:root {
    --primary-white: #FFFFFF;
    --secondary-gray: #F4F6F8;
    --dark-navy: #1A253C;
    --euler-blue: #005A9C;
    --euler-sky: #00AEEF;
    --text-main: #2C3E50;
    --text-sub: #5A6268;
    --border-color: #E0E0E0;

    --font-heading: 'Montserrat', sans-serif;
    --font-body: 'Noto Sans KR', sans-serif;
    --font-mono: 'Roboto Mono', monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }
body {
    font-family: var(--font-body);
    margin: 0;
    background-color: var(--primary-white);
    color: var(--text-sub);
    line-height: 1.6;
    overflow-wrap: break-word;
}

/* Korean needs keep-all to prevent breaks within syllable blocks */
:lang(ko) { word-break: keep-all; }

/* Chinese/Japanese break naturally between characters — override keep-all */
:lang(zh), :lang(ja) { word-break: normal; }

h1, h2, h3, h4 {
    font-family: var(--font-heading);
    color: var(--text-main);
    font-weight: 700;
    margin-top: 0;
}

a { text-decoration: none; color: inherit; transition: 0.3s; }
ul { list-style: none; padding: 0; margin: 0; }

/* Layout Utilities */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.section-padding { padding: 100px 0; border-bottom: 1px solid #E9ECEF; }
.bg-light { background-color: var(--secondary-gray); }
.text-center { text-align: center; }

.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 30px; }

/* Header CSS */
header {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    height: 80px;
    display: flex;
    align-items: center;
}

nav {
    display: flex;
    align-items: center;
    width: 100%;
}

.logo {
    display: flex;
    align-items: center;
    margin-right: 60px;
}

.logo img {
    height: 50px;
    width: auto;
    display: block;
}

.nav-links {
    display: flex;
    gap: 25px;
    align-items: center;
}

.nav-links a {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-main);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.nav-links a:hover { color: var(--euler-blue); }

.language-switcher {
    margin-left: auto;
    padding-left: 20px;
    display: flex;
    align-items: center;
}

.language-switcher a {
    margin-left: 15px;
    color: var(--text-sub);
    font-size: 0.85rem;
    font-weight: 500;
}
.language-switcher a.active { color: var(--euler-blue); font-weight: 700; }

/* Hero */
#hero {
    min-height: 90vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, rgba(26, 37, 60, 0.95), rgba(0, 90, 156, 0.8)),
                url('https://images.unsplash.com/photo-1550751827-4bd374c3f58b?q=80&w=2070&auto=format&fit=crop');
    background-size: cover;
    background-position: center;
    color: white;
    text-align: center;
    padding-top: 80px;
}

.hero-title {
    font-size: 3.5rem;
    line-height: 1.2;
    margin-bottom: 20px;
}

.hero-desc {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto 40px;
}

.btn {
    display: inline-block;
    padding: 14px 32px;
    border-radius: 50px;
    font-weight: 600;
    font-family: var(--font-heading);
    margin: 5px;
    transition: 0.3s;
}
.btn-primary { background: var(--euler-sky); color: white; box-shadow: 0 4px 15px rgba(0, 174, 239, 0.3); }
.btn-primary:hover { background: #0090c5; transform: translateY(-2px); }
.btn-outline { border: 2px solid white; color: white; }
.btn-outline:hover { background: white; color: var(--dark-navy); }

/* Sections */
.section-header { margin-bottom: 60px; text-align: center; }
.section-header h2 { font-size: 2.5rem; margin-bottom: 15px; color: var(--dark-navy); }
.section-header p { font-size: 1.1rem; color: var(--text-sub); max-width: 700px; margin: 0 auto; }

.card {
    background: white;
    padding: 30px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    transition: 0.3s;
    height: 100%;
    display: flex;
    flex-direction: column;
}
.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    border-color: var(--euler-blue);
}
.card h3 { color: var(--euler-blue); font-size: 1.3rem; margin-bottom: 15px; }

/* Resource List Styling */
.resource-list {
    margin-top: 10px;
    padding-left: 0;
}
.resource-list li {
    margin-bottom: 12px;
    display: flex;
    align-items: flex-start;
}
.resource-list li::before {
    content: "\2022";
    color: var(--euler-sky);
    font-weight: bold;
    margin-right: 10px;
}
.resource-list a {
    color: var(--text-main);
    font-weight: 500;
    border-bottom: 1px solid transparent;
}
.resource-list a:hover {
    color: var(--euler-blue);
    border-bottom-color: var(--euler-blue);
}

/* Tech Specs Table */
.tech-specs { width: 100%; border-collapse: collapse; margin-top: 20px; font-size: 0.9rem; }
.tech-specs th, .tech-specs td { border: 1px solid #eee; padding: 12px; text-align: left; }
.tech-specs th { background: #f9f9f9; color: var(--dark-navy); width: 30%; }

/* Integration Flow */
.flow-container { display: flex; justify-content: center; gap: 20px; flex-wrap: wrap; margin-top: 40px; }
.flow-step { background: white; padding: 15px 25px; border-radius: 50px; border: 1px solid #E0E0E0; font-weight: 600; color: var(--dark-navy); box-shadow: 0 2px 10px rgba(0,0,0,0.05); }
.flow-arrow { display: flex; align-items: center; color: var(--euler-sky); font-size: 1.5rem; }

/* Terminal/Code Block */
.terminal-block {
    background: #1e1e1e;
    color: #d4d4d4;
    padding: 20px;
    border-radius: 8px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    overflow-x: auto;
    border: 1px solid #333;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    margin-top: 20px;
}
.cmd { color: #ce9178; }
.opt { color: #9cdcfe; }
.comment { color: #6a9955; }

/* Product Detail Page Styles */
.product-hero {
    padding: 120px 0 60px;
    background: linear-gradient(135deg, rgba(26, 37, 60, 0.95), rgba(0, 90, 156, 0.8));
    color: white;
    text-align: center;
}
.product-hero h1 { font-size: 2.8rem; color: #fff; margin-bottom: 15px; }
.product-hero p { font-size: 1.15rem; color: rgba(255,255,255,0.9); max-width: 800px; margin: 0 auto; }
.product-hero .badge {
    display: inline-block;
    background: rgba(0,174,239,0.2);
    border: 1px solid var(--euler-sky);
    color: var(--euler-sky);
    padding: 6px 18px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-top: 15px;
}

/* Tier headers for two-tier layout */
.tier-header {
    padding: 20px 0 10px;
    border-top: 3px solid var(--euler-blue);
    margin-bottom: 40px;
    margin-top: 20px;
}
.tier-header h2 { text-align: left; font-size: 1.8rem; }
.tier-label {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--euler-sky);
    font-weight: 600;
    margin-bottom: 5px;
}

/* Architecture diagram (ASCII art) */
.arch-diagram {
    background: #f8f9fa;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 20px;
    font-family: var(--font-mono);
    font-size: 0.8rem;
    overflow-x: auto;
    line-height: 1.4;
    white-space: pre;
    color: var(--text-main);
}

/* Breadcrumb */
.breadcrumb {
    padding-top: 90px;
    padding-bottom: 10px;
    font-size: 0.85rem;
    color: var(--text-sub);
}
.breadcrumb a { color: var(--euler-blue); }
.breadcrumb a:hover { text-decoration: underline; }

/* Feature list with bullet */
.feature-list { padding-left: 20px; font-size: 0.95rem; }
.feature-list li { margin-bottom: 8px; }

/* Sub-section headers for product pages */
.sub-section { margin-bottom: 50px; }
.sub-section h3 { font-size: 1.5rem; color: var(--dark-navy); margin-bottom: 20px; border-bottom: 2px solid var(--euler-sky); padding-bottom: 10px; display: inline-block; }

/* ================================================================
   Tutorial Page Styles
   ================================================================ */

/* Tutorial content container */
.tutorial-content {
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 24px 80px;
    font-size: 1rem;
    line-height: 1.8;
    color: var(--text-main);
}

.tutorial-content h1 {
    font-size: 2rem;
    margin-bottom: 10px;
    padding-bottom: 15px;
    border-bottom: 3px solid var(--euler-blue);
}

.tutorial-content h2 {
    font-size: 1.6rem;
    margin-top: 50px;
    margin-bottom: 15px;
    padding-bottom: 8px;
    border-bottom: 1px solid var(--border-color);
}

.tutorial-content h3 {
    font-size: 1.3rem;
    margin-top: 35px;
    margin-bottom: 12px;
}

.tutorial-content h4 {
    font-size: 1.1rem;
    margin-top: 25px;
    margin-bottom: 10px;
}

.tutorial-content p {
    margin-bottom: 16px;
}

.tutorial-content ul,
.tutorial-content ol {
    padding-left: 24px;
    margin-bottom: 16px;
}

.tutorial-content ul { list-style: disc; }
.tutorial-content ol { list-style: decimal; }

.tutorial-content li {
    margin-bottom: 6px;
    line-height: 1.7;
}

.tutorial-content li ul,
.tutorial-content li ol {
    margin-top: 6px;
    margin-bottom: 6px;
}

.tutorial-content a {
    color: var(--euler-blue);
    text-decoration: underline;
}
.tutorial-content a:hover {
    color: var(--euler-sky);
}

/* Inline code */
.tutorial-content code {
    background: #f0f4f8;
    padding: 2px 7px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.88em;
    color: #c7254e;
}

/* Code blocks */
.tutorial-content pre {
    background: #1e1e1e;
    color: #d4d4d4;
    padding: 20px;
    border-radius: 8px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    overflow-x: auto;
    border: 1px solid #333;
    margin: 20px 0;
    line-height: 1.5;
}

.tutorial-content pre code {
    background: none;
    padding: 0;
    border-radius: 0;
    color: inherit;
    font-size: inherit;
}

/* Code language label */
.tutorial-content pre[data-lang]::before {
    content: attr(data-lang);
    display: block;
    font-size: 0.75rem;
    color: #888;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Tables */
.tutorial-content table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    font-size: 0.9rem;
}

.tutorial-content table th,
.tutorial-content table td {
    border: 1px solid var(--border-color);
    padding: 10px 14px;
    text-align: left;
}

.tutorial-content table th {
    background: #f4f6f8;
    color: var(--dark-navy);
    font-weight: 600;
}

.tutorial-content table tr:nth-child(even) {
    background: #fafbfc;
}

/* Blockquotes */
.tutorial-content blockquote {
    border-left: 4px solid var(--euler-sky);
    background: #f0f7ff;
    margin: 20px 0;
    padding: 16px 20px;
    border-radius: 0 8px 8px 0;
    color: var(--text-main);
}

.tutorial-content blockquote p:last-child {
    margin-bottom: 0;
}

/* Strong / Bold */
.tutorial-content strong {
    color: var(--dark-navy);
    font-weight: 600;
}

/* Horizontal rule */
.tutorial-content hr {
    border: none;
    border-top: 1px solid var(--border-color);
    margin: 40px 0;
}

/* Tutorial breadcrumb */
.tutorial-breadcrumb {
    padding-top: 90px;
    padding-bottom: 10px;
    font-size: 0.85rem;
    color: var(--text-sub);
    max-width: 900px;
    margin: 0 auto;
    padding-left: 24px;
    padding-right: 24px;
}
.tutorial-breadcrumb a { color: var(--euler-blue); }
.tutorial-breadcrumb a:hover { text-decoration: underline; }

/* Tutorial navigation (prev/next) */
.tutorial-nav {
    max-width: 900px;
    margin: 0 auto;
    padding: 30px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border-color);
}

.tutorial-nav a {
    color: var(--euler-blue);
    font-weight: 600;
    font-size: 0.9rem;
}
.tutorial-nav a:hover {
    color: var(--euler-sky);
}

.tutorial-nav .nav-center {
    color: var(--text-sub);
}

/* Tutorial index page */
.tutorial-index {
    max-width: 900px;
    margin: 0 auto;
    padding: 40px 24px 80px;
}

.tutorial-index h1 {
    font-size: 2rem;
    margin-bottom: 10px;
    color: var(--dark-navy);
}

.tutorial-index .index-desc {
    color: var(--text-sub);
    margin-bottom: 40px;
    font-size: 1.05rem;
}

.tutorial-index h2 {
    font-size: 1.4rem;
    color: var(--dark-navy);
    margin-top: 40px;
    margin-bottom: 20px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--euler-sky);
    display: inline-block;
}

.tutorial-list {
    list-style: none;
    padding: 0;
    margin: 0 0 30px;
}

.tutorial-list li {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 10px;
    transition: 0.3s;
}

.tutorial-list li:hover {
    border-color: var(--euler-blue);
    box-shadow: 0 4px 12px rgba(0,0,0,0.06);
}

.tutorial-list li a {
    display: block;
    padding: 16px 20px;
    color: var(--text-main);
    text-decoration: none;
}

.tutorial-list li a strong {
    color: var(--euler-blue);
    display: block;
    margin-bottom: 4px;
    font-size: 1.05rem;
}

.tutorial-list li a span {
    color: var(--text-sub);
    font-size: 0.9rem;
}

/* Tutorial card link styling */
.card-link {
    text-decoration: none;
    color: inherit;
    display: block;
    height: 100%;
}
.card-link .card {
    cursor: pointer;
}

@media (max-width: 768px) {
    .nav-links { display: none; }
    .grid-2 { grid-template-columns: 1fr; }
    .hero-title { font-size: 2.5rem; }
    .product-hero h1 { font-size: 2rem; }
    .flow-container { flex-direction: column; align-items: center; }
    .flow-arrow { transform: rotate(90deg); }
    .tutorial-content h1 { font-size: 1.6rem; }
    .tutorial-content h2 { font-size: 1.3rem; }
    .tutorial-content pre { font-size: 0.78rem; padding: 14px; }
    .tutorial-nav { flex-direction: column; gap: 10px; }
}