info-value.copyable { cursor: pointer; transition: color 0.15s; }
.info-value.copyable:hover { color: var(--primary); }
.info-binary { display: block; font-size: 0.7rem; color: var(--text-muted); margin-top: 4px; font-family: 'JetBrains Mono', monospace; }

/* ===== SIDE CARDS ===== */
.side-cards { display: flex; flex-direction: column; gap: 16px; }

.stat-card, .type-card, .binary-card { padding: 22px; }
.stat-title { font-size: 0.8125rem; text-transform: uppercase; letter-spacing: 0.07em; color: var(--text-muted); margin-bottom: 12px; font-weight: 600; }
.stat-value { font-size: 2.5rem; font-weight: 700; color: var(--primary); font-family: 'JetBrains Mono', monospace; line-height: 1; margin-bottom: 4px; }
.stat-sub { font-size: 0.8125rem; color: var(--text-muted); margin-bottom: 16px; }
.stat-divider { height: 1px; background: var(--border); margin: 14px 0; }
.stat-row { display: flex; justify-content: space-between; align-items: center; font-size: 0.875rem; padding: 6px 0; color: var(--text-dim); }
.stat-row strong { color: var(--text); }

.type-badges { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 4px; }
.type-badge {
    padding: 6px 14px; border-radius: 20px; font-size: 0.8125rem; font-weight: 500;
    background: var(--bg2); border: 1.5px solid var(--border2);
    color: var(--text-muted);
}
.type-badge.active { background: rgba(79,70,229,0.12); border-color: rgba(79,70,229,0.45); color: var(--primary); font-weight: 600; }

.repr-row { display: flex; justify-content: space-between; align-items: center; padding: 8px 0; border-bottom: 1px solid var(--border); }
.repr-row:last-child { border: none; }
.repr-label { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; }
.repr-val { font-size: 0.875rem; color: var(--text); }
.repr-val.small { font-size: 0.7rem; word-break: break-all; text-align: right; max-width: 200px; }

/* ===== BADGE ===== */
.badge {
    display: inline-flex; align-items: center; padding: 4px 12px;
    border-radius: 20px; font-size: 0.75rem; font-weight: 600;
    letter-spacing: 0.05em; text-transform: uppercase;
}
.badge-a { background: rgba(5,150,105,0.12); color: #065f46; border: 1px solid rgba(5,150,105,0.35); }
.badge-b { background: rgba(37,99,235,0.12); color: #1d4ed8; border: 1px solid rgba(37,99,235,0.35); }
.badge-c { background: rgba(79,70,229,0.12); color: #4338ca; border: 1px solid rgba(79,70,229,0.35); }
.badge-d { background: rgba(217,119,6,0.12); color: #92400e; border: 1px solid rgba(217,119,6,0.35); }
.badge-e { background: rgba(220,38,38,0.12); color: #991b1b; border: 1px solid rgba(220,38,38,0.35); }
.badge-info { background: rgba(8,145,178,0.12); color: #0e7490; border: 1px solid rgba(8,145,178,0.35); }

/* ===== BINARY TABLE ===== */
.binary-visual-card { margin-bottom: 24px; overflow: hidden; }
.binary-table-wrap { overflow-x: auto; }

.binary-table {
    width: 100%; border-collapse: collapse;
    font-family: 'JetBrains Mono', monospace; font-size: 0.7rem;
}
.binary-table th, .binary-table td {
    padding: 8px 4px; text-align: center;
    border: 1px solid rgba(99,102,241,0.12);
}
.binary-table thead th {
    background: var(--bg2); color: var(--text-muted);
    font-size: 0.6rem; padding: 6px 3px;
}
.binary-table .bit-col { min-width: 22px; }
.binary-table .bit-col.network-bit { background: rgba(79,70,229,0.1); color: var(--primary); }
.binary-table .bit-col.host-bit { background: rgba(5,150,105,0.08); color: var(--success); }

.binary-table .bit-label {
    text-align: left; padding: 8px 14px;
    background: var(--bg2); color: var(--text-dim);
    font-size: 0.75rem; white-space: nowrap;
    font-weight: 500;
}
.bit-cell { min-width: 22px; font-weight: 600; }
.bit-cell.net.one  { background: rgba(79,70,229,0.22); color: #3730a3; }
.bit-cell.net.zero { background: rgba(79,70,229,0.07); color: #4f46e5; }
.bit-cell.host.one  { background: rgba(5,150,105,0.18); color: #065f46; }
.bit-cell.host.zero { background: rgba(5,150,105,0.05); color: #059669; }

.bit-legend {
    display: flex; gap: 24px; margin-top: 16px;
    font-size: 0.8125rem; color: var(--text-muted);
}
.legend-item::before { content: ''; display: inline-block; width: 12px; height: 12px; border-radius: 3px; margin-right: 8px; vertical-align: middle; }
.legend-item.net::before { background: rgba(79,70,229,0.5); }
.legend-item.host::before { background: rgba(5,150,105,0.5); }

/* ===== EXAMPLES ===== */
.examples-card { margin-bottom: 0; }
.examples-card h3 { font-size: 0.9375rem; margin-bottom: 16px; color: var(--text-dim); }
.examples-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 10px; }

.example-btn {
    display: flex; flex-direction: column; gap: 4px;
    padding: 14px 18px; border-radius: 10px;
    background: #fff; border: 1.5px solid var(--border);
    cursor: pointer; text-align: left; transition: all 0.2s;
    color: inherit;
}
.example-btn:hover { border-color: var(--primary); background: rgba(79,70,229,0.06); transform: translateY(-1px); }
.ex-label { font-size: 0.8125rem; color: var(--text-muted); }
.ex-ip { font-size: 0.9375rem; color: var(--primary); font-weight: 500; }

/* ===== TOAST ===== */
.toast {
    position: fixed; bottom: 24px; right: 24px; z-index: 999;
    background: #fff; border: 1px solid var(--border2);
    color: var(--text); padding: 12px 20px; border-radius: 10px;
    font-size: 0.875rem; box-shadow: var(--shadow-lg);
    transform: translateY(20px); opacity: 0;
    transition: all 0.3s; pointer-events: none;
}
.toast.show { transform: translateY(0); opacity: 1; }

/* ===== FOOTER ===== */
.footer {
    border-top: 1px solid var(--border2);
    background: #fff;
    padding: 32px 0;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}
.footer-sub { margin-top: 4px; font-size: 0.8125rem; opacity: 0.6; }

/* ===== PAGE HEADERS ===== */
.page-header { margin-bottom: 40px; }
.page-header h1 { font-size: 2rem; font-weight: 700; letter-spacing: -0.025em; margin-bottom: 8px; }
.page-header p { color: var(--text-dim); }

/* ===== TABLE ===== */
.data-table { width: 100%; border-collapse: collapse; font-size: 0.875rem; }
.data-table th {
    padding: 12px 16px; text-align: left;
    background: var(--bg2); color: var(--text-muted);
    font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.06em;
    border-bottom: 1px solid var(--border2);
}
.data-table td {
    padding: 12px 16px; border-bottom: 1px solid rgba(99,102,241,0.07);
    color: var(--text-dim);
}
.data-table td .mono { color: var(--text); }
.data-table tr:hover td { background: rgba(79,70,229,0.04); }
.data-table tr:last-child td { border-bottom: none; }
.data-table td:first-child { color: var(--text-muted); font-size: 0.8125rem; }

/* ===== CONVERTER ===== */
.converter-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 24px; }
.conv-result { background: #fff; border: 1.5px solid var(--border2); border-radius: 10px; padding: 14px 18px; margin-top: 10px; box-shadow: 0 1px 6px rgba(99,102,241,0.07); }
.conv-result .conv-label { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 8px; display: block; }
.conv-result .conv-val { font-size: 0.9375rem; font-family: 'JetBrains Mono', monospace; color: var(--primary); word-break: break-all; }

/* ===== ABOUT ===== */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.feature-item { padding: 20px; background: #fff; border-radius: 10px; border: 1.5px solid var(--border2); box-shadow: var(--shadow); }
.feature-icon { font-size: 1.75rem; margin-bottom: 12px; }
.feature-item h4 { font-size: 0.9375rem; margin-bottom: 6px; }
.feature-item p { font-size: 0.875rem; color: var(--text-muted); }

/* ===== HOME / TOOLS DASHBOARD ===== */
.tools-hero { text-align: center; margin-bottom: 56px; }
.tools-hero-badge {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 6px 16px; border-radius: 20px;
    background: rgba(79,70,229,0.1); border: 1.5px solid rgba(79,70,229,0.35);
    font-size: 0.8125rem; font-weight: 600; color: var(--primary);
    text-transform: uppercase; letter-spacing: 0.07em;
    margin-bottom: 20px;
}
.tools-hero-badge svg { flex-shrink: 0; }

.tools-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
    margin-bottom: 48px;
}

.tool-card {
    background: #fff;
    border: 1.5px solid var(--border2);
    border-radius: var(--radius);
    padding: 28px;
    display: flex; flex-direction: column; gap: 16px;
    text-decoration: none; color: inherit;
    transition: all 0.25s; cursor: pointer;
    position: relative; overflow: hidden;
    box-shadow: 0 2px 12px rgba(99,102,241,0.07);
}
.tool-card::before {
    content: ''; position: absolute;
    inset: 0; opacity: 0;
    transition: opacity 0.25s;
    pointer-events: none;
}
.tool-card.indigo::before  { background: radial-gradient(circle at top left, rgba(99,102,241,0.12), transparent 60%); }
.tool-card.violet::before  { background: radial-gradient(circle at top left, rgba(139,92,246,0.12), transparent 60%); }
.tool-card.cyan::before    { background: radial-gradient(circle at top left, rgba(6,182,212,0.12), transparent 60%); }
.tool-card.emerald::before { background: radial-gradient(circle at top left, rgba(16,185,129,0.12), transparent 60%); }
.tool-card.amber::before   { background: radial-gradient(circle at top left, rgba(245,158,11,0.12), transparent 60%); }
.tool-card.rose::before    { background: radial-gradient(circle at top left, rgba(244,63,94,0.12), transparent 60%); }

.tool-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-lg); }
.tool-card:hover { border-color: var(--border2); }
.tool-card.indigo:hover  { border-color: rgba(99,102,241,0.4); }
.tool-card.violet:hover  { border-color: rgba(139,92,246,0.4); }
.tool-card.cyan:hover    { border-color: rgba(6,182,212,0.4); }
.tool-card.emerald:hover { border-color: rgba(16,185,129,0.4); }
.tool-card.amber:hover   { border-color: rgba(245,158,11,0.4); }
.tool-card.rose:hover    { border-color: rgba(244,63,94,0.4); }
.tool-card:hover::before { opacity: 1; }

.tool-icon-wrap {
    width: 52px; height: 52px; border-radius: 14px;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.5rem; flex-shrink: 0;
}
.tool-card.indigo  .tool-icon-wrap { background: rgba(99,102,241,0.15); }
.tool-card.violet  .tool-icon-wrap { background: rgba(139,92,246,0.15); }
.tool-card.cyan    .tool-icon-wrap { background: rgba(6,182,212,0.15); }
.tool-card.emerald .tool-icon-wrap { background: rgba(16,185,129,0.15); }
.tool-card.amber   .tool-icon-wrap { background: rgba(245,158,11,0.15); }
.tool-card.rose    .tool-icon-wrap { background: rgba(244,63,94,0.15); }

.tool-card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.tool-tag {
    padding: 3px 10px; border-radius: 20px;
    font-size: 0.7rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em;
    white-space: nowrap;
}
.tag-new { background: rgba(5,150,105,0.12); color: #065f46; border: 1px solid rgba(5,150,105,0.35); }
.tag-net { background: rgba(79,70,229,0.12); color: #3730a3; border: 1px solid rgba(79,70,229,0.35); }
.tag-electric { background: rgba(217,119,6,0.12); color: #92400e; border: 1px solid rgba(217,119,6,0.35); }
.tag-math { background: rgba(8,145,178,0.12); color: #0e7490; border: 1px solid rgba(8,145,178,0.35); }

.tool-title { font-size: 1.0625rem; font-weight: 700; letter-spacing: -0.01em; margin-bottom: 6px; }
.tool-desc { font-size: 0.875rem; color: var(--text-muted); line-height: 1.6; flex: 1; }
.tool-features { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 4px; }
.tool-feat-pill {
    padding: 3px 10px; border-radius: 6px;
    font-size: 0.7rem; color: var(--text-dim);
    background: var(--bg2); border: 1px solid var(--border2);
    font-weight: 500;
}
.tool-arrow {
    display: flex; align-items: center; justify-content: space-between;
    margin-top: 4px; font-size: 0.8125rem; font-weight: 600;
    color: var(--text-dim);
}
.tool-card.indigo:hover  .tool-arrow { color: var(--primary); }
.tool-card.violet:hover  .tool-arrow { color: #a78bfa; }
.tool-card.cyan:hover    .tool-arrow { color: var(--accent); }
.tool-card.emerald:hover .tool-arrow { color: var(--success); }
.tool-card.amber:hover   .tool-arrow { color: var(--warning); }
.tool-card.rose:hover    .tool-arrow { color: #fb7185; }

/* ===== ELECTRIC CALCULATOR ===== */
.calc-mode-tabs {
    display: flex; gap: 8px; margin-bottom: 28px;
    background: var(--bg2); border: 1.5px solid var(--border2);
    border-radius: 12px; padding: 6px;
}
.tab-btn {
    flex: 1; padding: 10px 16px; border-radius: 8px;
    border: none; cursor: pointer;
    font-size: 0.875rem; font-weight: 500;
    color: var(--text-muted); background: transparent;
    transition: all 0.2s;
}
.tab-btn.active { background: #fff; color: var(--primary); box-shadow: 0 2px 8px rgba(79,70,229,0.15); font-weight: 600; }
.tab-btn:hover:not(.active) { color: var(--text-dim); }

.calc-section { display: none; animation: fadeUp 0.3s ease; }
.calc-section.active { display: block; }

.ohm-diagram {
    display: flex; flex-direction: column; align-items: center;
    gap: 20px; margin-bottom: 28px;
}
.ohm-triangle {
    display: grid; grid-template-columns: 1fr 1fr;
    grid-template-rows: auto auto;
    gap: 12px; width: 100%; max-width: 500px;
}
.ohm-var {
    background: #fff; border: 1.5px solid var(--border2);
    border-radius: 12px; padding: 18px 20px;
    display: flex; flex-direction: column; gap: 8px;
    transition: all 0.2s;
}
.ohm-var.span2 { grid-column: span 2; }
.ohm-var:focus-within { border-color: var(--primary); background: rgba(79,70,229,0.04); }
.ohm-var label {
    font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.07em;
    color: var(--text-muted); font-weight: 600; display: flex; gap: 8px; align-items: center;
}
.ohm-var .symbol {
    display: inline-flex; align-items: center; justify-content: center;
    width: 22px; height: 22px; border-radius: 6px;
    font-size: 0.8125rem; font-weight: 700;
}
.sym-v { background: rgba(99,102,241,0.2); color: var(--primary); }
.sym-i { background: rgba(16,185,129,0.2); color: var(--success); }
.sym-r { background: rgba(245,158,11,0.2); color: var(--warning); }
.sym-p { background: rgba(244,63,94,0.2); color: #fb7185; }

.ohm-var input {
    background: transparent; border: none; outline: none;
    font-family: 'JetBrains Mono', monospace;
    font-size: 1.25rem; color: var(--text); width: 100%;
}
.ohm-var input::placeholder { color: var(--text-muted); font-size: 1rem; }
.ohm-unit { font-size: 0.8125rem; color: var(--text-muted); }

.elec-result-grid {
    display: grid; grid-template-columns: repeat(2, 1fr);
    gap: 12px; margin-top: 20px;
}
.elec-result-item {
    background: #fff; border: 1.5px solid var(--border2);
    border-radius: 10px; padding: 16px 20px;
    box-shadow: 0 1px 6px rgba(99,102,241,0.07);
}
.elec-result-item .r-label { font-size: 0.75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 8px; display: block; }
.elec-result-item .r-value { font-size: 1.25rem; font-weight: 700; font-family: 'JetBrains Mono', monospace; color: var(--primary); }
.elec-result-item .r-unit { font-size: 0.875rem; color: var(--text-muted); margin-left: 4px; }

.resistor-inputs { display: flex; flex-direction: column; gap: 10px; margin-bottom: 20px; }
.resistor-row { display: flex; align-items: center; gap: 10px; }
.resistor-row input { flex: 1; }
.resistor-row .r-num { width: 32px; height: 32px; border-radius: 8px; background: var(--bg2); border: 1.5px solid var(--border2); display: flex; align-items: center; justify-content: center; font-size: 0.8125rem; color: var(--text-dim); flex-shrink: 0; font-weight: 600; }
.btn-add-r { display: flex; align-items: center; gap: 8px; }

/* ===== MATH CALCULATOR ===== */
.math-calc-wrap {
    display: grid; grid-template-columns: 1fr 300px;
    gap: 24px; align-items: start;
}
.calc-display {
    background: #fff; border: 1.5px solid var(--border2);
    border-radius: 14px; padding: 24px 24px 20px;
    margin-bottom: 16px; min-height: 110px;
    display: flex; flex-direction: column; justify-content: flex-end;
    box-shadow: 0 2px 12px rgba(79,70,229,0.08);
}
.calc-expr { font-size: 0.875rem; color: var(--text-muted); min-height: 22px; text-align: right; word-break: break-all; }
.calc-screen {
    font-family: 'JetBrains Mono', monospace;
    font-size: 2.5rem; font-weight: 700; color: var(--text);
    text-align: right; word-break: break-all; line-height: 1.2;
}
.calc-screen.error { color: var(--danger); font-size: 1.25rem; }

.calc-buttons {
    display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px;
}
.calc-btn {
    padding: 14px 8px; border-radius: 10px;
    border: 1.5px solid var(--border2);
    font-size: 0.9375rem; font-weight: 600;
    cursor: pointer; transition: all 0.15s;
    background: #fff; color: var(--text);
    display: flex; align-items: center; justify-content: center;
    min-height: 52px;
    box-shadow: 0 1px 4px rgba(99,102,241,0.07);
}
.calc-btn:hover { background: var(--surface2); border-color: var(--primary); transform: scale(1.03); }
.calc-btn:active { transform: scale(0.97); }
.calc-btn.op  { color: var(--primary); border-color: rgba(79,70,229,0.35); background: rgba(79,70,229,0.07); }
.calc-btn.op:hover  { background: rgba(79,70,229,0.14); }
.calc-btn.fn  { color: var(--accent); border-color: rgba(8,145,178,0.35); background: rgba(8,145,178,0.07); font-size: 0.8125rem; }
.calc-btn.fn:hover  { background: rgba(8,145,178,0.14); }
.calc-btn.eq  { background: linear-gradient(135deg, var(--primary), var(--secondary)); color: #fff; border-color: transparent; box-shadow: 0 4px 14px rgba(79,70,229,0.35); }
.calc-btn.eq:hover  { transform: scale(1.03); box-shadow: 0 6px 20px rgba(79,70,229,0.45); }
.calc-btn.clear { color: var(--danger); border-color: rgba(220,38,38,0.35); background: rgba(220,38,38,0.07); }
.calc-btn.clear:hover { background: rgba(220,38,38,0.14); }
.calc-btn.span2 { grid-column: span 2; }

.math-history { background: #fff; border: 1.5px solid var(--border2); border-radius: var(--radius); padding: 20px; box-shadow: var(--shadow); }
.math-history h3 { font-size: 0.8125rem; text-transform: uppercase; letter-spacing: 0.07em; color: var(--text-muted); margin-bottom: 16px; font-weight: 600; }
.history-list { display: flex; flex-direction: column; gap: 8px; max-height: 400px; overflow-y: auto; }
.history-item {
    padding: 10px 14px; border-radius: 8px;
    background: var(--surface2); border: 1.5px solid var(--border);
    cursor: pointer; transition: all 0.15s;
}
.history-item:hover { border-color: var(--primary); background: rgba(79,70,229,0.07); }
.history-item .h-expr { font-size: 0.8125rem; color: var(--text-muted); }
.history-item .h-result { font-size: 1rem; font-weight: 600; color: var(--primary); font-family: 'JetBrains Mono', monospace; }
.history-empty { color: var(--text-muted); font-size: 0.875rem; text-align: center; padding: 20px; }

/* ===== RESPONSIVE ===== */
@media (max-width: 900px) {
    .results-grid { grid-template-columns: 1fr; }
    .side-cards { display: grid; grid-template-columns: 1fr 1fr; }
    .converter-grid { grid-template-columns: 1fr; }
    .about-grid { grid-template-columns: 1fr; }
}

@media (max-width: 900px) {
    .tools-grid { grid-template-columns: 1fr 1fr; }
    .math-calc-wrap { grid-template-columns: 1fr; }
    .elec-result-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 640px) {
    .form-grid { grid-template-columns: 1fr; }
    .cidr-group { min-width: unset; }
    .result-main .info-grid { grid-template-columns: 1fr; }
    .side-cards { grid-template-columns: 1fr; }
    .nav { display: none; }
    .hero-title { font-size: 1.75rem; }
    .examples-grid { grid-template-columns: 1fr 1fr; }
    .binary-table { font-size: 0.6rem; }
    .binary-table .bit-col { min-width: 16px; }
    .tools-grid { grid-template-columns: 1fr; }
    .calc-buttons { grid-template-columns: repeat(4, 1fr); }
    .elec-result-grid { grid-template-columns: 1fr; }
    .ohm-triangle { grid-template-columns: 1fr; }
    .ohm-var.span2 { grid-column: span 1; }
}