/* ==========================================================================
   MathTricks Design System
   Modern arcade-glass theme: deep space gradient, neon accents, glass panels.
   All shared site chrome lives here. Game pages layer their own <style> on top.
   ========================================================================== */

:root {
    /* Palette */
    --bg-0: #070b16;
    --bg-1: #0c1222;
    --bg-2: #121a30;
    --card: rgba(19, 27, 50, 0.82);
    --card-solid: #131b32;
    --panel: rgba(24, 33, 60, 0.9);
    --border: rgba(126, 140, 210, 0.16);
    --border-strong: rgba(126, 157, 255, 0.38);
    --text-0: #eef2ff;
    --text-1: #c6d0f2;
    --text-2: #8892b8;
    --blue: #5ea2ff;
    --cyan: #4dd7ff;
    --violet: #a48bff;
    --pink: #ff7ab8;
    --gold: #fdc44f;
    --green: #53e0a6;
    --red: #ff6b81;

    /* Brand gradient */
    --gradient: linear-gradient(120deg, var(--cyan) 0%, var(--violet) 45%, var(--pink) 100%);
    --gradient-soft: linear-gradient(120deg, rgba(93, 162, 255, 0.25), rgba(164, 139, 255, 0.25));

    --radius: 16px;
    --radius-sm: 10px;
    --shadow: 0 16px 40px rgba(0, 0, 0, 0.45);
    --glow: 0 0 24px rgba(93, 162, 255, 0.35);

    --font: 'Segoe UI', 'Inter', Tahoma, Verdana, sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    font-family: var(--font);
    margin: 0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
    color: var(--text-0);
    background:
        radial-gradient(1200px 600px at 85% -10%, rgba(164, 139, 255, 0.20), transparent 60%),
        radial-gradient(1000px 700px at -10% 30%, rgba(93, 162, 255, 0.16), transparent 55%),
        radial-gradient(900px 500px at 60% 110%, rgba(255, 122, 184, 0.12), transparent 60%),
        var(--bg-0);
    background-attachment: fixed;
}

a { color: var(--blue); }

/* ===================== Header ===================== */

header {
    position: sticky;
    top: 0;
    z-index: 1100;
    display: flex;
    align-items: center;
    gap: 12px;
    height: 62px;
    padding: 0 18px;
    background: rgba(8, 12, 24, 0.78);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
    box-sizing: border-box;
    width: 100%;
}

header h1 {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    white-space: nowrap;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

#menu-toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    background: rgba(255, 255, 255, 0.04);
    border: 1px solid var(--border);
    border-radius: 10px;
    cursor: pointer;
    padding: 10px;
    transition: border-color 0.2s, background 0.2s;
}

#menu-toggle:hover { border-color: var(--border-strong); background: rgba(255, 255, 255, 0.08); }

#menu-toggle span {
    width: 22px;
    height: 2.5px;
    border-radius: 2px;
    background: var(--text-0);
    transition: 0.3s;
}

#menu-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
#menu-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
#menu-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

#lang-switcher select,
#lang-select {
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-0);
    padding: 7px 10px;
    font-size: 0.85rem;
    outline: none;
    cursor: pointer;
}

#lang-select option { background: var(--bg-1); }

#auth-status-placeholder {
    margin-left: auto;
    display: flex;
    align-items: center;
    gap: 10px;
}

#auth-status .user-info {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 5px 10px;
    border: 1px solid var(--border);
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.05);
    cursor: pointer;
    transition: border-color 0.2s;
}

#auth-status .user-info:hover { border-color: var(--border-strong); }

#auth-status .user-info span { color: var(--text-0); font-weight: 700; font-size: 0.92rem; }

#auth-status .user-info img { width: 30px; height: 30px; border-radius: 50%; border: 2px solid var(--cyan); }

#auth-status button {
    background: var(--gradient);
    border: none;
    padding: 8px 18px;
    border-radius: 999px;
    color: #071018;
    font-weight: 800;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 18px rgba(93, 162, 255, 0.35);
}

#auth-status button:hover { transform: translateY(-1px); box-shadow: 0 6px 24px rgba(164, 139, 255, 0.5); }

/* ]========================================================
   Layout
   ]======================================================== */

.container {
    display: flex;
    flex: 1;
    width: 100%;
    position: relative;
}

main {
    flex: 1;
    width: 100%;
    box-sizing: border-box;
    padding: 28px 22px 40px;
}

.section {
    max-width: 1180px;
    margin: 0 auto;
}

/* ] Sidebar drawer */

nav#sidebar-nav {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    width: min(340px, 92vw);
    z-index: 1050;
    transform: translateX(-100%);
    background: rgba(9, 13, 25, 0.96);
    backdrop-filter: blur(16px);
    transition: transform 0.32s cubic-bezier(0.22, 1, 0.36, 1);
    padding: 78px 12px 20px;
    overflow-y: auto;
    border-right: 1px solid var(--border);
    box-shadow: 8px 0 30px rgba(0, 0, 0, 0.5);
}

nav#sidebar-nav.open { transform: translateX(0); }

nav#sidebar-nav ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 4px; }

nav#sidebar-nav ul li a {
    display: block;
    padding: 12px 16px;
    text-decoration: none;
    font-weight: 700;
    color: var(--text-1);
    border-radius: 10px;
    border-left: 3px solid transparent;
    transition: all 0.2s;
}

nav#sidebar-nav ul li a:hover,
nav#sidebar-nav ul li a.active {
    background: var(--gradient-soft);
    color: var(--text-0);
    border-left-color: var(--cyan);
}

.sidebar-label {
    display: block;
    color: var(--cyan);
    padding: 14px 16px 6px;
    font-weight: 800;
    font-size: 0.75rem;
    letter-spacing: 1.5px;
    text-transform: uppercase;
}

/* Compact dashboard tiles in the mobile drawer */
@media (max-width: 1024px) {
    nav#sidebar-nav ul {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
        gap: 8px;
    }

    nav#sidebar-nav .sidebar-label,
    nav#sidebar-nav ul li hr,
    nav#sidebar-nav ul li > span { grid-column: 1 / -1; }

    nav#sidebar-nav ul li a {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 6px;
        min-height: 72px;
        padding: 10px 8px;
        text-align: center;
        border: 1px solid var(--border);
        border-left: none;
        border-radius: 12px;
        background: rgba(255, 255, 255, 0.03);
    }

    nav#sidebar-nav ul li a::before {
        content: '🏠';
        font-size: 1.4rem;
        line-height: 1;
    }

    nav#sidebar-nav ul li a[href$="downloads.html"]::before { content: '📥'; }
    nav#sidebar-nav ul li a[href$="member.html"]::before { content: '👤'; }
    nav#sidebar-nav ul li a[href*="class-1-2"]::before { content: '🔢'; }
    nav#sidebar-nav ul li a[href*="class-3-5"]::before { content: '✏️'; }
    nav#sidebar-nav ul li a[href*="class-6-8"]::before { content: '📐'; }
    nav#sidebar-nav ul li a[href*="class-9-10"]::before { content: '🧮'; }
    nav#sidebar-nav ul li a[href*="class-11-12"]::before { content: '🎓'; }
}

.menu-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(4, 7, 14, 0.72);
    z-index: 1040;
    backdrop-filter: blur(4px);
}

.menu-overlay.show { display: block; }

body.menu-open { overflow: hidden; }

@media (min-width: 1025px) {
    body.has-sidebar nav#sidebar-nav {
        position: static;
        transform: none;
        backdrop-filter: none;
        background: transparent;
        border-right: 1px solid var(--border);
        box-shadow: none;
        width: 250px;
    }

    body.has-sidebar #menu-toggle { display: none; }
}

/* Fullscreen menu on desktop for pages without a permanent sidebar (game pages) */
@media (min-width: 1025px) {
    body:not(.has-sidebar) nav#sidebar-nav {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        width: 100%;
        transform: translateY(-100%);
        padding: 96px 24px 40px;
        background: rgba(6, 9, 18, 0.94);
        backdrop-filter: blur(22px);
        -webkit-backdrop-filter: blur(22px);
        border-right: none;
        box-shadow: none;
        transition: transform 0.4s cubic-bezier(0.22, 1, 0.36, 1);
    }

    body:not(.has-sidebar) nav#sidebar-nav::before {
        content: 'MathTricks';
        position: absolute;
        top: 22px;
        left: 28px;
        font-size: 1.35rem;
        font-weight: 800;
        letter-spacing: -0.5px;
        background: var(--gradient);
        -webkit-background-clip: text;
        background-clip: text;
        -webkit-text-fill-color: transparent;
    }

    body:not(.has-sidebar) nav#sidebar-nav::after {
        content: '✕';
        position: absolute;
        top: 18px;
        right: 22px;
        width: 44px;
        height: 44px;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 17px;
        color: var(--text-1);
        background: rgba(255, 255, 255, 0.06);
        border: 1px solid var(--border);
        border-radius: 12px;
        cursor: pointer;
        transition: all 0.2s;
    }

    body:not(.has-sidebar) nav#sidebar-nav::after:hover {
        color: var(--text-0);
        border-color: var(--border-strong);
        background: rgba(255, 255, 255, 0.1);
    }

    body:not(.has-sidebar) nav#sidebar-nav.open { transform: translateY(0); }

    body:not(.has-sidebar) nav#sidebar-nav ul {
        width: min(1100px, 100%);
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
        gap: 14px;
    }

    body:not(.has-sidebar) nav#sidebar-nav .sidebar-label,
    body:not(.has-sidebar) nav#sidebar-nav ul li span,
    body:not(.has-sidebar) nav#sidebar-nav ul li hr {
        grid-column: 1 / -1;
        text-align: center;
        font-size: 0.85rem;
        padding: 8px 16px 14px;
    }

    body:not(.has-sidebar) nav#sidebar-nav ul li a {
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        gap: 8px;
        min-height: 86px;
        padding: 14px 18px;
        font-size: 1rem;
        text-align: center;
        border: 1px solid var(--border);
        border-left: none;
        border-radius: 14px;
        background: rgba(255, 255, 255, 0.03);
        transition: all 0.2s;
    }

    body:not(.has-sidebar) nav#sidebar-nav ul li a::before {
        content: '🏠';
        font-size: 1.8rem;
        line-height: 1;
        filter: drop-shadow(0 4px 10px rgba(0, 0, 0, 0.4));
    }

    body:not(.has-sidebar) nav#sidebar-nav ul li a[href$="downloads.html"]::before { content: '📥'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href$="member.html"]::before { content: '👤'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href*="class-1-2"]::before { content: '🔢'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href*="class-3-5"]::before { content: '✏️'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href*="class-6-8"]::before { content: '📐'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href*="class-9-10"]::before { content: '🧮'; }
    body:not(.has-sidebar) nav#sidebar-nav ul li a[href*="class-11-12"]::before { content: '🎓'; }

    body:not(.has-sidebar) nav#sidebar-nav ul li a:hover,
    body:not(.has-sidebar) nav#sidebar-nav ul li a.active {
        background: var(--gradient-soft);
        border-color: var(--border-strong);
        transform: translateY(-2px);
    }
}

/* ===================== Hero ===================== */

.hero {
    position: relative;
    text-align: center;
    padding: 44px 20px 34px;
    border-radius: 24px;
    overflow: hidden;
    border: 1px solid var(--border);
    background:
        radial-gradient(600px 260px at 20% 0%, rgba(93, 162, 255, 0.22), transparent 60%),
        radial-gradient(600px 260px at 80% 100%, rgba(255, 122, 184, 0.18), transparent 60%),
        var(--bg-1);
}

.hero h2 {
    margin: 0 0 10px;
    font-size: clamp(1.6rem, 4vw, 2.6rem);
    font-weight: 800;
    letter-spacing: -0.5px;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    margin: 0 auto;
    max-width: 640px;
    color: var(--text-1);
    font-size: 1.05rem;
    line-height: 1.55;
}

/* ================== Games Grid & Cards ================== */

.games-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 22px;
    margin-top: 28px;
}

.game-card {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    padding: 28px 22px;
    text-align: center;
    text-decoration: none;
    color: var(--text-0);
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}

.game-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--gradient);
    opacity: 0;
    transition: opacity 0.25s;
    z-index: 0;
}

.game-card:hover {
    transform: translateY(-6px);
    border-color: var(--border-strong);
    box-shadow: var(--shadow), var(--glow);
}

.game-card:hover::before { opacity: 0.06; }

.game-card > * { position: relative; z-index: 1; }

.game-icon {
    font-size: 58px;
    line-height: 1;
    filter: drop-shadow(0 8px 16px rgba(0, 0, 0, 0.4));
    transition: transform 0.3s cubic-bezier(0.2, 0.9, 0.3, 1.4);
}

.game-card:hover .game-icon { transform: scale(1.15) rotate(-4deg); }

.game-card h3 {
    margin: 0;
    font-size: 1.35rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.game-card p {
    margin: 0;
    color: var(--text-1);
    line-height: 1.5;
    font-size: 0.96rem;
}

.game-badge {
    position: absolute;
    top: 14px;
    left: 14px;
    z-index: 2;
    padding: 4px 10px;
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    color: #0b1020;
    background: var(--gradient);
    border-radius: 999px;
}

.btn-play {
    margin-top: auto;
    display: inline-block;
    padding: 10px 26px;
    border-radius: 999px;
    font-weight: 800;
    letter-spacing: 0.6px;
    text-transform: uppercase;
    font-size: 0.85rem;
    color: #0b1020;
    background: var(--gradient);
    box-shadow: 0 6px 20px rgba(93, 162, 255, 0.35);
    transition: transform 0.2s, box-shadow 0.2s;
}

.game-card:hover .btn-play { transform: translateY(-2px); box-shadow: 0 10px 28px rgba(164, 139, 255, 0.5); }

/* ================== Generic buttons ================== */

.btn {
    display: inline-block;
    padding: 10px 22px;
    border-radius: 999px;
    border: 1px solid var(--border-strong);
    background: rgba(255, 255, 255, 0.06);
    color: var(--text-0);
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    transition: all 0.2s;
}

.btn:hover { background: rgba(255, 255, 255, 0.12); border-color: var(--cyan); }

.btn-primary {
    background: var(--gradient);
    border: none;
    color: #0b1020;
    box-shadow: 0 6px 20px rgba(93, 162, 255, 0.35);
}

.btn-primary:hover { background: var(--gradient); box-shadow: 0 10px 28px rgba(164, 139, 255, 0.5); transform: translateY(-1px); }

/* ======================= Content panels ======================= */

.panel {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    backdrop-filter: blur(10px);
}

.panel h2 { margin-top: 0; color: var(--text-0); }

.panel h3 {
    font-size: 1.05rem;
    color: var(--cyan);
    border-bottom: 1px solid var(--border);
    padding-bottom: 10px;
    margin-bottom: 14px;
}

/* ========================= Footer ========================= */

footer {
    margin-top: auto;
    background: rgba(8, 12, 24, 0.85);
    border-top: 1px solid var(--border);
    padding: 20px 16px;
    text-align: center;
    color: var(--text-2);
    font-size: 0.9rem;
}

footer a { color: var(--text-1); text-decoration: none; }
footer a:hover { color: var(--cyan); }

/* ====================== Responsive ====================== */

@media (max-width: 640px) {
    main { padding: 18px 12px 32px; }
    header { padding: 0 12px; gap: 8px; }
    header h1 { font-size: 1.05rem; }
    .hero { padding: 30px 16px 24px; border-radius: 18px; }
    .games-grid { gap: 16px; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); }
}