@charset "UTF-8";

* { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --background: #f7f7fb;
    --card: #ffffff;
    --text: #1f2030;
    --muted: #747689;
    --primary: #6c5ce7;
    --primary-dark: #5545d4;
    --border: #e8e8f0;
    --shadow: 0 15px 40px rgba(40, 35, 80, 0.08);
}

html { scroll-behavior: smooth; }

body {
    font-family: Arial, Helvetica, sans-serif;
    background: var(--background);
    color: var(--text);
    line-height: 1.6;
}

button, select, input { font: inherit; }
button { cursor: pointer; }

.wrap {
    width: min(1120px, calc(100% - 40px));
    margin: 0 auto;
}

/* HEADER */
header {
    background: rgba(255,255,255,.9);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.nav {
    min-height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    color: var(--text);
    text-decoration: none;
    font-weight: 800;
    font-size: 18px;
}

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

.nav nav {
    display: flex;
    gap: 28px;
}

.nav nav a {
    color: var(--muted);
    text-decoration: none;
    font-size: 15px;
    transition: .2s;
}

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

/* PAGES */
.page { display: none; }
.page.active { display: block; }

/* COMMON */
.eyebrow {
    color: var(--primary);
    font-size: 12px;
    font-weight: 800;
    letter-spacing: 1.5px;
    text-transform: uppercase;
}

h1, h2, h3 { line-height: 1.15; }

/* HERO */
.hero {
    min-height: 620px;
    display: grid;
    grid-template-columns: 1.15fr .85fr;
    align-items: center;
    gap: 60px;
}

.hero h1 {
    margin-top: 18px;
    font-size: clamp(42px, 6vw, 70px);
    letter-spacing: -2px;
}

.hero h1 em {
    color: var(--primary);
    font-style: normal;
}

.hero > div:first-child > p {
    margin-top: 24px;
    max-width: 650px;
    color: var(--muted);
    font-size: 18px;
}

.actions {
    display: flex;
    gap: 12px;
    margin-top: 28px;
}

.primary, .ghost, .secondary, .convert, .copy {
    border-radius: 12px;
    font-weight: 700;
    transition: .2s;
}

.primary {
    border: 0;
    padding: 13px 22px;
    background: var(--primary);
    color: white;
}

.primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.ghost {
    border: 1px solid var(--border);
    padding: 12px 22px;
    background: white;
    color: var(--text);
}

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

/* HERO CARD */
.hero-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 28px;
    padding: 50px 30px;
    box-shadow: var(--shadow);
    text-align: center;
}

.bits, .dec {
    font-family: monospace;
    font-size: 52px;
    font-weight: 700;
}

.bits sub, .dec sub { color: var(--primary); font-size: 22px; }

.arrow {
    margin: 20px 0;
    font-size: 30px;
    color: var(--primary);
}

.hero-card p { margin-top: 14px; color: var(--muted); }

/* BASES */
.bases {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 14px;
    margin-bottom: 80px;
}

.bases > div {
    padding: 18px;
    background: #fafaff;
    border: 1px solid var(--border);
    border-radius: 14px;
}

.bases b {
    display: block;
    color: var(--primary);
    font-size: 28px;
}

.bases span { color: var(--muted); }

/* SECTIONS */
.section { padding: 40px 0 80px; }

.heading {
    text-align: center;
    margin-bottom: 45px;
}

.heading h2, .topic h2 {
    margin-top: 8px;
    font-size: 38px;
}

.heading p { margin-top: 12px; color: var(--muted); }

/* TOOLS */
.cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 22px;
}

.card {
    position: relative;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.card .num {
    position: absolute;
    top: 20px;
    right: 22px;
    color: #aaaabd;
    font-size: 13px;
    font-weight: 800;
}

.icon {
    width: 48px;
    height: 48px;
    display: grid;
    place-items: center;
    border-radius: 14px;
    background: #f0eeff;
    color: var(--primary);
    font-size: 24px;
    margin-bottom: 22px;
}

.card h3 { font-size: 23px; }
.card p { margin: 12px 0 22px; color: var(--muted); }

.secondary {
    border: 0;
    padding: 11px 16px;
    background: #f0eeff;
    color: var(--primary);
}

.secondary:hover { background: #e5e1ff; }

.card.coming { opacity: .88; }
.soon {
    display: inline-block;
    padding: 7px 12px;
    border-radius: 999px;
    background: #f3f2f8;
    color: var(--muted);
    font-size: 13px;
    font-weight: 700;
}

/* TOPIC */
.topic {
    margin: 50px 0 100px;
    padding: 45px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 24px;
}

.topic p { margin-top: 25px; max-width: 650px; color: var(--muted); }

.example {
    padding: 25px;
    background: #fafaff;
    border: 1px solid var(--border);
    border-radius: 18px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 10px;
}

.example small { color: var(--muted); font-weight: 800; }
.example strong, .example b { font-family: monospace; font-size: 26px; }
.example strong sub, .example b sub { color: var(--primary); font-size: 14px; }
.example code {
    padding: 14px;
    background: white;
    border-radius: 10px;
    overflow-x: auto;
}

/* ABOUT */
.page-head { padding: 90px 0 50px; }
.page-head h1 { margin-top: 10px; font-size: 48px; }
.page-head p { margin-top: 15px; color: var(--muted); max-width: 650px; }

.about-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 22px;
    padding-bottom: 100px;
}

.about-grid article {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.about-grid article > b {
    color: var(--primary);
    font-size: 13px;
}

.about-grid h3 { margin: 14px 0 12px; }
.about-grid p { color: var(--muted); }

/* TOOL PAGE */
#tool-page { padding: 60px 0 100px; }

.back {
    background: none;
    border: none;
    color: var(--muted);
    margin-bottom: 35px;
    font-weight: 700;
}

.back:hover { color: var(--primary); }

/* CONVERTER */
.converter-wrapper { max-width: 850px; margin: 0 auto; }

.converter-heading {
    text-align: center;
    margin-bottom: 35px;
}

.converter-heading h1 { font-size: 44px; }
.converter-heading p { color: var(--muted); margin-top: 10px; }

.converter-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 24px;
    padding: 30px;
    box-shadow: var(--shadow);
}

.converter-fields {
    display: grid;
    grid-template-columns: 1fr 170px 60px 170px;
    gap: 14px;
    align-items: end;
}

.field {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.field label { font-size: 13px; font-weight: 700; }

.field input, .field select {
    width: 100%;
    height: 48px;
    border: 1px solid var(--border);
    border-radius: 12px;
    background: #fafaff;
    padding: 0 14px;
    outline: none;
}

.field input:focus, .field select:focus { border-color: var(--primary); }

.swap {
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 12px;
    background: #f0eeff;
    color: var(--primary);
    font-size: 22px;
}

.convert {
    width: 100%;
    margin-top: 20px;
    height: 50px;
    border: none;
    background: var(--primary);
    color: white;
    font-weight: 800;
}

.convert:hover { background: var(--primary-dark); }
.message { margin-top: 15px; color: #d34b4b; font-size: 14px; }

/* RESULT */
.result { margin-top: 25px; }
.result {
    background: #f8f7ff;
    border: 1px solid #e4e0ff;
    border-radius: 18px;
    padding: 25px;
    text-align: center;
}

.result-number {
    margin: 10px 0 18px;
    font-family: monospace;
    font-size: 36px;
    font-weight: 800;
    overflow-wrap: anywhere;
}

.result-number span { color: var(--primary); font-size: 18px; vertical-align: super; }

.copy {
    border: 1px solid var(--border);
    background: white;
    padding: 9px 16px;
    color: var(--text);
}

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

/* LEARNING */
.learn { margin-top: 25px; display: grid; gap: 22px; }

.learn-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 20px;
    padding: 28px;
    box-shadow: var(--shadow);
}

.learn-card h2 { font-size: 24px; margin-bottom: 14px; }
.learn-card > p, .learn-card p { color: var(--muted); }

.method {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
    margin-top: 20px;
}

.method > div {
    background: #fafaff;
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 20px;
}

.method > div > b { display: block; margin-bottom: 10px; font-size: 18px; }

.formula {
    margin-top: 15px;
    padding: 15px;
    background: white;
    border-radius: 12px;
    font-family: monospace;
    overflow-x: auto;
}

.step {
    margin-top: 18px;
    padding: 18px;
    background: #fafaff;
    border-radius: 14px;
    border: 1px solid var(--border);
}

.step h3 { margin-bottom: 12px; }
.step-code {
    padding: 13px;
    background: white;
    border-radius: 10px;
    font-family: monospace;
    overflow-x: auto;
    margin-top: 10px;
}

.division {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
}

.division th, .division td {
    padding: 10px;
    border: 1px solid var(--border);
    text-align: center;
}

.division th { background: #f4f2ff; }

.final {
    margin-top: 18px;
    padding: 18px;
    border-radius: 14px;
    background: #f0eeff;
    color: var(--primary-dark);
    font-weight: 700;
}

details summary {
    cursor: pointer;
    font-weight: 800;
    list-style: none;
}

details summary::-webkit-details-marker { display: none; }
details summary::before { content: "+"; margin-right: 10px; color: var(--primary); }
details[open] summary::before { content: "−"; }

/* FOOTER */
footer {
    border-top: 1px solid var(--border);
    background: white;
    padding: 25px 0;
}

footer .wrap {
    display: flex;
    justify-content: space-between;
    color: var(--muted);
    font-size: 13px;
}

/* RESPONSIVE */
@media (max-width: 850px) {
    .hero { grid-template-columns: 1fr; padding: 70px 0; }
    .cards, .about-grid { grid-template-columns: 1fr; }
    .bases { grid-template-columns: repeat(2, 1fr); }
    .topic { grid-template-columns: 1fr; }
    .converter-fields { grid-template-columns: 1fr; }
    .swap { width: 100%; }
    .method { grid-template-columns: 1fr; }
    footer .wrap { flex-direction: column; gap: 8px; }
}

@media (max-width: 600px) {
    .wrap { width: min(100% - 24px, 1120px); }
    .nav { flex-direction: column; gap: 12px; padding: 15px 0; }
    .nav nav { gap: 16px; }
    .hero h1 { font-size: 42px; }
    .hero-card { padding: 35px 20px; }
    .bits, .dec { font-size: 38px; }
    .topic { padding: 25px; }
    .converter-card { padding: 20px; }
    .converter-heading h1 { font-size: 36px; }
    .result-number { font-size: 27px; }
}

/* FIX: converter input must receive mouse and keyboard input */
.converter-card .field input#n {
    position: relative;
    z-index: 2;
    pointer-events: auto;
    user-select: text;
    -webkit-user-select: text;
    cursor: text;
    caret-color: var(--text);
}

/* KEYBOARD INPUT FIX */
.converter-card .field input#n {
    display: block;
    width: 100%;
    pointer-events: auto;
    user-select: text;
    -webkit-user-select: text;
    -webkit-touch-callout: default;
}