/* QUIC vs TCP Whitepaper - Main Stylesheet
   Theme: Deep space navy + QUIC teal (#00d4ff) + TCP orange (#ff6b35) + quantum purple (#7b2fff)
   No inline styles - all classes
*/

/* ── Reset & Base ── */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    background: transparent;
}

:root {
    --quic: #00d4ff;
    --tcp:  #ff6b35;
    --pq:   #7b2fff;
    --bg:   #030810;
    --surface: #080f1e;
    --card:    rgba(8,16,30,0.82);
    --border:  rgba(0,212,255,0.18);
    --border-tcp: rgba(255,107,53,0.18);
    --text:    #d8e8f8;
    --text-dim: #7890a8;
    --heading: #e8f4ff;
    --quic-glow: 0 0 20px rgba(0,212,255,0.35);
    --tcp-glow:  0 0 20px rgba(255,107,53,0.3);
    --pq-glow:   0 0 20px rgba(123,47,255,0.35);
}

html { scroll-behavior: smooth; }

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    color: var(--text);
    line-height: 1.7;
    min-height: 100vh;
    position: relative;
}

/* ── Layout ── */
main {
    position: relative;
    z-index: 1;
}

.content-wrapper {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 24px 80px;
    position: relative;
}

/* ── Header ── */
.qw-header {
    position: relative;
    z-index: 2;
    padding: 0;
    background: linear-gradient(180deg, rgba(3,8,16,0.92) 0%, rgba(8,15,30,0.88) 100%);
    border-bottom: 1px solid var(--border);
}

.header-container {
    max-width: 960px;
    margin: 0 auto;
    padding: 28px 24px 22px;
}

.header-top {
    display: flex;
    align-items: center;
    gap: 20px;
    flex-wrap: wrap;
}

.logo-link {
    flex-shrink: 0;
    display: block;
}

.logo-image {
    height: 52px;
    width: auto;
    border-radius: 8px;
    display: block;
}

.header-text {
    flex: 1;
    min-width: 200px;
}

.page-title {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--quic);
    text-shadow: var(--quic-glow);
    letter-spacing: -0.02em;
    line-height: 1.2;
}

.page-subtitle {
    font-size: 0.92rem;
    color: var(--text-dim);
    margin-top: 4px;
    letter-spacing: 0.02em;
}

.header-meta {
    margin-top: 14px;
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    align-items: center;
}

.meta-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 12px;
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.meta-badge-quic {
    background: rgba(0,212,255,0.12);
    color: var(--quic);
    border: 1px solid rgba(0,212,255,0.3);
}

.meta-badge-tcp {
    background: rgba(255,107,53,0.12);
    color: var(--tcp);
    border: 1px solid rgba(255,107,53,0.3);
}

.meta-badge-pq {
    background: rgba(123,47,255,0.12);
    color: #aa80ff;
    border: 1px solid rgba(123,47,255,0.3);
}

.meta-author {
    font-size: 0.8rem;
    color: var(--text-dim);
    margin-left: auto;
}

/* ── Tab Navigation ── */
.tab-nav {
    position: sticky;
    top: 0;
    z-index: 10;
    display: flex;
    justify-content: center;
    gap: 0;
    background: rgba(3,8,16,0.97);
    border-bottom: 1px solid var(--border);
    overflow-x: auto;
    scrollbar-width: none;
}

.tab-nav::-webkit-scrollbar { display: none; }

.tab-btn {
    flex-shrink: 0;
    padding: 14px 22px;
    background: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    color: var(--text-dim);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: color 0.2s, border-color 0.2s;
    letter-spacing: 0.03em;
    white-space: nowrap;
}

.tab-btn:hover {
    color: var(--quic);
}

.tab-btn.active {
    color: var(--quic);
    border-bottom-color: var(--quic);
    text-shadow: 0 0 12px rgba(0,212,255,0.4);
}

/* ── Tab Content ── */
.tab-content {
    display: none;
    animation: fadeInTab 0.25s ease;
}

.tab-content.active {
    display: block;
}

@keyframes fadeInTab {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ── Section Headings ── */
.section-heading {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--heading);
    margin: 48px 0 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 10px;
}

.section-heading.quic-accent {
    color: var(--quic);
    text-shadow: 0 0 16px rgba(0,212,255,0.25);
    border-bottom-color: rgba(0,212,255,0.25);
}

.section-heading.tcp-accent {
    color: var(--tcp);
    text-shadow: 0 0 16px rgba(255,107,53,0.2);
    border-bottom-color: rgba(255,107,53,0.2);
}

.sub-heading {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--quic);
    margin: 32px 0 12px;
}

.sub-heading-tcp {
    color: var(--tcp);
}

/* ── Prose ── */
.prose {
    font-size: 0.95rem;
    color: var(--text);
    line-height: 1.8;
    margin-bottom: 18px;
}

.prose strong {
    color: var(--heading);
    font-weight: 700;
}

.prose em {
    color: var(--quic);
    font-style: normal;
    font-weight: 600;
}

/* ── Cards ── */
.card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 24px;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--quic), var(--pq), var(--tcp));
    opacity: 0.7;
}

.card-quic {
    border-color: rgba(0,212,255,0.22);
}

.card-quic::before {
    background: linear-gradient(90deg, var(--quic), transparent);
}

.card-tcp {
    border-color: rgba(255,107,53,0.22);
}

.card-tcp::before {
    background: linear-gradient(90deg, var(--tcp), transparent);
}

.card-pq {
    border-color: rgba(123,47,255,0.25);
}

.card-pq::before {
    background: linear-gradient(90deg, var(--pq), transparent);
}

.card-title {
    font-size: 1rem;
    font-weight: 700;
    color: var(--quic);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.card-title-tcp { color: var(--tcp); }
.card-title-pq  { color: #aa80ff; }

/* ── Abstract Card ── */
.abstract-card {
    background: linear-gradient(135deg, rgba(0,212,255,0.08) 0%, rgba(8,16,30,0.7) 50%, rgba(255,107,53,0.06) 100%);
    border: 1px solid rgba(0,212,255,0.2);
    border-radius: 14px;
    padding: 28px 32px;
    margin: 32px 0;
}

.abstract-label {
    font-size: 0.7rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--quic);
    margin-bottom: 12px;
    display: block;
}

.abstract-text {
    font-size: 0.95rem;
    line-height: 1.85;
    color: var(--text);
    font-style: italic;
}

/* ── Info Box ── */
.info-box {
    background: rgba(0,212,255,0.07);
    border-left: 3px solid var(--quic);
    border-radius: 0 8px 8px 0;
    padding: 14px 18px;
    margin: 18px 0;
    font-size: 0.88rem;
    color: var(--text);
}

.warning-box {
    background: rgba(255,107,53,0.07);
    border-left: 3px solid var(--tcp);
    border-radius: 0 8px 8px 0;
    padding: 14px 18px;
    margin: 18px 0;
    font-size: 0.88rem;
    color: var(--text);
}

.success-box {
    background: rgba(0,230,118,0.07);
    border-left: 3px solid #00e676;
    border-radius: 0 8px 8px 0;
    padding: 14px 18px;
    margin: 18px 0;
    font-size: 0.88rem;
    color: var(--text);
}

/* ── Tables ── */
.table-wrapper {
    overflow-x: auto;
    margin: 20px 0;
    border-radius: 10px;
    border: 1px solid var(--border);
}

table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
}

thead tr {
    background: linear-gradient(90deg, rgba(0,212,255,0.15), rgba(123,47,255,0.12));
}

thead th {
    padding: 12px 16px;
    text-align: left;
    font-weight: 700;
    color: var(--quic);
    white-space: nowrap;
    font-size: 0.8rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

tbody tr {
    border-top: 1px solid rgba(255,255,255,0.05);
    transition: background 0.15s;
}

tbody tr:hover {
    background: rgba(0,212,255,0.05);
}

tbody td {
    padding: 10px 16px;
    color: var(--text);
    vertical-align: top;
}

tbody td:first-child {
    color: var(--quic);
    font-weight: 600;
    white-space: nowrap;
}

.td-tcp {
    color: var(--tcp) !important;
}

.td-quic {
    color: var(--quic) !important;
}

.grade-app {
    background: rgba(0,212,255,0.15);
    color: var(--quic);
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
}

.grade-ap {
    background: rgba(0,200,130,0.15);
    color: #00e676;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
}

.grade-a {
    background: rgba(0,230,118,0.1);
    color: #69f0ae;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
}

.grade-c {
    background: rgba(255,200,0,0.12);
    color: #ffd740;
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
}

.grade-f {
    background: rgba(255,107,53,0.15);
    color: var(--tcp);
    font-weight: 700;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.8rem;
}

/* ── Code Blocks ── */
.code-wrapper {
    position: relative;
    margin: 16px 0;
}

pre {
    background: rgba(0,0,0,0.55);
    border: 1px solid rgba(0,212,255,0.15);
    border-radius: 8px;
    padding: 18px 20px;
    overflow-x: auto;
    font-size: 0.83rem;
    line-height: 1.6;
}

code {
    font-family: 'Courier New', 'Fira Code', monospace;
    color: #a8d8f0;
}

pre code {
    color: #a8d8f0;
}

.copy-btn {
    position: absolute;
    top: 8px;
    right: 8px;
    background: rgba(0,212,255,0.15);
    border: 1px solid rgba(0,212,255,0.3);
    color: var(--quic);
    font-size: 0.72rem;
    font-weight: 600;
    padding: 3px 10px;
    border-radius: 4px;
    cursor: pointer;
    transition: background 0.2s, opacity 0.2s;
    opacity: 0;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.code-wrapper:hover .copy-btn {
    opacity: 1;
}

.copy-btn:hover {
    background: rgba(0,212,255,0.28);
}

/* ── Lists ── */
.wp-list {
    list-style: none;
    padding: 0;
    margin: 14px 0;
}

.wp-list li {
    padding: 6px 0 6px 22px;
    position: relative;
    font-size: 0.92rem;
    color: var(--text);
    line-height: 1.6;
}

.wp-list li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--quic);
    font-size: 0.85rem;
}

.wp-list-tcp li::before { color: var(--tcp); }
.wp-list-pq  li::before { color: #aa80ff; }

/* ── Formula Box ── */
.formula-box {
    background: rgba(0,0,0,0.5);
    border: 1px solid rgba(0,212,255,0.2);
    border-radius: 8px;
    padding: 18px 22px;
    margin: 16px 0;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    color: #80d8ff;
    text-align: center;
    letter-spacing: 0.03em;
}

.formula-label {
    font-family: 'Segoe UI', system-ui, sans-serif;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    display: block;
    margin-bottom: 8px;
    text-align: left;
}

/* ── Stats Grid ── */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 16px;
    margin: 24px 0;
}

.stat-card {
    background: rgba(8,16,30,0.78);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 18px 20px;
    text-align: center;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--quic);
    text-shadow: 0 0 14px rgba(0,212,255,0.3);
    line-height: 1;
    margin-bottom: 6px;
}

.stat-value-tcp { color: var(--tcp); text-shadow: 0 0 14px rgba(255,107,53,0.25); }

.stat-label {
    font-size: 0.75rem;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-weight: 600;
}

/* ── Protocol Compare ── */
.compare-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin: 20px 0;
}

.compare-panel {
    background: rgba(8,16,30,0.78);
    border-radius: 10px;
    padding: 20px;
}

.compare-panel-quic {
    border: 1px solid rgba(0,212,255,0.22);
}

.compare-panel-tcp {
    border: 1px solid rgba(255,107,53,0.22);
}

.compare-label {
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 12px;
}

.compare-label-quic { color: var(--quic); }
.compare-label-tcp  { color: var(--tcp); }

/* ── Reference List ── */
.ref-list {
    list-style: none;
    padding: 0;
    counter-reset: ref-counter;
}

.ref-list li {
    counter-increment: ref-counter;
    padding: 8px 0 8px 36px;
    position: relative;
    font-size: 0.85rem;
    color: var(--text);
    border-bottom: 1px solid rgba(255,255,255,0.04);
    line-height: 1.6;
}

.ref-list li::before {
    content: '[' counter(ref-counter) ']';
    position: absolute;
    left: 0;
    color: var(--quic);
    font-weight: 700;
    font-size: 0.8rem;
    min-width: 30px;
}

/* ── Tool Cards ── */
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 18px;
    margin: 24px 0;
}

.tool-card {
    background: rgba(8,16,30,0.80);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 22px;
    position: relative;
    overflow: hidden;
    transition: border-color 0.25s, box-shadow 0.25s;
}

.tool-card:hover {
    border-color: rgba(0,212,255,0.4);
    box-shadow: var(--quic-glow);
}

.tool-card-icon {
    font-size: 2rem;
    margin-bottom: 10px;
    display: block;
}

.tool-card-name {
    font-size: 1rem;
    font-weight: 700;
    color: var(--quic);
    margin-bottom: 6px;
}

.tool-card-url {
    font-size: 0.75rem;
    color: var(--text-dim);
    font-family: monospace;
    margin-bottom: 12px;
}

.tool-card-desc {
    font-size: 0.88rem;
    color: var(--text);
    line-height: 1.6;
}

/* ── Footer ── */
.qw-footer {
    position: relative;
    z-index: 2;
    background: rgba(3,8,16,0.97);
    border-top: 1px solid var(--border);
    padding: 36px 24px;
    text-align: center;
}

.footer-content {
    max-width: 700px;
    margin: 0 auto;
}

.footer-copyright {
    color: var(--text-dim);
    font-size: 0.85rem;
    margin-bottom: 8px;
}

.footer-copyright strong {
    color: var(--text);
}

.footer-notice {
    font-size: 0.78rem;
    color: var(--text-dim);
    margin-bottom: 16px;
}

.footer-links {
    display: flex;
    gap: 8px;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    margin-bottom: 16px;
}

.footer-link {
    color: var(--quic);
    text-decoration: none;
    font-size: 0.82rem;
    transition: opacity 0.2s;
}

.footer-link:hover { opacity: 0.75; }

.footer-sep {
    color: var(--text-dim);
    font-size: 0.7rem;
}

.footer-doc-info {
    font-size: 0.78rem;
    color: var(--text-dim);
    line-height: 1.7;
}

.footer-doc-info strong {
    color: var(--text);
}

/* ── Overview special layout ── */
.overview-intro {
    margin: 36px 0 0;
}

/* ── TOC ── */
.toc {
    background: rgba(8,16,30,0.78);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 20px 24px;
    margin: 24px 0;
}

.toc-title {
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.07em;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-bottom: 12px;
}

.toc-list {
    list-style: none;
    padding: 0;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 4px 24px;
}

.toc-list li a {
    color: var(--text);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 3px 0;
}

.toc-list li a:hover { color: var(--quic); }

.toc-num {
    color: var(--text-dim);
    font-size: 0.75rem;
    min-width: 24px;
}

/* ── Deployment Reality counters ── */
.reality-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin: 20px 0;
}

.reality-item {
    background: rgba(8,16,30,0.78);
    border-radius: 10px;
    padding: 18px;
    text-align: center;
    border: 1px solid var(--border);
}

.reality-count {
    font-size: 2.2rem;
    font-weight: 800;
    line-height: 1;
    margin-bottom: 6px;
}

.reality-count-ap  { color: var(--quic); }
.reality-count-a   { color: #69f0ae; }
.reality-count-f   { color: var(--tcp); }

.reality-label {
    font-size: 0.75rem;
    color: var(--text-dim);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* ── Responsive ── */
@media (max-width: 680px) {
    .compare-row { grid-template-columns: 1fr; }
    .reality-grid { grid-template-columns: repeat(2, 1fr); }
    .page-title { font-size: 1.35rem; }
    .header-meta { flex-direction: column; align-items: flex-start; }
    .meta-author { margin-left: 0; }
}

@media (max-width: 480px) {
    .content-wrapper { padding: 0 16px 60px; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .reality-grid { grid-template-columns: 1fr 1fr; }
}

/* ── Utility classes replacing inline styles ── */
.tool-grid-top {
    margin-top: 36px;
}

.section-top {
    margin-top: 36px;
}

.ref-note {
    margin-top: 12px;
    font-size: 0.83rem;
    color: var(--text-dim);
}

/* ── Accessibility ── */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}