/* ── Scale-o-Tron Website ── */
/* Static HTML/CSS/vanilla JS. Mobile-first, renders full-width on desktop. */

:root {
    /* Neutral site palette (dark default) */
    --clr-bg:        #0d0d0d;
    --clr-surface:   #1a1a1a;
    --clr-card:      #1e1e1e;
    --clr-border:    #333;
    --clr-text:      #e8e8e8;
    --clr-muted:     #9a9a9a;
    --clr-header-bg: rgba(13,13,13,.85);
    --radius:        14px;
    --max-w:         860px;
    --font:          -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --mono:          ui-monospace, "SF Mono", Menlo, Consolas, monospace;

    /* App accent colors — sampled from Scale-o-Tron's Assets.xcassets so the
       site's key colors match the calculator on-device. Light-appearance
       values; dark-appearance variants are applied under the dark-scheme
       block below. */
    --clr-success:  #34c759; /* SuccessGreen */
    --clr-operator: #66a6ff; /* OperatorKeyBackground */
    --clr-danger:   #ff3b30; /* DangerRed */
    --clr-warning:  #ffcc00; /* WarningYellow */
    --clr-neutral:  #8e8e93; /* NeutralKeyBackground */

    --clr-accent:   var(--clr-success);
    --clr-accent2:  var(--clr-operator);
    --clr-warn:     var(--clr-warning);
}

/* ── Dark appearance variants (system default is dark for this site) ── */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --clr-success:  #59b059;
        --clr-operator: #578dd9;
        --clr-danger:   #ff453a;
        --clr-warning:  #ffd60a;
    }
}
:root[data-theme="dark"] {
    --clr-success:  #59b059;
    --clr-operator: #578dd9;
    --clr-danger:   #ff453a;
    --clr-warning:  #ffd60a;
}

/* ── Light appearance ── */
@media (prefers-color-scheme: light) {
    :root:not([data-theme="dark"]) {
        --clr-bg:        #f5f5f7;
        --clr-surface:   #fff;
        --clr-card:      #fff;
        --clr-border:    #d2d2d7;
        --clr-text:      #1d1d1f;
        --clr-muted:     #6e6e73;
        --clr-header-bg: rgba(245,245,247,.85);
    }
}
:root[data-theme="light"] {
    --clr-bg:        #f5f5f7;
    --clr-surface:   #fff;
    --clr-card:      #fff;
    --clr-border:    #d2d2d7;
    --clr-text:      #1d1d1f;
    --clr-muted:     #6e6e73;
    --clr-header-bg: rgba(245,245,247,.85);
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
    font-family: var(--font);
    background: var(--clr-bg);
    color: var(--clr-text);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}
a { color: var(--clr-accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img, svg { max-width: 100%; height: auto; display: block; }
button { font: inherit; }

/* ── Layout ── */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.25rem; }
.container-wide { max-width: 1080px; margin: 0 auto; padding: 0 1.25rem; }

/* ── Header / Nav ── */
header {
    position: sticky; top: 0; z-index: 100;
    background: var(--clr-header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--clr-border);
}
nav {
    display: flex; align-items: center; justify-content: space-between;
    max-width: 1080px; margin: 0 auto; padding: .75rem 1.25rem;
    gap: .75rem;
}
nav .logo { font-size: 1.15rem; font-weight: 700; letter-spacing: .02em; white-space: nowrap; }
nav .logo span { color: var(--clr-accent); }
nav ul { list-style: none; display: flex; gap: 1.25rem; flex-wrap: wrap; }
nav ul a { color: var(--clr-muted); font-size: .88rem; transition: color .2s; }
nav ul a:hover, nav ul a[aria-current="page"] { color: var(--clr-text); text-decoration: none; }

.nav-controls { display: flex; align-items: center; gap: .5rem; }

#theme-toggle {
    background: transparent; color: var(--clr-muted); border: 1px solid var(--clr-border);
    border-radius: 6px; padding: .3rem .55rem; font-size: .9rem; cursor: pointer;
    line-height: 1; transition: color .2s, border-color .2s;
    min-width: 44px; min-height: 36px;
}
#theme-toggle:hover { color: var(--clr-text); border-color: var(--clr-muted); }

#lang-switcher {
    background: transparent; color: var(--clr-muted); border: 1px solid var(--clr-border);
    border-radius: 6px; padding: .3rem .5rem; font-size: .82rem; cursor: pointer;
    min-height: 36px;
}
#lang-switcher:hover { color: var(--clr-text); border-color: var(--clr-muted); }

/* ── Hero ── */
.hero { text-align: center; padding: 4.5rem 1.25rem 3rem; }
.hero h1 { font-size: clamp(2rem, 6vw, 3.25rem); font-weight: 800; letter-spacing: -.02em; margin-bottom: .75rem; color: var(--clr-accent); }
.hero .tagline { font-size: 1.1rem; color: var(--clr-muted); max-width: 560px; margin: 0 auto 2rem; }
.hero .cta { display: inline-flex; gap: .75rem; flex-wrap: wrap; justify-content: center; }
.hero-help-links { margin-top: 1rem; font-size: .92rem; color: var(--clr-muted); }
.hero-help-links a { font-weight: 600; }
.hero-help-links span { margin: 0 .5rem; }

/* ── Buttons ── */
.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: .4rem;
    padding: .75rem 1.5rem; border-radius: 10px; min-height: 44px;
    font-weight: 600; font-size: .95rem; transition: background .2s, transform .1s;
    border: none; cursor: pointer;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-primary { background: var(--clr-accent); color: #fff; }
.btn-primary:hover { background: #2db84e; }
.btn-secondary { background: var(--clr-card); color: var(--clr-text); border: 1px solid var(--clr-border); }
.btn-secondary:hover { background: var(--clr-border); }

/* Apple's "Download on the App Store" badge. Artwork is used unmodified;
   Apple asks for at least 40px height and clear space of a quarter of it. */
.appstore-badge { display: inline-block; line-height: 0; margin: 12px; transition: transform .1s; }
.appstore-badge:hover { transform: translateY(-1px); }
.appstore-badge img { height: 48px; width: auto; display: block; }

/* ── Sections ── */
section { padding: 3.5rem 0; }
section + section { border-top: 1px solid var(--clr-border); }
.section-title { font-size: 1.65rem; font-weight: 700; margin-bottom: .5rem; }
.section-subtitle { color: var(--clr-muted); margin-bottom: 2rem; max-width: 600px; }

/* ── Cards / Feature Grid ── */
.grid { display: grid; gap: 1.25rem; }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); }
.card { background: var(--clr-card); border: 1px solid var(--clr-border); border-radius: var(--radius); padding: 1.5rem; }
.card h3 { font-size: 1.05rem; margin-bottom: .5rem; }
.card p  { color: var(--clr-muted); font-size: .92rem; }
.card .icon {
    width: 40px; height: 40px; border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-size: 1.2rem; margin-bottom: .75rem;
}
.icon-success  { background: color-mix(in srgb, var(--clr-success) 18%, transparent); color: var(--clr-success); }
.icon-operator { background: color-mix(in srgb, var(--clr-operator) 18%, transparent); color: var(--clr-operator); }
.icon-warning  { background: color-mix(in srgb, var(--clr-warning) 22%, transparent); color: #a97a00; }
@media (prefers-color-scheme: dark) { .icon-warning { color: var(--clr-warning); } }
:root[data-theme="dark"] .icon-warning { color: var(--clr-warning); }

/* ── FAQ / Accordion ── */
details { border-bottom: 1px solid var(--clr-border); }
details summary { padding: 1rem 0; cursor: pointer; font-weight: 600; font-size: 1rem; list-style: none; }
details summary::-webkit-details-marker { display: none; }
details summary::before { content: "+ "; color: var(--clr-accent); font-weight: 700; }
details[open] summary::before { content: "− "; }
details .answer { padding: 0 0 1rem; color: var(--clr-muted); font-size: .92rem; line-height: 1.7; }

/* ── Guide steps ── */
.step { display: flex; gap: 1.25rem; margin-bottom: 2rem; align-items: flex-start; }
.step-number {
    flex-shrink: 0; width: 34px; height: 34px; border-radius: 50%;
    background: var(--clr-accent); color: #fff; font-weight: 700;
    display: flex; align-items: center; justify-content: center; font-size: .92rem;
}
.step-content h3 { font-size: 1.02rem; margin-bottom: .25rem; }
.step-content p  { color: var(--clr-muted); font-size: .92rem; }

/* ── Footer ── */
footer { margin-top: 2rem; border-top: 1px solid var(--clr-border); padding: 2rem 0; text-align: center; color: var(--clr-muted); font-size: .82rem; }
footer .footer-links { margin-bottom: .75rem; }
footer .footer-links a { color: var(--clr-muted); margin: 0 .6rem; }
footer .footer-links a:hover { color: var(--clr-text); }

/* ── Legal pages ── */
.legal { max-width: 700px; margin: 0 auto; }
.legal h2 { margin-top: 2rem; margin-bottom: .5rem; font-size: 1.2rem; }
.legal p, .legal li { color: var(--clr-muted); font-size: .92rem; line-height: 1.75; }
.legal ul { padding-left: 1.25rem; margin: .5rem 0; }

/* ── Changelog ── */
.release { margin-bottom: 2rem; }
.release h3 { font-size: 1.1rem; margin-bottom: .75rem; }
.release ul { list-style: none; display: flex; flex-direction: column; gap: .6rem; }
.release li { display: flex; gap: .6rem; align-items: flex-start; color: var(--clr-text); font-size: .93rem; }
.release .cat-icon { flex-shrink: 0; width: 22px; text-align: center; font-size: 1rem; line-height: 1.5; }
.cat-feature .cat-icon { color: var(--clr-warning); }
:root:not([data-theme="dark"]) .cat-feature .cat-icon { color: #a97a00; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .cat-feature .cat-icon { color: var(--clr-warning); } }
:root[data-theme="dark"] .cat-feature .cat-icon { color: var(--clr-warning); }
.cat-bugfix .cat-icon { color: var(--clr-operator); }

/* ── Utilities ── */
.text-center { text-align: center; }
.mt-1 { margin-top: .5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 2rem; }
.mb-2 { margin-bottom: 1rem; }
.visually-hidden {
    position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

/* ── Responsive ── */
@media (max-width: 640px) {
    nav ul { gap: .65rem; }
    nav ul a { font-size: .8rem; }
    .hero { padding: 3rem 1rem 2rem; }
    .step { flex-direction: column; gap: .5rem; }
}