/* --- Global Styles & Fonts --- */
:root {
    --primary-color: #f7931a;
    --primary-hover: #e68917;
    --stop-color: #d9534f;
    --stop-hover: #c9302c;
    --success-color: #28a745;
    --success-bg: #f0fff4;
    --dark-bg: #2d2d2d;
    --light-bg: #f8f9fa;
    --text-color: #212529;
    --text-muted: #6c757d;
    --border-color: #dee2e6;
    --error-color: #d9534f;
    --error-bg: #fdf2f2;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    
    /* Light mode colors */
    --body-bg: #f0f2f5;
    --card-bg: #ffffff;
    --input-bg: #f8f9fa;
    --log-bg: #2d2d2d;
    --log-text: #f0f0f0;
    --fact-banner-bg: #e6f7ff;
    --fact-banner-border: #91d5ff;
    --fact-banner-text: #005085;
    --fact-banner-strong: #003a61;
    --result-item-bg: #e9ecef;
    --hash-color: #0056b3;
}

/* Dark mode colors */
[data-theme="dark"] {
    --body-bg: #1a1a1a;
    --card-bg: #2d2d2d;
    --text-color: #e0e0e0;
    --text-muted: #a0a0a0;
    --border-color: #404040;
    --input-bg: #3a3a3a;
    --log-bg: #1e1e1e;
    --log-text: #e0e0e0;
    --success-bg: #1a2e1a;
    --error-bg: #2e1a1a;
    --fact-banner-bg: #1a2a3a;
    --fact-banner-border: #2a4a6a;
    --fact-banner-text: #7db8e8;
    --fact-banner-strong: #a0c8f0;
    --result-item-bg: #404040;
    --hash-color: #4a9eff;
}

body {
    font-family: var(--font-family);
    background-color: var(--body-bg);
    color: var(--text-color);
    margin: 0;
    padding: 2rem;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* --- Header & Banners --- */
.main-header { text-align: center; margin-bottom: 2rem; }
.header-content { display: flex; flex-wrap: wrap; align-items: center; justify-content: center; gap: 1rem; margin-bottom: 1rem; }
.header-actions { display: flex; align-items: center; gap: 0.75rem; flex-shrink: 0; }
.main-header h1 { color: var(--text-color); margin: 0; }
.main-header p { color: var(--text-muted); font-size: 1.1rem; margin: 0.5rem 0 0 0; }
.main-header .credit { margin-top: 0.75rem; font-size: 0.9rem; }
.main-header .credit a { color: var(--primary-color); text-decoration: none; font-weight: 500; }
.main-header .credit a:hover { text-decoration: underline; }

/* Header Icon Controls */
.theme-toggle,
.social-link {
    box-sizing: border-box;
    flex-shrink: 0;
    padding: 0;
    text-decoration: none;
    background: none;
    border: 2px solid var(--border-color);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    color: var(--text-color);
}

.theme-toggle:hover,
.social-link:hover {
    border-color: var(--primary-color);
    transform: scale(1.05);
}

.theme-toggle:focus-visible,
.social-link:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 4px;
}

.theme-toggle svg,
.social-link svg {
    width: 20px;
    height: 20px;
    transition: opacity 0.3s ease;
}

.theme-toggle .moon-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .sun-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .moon-icon {
    display: block;
}

.cool-fact-banner {
    max-width: 1200px;
    margin: 0 auto 2.5rem auto;
    background-color: var(--fact-banner-bg);
    border: 1px solid var(--fact-banner-border);
    border-radius: 12px;
    padding: 1rem 1.75rem;
    text-align: center;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}
.cool-fact-banner p { margin: 0; font-size: 1.05rem; line-height: 1.6; color: var(--fact-banner-text); }
.cool-fact-banner strong { color: var(--fact-banner-strong); }
.cool-fact-banner br { content: ""; display: block; margin: 0.5rem 0; }

/* NEW: Error banner for crypto API failure */
.error-banner { max-width: 1200px; margin: 0 auto 2.5rem auto; background-color: var(--error-bg); border: 1px solid var(--error-color); border-radius: 12px; padding: 1rem 1.75rem; text-align: center; }
.error-banner p { margin: 0; color: var(--error-color); }
.error-banner code { background-color: #e9ecef; color: #c7254e; padding: 2px 6px; border-radius: 4px; }

/* --- Main Layout --- */
.simulator-layout { display: grid; grid-template-columns: 1fr 1.5fr; gap: 2rem; max-width: 1200px; margin: 0 auto 2rem auto; }

/* --- General Card Style --- */
.card {
    background-color: var(--card-bg);
    padding: 1.5rem 2rem;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
    transition: background-color 0.3s ease, box-shadow 0.3s ease;
}
[data-theme="dark"] .card {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}
.card h2 { margin-top: 0; border-bottom: 1px solid var(--border-color); padding-bottom: 0.75rem; margin-bottom: 1.5rem; }

/* --- Controls Card --- */
.form-group { margin-bottom: 1.25rem; }
.form-group label { display: block; margin-bottom: 0.5rem; font-weight: 500; font-size: 0.9rem; }
textarea, select, input[type="number"] {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    box-sizing: border-box;
    background-color: var(--input-bg);
    color: var(--text-color);
    transition: border-color 0.2s, box-shadow 0.2s, background-color 0.3s ease, color 0.3s ease;
}
textarea:focus, select:focus, input[type="number"]:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 3px rgba(247, 147, 26, 0.2); }
textarea:disabled, select:disabled, input[type="number"]:disabled { background-color: #e9ecef; cursor: not-allowed; }
textarea { font-family: monospace; resize: vertical; }

#mine-button { width: 100%; padding: 0.8rem; font-size: 1.1rem; font-weight: bold; color: #fff; border: none; border-radius: 8px; cursor: pointer; transition: background-color 0.2s, transform 0.1s; }
#mine-button:disabled { background-color: #ccc; cursor: not-allowed; }
#mine-button:active:not(:disabled) { transform: scale(0.98); }
#mine-button.start { background-color: var(--primary-color); }
#mine-button.start:hover { background-color: var(--primary-hover); }
#mine-button.stop { background-color: var(--stop-color); }
#mine-button.stop:hover { background-color: var(--stop-hover); }
.hidden { display: none !important; }

/* --- Output Card & Stats --- */
.output-card #initial-message { text-align: center; color: var(--text-muted); padding: 3rem 0; }
#stats-container { display: flex; justify-content: space-around; gap: 1rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--border-color); margin-bottom: 1.5rem; }
.stat-item { display: flex; align-items: center; gap: 0.75rem; }
.stat-item .label { font-size: 0.9rem; color: var(--text-muted); display: block; }
.stat-value { font-weight: 700; font-size: 1.6rem; color: var(--text-color); }
.icon { width: 32px; height: 32px; fill: var(--primary-color); }

/* --- Results & Log --- */
.status-log {
    background-color: var(--log-bg);
    color: var(--log-text);
    padding: 1rem;
    border-radius: 8px;
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 0.9rem;
    transition: background-color 0.3s ease, color 0.3s ease;
    font-family: monospace;
}

.hash-value { color: var(--hash-color); font-weight: bold; }

#success-block { border: 2px solid var(--success-color); background-color: var(--success-bg); padding: 1rem 1.5rem; border-radius: 12px; }
#success-block h2 { text-align: center; color: var(--success-color); margin-top: 0; border: none; }
.result-item { margin-bottom: 0.75rem; }
.result-item .label { font-size: 0.9rem; color: var(--text-muted); display: block; font-weight: 500; }
.result-value {
    font-family: monospace;
    font-size: 1.1rem;
    word-wrap: break-word;
    padding: 0.6rem;
    background-color: var(--result-item-bg);
    color: var(--text-color);
    border-radius: 6px;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* --- Responsive Design --- */
@media (max-width: 900px) { .simulator-layout, .explanation-container { grid-template-columns: 1fr 1fr; } }
@media (max-width: 500px) { body { padding: 1rem; } .card { padding: 1.25rem; } #stats-container { flex-direction: column; align-items: flex-start; } }

/* --- Threads Input --- */
#threads { width: 100%; padding: 0.75rem; border: 1px solid var(--border-color); border-radius: 8px; font-size: 1rem; box-sizing: border-box; background-color: var(--input-bg); color: var(--text-color); transition: border-color 0.2s, box-shadow 0.2s, background-color 0.3s ease, color 0.3s ease; }
#threads:focus { outline: none; border-color: var(--primary-color); box-shadow: 0 0 0 3px rgba(247, 147, 26, 0.2); }
#threads:disabled { background-color: #e9ecef; cursor: not-allowed; }

/* --- Mini-Blockchain Visualizer --- */
.blockchain-layout { max-width: 1200px; margin: 0 auto 2rem auto; padding: 1.5rem; background-color: var(--card-bg); border-radius: 12px; box-shadow: 0 4px 12px rgba(0,0,0,0.05); transition: background-color 0.3s ease; }
[data-theme="dark"] .blockchain-layout { box-shadow: 0 4px 12px rgba(0,0,0,0.3); }
.blockchain-layout h2 { margin-top: 0; border-bottom: 1px solid var(--border-color); padding-bottom: 0.75rem; margin-bottom: 1rem; }
.blocks-wrapper { display: flex; flex-direction: column; gap: 1.5rem; margin-top: 1rem; }
.block-card { background-color: var(--result-item-bg); border-left: 4px solid var(--success-color); border-radius: 6px; padding: 1rem; display: flex; flex-direction: column; gap: 0.5rem; position: relative; transition: background-color 0.3s ease; }
.block-card::before { content: '↓'; position: absolute; top: -1.75rem; left: 1rem; font-size: 1.5rem; color: var(--text-muted); font-weight: bold; }
.block-card:first-child::before { display: none; }
.block-header { font-weight: bold; color: var(--primary-color); margin-bottom: 0.5rem; font-size: 1.1rem; }
.block-data-row { display: flex; flex-direction: column; font-size: 0.9rem; margin-bottom: 0.25rem; }
.block-data-label { color: var(--text-muted); font-weight: bold; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.5px; }
.block-data-value { font-family: monospace; white-space: pre-wrap; word-wrap: break-word; color: var(--text-color); margin-top: 0.2rem; }

/* --- Confetti --- */
#confetti-canvas { position: fixed; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; z-index: 9999; }

/* --- Interactive labs --- */
html { scroll-behavior: smooth; scroll-padding-top: 1rem; }
body { line-height: 1.6; }
main, .simulator-layout > *, .lab-section, .miner-card { min-width: 0; }
button, input, select, textarea { font: inherit; }
button:disabled { opacity: 0.5; cursor: not-allowed; }
button:focus-visible, a:focus-visible, input:focus-visible { outline: 3px solid var(--primary-color); outline-offset: 3px; }
textarea:disabled, select:disabled, input[type="number"]:disabled, #threads:disabled { background: var(--input-bg); color: var(--text-muted); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.muted { color: var(--text-muted); }
.small { font-size: 0.85rem; }
.language-select { width: auto; padding: 0.45rem 0.6rem; min-height: 44px; }
.social-link { font-weight: 700; }
.lab-nav { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.5rem; margin-top: 1.5rem; }
.lab-nav a { color: var(--text-color); background: var(--card-bg); border: 1px solid var(--border-color); padding: 0.5rem 1rem; border-radius: 999px; text-decoration: none; font-size: 0.9rem; }
.lab-nav a:hover { border-color: var(--primary-color); }
.lab-section { box-sizing: border-box; max-width: 1200px; margin: 0 auto 2rem; }
.section-heading { display: flex; justify-content: space-between; align-items: flex-start; flex-wrap: wrap; gap: 1rem; margin-bottom: 1rem; }
.section-heading h2 { flex: 1 1 200px; margin: 0; }
.button-group { display: flex; flex-wrap: wrap; gap: 0.6rem; }
.button { border: 1px solid transparent; border-radius: 8px; background: var(--primary-color); color: #212529; padding: 0.65rem 1rem; cursor: pointer; font-weight: 700; min-height: 44px; }
.button:hover:not(:disabled) { background: var(--primary-hover); }
.button.secondary { background: var(--input-bg); color: var(--text-color); border-color: var(--border-color); }
.button.secondary:hover:not(:disabled) { border-color: var(--primary-color); }
.button.danger { background: var(--stop-color); color: #fff; }
.lab-status { padding: 0.75rem 1rem; background: var(--input-bg); border: 1px solid var(--border-color); border-radius: 8px; }
.empty-state { text-align: center; color: var(--text-muted); }
.chart-container { position: relative; width: 100%; height: 260px; }
#performance-chart { display: block; width: 100%; height: 260px; }
.table-scroll { overflow-x: auto; margin-top: 1rem; }
table { width: 100%; border-collapse: collapse; font-size: 0.85rem; text-align: left; }
th, td { padding: 0.7rem 0.6rem; border-bottom: 1px solid var(--border-color); white-space: nowrap; }
thead th { color: var(--text-muted); font-weight: 500; }
.block-card { border: 1px solid var(--border-color); border-left: 4px solid var(--success-color); }
.block-card.block-invalid { border-left-color: var(--error-color); background: var(--error-bg); }
.block-card.block-checking { border-left-color: var(--primary-color); }
.block-heading { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 0.75rem; }
.block-heading h3 { margin: 0; }
.badge { display: inline-block; font-size: 0.8rem; font-weight: 700; padding: 0.2rem 0.7rem; border: 1px solid var(--border-color); border-radius: 999px; background: var(--card-bg); }
.block-card:not(.block-invalid):not(.block-checking) .badge { color: var(--success-color); }
.block-invalid .badge, .block-invalid .block-reason { color: var(--error-color); }
.block-data-value, .result-value { overflow-wrap: anywhere; word-break: break-word; }
.block-reason { margin: 0.5rem 0 0; font-size: 0.85rem; }
.block-card label { font-weight: 500; font-size: 0.9rem; }
.race-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1rem; margin: 1.5rem 0; }
.miner-card { padding: 1.25rem; border: 2px solid var(--border-color); border-radius: 10px; background: var(--input-bg); transition: border-color 0.2s; }
.miner-card h3 { margin: 0 0 1rem; }
.miner-card label { display: block; font-size: 0.9rem; color: var(--text-muted); }
.miner-card input { display: block; width: 100%; margin: 1rem 0; accent-color: var(--primary-color); cursor: pointer; }
.miner-card output { font-size: 1.6rem; font-weight: 700; }
.miner-card p { font-size: 0.9rem; }
.miner-card.race-winner { border-color: var(--success-color); background: var(--success-bg); }
.race-track { height: 10px; border-radius: 999px; background: var(--border-color); overflow: hidden; }
.race-bar { width: 0; height: 100%; background: var(--primary-color); transition: width 0.3s; }
.race-result { font-weight: 500; }
.explanation-container { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1.5rem; }
.explanation-card p { line-height: 1.8; }
#success-block { margin-top: 1rem; }
.output-card #initial-message { padding: 1rem 0; }
#mine-button { color: #212529; }
#mine-button.stop { color: #fff; }
[data-theme="dark"] { --success-color: #64cc82; --error-color: #ff8580; }

@media (max-width: 800px) {
    .simulator-layout, .explanation-container { grid-template-columns: 1fr; }
    .race-grid { grid-template-columns: 1fr; }
    .main-header h1 { font-size: 1.7rem; }
}
@media (max-width: 500px) {
    .header-actions { flex-wrap: wrap; justify-content: center; }
    .blockchain-layout { padding: 1rem; }
    .blockchain-layout .button-group { width: 100%; }
    .button-group .button { flex: 1 1 auto; }
    .lab-nav a { font-size: 0.8rem; padding: 0.4rem 0.7rem; }
    .stat-value { font-size: 1.4rem; }
}
@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { transition: none !important; }
}