/* Gehihi — Modern Clean Light SaaS / AI Design System */

:root {
    --bg: #f8fafc;
    --bg-surface: #ffffff;
    --bg-surface-subtle: #f1f5f9;
    --bg-surface-muted: #e2e8f0;
    --bg-glass: rgba(255, 255, 255, 0.85);
    
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    
    --border-subtle: #e2e8f0;
    --border-hover: #cbd5e1;
    --border-highlight: rgba(99, 102, 241, 0.35);
    
    --brand-coral: #ff5a36;
    --brand-coral-hover: #e04523;
    --brand-coral-glow: rgba(255, 90, 54, 0.28);
    --brand-coral-subtle: #fff1ee;
    --brand-coral-border: #ffd2c7;
    
    --ai-indigo: #4f46e5;
    --ai-cyan: #0891b2;
    --ai-emerald: #059669;
    --ai-amber: #d97706;
    --ai-purple: #7c3aed;
    
    --grad-brand: linear-gradient(135deg, #ff6e4a 0%, #ff5a36 60%, #e11d48 100%);
    --grad-ai: linear-gradient(135deg, #0284c7 0%, #6366f1 50%, #9333ea 100%);
    --grad-text: linear-gradient(180deg, #0f172a 0%, #334155 100%);
    --grad-card: linear-gradient(180deg, #ffffff 0%, #fafbfc 100%);
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-card: 0 1px 3px 0 rgba(0, 0, 0, 0.04), 0 4px 12px -2px rgba(0, 0, 0, 0.05);
    --shadow-card-hover: 0 12px 28px -4px rgba(0, 0, 0, 0.08), 0 4px 10px -2px rgba(0, 0, 0, 0.04);
    
    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 20px;
    --radius-xl: 26px;
    --radius-pill: 9999px;
    
    color-scheme: light;
}

*, *::before, *::after {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    scroll-padding-top: 88px;
    background-color: var(--bg);
}

body {
    margin: 0;
    background-color: var(--bg);
    color: var(--text-primary);
    font: 400 16px/1.65 "Be Vietnam Pro", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-image:
        radial-gradient(circle at 50% -120px, rgba(99, 102, 241, 0.08), transparent 700px),
        radial-gradient(circle at 90% 250px, rgba(56, 189, 248, 0.08), transparent 500px),
        radial-gradient(circle at 10% 650px, rgba(255, 90, 54, 0.06), transparent 450px),
        radial-gradient(rgba(15, 23, 42, 0.05) 1px, transparent 1px);
    background-size: 100% 100%, 100% 100%, 100% 100%, 28px 28px;
    background-repeat: no-repeat, no-repeat, no-repeat, repeat;
    min-height: 100vh;
}

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

a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s ease, opacity 0.2s ease;
}

h1, h2, h3, h4 {
    line-height: 1.18;
    letter-spacing: -0.025em;
    margin: 0 0 0.5em;
    color: var(--text-primary);
    font-weight: 700;
}

h1 {
    font-size: clamp(2.4rem, 5.5vw, 4.2rem);
    font-weight: 800;
    letter-spacing: -0.035em;
}

h2 {
    font-size: clamp(1.8rem, 3.4vw, 2.7rem);
    font-weight: 800;
    letter-spacing: -0.03em;
}

h3 {
    font-size: 1.25rem;
    font-weight: 700;
}

p {
    margin: 0 0 1em;
}

mark {
    background: var(--grad-brand);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    padding: 0;
    font-weight: 800;
}

:focus-visible {
    outline: 2px solid var(--brand-coral);
    outline-offset: 3px;
    border-radius: 6px;
}

/* Layout Utilities */
.container {
    width: min(1180px, 100% - 40px);
    margin-inline: auto;
}

.narrow {
    width: min(800px, 100% - 40px);
}

.section {
    padding: clamp(64px, 10vw, 116px) 0;
    position: relative;
}

.section-head {
    max-width: 680px;
    margin-bottom: 48px;
}

.eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 14px;
    border-radius: var(--radius-pill);
    background: var(--brand-coral-subtle);
    border: 1px solid var(--brand-coral-border);
    color: #c23315;
    font-size: 0.82rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    margin-bottom: 1.2em;
    box-shadow: 0 1px 3px rgba(255, 90, 54, 0.08);
}

.skip-link {
    position: absolute;
    left: -999px;
    top: 12px;
    background: var(--brand-coral);
    color: #ffffff;
    padding: 10px 18px;
    border-radius: var(--radius-sm);
    z-index: 100;
    font-weight: 600;
}

.skip-link:focus {
    left: 16px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5em;
    padding: 0.85em 1.6em;
    border-radius: var(--radius-pill);
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    border: 1px solid transparent;
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    white-space: nowrap;
}

.btn-primary {
    background: var(--grad-brand);
    color: #ffffff;
    border-color: transparent;
    box-shadow: 0 4px 14px var(--brand-coral-glow), inset 0 1px 0 rgba(255, 255, 255, 0.25);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(255, 90, 54, 0.4), inset 0 1px 0 rgba(255, 255, 255, 0.35);
    filter: brightness(1.03);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-ghost {
    background: #ffffff;
    color: var(--text-primary);
    border: 1px solid var(--border-subtle);
    box-shadow: var(--shadow-sm);
}

.btn-ghost:hover {
    background: #f8fafc;
    border-color: var(--border-hover);
    color: #0f172a;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

.btn-small {
    padding: 0.55em 1.15em;
    font-size: 0.9rem;
}

.text-link {
    font-weight: 600;
    color: var(--brand-coral);
    display: inline-flex;
    align-items: center;
    gap: 4px;
    text-underline-offset: 4px;
    transition: all 0.2s ease;
}

.text-link:hover {
    color: var(--brand-coral-hover);
    transform: translateX(3px);
}

/* Header */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(15, 23, 42, 0.08);
    transition: background 0.3s ease;
}

.header-inner {
    display: flex;
    align-items: center;
    gap: 32px;
    height: 72px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    font-weight: 800;
    font-size: 1.35rem;
    color: var(--text-primary);
    letter-spacing: -0.02em;
}

.brand img {
    filter: drop-shadow(0 2px 8px var(--brand-coral-glow));
    transition: transform 0.3s ease;
}

.brand:hover img {
    transform: rotate(-6deg) scale(1.08);
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 28px;
    margin-left: auto;
}

.site-nav a {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--text-secondary);
    padding: 6px 14px;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease;
}

.site-nav a:hover {
    color: var(--text-primary);
    background: rgba(15, 23, 42, 0.05);
}

/* Hero Section */
.hero {
    padding: clamp(48px, 8vw, 96px) 0 clamp(64px, 10vw, 108px);
    position: relative;
}

.hero-grid {
    display: grid;
    grid-template-columns: 1.12fr 1fr;
    gap: clamp(36px, 6vw, 72px);
    align-items: center;
}

.lead {
    font-size: 1.2rem;
    color: var(--text-secondary);
    max-width: 36em;
    line-height: 1.7;
    margin-bottom: 0;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    margin: 32px 0 18px;
}

.hero-note {
    font-size: 0.9rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Chat Demo Window */
.chat-demo {
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    box-shadow:
        0 20px 45px -10px rgba(15, 23, 42, 0.1),
        0 4px 16px -2px rgba(15, 23, 42, 0.04),
        0 0 0 1px rgba(15, 23, 42, 0.04);
    padding: 0 22px 24px;
    display: grid;
    gap: 14px;
    position: relative;
    overflow: hidden;
}

.chat-bar {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 0 -22px 6px;
    padding: 14px 22px;
    background: #fafbfc;
    border-bottom: 1px solid var(--border-subtle);
    font-size: 0.85rem;
}

.chat-bar span {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    display: inline-block;
}

.chat-bar span:nth-child(1) { background: #ff5f56; }
.chat-bar span:nth-child(2) { background: #ffbd2e; }
.chat-bar span:nth-child(3) { background: #27c93f; }

.chat-bar b {
    margin-left: auto;
    font-weight: 500;
    color: var(--text-secondary);
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: #ffffff;
    padding: 4px 12px;
    border-radius: var(--radius-pill);
    border: 1px solid var(--border-subtle);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.03);
}

.chat-bar b::before {
    content: "";
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--ai-emerald);
}

.bubble {
    max-width: 90%;
    padding: 14px 18px;
    border-radius: var(--radius-lg);
    font-size: 0.95rem;
    line-height: 1.55;
    position: relative;
}

.bubble small {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 0.74rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 6px;
}

.bubble-user {
    justify-self: end;
    background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
    color: #ffffff;
    border-bottom-right-radius: 4px;
    box-shadow: 0 4px 14px rgba(37, 99, 235, 0.25);
}

.bubble-ai {
    background: #f8fafc;
    border: 1px solid var(--border-subtle);
    border-bottom-left-radius: 4px;
    color: var(--text-primary);
}

.bubble-ai small {
    color: var(--ai-indigo);
}

.bubble-ai.is-off {
    background: #fff1f2;
    border: 1px solid #fecdd3;
    color: #9f1239;
    text-decoration: line-through wavy rgba(244, 63, 94, 0.5);
}

.bubble-ai.is-off small {
    color: #e11d48;
}

.switcher {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px;
    padding: 10px 14px;
    background: #f8fafc;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-pill);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.chip {
    border-radius: var(--radius-pill);
    padding: 3px 12px;
    font-weight: 600;
    font-size: 0.82rem;
    transition: all 0.2s ease;
    cursor: default;
}

.chip:nth-of-type(1) {
    background: #fffbeb;
    border: 1px solid #fde68a;
    color: #b45309;
}

.chip:nth-of-type(2) {
    background: #ecfdf5;
    border: 1px solid #a7f3d0;
    color: #047857;
}

.chip:nth-of-type(3) {
    background: #eef2ff;
    border: 1px solid #c7d2fe;
    color: #4338ca;
}

.chip:nth-of-type(4) {
    background: #ecfeff;
    border: 1px solid #a5f3fc;
    color: #0e7490;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.feature {
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-card);
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.feature:hover {
    transform: translateY(-4px);
    border-color: var(--border-hover);
    box-shadow: var(--shadow-card-hover);
}

.feature h3 {
    margin-bottom: 10px;
    color: var(--text-primary);
}

.feature p {
    color: var(--text-secondary);
    margin: 0;
    font-size: 0.95rem;
    line-height: 1.65;
}

.feature-icon {
    display: inline-grid;
    place-items: center;
    width: 52px;
    height: 52px;
    border-radius: 16px;
    background: #f8fafc;
    border: 1px solid var(--border-subtle);
    font-size: 1.55rem;
    margin-bottom: 20px;
    box-shadow: var(--shadow-sm);
}

/* Meme / Philosophy Section */
.meme {
    background: #f1f5f9;
    border-top: 1px solid var(--border-subtle);
    border-bottom: 1px solid var(--border-subtle);
    position: relative;
    overflow: hidden;
}

.meme-grid {
    display: grid;
    grid-template-columns: 1fr 1.25fr;
    gap: clamp(40px, 6vw, 84px);
    align-items: center;
    position: relative;
    z-index: 1;
}

.dict-card {
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    padding: 36px;
    box-shadow: 0 15px 35px -5px rgba(15, 23, 42, 0.08);
    position: relative;
    transition: transform 0.3s ease;
}

.dict-card:hover {
    transform: translateY(-3px);
}

.dict-word {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    color: var(--brand-coral);
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 8px;
    margin-bottom: 14px;
}

.dict-word i {
    font-size: 0.95rem;
    font-weight: 500;
    color: #c23315;
    font-style: normal;
    background: var(--brand-coral-subtle);
    padding: 2px 10px;
    border-radius: var(--radius-pill);
    border: 1px solid var(--brand-coral-border);
}

.dict-card p {
    color: var(--text-secondary);
    line-height: 1.65;
}

.dict-example {
    font-style: italic;
    color: var(--text-primary) !important;
    background: #f8fafc;
    border-left: 3px solid var(--brand-coral);
    padding: 12px 16px;
    border-radius: 0 10px 10px 0;
    margin: 18px 0 0 !important;
}

.meme p {
    color: var(--text-secondary);
    line-height: 1.7;
}

/* Steps Section */
.steps {
    list-style: none;
    counter-reset: step;
    padding: 0;
    margin: 0;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.steps li {
    counter-increment: step;
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 32px 28px;
    color: var(--text-secondary);
    box-shadow: var(--shadow-card);
    position: relative;
    transition: all 0.3s ease;
}

.steps li:hover {
    transform: translateY(-3px);
    border-color: var(--border-hover);
    box-shadow: var(--shadow-card-hover);
}

.steps li::before {
    content: counter(step, decimal-leading-zero);
    display: block;
    font-size: 2.2rem;
    font-weight: 800;
    background: var(--grad-brand);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    line-height: 1;
    margin-bottom: 16px;
}

.steps b {
    display: block;
    color: var(--text-primary);
    font-size: 1.2rem;
    margin-bottom: 8px;
}

/* FAQ Section */
.faq {
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    margin-bottom: 14px;
    box-shadow: var(--shadow-sm);
    transition: all 0.25s ease;
    overflow: hidden;
}

.faq:hover {
    border-color: var(--border-hover);
}

.faq[open] {
    border-color: #c7d2fe;
    box-shadow: 0 4px 16px rgba(99, 102, 241, 0.08);
}

.faq summary {
    cursor: pointer;
    list-style: none;
    padding: 22px 48px 22px 24px;
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-primary);
    position: relative;
    transition: color 0.2s ease;
}

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

.faq summary::after {
    content: "+";
    position: absolute;
    right: 24px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 1.6rem;
    font-weight: 400;
    color: var(--ai-indigo);
    transition: transform 0.25s ease, color 0.25s ease;
    line-height: 1;
}

.faq[open] summary::after {
    transform: translateY(-50%) rotate(45deg);
    color: var(--brand-coral);
}

.faq p {
    color: var(--text-secondary);
    padding: 0 24px 22px;
    line-height: 1.7;
    margin: 0;
}

/* CTA Band */
.cta-band {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 32px;
    background: linear-gradient(135deg, #fff7ed 0%, #f0fdf4 40%, #eef2ff 100%);
    border: 1px solid #fed7aa;
    border-radius: var(--radius-xl);
    padding: clamp(36px, 6vw, 64px);
    margin-bottom: clamp(64px, 10vw, 110px);
    box-shadow: 0 20px 45px -10px rgba(255, 90, 54, 0.12);
    position: relative;
    overflow: hidden;
}

.cta-band h2 {
    margin-bottom: 0.25em;
    color: var(--text-primary);
}

.cta-band p {
    margin: 0;
    color: var(--text-secondary);
    font-size: 1.15rem;
}

/* Article Page */
.article {
    max-width: 800px;
    padding: 40px 0 90px;
}

.breadcrumb ol {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 0;
    margin: 0 0 36px;
    font-size: 0.92rem;
    color: var(--text-muted);
}

.breadcrumb li + li::before {
    content: "/";
    margin-right: 10px;
    color: var(--border-hover);
}

.breadcrumb a:hover {
    color: var(--text-primary);
}

.article-meta {
    color: var(--text-muted);
    font-size: 0.92rem;
    margin-top: 12px;
}

.answer-box {
    background: #fff7ed;
    border: 1px solid #fed7aa;
    border-left: 5px solid var(--brand-coral);
    border-radius: var(--radius-md);
    padding: 24px 28px;
    margin: 32px 0 44px;
    font-size: 1.12rem;
    color: var(--text-primary);
    line-height: 1.7;
    box-shadow: 0 4px 16px rgba(255, 90, 54, 0.08);
}

.answer-box p {
    margin: 0;
}

.answer-box b {
    color: var(--text-primary);
}

.prose h2 {
    font-size: 1.75rem;
    margin-top: 2em;
    margin-bottom: 0.6em;
    color: var(--text-primary);
}

.prose p {
    color: var(--text-secondary);
    font-size: 1.05rem;
    line-height: 1.75;
}

.prose ul {
    color: var(--text-secondary);
    line-height: 1.75;
    padding-left: 1.4em;
}

.prose li {
    margin-bottom: 10px;
}

.prose b {
    color: var(--text-primary);
}

.prose a:not(.btn) {
    color: var(--brand-coral);
    text-underline-offset: 4px;
    text-decoration: underline;
    transition: color 0.2s ease;
}

.prose a:not(.btn):hover {
    color: var(--brand-coral-hover);
}

.prose .btn {
    margin-right: 16px;
    margin-top: 12px;
}

.article-faq {
    margin-top: 64px;
}

.article-faq h2, .sources h2 {
    font-size: 1.5rem;
    margin-bottom: 20px;
}

.sources {
    margin-top: 56px;
    padding-top: 28px;
    border-top: 1px solid var(--border-subtle);
    font-size: 0.92rem;
    color: var(--text-muted);
}

.sources ul {
    padding-left: 1.2em;
}

.sources li {
    margin-bottom: 8px;
}

.sources a {
    color: var(--text-secondary);
}

.sources a:hover {
    color: var(--brand-coral);
}

/* Site Footer */
.site-footer {
    border-top: 1px solid var(--border-subtle);
    padding: 64px 0 32px;
    font-size: 0.95rem;
    background: #f1f5f9;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 48px;
}

.footer-description {
    color: var(--text-secondary);
    margin-top: 14px;
    max-width: 34em;
    line-height: 1.65;
}

.footer-links {
    display: grid;
    align-content: start;
    gap: 12px;
}

.footer-links h2 {
    font-size: 0.82rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    margin: 0 0 6px;
    font-weight: 700;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: var(--brand-coral);
}

.footer-bottom {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
    margin-top: 48px;
    padding-top: 24px;
    border-top: 1px solid var(--border-subtle);
    font-size: 0.85rem;
    color: var(--text-muted);
}

.footer-bottom p {
    margin: 0;
    max-width: 48em;
    line-height: 1.6;
}

.footer-bottom a {
    color: var(--text-secondary);
    padding: 6px 14px;
    background: #ffffff;
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-pill);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease;
}

.footer-bottom a:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
    background: #ffffff;
}

/* Responsive */
@media (max-width: 960px) {
    .hero-grid, .meme-grid, .footer-grid {
        grid-template-columns: 1fr;
    }
    .feature-grid, .steps {
        grid-template-columns: 1fr;
    }
    .site-nav {
        display: none;
    }
    .header-inner .btn {
        margin-left: auto;
    }
    .chat-demo {
        padding: 0 16px 20px;
    }
    .chat-bar {
        margin: 0 -16px 6px;
        padding: 12px 16px;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }
    .btn, .feature, .dict-card, .steps li {
        transition: none;
    }
}