/*
 * Copyright 2026 Lemi Orhan Ergin
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
/* Grand Unified Divisibility Rule — site styles */

:root {
    --bg: #0b0d14;
    --bg-soft: #11141f;
    --card: #161a28;
    --card-border: #232a3d;
    --text: #e8ecf6;
    --text-soft: #9aa4bd;
    --accent: #7c6cff;
    --accent-2: #22d3ee;
    --good: #34d399;
    --bad: #fbbf24;
    --danger: #f87171;
    --mono: ui-monospace, "SF Mono", SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
    --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial,
            "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
    --radius: 16px;
    --shadow: 0 10px 40px rgba(0, 0, 0, .35);
}

html[data-theme="light"] {
    --bg: #f6f7fb;
    --bg-soft: #eef0f7;
    --card: #ffffff;
    --card-border: #e3e7f2;
    --text: #171c2b;
    --text-soft: #5a647c;
    --accent: #5b4bdb;
    --accent-2: #0e7490;
    --link: #0d6a80;
    --good: #065f46;
    --bad: #92400e;
    --danger: #dc2626;
    --shadow: 0 10px 30px rgba(23, 28, 43, .08);
}

* { box-sizing: border-box; }

.sr-only {
    position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}

html { scroll-behavior: smooth; }

body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font-family: var(--sans);
    line-height: 1.65;
    -webkit-font-smoothing: antialiased;
}

.container { max-width: 1060px; margin: 0 auto; padding: 0 24px; }

/* ---------- nav ---------- */
.nav {
    position: sticky; top: 0; z-index: 50;
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    background: color-mix(in srgb, var(--bg) 78%, transparent);
    border-bottom: 1px solid var(--card-border);
}
.nav-inner {
    display: flex; align-items: center; justify-content: space-between;
    padding: 14px 24px; max-width: 1060px; margin: 0 auto;
}
.nav-brand { font-weight: 700; letter-spacing: .2px; text-decoration: none; color: var(--text); font-size: 15px; }
.nav-brand span { color: var(--accent); }
.nav-links { display: flex; gap: 18px; align-items: center; }
.nav-links a { color: var(--text-soft); text-decoration: none; font-size: 14px; }
.nav-links a:hover { color: var(--text); }
.theme-toggle {
    background: var(--card); border: 1px solid var(--card-border); color: var(--text);
    border-radius: 999px; padding: 6px 12px; cursor: pointer; font-size: 13px;
}
.lang-select {
    background: var(--card); border: 1px solid var(--card-border); color: var(--text);
    border-radius: 999px; padding: 6px 10px; cursor: pointer; font-size: 13px;
    font-family: inherit;
}
.lang-select:focus-visible, .theme-toggle:focus-visible, .example-chip:focus-visible,
.copy-btn:focus-visible, a:focus-visible, button:focus-visible, summary:focus-visible {
    outline: 2px solid var(--accent-2); outline-offset: 2px;
}
/* keep the section links reachable on phones instead of hiding them */
@media (max-width: 720px) {
    .nav-inner { flex-wrap: wrap; row-gap: 8px; }
    .nav-links { flex-wrap: wrap; gap: 12px; row-gap: 6px; }
    .nav-links a { font-size: 13px; }
}

/* ---------- hero ---------- */
.hero { position: relative; overflow: hidden; padding: 96px 0 72px; text-align: center; }
.hero::before {
    content: ""; position: absolute; inset: -40% -20% auto -20%; height: 130%;
    background:
        radial-gradient(600px 300px at 30% 20%, color-mix(in srgb, var(--accent) 22%, transparent), transparent 70%),
        radial-gradient(500px 260px at 72% 12%, color-mix(in srgb, var(--accent-2) 16%, transparent), transparent 70%);
    pointer-events: none;
}
.hero > .container { position: relative; }
.hero-kicker {
    display: inline-block; font-size: 13px; letter-spacing: .12em; text-transform: uppercase;
    color: var(--accent-2); font-weight: 600; margin-bottom: 18px;
}
.hero h1 {
    font-size: clamp(34px, 6vw, 58px); line-height: 1.08; margin: 0 0 18px;
    background: linear-gradient(92deg, var(--text), color-mix(in srgb, var(--accent) 70%, var(--text)));
    -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.hero p.lead { font-size: clamp(16px, 2.4vw, 20px); color: var(--text-soft); max-width: 680px; margin: 0 auto 32px; }
.hero-actions { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.btn {
    display: inline-block; text-decoration: none; font-weight: 600; font-size: 15px;
    padding: 12px 22px; border-radius: 12px; border: 1px solid transparent; cursor: pointer;
}
.btn-primary { background: linear-gradient(92deg, var(--accent), color-mix(in srgb, var(--accent) 55%, var(--accent-2))); color: #fff; }
.btn-primary:hover { filter: brightness(1.1); }
.btn-ghost { border-color: var(--card-border); color: var(--text); background: var(--card); }
.btn-ghost:hover { border-color: var(--accent); }
.hero-stats { display: flex; gap: 34px; justify-content: center; margin-top: 46px; flex-wrap: wrap; }
.hero-stat { text-align: center; }
.hero-stat .num { font-size: 26px; font-weight: 700; color: var(--text); }
.hero-stat .cap { font-size: 13px; color: var(--text-soft); }

/* ---------- sections ---------- */
section { padding: 72px 0; }
section.alt { background: var(--bg-soft); }
.section-kicker { font-size: 13px; letter-spacing: .12em; text-transform: uppercase; color: var(--accent); font-weight: 700; }
h2 { font-size: clamp(26px, 4vw, 36px); margin: 8px 0 14px; line-height: 1.15; }
.section-intro { color: var(--text-soft); max-width: 760px; margin-bottom: 34px; }
a { color: var(--link, var(--accent-2)); }

/* ---------- timeline ---------- */
.timeline { display: grid; grid-template-columns: repeat(auto-fit, minmax(225px, 1fr)); gap: 18px; }
@media (max-width: 820px) { .timeline { grid-template-columns: 1fr; } }
.time-card {
    background: var(--card); border: 1px solid var(--card-border); border-radius: var(--radius);
    padding: 24px; box-shadow: var(--shadow);
}
.time-card .year { font-family: var(--mono); color: var(--accent-2); font-weight: 700; font-size: 15px; }
.time-card h3 { margin: 8px 0 8px; font-size: 18px; }
.time-card p { margin: 0; color: var(--text-soft); font-size: 14.5px; }

/* ---------- formula / math blocks ---------- */
.math-block {
    background: var(--card); border: 1px solid var(--card-border); border-radius: var(--radius);
    padding: 22px 26px; font-family: var(--mono); font-size: clamp(14px, 2.2vw, 17px);
    overflow-x: auto; box-shadow: var(--shadow); margin: 22px 0;
    display: flex; flex-wrap: wrap; gap: 6px 18px;
}
.math-block.wrap { display: block; font-family: var(--sans); line-height: 1.7; }
/* each sub-expression stays intact; breaks happen only between them */
.math-block .nw { white-space: nowrap; }
.math-block .hl { color: var(--accent-2); }
.raw-note { color: var(--text-soft); font-size: 13px; margin: 10px 0 0; }
.math-note { color: var(--text-soft); font-size: 14.5px; }

.rule-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 14px; margin-top: 26px; }
.rule-card {
    background: var(--card); border: 1px solid var(--card-border); border-radius: 14px; padding: 16px 18px;
    font-size: 14px;
}
.rule-card .rule-d { font-weight: 700; font-size: 16px; }
.rule-card .rule-f { font-family: var(--mono); color: var(--text-soft); font-size: 13px; margin-top: 4px; }
.rule-card.broken { border-color: color-mix(in srgb, var(--danger) 45%, var(--card-border)); }
.badge {
    display: inline-block; font-size: 11px; font-weight: 700; letter-spacing: .04em;
    border-radius: 999px; padding: 2px 9px; margin-left: 8px; vertical-align: 2px;
}
.badge-broken { background: color-mix(in srgb, var(--danger) 18%, transparent); color: var(--danger); }
.badge-ok { background: color-mix(in srgb, var(--good) 16%, transparent); color: var(--good); }

/* ---------- weights table ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--card-border); border-radius: var(--radius); box-shadow: var(--shadow); }
table.weights { border-collapse: collapse; width: 100%; background: var(--card); font-size: 14.5px; }
table.weights th, table.weights td { padding: 12px 16px; text-align: left; border-bottom: 1px solid var(--card-border); }
table.weights th { font-size: 12.5px; text-transform: uppercase; letter-spacing: .08em; color: var(--text-soft); }
table.weights tr:last-child td { border-bottom: none; }
table.weights td.w { font-family: var(--mono); white-space: nowrap; color: var(--accent-2); }
table.weights td.d { font-weight: 700; }

/* ---------- prior art ---------- */
.notice-box {
    background: color-mix(in srgb, var(--accent-2) 8%, var(--card));
    border: 1px solid color-mix(in srgb, var(--accent-2) 32%, var(--card-border));
    border-left-width: 4px; border-radius: var(--radius);
    padding: 18px 22px; margin: 22px 0; font-size: 14.5px; line-height: 1.65;
    color: var(--text-soft);
}
.notice-box b { color: var(--text); }
.hero-notice { margin: 26px auto 0; max-width: 760px; text-align: left; }

table.weights.prior { font-size: 13.5px; }
table.weights.prior td { vertical-align: top; }
table.weights.prior td:first-child { min-width: 190px; color: var(--text); }
table.weights.prior td.src { min-width: 150px; font-family: var(--mono); font-size: 12.5px; color: var(--accent-2); }
table.weights.prior td.src a { color: inherit; }
table.weights.prior td:last-child { color: var(--text-soft); min-width: 260px; }

.prior-h3 { margin: 44px 0 6px; font-size: 20px; }
.adds-list { margin: 18px 0 0; padding-left: 26px; display: grid; gap: 14px; }
.adds-list li { color: var(--text-soft); font-size: 14.5px; line-height: 1.7; }
.adds-list li b { color: var(--text); }

.refs { margin: 18px 0 22px; padding-left: 0; list-style: none; display: grid; gap: 12px; }
.refs li {
    color: var(--text-soft); font-size: 13.5px; line-height: 1.65;
    padding-left: 16px; border-left: 2px solid var(--card-border);
}
.refs li:target { border-left-color: var(--accent-2); background: color-mix(in srgb, var(--accent-2) 7%, transparent); }
.refs li b { color: var(--accent-2); font-family: var(--mono); }

/* ---------- proof ---------- */
.proof-steps { counter-reset: proof; display: grid; gap: 14px; margin-top: 26px; }
.proof-step {
    background: var(--card); border: 1px solid var(--card-border); border-radius: 14px; padding: 18px 20px 18px 64px;
    position: relative;
}
.proof-step::before {
    counter-increment: proof; content: counter(proof);
    position: absolute; left: 18px; top: 16px; width: 30px; height: 30px; border-radius: 999px;
    display: grid; place-items: center; font-weight: 700; font-size: 14px; color: #fff;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
}
.proof-step p { margin: 0; color: var(--text-soft); }
.proof-step code, .inline-code, p code, li code {
    font-family: var(--mono); font-size: .92em; background: color-mix(in srgb, var(--accent) 12%, transparent);
    border-radius: 6px; padding: 1px 6px; color: var(--text);
}

/* ---------- calculator ---------- */
.calc {
    background: var(--card); border: 1px solid var(--card-border); border-radius: 20px;
    padding: 28px; box-shadow: var(--shadow);
}
.calc-form { display: grid; grid-template-columns: 2.2fr 1.2fr auto; gap: 14px; align-items: end; }
@media (max-width: 760px) { .calc-form { grid-template-columns: 1fr; } }
.field label { display: block; font-size: 13px; font-weight: 600; color: var(--text-soft); margin-bottom: 6px; }
.field input {
    width: 100%; font-family: var(--mono); font-size: 17px; padding: 12px 14px;
    background: var(--bg-soft); color: var(--text); border: 1px solid var(--card-border); border-radius: 12px;
    outline: none;
}
.field input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent); }
.examples { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.example-chip {
    font-family: var(--mono); font-size: 13px; cursor: pointer; background: var(--bg-soft);
    color: var(--text-soft); border: 1px solid var(--card-border); border-radius: 999px; padding: 5px 12px;
}
.example-chip:hover { color: var(--text); border-color: var(--accent); }
.calc-error { color: var(--danger); font-size: 14px; margin-top: 12px; display: none; }

.calc-output { margin-top: 28px; display: none; }
.out-block { margin-bottom: 22px; }
.out-label { font-size: 12.5px; text-transform: uppercase; letter-spacing: .1em; color: var(--text-soft); font-weight: 700; margin-bottom: 10px; }

.formula-chips { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.term-chip {
    font-family: var(--mono); font-size: 14px; border-radius: 10px; padding: 6px 11px;
    background: color-mix(in srgb, var(--accent) 13%, transparent);
    border: 1px solid color-mix(in srgb, var(--accent) 30%, var(--card-border));
}
.term-chip b { color: var(--accent-2); font-weight: 700; }
.term-plus { color: var(--text-soft); font-family: var(--mono); }

/* row-gap must clear the position labels that hang 18px below each box */
.digit-row { display: flex; gap: 28px 6px; flex-wrap: wrap; }
.digit-box {
    font-family: var(--mono); font-size: 20px; font-weight: 700; width: 42px; height: 48px;
    display: grid; place-items: center; border-radius: 10px;
    background: var(--bg-soft); border: 1px solid var(--card-border); position: relative;
    transition: all .25s ease;
}
.digit-box .pos { position: absolute; bottom: -18px; font-size: 10px; color: var(--text-soft); font-weight: 500; }
.digit-box.active { border-color: var(--accent-2); background: color-mix(in srgb, var(--accent-2) 14%, transparent); transform: translateY(-3px); }
.digit-box.done { border-color: color-mix(in srgb, var(--good) 45%, var(--card-border)); }
.digit-row-wrap { padding-bottom: 20px; }

.steps-list { display: grid; gap: 10px; }
.step-row {
    display: flex; gap: 14px; align-items: baseline; flex-wrap: wrap;
    background: var(--bg-soft); border: 1px solid var(--card-border); border-radius: 12px; padding: 12px 16px;
    opacity: 0; transform: translateY(6px); animation: rise .35s ease forwards;
}
@keyframes rise { to { opacity: 1; transform: none; } }
.step-row.weight-row { background: transparent; border-style: dashed; font-size: 13.5px; color: var(--text-soft); }
.step-no { font-size: 12px; font-weight: 700; color: var(--accent); min-width: 58px; text-transform: uppercase; letter-spacing: .06em; }
.step-math { font-family: var(--mono); font-size: 14.5px; }
.step-math b { color: var(--accent-2); }
.reduce-pill {
    font-family: var(--mono); font-size: 12.5px; border-radius: 999px; padding: 2px 10px;
    background: color-mix(in srgb, var(--bad) 15%, transparent); color: var(--bad);
}
.total-pill {
    font-family: var(--mono); font-size: 13px; border-radius: 999px; padding: 2px 10px; font-weight: 700;
    background: color-mix(in srgb, var(--accent) 16%, transparent); color: var(--text);
}

.verdict {
    border-radius: 14px; padding: 18px 22px; font-size: 17px; font-weight: 600;
    display: none; align-items: baseline; gap: 12px; flex-wrap: wrap;
    opacity: 0; animation: rise .4s ease forwards;
}
.verdict.divisible { background: color-mix(in srgb, var(--good) 14%, transparent); border: 1px solid color-mix(in srgb, var(--good) 40%, transparent); color: var(--good); display: flex; }
.verdict.not-divisible { background: color-mix(in srgb, var(--bad) 12%, transparent); border: 1px solid color-mix(in srgb, var(--bad) 40%, transparent); color: var(--bad); display: flex; }
.verdict small { color: var(--text-soft); font-weight: 500; font-size: 14px; }

details.rawlog { margin-top: 20px; }
details.rawlog summary { cursor: pointer; color: var(--text-soft); font-size: 14px; }
.rawlog pre {
    background: #0a0c12; color: #c9d4ee; border: 1px solid var(--card-border); border-radius: 12px;
    padding: 18px; overflow-x: auto; font-family: var(--mono); font-size: 12.8px; line-height: 1.7;
}
html[data-theme="light"] .rawlog pre { background: #14182a; }
.copy-btn {
    margin-top: 8px; font-size: 12.5px; background: var(--bg-soft); color: var(--text-soft);
    border: 1px solid var(--card-border); border-radius: 8px; padding: 5px 12px; cursor: pointer;
}
.copy-btn:hover { color: var(--text); }

/* ---------- footer ---------- */
footer { border-top: 1px solid var(--card-border); padding: 44px 0 60px; color: var(--text-soft); font-size: 14px; }
footer .container { display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; }
footer a { color: var(--text-soft); }
footer a:hover { color: var(--text); }

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    .step-row, .verdict { animation-duration: .01s; }
    .digit-box { transition: none; }
}