:root {
    --bg: #f8fafc;
    --card: #ffffff;
    --panel: #f8fafc;
    --text: #0f172a;
    --muted: #64748b;
    --line: #dbe4ee;
    --line-strong: #cbd5e1;
    --primary: #0f766e;
    --primary-hover: #115e59;
    --accent-soft: #e0f2fe;
    --accent-strong: #dbeafe;
    --shadow: 0 18px 48px rgba(15, 23, 42, 0.07);
    --radius: 24px;
    --radius-sm: 18px;
}

* {
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

img {
    max-width: 100%;
    display: block;
}

a {
    color: var(--primary);
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

.container {
    width: min(100% - 32px, 1180px);
    margin: 24px auto;
    padding: 28px;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 36px;
    box-shadow: var(--shadow);
}

.site-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    padding: 0 0 28px;
    margin-bottom: 24px;
    border-bottom: 1px solid var(--line);
}

.header-logo {
    display: inline-flex;
    align-items: center;
    flex: 0 0 auto;
}

.header-logo:hover {
    text-decoration: none;
}

.header-logo-image {
    width: 340px;
    height: auto;
}

.top-nav {
    display: flex;
    gap: 22px;
    flex-wrap: wrap;
    align-items: center;
}

.nav-item {
    position: relative;
}

.top-nav a,
.nav-link {
    display: inline-flex;
    align-items: center;
    color: var(--muted);
    font-weight: 600;
    font-size: 0.96rem;
}

.top-nav a:hover,
.nav-link:hover,
.nav-dropdown:focus-within .nav-link,
.nav-dropdown:hover .nav-link {
    color: var(--text);
    text-decoration: none;
}

.nav-toggle::after {
    content: "";
    width: 7px;
    height: 7px;
    border-right: 2px solid currentColor;
    border-bottom: 2px solid currentColor;
    transform: rotate(45deg) translateY(-1px);
}

.nav-dropdown summary {
    list-style: none;
    cursor: pointer;
    gap: 8px;
}

.nav-dropdown summary::-webkit-details-marker {
    display: none;
}

.nav-menu {
    position: absolute;
    top: calc(100% + 10px);
    left: 0;
    min-width: 240px;
    max-height: 360px;
    overflow-y: auto;
    padding: 10px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: var(--card);
    box-shadow: 0 14px 28px rgba(15, 23, 42, 0.12);
    display: none;
    z-index: 20;
}

.nav-dropdown[open] .nav-menu {
    display: grid;
    gap: 2px;
}

.nav-menu a {
    display: block;
    padding: 10px 12px;
    border-radius: 12px;
    color: var(--muted);
    font-size: 0.92rem;
    font-weight: 600;
    white-space: nowrap;
}

.nav-menu a:hover,
.nav-menu a:focus-visible {
    background: var(--panel);
    color: var(--text);
    text-decoration: none;
}

.hero {
    margin-bottom: 24px;
    padding: 36px 38px;
    border: 1px solid var(--line);
    border-radius: 28px;
    background:
        radial-gradient(circle at top right, var(--accent-soft), transparent 28%),
        var(--panel);
}

.hero h1 {
    margin: 0 0 12px;
    font-size: clamp(1.45rem, 2.3vw, 1.9rem);
    line-height: 1.16;
    letter-spacing: -0.03em;
    max-width: 18ch;
}

.eyebrow {
    margin: 0 0 10px;
    color: var(--primary);
    font-size: 0.8rem;
    font-weight: 800;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

.lead {
    margin: 0;
    color: var(--muted);
    font-size: 0.92rem;
    max-width: 96ch;
}

.breadcrumbs {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    align-items: center;
    color: var(--muted);
    font-size: 0.92rem;
    margin-bottom: 18px;
}

.card,
.converter-box {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: var(--radius);
    box-shadow: none;
}

.card {
    padding: 24px;
    margin-top: 22px;
}

.card h2 {
    margin-top: 0;
    margin-bottom: 14px;
    font-size: 1.08rem;
    line-height: 1.25;
}

.error-hero {
    max-width: 720px;
}

.error-card {
    margin-top: 20px;
}

.queue-card p {
    margin: 0 0 12px;
}

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

.grid-cards {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px;
}

.search-card {
    margin-top: 20px;
    background: var(--panel);
}

.search-form {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 14px;
    align-items: end;
}

.search-label {
    display: block;
    grid-column: 1 / -1;
    font-weight: 700;
}

.search-input {
    width: 100%;
    padding: 15px 18px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    font: inherit;
}

.search-helper {
    margin: 12px 0 0;
    color: var(--muted);
    font-size: 0.95rem;
}

.converter-box {
    padding: 34px 28px;
    margin-top: 22px;
    text-align: center;
    background: var(--panel);
}

.file-label {
    display: block;
    font-weight: 700;
    margin-bottom: 12px;
}

.drop-copy,
.trust-copy {
    margin: 12px auto 0;
    max-width: 560px;
    color: var(--muted);
    font-size: 0.95rem;
}

.trust-grid {
    display: grid;
    gap: 6px;
    margin-top: 10px;
}

input[type="file"] {
    display: block;
    width: 100%;
    max-width: 420px;
    margin: 0 auto 18px;
    padding: 14px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
}

.contact-form {
    display: grid;
    gap: 12px;
}

.contact-label {
    font-weight: 700;
}

.contact-form input,
.contact-form textarea {
    width: 100%;
    padding: 15px 18px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    color: var(--text);
    font: inherit;
}

.contact-form textarea {
    resize: vertical;
    min-height: 160px;
}

.text-converter-form {
    display: grid;
    gap: 18px;
}

.text-converter-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
}

.json-diff-merge-grid {
    align-items: start;
}

.text-pane-full-span {
    grid-column: 1 / -1;
}

.paired-pane-toolbar {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.tool-field-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 18px;
    margin-bottom: 18px;
}

.tool-field-input {
    width: 100%;
    padding: 15px 18px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    color: var(--text);
    font: inherit;
}

.tool-field-textarea {
    min-height: 112px;
}

.text-pane-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 10px;
    flex-wrap: nowrap;
}

.text-pane-header > .search-label {
    margin: 0;
    flex: 1 1 auto;
    min-width: 0;
}

.text-pane-actions {
    display: flex;
    gap: 10px;
    flex-wrap: nowrap;
    align-items: center;
    justify-content: flex-end;
    flex: 0 0 auto;
}

.line-number-toggle {
    white-space: nowrap;
}

@media (max-width: 720px) {
    .text-pane-header {
        flex-wrap: wrap;
    }

    .text-pane-actions {
        flex-wrap: wrap;
    }
}

.text-converter-textarea {
    width: 100%;
    min-height: 320px;
    padding: 16px 18px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    color: var(--text);
    font: 0.95rem/1.5 "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
    resize: vertical;
    white-space: pre;
}

.text-editor-shell {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    overflow: hidden;
}

.text-editor-shell.line-numbers-disabled {
    grid-template-columns: minmax(0, 1fr);
}

.text-editor-shell.line-numbers-disabled .text-editor-line-numbers {
    display: none;
}

.text-editor-line-numbers {
    min-width: 56px;
    padding: 16px 12px;
    border-right: 1px solid var(--line);
    background: var(--panel);
    color: var(--muted);
    font: 0.95rem/1.5 "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
    text-align: right;
    white-space: pre;
    overflow: hidden;
    user-select: none;
}

.text-converter-textarea-lined {
    min-height: 320px;
    padding-left: 16px;
    border: 0;
    border-radius: 0;
    resize: vertical;
}

.text-editor-shell.line-numbers-disabled .text-converter-textarea-lined {
    padding-left: 18px;
}

.line-number-toggle {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--muted);
    font-size: 0.92rem;
    cursor: pointer;
    user-select: none;
}

.line-number-toggle input {
    margin: 0;
}

.markdown-preview-card {
    margin-top: 18px;
}

.markdown-preview-surface {
    min-height: 180px;
    padding: 18px;
    border: 1px solid var(--line);
    border-radius: 18px;
    background: var(--panel);
    overflow-x: auto;
}

.markdown-preview-surface:empty::before {
    content: "Rendered markdown preview will appear here.";
    color: var(--muted);
}

.markdown-preview-surface h1,
.markdown-preview-surface h2,
.markdown-preview-surface h3 {
    margin-top: 0;
    line-height: 1.2;
}

.markdown-preview-surface pre {
    padding: 14px;
    border-radius: 14px;
    background: #e8eef5;
    overflow-x: auto;
}

.markdown-preview-surface code {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

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

.regex-tester-form {
    display: grid;
    gap: 18px;
}

.regex-controls {
    display: grid;
    grid-template-columns: minmax(0, 1fr) 180px auto;
    gap: 14px;
    align-items: end;
}

.regex-actions {
    justify-content: flex-start;
}

.cron-generator-form {
    display: grid;
    gap: 18px;
}

.cron-generator-grid {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 14px;
}

.cron-actions {
    justify-content: flex-start;
}

.text-converter-error {
    color: #b91c1c;
}

.unit-converter-box {
    text-align: left;
}

.unit-converter-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.3fr) minmax(0, 1fr) auto minmax(0, 1fr);
    gap: 16px;
    align-items: end;
}

.unit-field {
    min-width: 0;
}

.unit-field select,
.unit-field input {
    width: 100%;
}

.unit-field select {
    padding: 15px 18px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    color: var(--text);
    font: inherit;
}

.unit-swap {
    display: flex;
    align-items: end;
}

.unit-actions {
    margin-top: 18px;
}

.unit-result {
    margin-top: 16px;
    color: var(--text);
    font-size: 1.02rem;
}

.unit-topic-grid .card p {
    margin-bottom: 0;
}

.unit-example-copy {
    color: var(--muted);
}

.primary-button {
    display: inline-block;
    padding: 15px 24px;
    border: 0;
    border-radius: 18px;
    background: var(--primary);
    color: #fff;
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    transition: background .15s ease, transform .15s ease;
}

.primary-button:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
}

.secondary-button {
    display: inline-block;
    padding: 15px 24px;
    border: 1px solid var(--line-strong);
    border-radius: 18px;
    background: #fff;
    color: var(--text);
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    transition: border-color .15s ease, transform .15s ease;
}

.secondary-button:hover {
    border-color: var(--primary);
    transform: translateY(-1px);
}

.cookie-banner {
    position: fixed;
    inset: auto 20px 20px auto;
    z-index: 40;
}

.cookie-banner-card {
    width: min(100vw - 40px, 420px);
    padding: 18px 20px;
    border: 1px solid var(--line);
    border-radius: 24px;
    background: rgba(255, 255, 255, 0.98);
    box-shadow: 0 20px 40px rgba(15, 23, 42, 0.18);
    backdrop-filter: blur(8px);
}

.cookie-banner-title {
    margin: 0 0 8px;
    font-size: 1rem;
    font-weight: 800;
}

.cookie-banner-copy {
    margin: 0;
    color: var(--muted);
    font-size: 0.94rem;
}

.cookie-banner-actions {
    display: flex;
    gap: 12px;
    margin-top: 16px;
    flex-wrap: wrap;
}

.status {
    min-height: 24px;
    margin: 14px 0 0;
    color: var(--muted);
    font-weight: 600;
}

.guide-date-note {
    color: var(--muted);
    font-size: 0.95rem;
}

.link-list,
.feature-list,
.steps {
    margin: 0;
    padding-left: 20px;
}

.link-list li,
.feature-list li,
.steps li {
    margin: 8px 0;
}

.site-footer {
    margin-top: 32px;
    padding-top: 24px;
    border-top: 1px solid var(--line);
    color: var(--muted);
    font-size: 0.95rem;
}

.footer-menu {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin-bottom: 10px;
}

.footer-menu a {
    color: var(--muted);
    display: inline-flex;
    align-items: center;
    font-weight: 600;
    font-size: 0.96rem;
    text-decoration: none;
}

.footer-menu a:hover,
.footer-menu a:focus-visible {
    color: var(--text);
}

.site-footer-note {
    margin: 0 0 10px;
}

.site-footer-note a {
    color: var(--text);
    font-weight: 600;
}

.site-footer-note a:hover,
.site-footer-note a:focus-visible {
    color: var(--accent);
}

.faq-list {
    display: grid;
    gap: 12px;
}

.faq-item {
    border: 1px solid var(--line);
    border-radius: 18px;
    padding: 14px 16px;
    background: var(--panel);
}

.faq-item summary {
    cursor: pointer;
    font-weight: 700;
}

.faq-item p {
    margin: 12px 0 0;
}

@media (max-width: 720px) {
    .page-shell {
        width: min(100% - 16px, 920px);
        grid-template-columns: 1fr;
    }

    .side-ad {
        display: none;
    }

    .grid-cards,
    .search-form,
    .tool-field-grid,
    .unit-converter-grid,
    .regex-controls,
    .cron-generator-grid {
        grid-template-columns: 1fr;
    }

    .text-converter-grid {
        grid-template-columns: 1fr;
    }

    .json-diff-merge-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .unit-swap {
        align-items: stretch;
    }

    .hero {
        padding: 28px 24px;
    }
}

@media (max-width: 640px) {
    .container {
        width: min(100% - 24px, 1180px);
        margin: 12px auto;
        padding: 20px;
        border-radius: 28px;
    }

    .site-header {
        align-items: flex-start;
        flex-direction: column;
        padding-bottom: 20px;
    }

    .header-logo-image {
        width: 250px;
    }

    .top-nav {
        gap: 14px;
    }

    .json-diff-merge-grid {
        grid-template-columns: 1fr;
    }

    .footer-menu {
        gap: 12px;
    }

    .cookie-banner {
        inset: auto 12px 12px 12px;
    }

    .cookie-banner-card {
        width: 100%;
        padding: 16px;
    }

    .nav-menu {
        left: 0;
        right: auto;
    }

    .converter-box,
    .card {
        padding: 18px;
    }

    .hero h1 {
        max-width: none;
    }
}