:root {
    --bg: #0a0b0d;
    --surface: #111317;
    --surface-2: #16191e;
    --surface-3: #1b1f25;
    --text: #f4f5f7;
    --muted: #9ca3af;
    --muted-2: #6f7782;
    --line: #242932;
    --line-strong: #343b46;
    --accent: #5f8cff;
    --accent-hover: #7aa0ff;
    --warning: #d39a45;
    --radius: 14px;
    --radius-small: 10px;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: var(--font);
}

html {
    scroll-behavior: smooth;
}

body {
    min-height: 100vh;
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
    overflow-x: hidden;
}

a {
    color: inherit;
}

::selection {
    background: rgba(95, 140, 255, 0.25);
    color: #fff;
}

.container {
    width: min(1120px, calc(100% - 40px));
    margin: 0 auto;
    padding: 28px 0 0;
}

/* HERO */
.hero {
    text-align: left;
    padding: 56px 0 44px;
    border-bottom: 1px solid var(--line);
}

.icon {
    display: block;
    width: 92px;
    height: 92px;
    object-fit: cover;
    border-radius: 22px;
    margin-bottom: 24px;
    border: 1px solid var(--line);
}

.title {
    max-width: 760px;
    margin-bottom: 14px;
    color: var(--text);
    font-size: clamp(3rem, 7vw, 5.25rem);
    font-weight: 800;
    line-height: 0.98;
    letter-spacing: -0.055em;
}

.description {
    max-width: 700px;
    margin: 0 0 30px;
    color: var(--muted);
    font-size: 1.1rem;
    line-height: 1.72;
}

.buttons {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 30px;
}

.button {
    min-height: 48px;
    padding: 0 18px;
    border-radius: 11px;
    border: 1px solid var(--line-strong);
    text-decoration: none;
    font-size: 0.96rem;
    font-weight: 650;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 9px;
    transition: background 0.16s ease, border-color 0.16s ease, color 0.16s ease;
}

.button svg {
    width: 20px;
    height: 20px;
}

.button.primary {
    background: var(--text);
    border-color: var(--text);
    color: #0b0c0e;
}

.button.primary:hover {
    background: #dfe3e8;
    border-color: #dfe3e8;
}

.button.secondary {
    background: var(--surface);
    color: var(--text);
}

.button.secondary:hover {
    background: var(--surface-2);
    border-color: #4a5360;
}

.social-container {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 26px;
}

.social-button {
    min-height: 42px;
    padding: 0 14px;
    border-radius: 10px;
    border: 1px solid var(--line);
    background: transparent;
    color: var(--muted);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 560;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: color 0.16s ease, border-color 0.16s ease, background 0.16s ease;
}

.social-button:hover {
    color: var(--text);
    border-color: var(--line-strong);
    background: var(--surface);
}

.yt-icon {
    width: 20px;
    height: 20px;
    border-radius: 5px;
}

/* MAIN */
.content-section {
    margin: 54px 0 0;
}

.section-title {
    margin-bottom: 22px;
    text-align: left;
    color: var(--text);
    font-size: clamp(1.8rem, 4vw, 2.45rem);
    font-weight: 760;
    letter-spacing: -0.03em;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    border-top: 1px solid var(--line);
    border-left: 1px solid var(--line);
}

.feature-card {
    min-height: 170px;
    padding: 24px;
    background: transparent;
    border-right: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
}

.feature-card h3 {
    margin-bottom: 8px;
    color: var(--text);
    font-size: 1.12rem;
    font-weight: 680;
    letter-spacing: -0.015em;
}

.feature-card p {
    max-width: 440px;
    color: var(--muted);
    line-height: 1.7;
    font-size: 0.96rem;
}

/* ARTICLE */
.delta-guide {
    max-width: 860px;
    margin: 76px 0 0;
    color: var(--text);
}

.delta-guide-header {
    text-align: left;
    max-width: 800px;
    margin-bottom: 34px;
}

.delta-guide-kicker {
    display: inline-block;
    margin-bottom: 14px;
    color: var(--accent);
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.09em;
    text-transform: uppercase;
}

.delta-guide h2 {
    margin-bottom: 16px;
    color: var(--text);
    font-size: clamp(2rem, 5vw, 3.15rem);
    line-height: 1.08;
    font-weight: 780;
    letter-spacing: -0.045em;
}

.delta-guide-intro {
    max-width: 760px;
    color: var(--muted) !important;
    font-size: 1.08rem !important;
    line-height: 1.8 !important;
}

.delta-toc {
    margin: 0 0 44px;
    padding: 20px 22px;
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-small);
}

.delta-toc strong {
    display: block;
    margin-bottom: 10px;
    color: var(--text);
    font-size: 0.95rem;
}

.delta-toc ol {
    columns: 2;
    column-gap: 36px;
    margin: 0;
    padding-left: 20px;
}

.delta-toc li {
    margin-bottom: 6px;
    color: var(--muted);
    break-inside: avoid;
    font-size: 0.94rem;
}

.delta-toc a {
    color: var(--muted);
    text-decoration: none;
}

.delta-toc a:hover {
    color: var(--text);
}

.delta-guide section {
    padding: 34px 0;
    border-top: 1px solid var(--line);
    scroll-margin-top: 24px;
}

.delta-guide h3 {
    margin-bottom: 14px;
    color: var(--text);
    font-size: 1.55rem;
    font-weight: 720;
    letter-spacing: -0.025em;
}

.delta-guide h4 {
    margin: 24px 0 9px;
    color: #dfe3e8;
    font-size: 1.05rem;
    font-weight: 670;
}

.delta-guide p,
.delta-guide li {
    color: var(--muted);
    font-size: 1rem;
    line-height: 1.82;
}

.delta-guide p {
    margin-bottom: 16px;
}

.delta-guide strong {
    color: var(--text);
    font-weight: 650;
}

.delta-guide ul,
.delta-guide ol {
    padding-left: 22px;
    margin-bottom: 18px;
}

.delta-guide li {
    margin-bottom: 7px;
}

.delta-guide li::marker {
    color: var(--muted-2);
}

.delta-guide a {
    color: var(--accent);
    text-decoration-color: rgba(95, 140, 255, 0.45);
    text-underline-offset: 3px;
}

.delta-guide a:hover {
    color: var(--accent-hover);
}

.delta-note,
.delta-tip,
.delta-warning {
    margin: 22px 0;
    padding: 16px 18px;
    border-radius: var(--radius-small);
    background: var(--surface);
    border: 1px solid var(--line);
}

.delta-tip {
    border-left: 3px solid var(--accent);
}

.delta-warning {
    border-left: 3px solid var(--warning);
}

.delta-note p,
.delta-tip p,
.delta-warning p {
    margin: 0;
}

.delta-steps {
    list-style: none;
    padding-left: 0 !important;
    counter-reset: step;
}

.delta-steps > li {
    position: relative;
    min-height: 32px;
    padding-left: 44px;
    margin-bottom: 14px;
}

.delta-steps > li::before {
    counter-increment: step;
    content: counter(step);
    position: absolute;
    left: 0;
    top: 2px;
    width: 28px;
    height: 28px;
    border-radius: 8px;
    background: var(--surface-3);
    border: 1px solid var(--line-strong);
    color: var(--text);
    font-size: 0.78rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
}

.delta-fixes {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
    margin: 20px 0 30px;
}

.delta-fix-card {
    padding: 18px;
    border: 1px solid var(--line);
    border-radius: var(--radius-small);
    background: var(--surface);
}

.delta-fix-card h4 {
    margin-top: 0;
    color: var(--text);
}

.delta-fix-card p:last-child {
    margin-bottom: 0;
}

.delta-faq {
    margin-top: 18px;
}

.delta-faq details {
    border-top: 1px solid var(--line);
    padding: 18px 0;
}

.delta-faq details:last-child {
    border-bottom: 1px solid var(--line);
}

.delta-faq summary {
    cursor: pointer;
    color: var(--text);
    font-size: 1rem;
    font-weight: 650;
    list-style: none;
}

.delta-faq summary::-webkit-details-marker {
    display: none;
}

.delta-faq summary::after {
    content: "+";
    float: right;
    color: var(--muted-2);
    font-size: 1.2rem;
    font-weight: 400;
}

.delta-faq details[open] summary::after {
    content: "−";
}

.delta-faq details p {
    margin-top: 10px;
    margin-bottom: 0;
}

/* OTHER */
.guide-content {
    max-width: 860px;
    margin: 0;
    padding: 24px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
}

.guide-content h3 {
    margin: 24px 0 8px;
    color: var(--text);
    font-size: 1.15rem;
}

.guide-content h3:first-child {
    margin-top: 0;
}

.guide-content ol,
.guide-content ul {
    padding-left: 22px;
    color: var(--muted);
}

.guide-content li {
    margin-bottom: 8px;
}

.faq-content {
    max-width: 860px;
    margin: 0;
}

.faq-item {
    padding: 18px 0;
    border-top: 1px solid var(--line);
}

.faq-item:last-child {
    border-bottom: 1px solid var(--line);
}

.faq-question {
    margin-bottom: 6px;
    color: var(--text);
    font-size: 1rem;
    font-weight: 650;
}

.faq-answer {
    color: var(--muted);
}

footer {
    width: min(1120px, calc(100% - 40px));
    margin: 70px auto 24px;
    padding: 22px 0;
    color: var(--muted-2);
    border-top: 1px solid var(--line);
    text-align: left;
    font-size: 0.88rem;
}

/* POPUPS */
.overlay1 {
    position: fixed;
    inset: 0;
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    visibility: hidden;
    opacity: 0;
    background: rgba(0, 0, 0, 0.72);
    transition: opacity 0.18s ease, visibility 0.18s ease;
}

.overlay1:target {
    visibility: visible;
    opacity: 1;
}

.popup {
    width: min(92vw, 420px);
    padding: 24px;
    position: relative;
    background: var(--surface);
    border: 1px solid var(--line-strong);
    border-radius: var(--radius);
    box-shadow: 0 24px 80px rgba(0, 0, 0, 0.45);
}

.popup h3 {
    margin-bottom: 18px;
    color: var(--text);
    text-align: left;
    font-size: 1.25rem;
}

.popup .close {
    position: absolute;
    top: 16px;
    right: 16px;
    color: var(--muted-2);
    text-decoration: none;
    font-size: 1.4rem;
}

.popup .close:hover {
    color: var(--text);
}

.popup .button1 {
    display: flex;
    width: 100%;
    min-height: 46px;
    padding: 0 14px;
    margin-bottom: 10px;
    align-items: center;
    justify-content: center;
    gap: 8px;
    color: var(--text);
    background: var(--surface-2);
    border: 1px solid var(--line);
    border-radius: 10px;
    text-decoration: none;
    font-size: 0.94rem;
    font-weight: 650;
}

.popup .button1:hover {
    border-color: var(--line-strong);
    background: var(--surface-3);
}

/* MOBILE */
@media (max-width: 800px) {
    .container,
    footer {
        width: min(100% - 28px, 1120px);
    }

    .hero {
        padding: 40px 0 34px;
    }

    .icon {
        width: 80px;
        height: 80px;
        border-radius: 18px;
        margin-bottom: 20px;
    }

    .description {
        font-size: 1rem;
    }

    .buttons {
        flex-direction: column;
        align-items: stretch;
    }

    .button {
        width: 100%;
    }

    .social-container {
        flex-direction: column;
        align-items: stretch;
    }

    .social-button {
        width: 100%;
        justify-content: flex-start;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .delta-guide {
        margin-top: 54px;
    }

    .delta-toc ol {
        columns: 1;
    }

    .delta-fixes {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container,
    footer {
        width: min(100% - 20px, 1120px);
    }

    .hero {
        padding-top: 30px;
    }

    .content-section {
        margin-top: 42px;
    }

    .feature-card {
        padding: 20px;
        min-height: 0;
    }

    .delta-guide h3 {
        font-size: 1.35rem;
    }

    .delta-guide p,
    .delta-guide li {
        font-size: 0.97rem;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        transition: none !important;
        animation: none !important;
    }
}