/* Shift AI — design system & site styles. No external fonts or CDNs. */

:root {
	color-scheme: light;
	/* surfaces */
	--c-bg: #f7f8fc;
	--c-bg-soft: #eef1f8;
	--c-surface: #ffffff;
	--c-surface-2: #f9fafc;
	--c-surface-3: #f3f5fa;
	--c-line: #e4e8f0;
	--c-line-strong: #c8cfe0;
	/* text */
	--c-text: #151926;
	--c-muted: #586174;
	--c-faint: #8c95a8;
	/* brand */
	--c-primary: #3355e8;
	--c-primary-d: #2742c4;
	--c-primary-l: #5b78f0;
	--c-primary-soft: rgba(51, 85, 232, .08);
	--c-primary-soft-2: rgba(51, 85, 232, .04);
	--c-accent: #0ea594;
	--c-accent-d: #0b8a7c;
	--c-accent-soft: rgba(14, 165, 148, .10);
	/* semantic */
	--c-danger: #d13b3b;
	--c-danger-bg: #fef0f0;
	--c-danger-fg: #a52020;
	--c-danger-line: #f3c6c6;
	--c-warn: #b07400;
	--c-warn-bg: #fef8e8;
	--c-warn-fg: #8a5a00;
	--c-warn-line: #f0dca8;
	--c-ok: #0f7a4a;
	--c-ok-bg: #eaf7f0;
	--c-ok-fg: #0d6b41;
	--c-sat: #2f5bea;
	--c-sun: #c0392b;
	/* shape */
	--r-sm: 8px;
	--r-md: 12px;
	--r-lg: 16px;
	--r-xl: 20px;
	--shadow-xs: 0 1px 2px rgba(15, 23, 42, .04);
	--shadow-1: 0 1px 3px rgba(15, 23, 42, .05), 0 1px 2px rgba(15, 23, 42, .03);
	--shadow-2: 0 4px 12px rgba(15, 23, 42, .06), 0 1px 4px rgba(15, 23, 42, .04);
	--shadow-3: 0 20px 50px rgba(15, 23, 42, .14), 0 8px 20px rgba(15, 23, 42, .06);
	--shadow-glow: 0 0 0 3px var(--c-primary-soft);
	--font: system-ui, -apple-system, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic UI", Meiryo, sans-serif;
	--mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
	--ease: cubic-bezier(.22, 1, .36, 1);
	--dur: .2s;
}

@media (prefers-color-scheme: dark) {
	:root {
		color-scheme: dark;
		--c-bg: #0d1219;
		--c-bg-soft: #131a26;
		--c-surface: #171f2d;
		--c-surface-2: #1c2536;
		--c-surface-3: #212b3e;
		--c-line: #283348;
		--c-line-strong: #384862;
		--c-text: #e8ecf4;
		--c-muted: #a0aabe;
		--c-faint: #788399;
		--c-primary: #6f8dff;
		--c-primary-d: #8aa2ff;
		--c-primary-l: #5674e8;
		--c-primary-soft: rgba(111, 141, 255, .14);
		--c-primary-soft-2: rgba(111, 141, 255, .06);
		--c-accent: #2fc9b4;
		--c-accent-d: #26a896;
		--c-accent-soft: rgba(47, 201, 180, .14);
		--c-danger: #ff8b8b;
		--c-danger-bg: #3a2126;
		--c-danger-fg: #ffb3b3;
		--c-danger-line: #5b2f35;
		--c-warn: #e8b55c;
		--c-warn-bg: #352b16;
		--c-warn-fg: #f0c97e;
		--c-warn-line: #574427;
		--c-ok: #5fd6a0;
		--c-ok-bg: #163227;
		--c-ok-fg: #86e2b8;
		--c-sat: #8aa2ff;
		--c-sun: #ff9b8e;
		--shadow-xs: 0 1px 2px rgba(0, 0, 0, .3);
		--shadow-1: 0 1px 3px rgba(0, 0, 0, .35);
		--shadow-2: 0 4px 16px rgba(0, 0, 0, .35), 0 2px 6px rgba(0, 0, 0, .25);
		--shadow-3: 0 24px 64px rgba(0, 0, 0, .55);
		--shadow-glow: 0 0 0 3px var(--c-primary-soft);
	}
}

/* ---------- reset & base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
	margin: 0;
	font-family: var(--font);
	color: var(--c-text);
	background: var(--c-bg);
	line-height: 1.7;
	font-size: 15px;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--c-primary); text-underline-offset: 3px; transition: color var(--dur) var(--ease); }
a:hover { color: var(--c-primary-d); }
h1, h2, h3 { line-height: 1.3; letter-spacing: -.01em; }
:focus-visible { outline: 2px solid var(--c-primary); outline-offset: 2px; border-radius: 4px; }
::selection { background: var(--c-primary-soft); }

.container { width: min(1200px, 100% - 40px); margin-inline: auto; }
.content { padding: 56px 0 80px; }
.content--narrow { max-width: 760px; margin-inline: auto; }

.skip-link { position: absolute; left: -9999px; top: 0; background: var(--c-text); color: var(--c-bg); padding: 8px 16px; z-index: 1000; border-radius: 0 0 var(--r-sm) 0; font-size: .88rem; font-weight: 600; }
.skip-link:focus { left: 0; top: 0; }

/* ---------- header ---------- */
.site-header {
	background: color-mix(in srgb, var(--c-surface) 86%, transparent);
	backdrop-filter: saturate(1.8) blur(14px);
	-webkit-backdrop-filter: saturate(1.8) blur(14px);
	border-bottom: 1px solid var(--c-line);
	position: sticky; top: 0; z-index: 50;
}
.site-header__inner { display: flex; align-items: center; justify-content: space-between; gap: 16px; min-height: 60px; }
.site-logo {
	display: inline-flex; align-items: center; gap: 10px;
	text-decoration: none; color: var(--c-text); font-weight: 800; font-size: 1.05rem; letter-spacing: -.01em;
}
.site-logo__mark {
	display: inline-flex; align-items: center; justify-content: center;
	width: 32px; height: 32px; border-radius: var(--r-sm);
	background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
	color: #fff; font-size: .9rem; font-weight: 800; line-height: 1;
	box-shadow: 0 2px 8px rgba(51, 85, 232, .25);
}
.site-nav { display: flex; align-items: center; gap: 20px; }
.site-nav ul { display: flex; gap: 6px; list-style: none; margin: 0; padding: 0; }
.site-nav ul a {
	text-decoration: none; color: var(--c-muted); font-size: .9rem; font-weight: 500;
	padding: 6px 12px; border-radius: 999px;
	transition: color var(--dur), background var(--dur);
}
.site-nav ul a:hover { color: var(--c-text); background: var(--c-primary-soft-2); }

/* ---------- footer ---------- */
.site-footer { border-top: 1px solid var(--c-line); background: var(--c-surface); padding: 40px 0 32px; color: var(--c-muted); font-size: .85rem; }
.site-footer__top { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px; margin-bottom: 20px; }
.site-logo--footer { font-size: .92rem; }
.site-logo--footer .site-logo__mark { width: 26px; height: 26px; font-size: .75rem; }
.site-footer ul { display: flex; flex-wrap: wrap; gap: 18px; list-style: none; margin: 0; padding: 0; }
.site-footer__note { margin: 0 0 8px; line-height: 1.6; }
.site-footer__copy { margin: 0; color: var(--c-faint); font-size: .82rem; }

/* ---------- buttons ---------- */
.btn {
	display: inline-flex; align-items: center; justify-content: center; gap: 6px;
	border: 1px solid transparent; border-radius: var(--r-md);
	padding: 9px 20px; font: inherit; font-weight: 600; font-size: .9rem; line-height: 1.3;
	cursor: pointer; text-decoration: none; white-space: nowrap;
	transition: background var(--dur) var(--ease), border-color var(--dur), color var(--dur), box-shadow var(--dur), transform .1s;
}
.btn:active:not(:disabled) { transform: scale(.98); }
.btn--primary {
	background: var(--c-primary); color: #fff;
	box-shadow: 0 1px 3px rgba(51, 85, 232, .25), 0 4px 16px rgba(51, 85, 232, .18);
}
.btn--primary:hover { background: var(--c-primary-d); box-shadow: 0 2px 6px rgba(51, 85, 232, .3), 0 8px 24px rgba(51, 85, 232, .22); }
.btn--ghost { background: var(--c-surface); color: var(--c-text); border-color: var(--c-line-strong); }
.btn--ghost:hover { border-color: var(--c-primary); color: var(--c-primary); background: var(--c-primary-soft-2); }
.btn--danger { background: var(--c-surface); color: var(--c-danger); border-color: var(--c-danger-line); }
.btn--danger:hover { background: var(--c-danger); color: #fff; border-color: transparent; }
.btn--sm { padding: 6px 14px; font-size: .84rem; border-radius: var(--r-sm); }
.btn--lg { padding: 14px 32px; font-size: 1rem; border-radius: var(--r-md); }
.btn--icon { width: 30px; height: 30px; padding: 0; border-radius: var(--r-sm); background: transparent; border-color: var(--c-line); color: var(--c-faint); font-size: 1rem; }
.btn--icon:hover { color: var(--c-danger); border-color: var(--c-danger-line); background: var(--c-danger-bg); }
.btn:disabled { opacity: .4; cursor: not-allowed; box-shadow: none; transform: none; }

/* ---------- hero ---------- */
.hero {
	position: relative; overflow: hidden;
	background: var(--c-surface);
	border-bottom: 1px solid var(--c-line);
}
.hero::before {
	content: ""; position: absolute; inset: 0; pointer-events: none;
	background:
		radial-gradient(ellipse 900px 450px at 85% -20%, rgba(14, 165, 148, .10), transparent 65%),
		radial-gradient(ellipse 800px 500px at -5% 10%, rgba(51, 85, 232, .08), transparent 60%),
		radial-gradient(ellipse 500px 500px at 50% 120%, rgba(51, 85, 232, .04), transparent 70%);
}
.hero__inner { position: relative; padding: 100px 0 88px; max-width: 880px; }
.hero__eyebrow {
	display: inline-flex; align-items: center; gap: 6px; margin: 0 0 20px; padding: 5px 16px;
	border-radius: 999px; background: var(--c-accent-soft); color: var(--c-accent);
	font-weight: 700; font-size: .82rem; letter-spacing: .02em;
	border: 1px solid color-mix(in srgb, var(--c-accent) 20%, transparent);
}
.hero__title {
	font-size: clamp(2rem, 4.8vw, 3.2rem); margin: 0 0 20px;
	letter-spacing: -.02em; font-weight: 800; line-height: 1.2;
}
.hero__title span {
	background: linear-gradient(135deg, var(--c-primary), var(--c-accent));
	-webkit-background-clip: text; -webkit-text-fill-color: transparent;
	background-clip: text;
}
.hero__lead { font-size: 1.05rem; color: var(--c-muted); max-width: 640px; margin: 0 0 36px; line-height: 1.8; }
.hero__cta { display: flex; flex-wrap: wrap; gap: 12px; margin: 0; }
.hero__cta .btn--primary { padding: 14px 32px; font-size: 1rem; }

/* ---------- sections ---------- */
.section { padding: 88px 0; }
.section--alt { background: var(--c-surface); border-block: 1px solid var(--c-line); }
.section__title {
	font-size: 1.6rem; margin: 0 0 12px; text-align: center; font-weight: 800;
	letter-spacing: -.01em;
}
.section__subtitle {
	text-align: center; color: var(--c-muted); font-size: .95rem;
	max-width: 540px; margin: 0 auto 44px;
}

/* ---------- features ---------- */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(270px, 1fr)); gap: 18px; }
.feature {
	position: relative;
	background: var(--c-surface); border: 1px solid var(--c-line); border-radius: var(--r-xl);
	padding: 30px 26px; box-shadow: var(--shadow-1);
	transition: box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease), border-color var(--dur);
}
.feature:hover { box-shadow: var(--shadow-2); transform: translateY(-3px); border-color: var(--c-line-strong); }
.feature__icon {
	display: inline-flex; align-items: center; justify-content: center;
	width: 44px; height: 44px; border-radius: var(--r-md);
	background: var(--c-primary-soft); color: var(--c-primary); font-size: 1.3rem; line-height: 1;
}
.feature h3 { margin: 16px 0 8px; font-size: 1.08rem; font-weight: 700; }
.feature p { margin: 0; color: var(--c-muted); font-size: .93rem; line-height: 1.65; }

/* ---------- steps ---------- */
.steps { counter-reset: step; list-style: none; padding: 0; margin: 0 auto 48px; max-width: 820px; display: grid; gap: 12px; }
.steps li {
	counter-increment: step; display: grid; grid-template-columns: 48px 1fr; grid-template-rows: auto auto;
	column-gap: 18px; padding: 20px 24px; border: 1px solid var(--c-line); border-radius: var(--r-lg);
	background: var(--c-surface); transition: border-color var(--dur), box-shadow var(--dur);
}
.steps li:hover { border-color: var(--c-primary-soft); box-shadow: var(--shadow-1); }
.steps li::before {
	content: counter(step); grid-row: span 2; width: 48px; height: 48px; border-radius: var(--r-md);
	display: grid; place-items: center;
	background: linear-gradient(135deg, var(--c-primary), var(--c-primary-l));
	color: #fff; font-weight: 800; font-size: 1.1rem;
	box-shadow: 0 2px 8px rgba(51, 85, 232, .2);
}
.steps strong { font-size: 1.02rem; }
.steps span { color: var(--c-muted); font-size: .93rem; }

/* ---------- diagram ---------- */
.diagram { display: flex; align-items: center; justify-content: center; gap: 20px; flex-wrap: wrap; }
.diagram__box {
	border-radius: var(--r-lg); padding: 20px 28px; min-width: 220px; text-align: center; display: grid; gap: 6px;
	transition: transform var(--dur), box-shadow var(--dur);
}
.diagram__box:hover { transform: translateY(-2px); }
.diagram__box small { color: var(--c-muted); font-size: .88rem; }
.diagram__box--you { background: var(--c-primary-soft); border: 1px solid color-mix(in srgb, var(--c-primary) 25%, transparent); }
.diagram__box--server { background: var(--c-surface-2); border: 1px dashed var(--c-line-strong); }
.diagram__arrow { color: var(--c-accent); font-weight: 800; font-size: .92rem; }

/* ---------- FAQ ---------- */
.faq {
	border: 1px solid var(--c-line); border-radius: var(--r-lg);
	background: var(--c-surface); padding: 0; margin-bottom: 10px;
	overflow: hidden; transition: border-color var(--dur);
}
.faq:hover { border-color: var(--c-line-strong); }
.faq summary {
	cursor: pointer; font-weight: 600; padding: 16px 22px;
	list-style: none; display: flex; align-items: center; gap: 10px;
	transition: color var(--dur);
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::before { content: "›"; font-size: 1.2em; color: var(--c-faint); transition: transform .25s var(--ease); display: inline-block; }
.faq[open] summary::before { transform: rotate(90deg); }
.faq summary:hover { color: var(--c-primary); }
.faq p { color: var(--c-muted); margin: 0; padding: 0 22px 18px; font-size: .93rem; line-height: 1.7; }

/* ---------- CTA section ---------- */
.section--cta {
	text-align: center; position: relative; overflow: hidden;
	background: linear-gradient(135deg, #1a2f8c, var(--c-primary) 50%, var(--c-accent) 120%);
	color: #fff;
}
.section--cta::before {
	content: ""; position: absolute; inset: 0;
	background: radial-gradient(ellipse 600px 300px at 75% -15%, rgba(255, 255, 255, .08), transparent 55%);
	pointer-events: none;
}
.section--cta h2 { position: relative; margin: 0 0 12px; font-size: 1.55rem; font-weight: 800; }
.section--cta p { position: relative; margin: 0 0 28px; opacity: .85; font-size: 1rem; }
.section--cta .btn--primary {
	position: relative;
	background: #fff; color: var(--c-primary-d);
	box-shadow: 0 4px 20px rgba(0, 0, 0, .15);
	font-size: 1rem; padding: 14px 32px;
}
.section--cta .btn--primary:hover { box-shadow: 0 8px 30px rgba(0, 0, 0, .2); transform: translateY(-1px); }

/* ---------- entries (blog, generic) ---------- */
.entry {
	background: var(--c-surface); border: 1px solid var(--c-line); border-radius: var(--r-xl);
	padding: 32px; margin-bottom: 20px; box-shadow: var(--shadow-1);
	transition: box-shadow var(--dur), border-color var(--dur);
}
.entry:hover { box-shadow: var(--shadow-2); border-color: var(--c-line-strong); }
.entry__title { margin-top: 0; }
.entry__title a { text-decoration: none; color: inherit; }

/* ---------- responsive ---------- */
@media (max-width: 640px) {
	.site-nav ul { display: none; }
	.hero__inner { padding: 60px 0 52px; }
	.hero__title { font-size: clamp(1.6rem, 6vw, 2.4rem); }
	.section { padding: 56px 0; }
	.section__title { font-size: 1.35rem; }
	.steps li { padding: 16px 18px; column-gap: 14px; grid-template-columns: 40px 1fr; }
	.steps li::before { width: 40px; height: 40px; font-size: 1rem; }
	.feature { padding: 22px 20px; }
}