:root {
    --light-bg: #f0f2f5;
    --light-surface: #ffffff;
    --light-text: #1c1e21;
    --light-secondary-text: #606770;
    --light-border: #ccd0d5;

    --dark-bg: #10101a;
    --dark-surface: #1a1a2e;
    --dark-text: #e4e6eb;
    --dark-secondary-text: #b0b3b8;
    --dark-border: #3a3b3c;

    --glow-cyan: #00f6ff;
    --glow-magenta: #ff00ff;
    --x-color: var(--glow-cyan);
    --o-color: var(--glow-magenta);

    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* Basic Setup */
*, *::before, *::after { box-sizing: border-box; }
body {
    font-family: var(--font-family);
    margin: 0;
    background-color: var(--light-bg);
    color: var(--light-text);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}
body.dark-mode {
    background-color: var(--dark-bg);
    color: var(--dark-text);
}

/* Header */
header {
    background-color: var(--light-surface);
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--light-border);
    transition: background-color 0.3s, border-color 0.3s;
    position: sticky;
    top: 0;
    z-index: 100;
}
body.dark-mode header {
    background-color: var(--dark-surface);
    border-bottom-color: var(--dark-border);
}

/* NEW: Polished Logo Styling */
.header-logo a {
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 12px;
}
.header-logo h1 {
    margin: 0;
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--light-text);
    transition: color 0.3s;
}
body.dark-mode .header-logo h1 { color: var(--glow-cyan); text-shadow: 0 0 5px var(--glow-cyan); }
.header-logo img {
    height: 40px;
    width: auto;
    border-radius: 50%;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    display: block;
}
body.dark-mode .header-logo img {
    box-shadow: 0 0 15px var(--glow-cyan);
}


/* Hamburger Menu Button */
.menu-btn {
    background: none; border: none; cursor: pointer; padding: 10px; z-index: 2001;
}
.menu-btn .line {
    width: 30px; height: 3px; background-color: var(--light-secondary-text); margin: 6px 0;
    transition: all 0.3s ease-in-out;
}
body.dark-mode .menu-btn .line { background-color: var(--dark-secondary-text); }

/* Off-Screen Menu */
.off-screen-menu {
    position: fixed; top: 0; right: 0;
    width: 280px; height: 100%;
    background-color: var(--light-surface);
    box-shadow: -5px 0 15px rgba(0,0,0,0.1);
    transform: translateX(100%);
    transition: transform 0.3s ease-in-out;
    z-index: 2000;
    padding-top: 80px;
    display: flex;
    flex-direction: column;
}
.off-screen-menu.active { transform: translateX(0); }
body.dark-mode .off-screen-menu {
    background-color: var(--dark-surface);
    box-shadow: -5px 0 25px rgba(0,0,0,0.3);
    border-left: 1px solid var(--dark-border);
}
.off-screen-menu nav a {
    display: block; width: 100%; text-align: left;
    text-decoration: none;
    padding: 1rem 1.5rem; font-size: 1.1rem;
    color: var(--light-text);
    transition: background-color 0.2s, color 0.2s;
}
body.dark-mode .off-screen-menu nav a { color: var(--dark-text); }
.off-screen-menu nav a:hover {
    background-color: var(--light-border);
}
body.dark-mode .off-screen-menu nav a:hover {
    background-color: var(--dark-border);
    color: var(--glow-cyan);
}
.dark-mode-toggle {
    padding: 1rem 1.5rem; margin-top: auto;
    display: flex; justify-content: space-between; align-items: center;
    border-top: 1px solid var(--light-border);
}
body.dark-mode .dark-mode-toggle { border-top-color: var(--dark-border); }
.switch {
    position: relative; display: inline-block; width: 60px; height: 34px;
}
.switch input { opacity: 0; width: 0; height: 0; }
.slider {
    position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0;
    background-color: #ccc; transition: .4s; border-radius: 34px;
}
.slider:before {
    position: absolute; content: ""; height: 26px; width: 26px; left: 4px; bottom: 4px;
    background-color: white; transition: .4s; border-radius: 50%;
}
input:checked + .slider { background-color: var(--glow-cyan); }
input:checked + .slider:before { transform: translateX(26px); }

/* Main Content */
main { padding: 1.5rem; flex-grow: 1; display: flex; flex-direction: column; align-items: center; }
.game-wrapper, .content-page {
    background-color: var(--light-surface);
    padding: 1.5rem; border-radius: 16px;
    box-shadow: 0 8px 30px rgba(0,0,0,0.1);
    width: 100%; max-width: 500px;
    transition: background-color 0.3s;
}
.content-page { max-width: 800px; }
body.dark-mode .game-wrapper, body.dark-mode .content-page {
    background-color: var(--dark-surface);
    box-shadow: 0 0 20px rgba(0, 0, 0, 0.5), 0 0 40px var(--dark-surface);
    border: 1px solid var(--dark-border);
}
.content-page h2 {
    font-size: 2rem;
    color: var(--light-text);
    border-bottom: 2px solid var(--light-border);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
}
body.dark-mode .content-page h2 { color: var(--glow-cyan); border-bottom-color: var(--dark-border); }

/* NEW: Game Info Bar */
.game-info-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding: 0.5rem 1rem;
    background-color: var(--light-bg);
    border-radius: 8px;
}
body.dark-mode .game-info-bar {
    background-color: var(--dark-bg);
    border: 1px solid var(--dark-border);
}
.level-display, .timer-display {
    font-size: 1rem;
    font-weight: 600;
    color: var(--light-secondary-text);
}
body.dark-mode .level-display, body.dark-mode .timer-display {
    color: var(--dark-secondary-text);
}
.level-display span, .timer-display span {
    color: var(--light-text);
    font-weight: 700;
    min-width: 4ch;
    display: inline-block;
}
body.dark-mode .level-display span, body.dark-mode .timer-display span {
    color: var(--dark-text);
}
.action-icons { display: flex; gap: 10px; }
.icon-btn {
    width: 40px; height: 40px; background-color: transparent;
    border: 2px solid var(--light-border); border-radius: 50%;
    cursor: pointer; display: flex; align-items: center; justify-content: center;
    transition: all 0.3s ease;
}
body.dark-mode .icon-btn { border-color: var(--dark-border); }
.icon-btn:hover { background-color: var(--light-border); transform: translateY(-2px); }
body.dark-mode .icon-btn:hover { border-color: var(--glow-cyan); box-shadow: 0 0 10px var(--glow-cyan); }

/* NEW: CSS Icons */
.icon-hint { width: 20px; height: 20px; background-color: var(--light-secondary-text); border-radius: 50%; position: relative; }
.icon-hint::after { content: ''; position: absolute; width: 10px; height: 6px; background-color: var(--light-secondary-text); bottom: -4px; left: 5px; border-radius: 2px; }
body.dark-mode .icon-hint, body.dark-mode .icon-hint::after { background-color: var(--dark-secondary-text); }
.icon-undo { width: 20px; height: 20px; border: 3px solid var(--light-secondary-text); border-radius: 50%; border-right-color: transparent; position: relative; transform: rotate(45deg); }
.icon-undo::before { content: ''; position: absolute; width: 0; height: 0; border-style: solid; border-width: 6px 6px 0 6px; border-color: var(--light-secondary-text) transparent transparent transparent; top: -5px; left: -1px; }
body.dark-mode .icon-undo { border-color: var(--dark-secondary-text); border-right-color: transparent; }
body.dark-mode .icon-undo::before { border-color: var(--dark-secondary-text) transparent transparent transparent; }

/* Game UI */
.status { text-align: center; font-size: 1.2rem; font-weight: 500; margin-bottom: 1.5rem; min-height: 2rem; }
body.dark-mode .status { color: var(--dark-secondary-text); }
.board-container { position: relative; margin-top: 1rem; }
.board { display: grid; grid-template-columns: repeat(3, 1fr); gap: 15px; max-width: 360px; margin: 0 auto; }
body.dark-mode .board { border-radius: 10px; box-shadow: inset 0 0 15px rgba(0,0,0,0.5); background: #10101a; padding: 15px; }
.cell { width: 100%; aspect-ratio: 1 / 1; background-color: var(--light-bg); display: flex; justify-content: center; align-items: center; font-size: 3.5rem; font-weight: bold; cursor: pointer; border-radius: 8px; transition: all 0.3s ease; }
body.dark-mode .cell { background-color: var(--dark-bg); border: 2px solid var(--dark-border); box-shadow: 0 0 5px rgba(0,0,0,0.2); }
.cell:hover { transform: translateY(-3px); }
body.dark-mode .cell:hover { border-color: var(--glow-cyan); box-shadow: 0 0 10px var(--glow-cyan); }
.cell .symbol { transform: scale(0); transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275); }
.cell.occupied .symbol { transform: scale(1); }
.cell.x { color: var(--x-color); }
body.dark-mode .cell.x { text-shadow: 0 0 8px var(--x-color); }
.cell.o { color: var(--o-color); }
body.dark-mode .cell.o { text-shadow: 0 0 8px var(--o-color); }
.win-line { position: absolute; background-color: var(--light-text); height: 6px; border-radius: 3px; transform-origin: left; transition: transform 0.5s ease-in-out; transform: scaleX(0); }
body.dark-mode .win-line { background-color: #fff; box-shadow: 0 0 10px #fff, 0 0 20px #fff; }
.cell.hint-cell { animation: hint-pulse 1.5s infinite; }
@keyframes hint-pulse { 0% { box-shadow: 0 0 0 0 rgba(0, 246, 255, 0.7); } 70% { box-shadow: 0 0 10px 20px rgba(0, 246, 255, 0); } 100% { box-shadow: 0 0 0 0 rgba(0, 246, 255, 0); } }

/* Controls */
.game-settings { text-align: center; margin-top: 2rem; }
button.primary, button.secondary { padding: 12px 24px; font-size: 1rem; font-weight: 600; margin: 5px; cursor: pointer; border-radius: 8px; border: 2px solid; transition: all 0.3s ease; background: transparent; }
button.primary { border-color: var(--light-text); color: var(--light-text); }
button.primary:hover { background-color: var(--light-text); color: var(--light-surface); }
body.dark-mode button.primary { border-color: var(--glow-cyan); color: var(--glow-cyan); text-shadow: 0 0 3px var(--glow-cyan); }
body.dark-mode button.primary:hover { background-color: var(--glow-cyan); color: var(--dark-bg); text-shadow: none; box-shadow: 0 0 15px var(--glow-cyan); }
button.secondary { border-color: var(--light-border); color: var(--light-secondary-text); }
button.secondary:hover { background-color: var(--light-border); }
body.dark-mode button.secondary { border-color: var(--dark-border); color: var(--dark-secondary-text); }
body.dark-mode button.secondary:hover { background-color: var(--dark-border); }

/* Ad Modal & Container */
.ad-modal-overlay { position: fixed; inset: 0; background-color: rgba(0, 0, 0, 0.7); display: none; align-items: center; justify-content: center; z-index: 1000; opacity: 0; transition: opacity 0.3s ease; backdrop-filter: blur(5px); }
.ad-modal-overlay.visible { display: flex; opacity: 1; }
.ad-modal-content { background-color: var(--light-surface); color: var(--light-text); padding: 2rem; border-radius: 12px; box-shadow: 0 10px 40px rgba(0,0,0,0.2); max-width: 500px; width: 90%; transform: scale(0.95); transition: transform 0.3s ease; text-align: center; }
.ad-modal-overlay.visible .ad-modal-content { transform: scale(1); }
body.dark-mode .ad-modal-content { background-color: var(--dark-surface); color: var(--dark-text); border: 1px solid var(--dark-border); box-shadow: 0 0 50px rgba(0,0,0,0.5); }
.ad-modal-content h2 { margin-top: 0; }
body.dark-mode .ad-modal-content h2 { color: var(--glow-cyan); }
.ad-container { margin-top: 2rem; text-align: center; width: 100%; }

/* Prose for content pages */
.prose { max-width: none; line-height: 1.7; }
.prose h3 { font-size: 1.5rem; color: var(--light-text); margin-top: 2em; margin-bottom: 0.5em; }
body.dark-mode .prose h3 { color: var(--glow-cyan); }
.prose a { color: var(--primary-color); text-decoration: none; font-weight: 500;}
body.dark-mode .prose a { color: var(--glow-cyan); }
.prose a:hover { text-decoration: underline; }
.prose ul, .prose ol { padding-left: 20px; }

/* Cookie Banner */
#cookie-consent-banner { position: fixed; bottom: 0; left: 0; right: 0; background-color: var(--light-surface); border-top: 1px solid var(--light-border); padding: 1rem; z-index: 1001; display: none; align-items: center; justify-content: space-between; gap: 1rem; box-shadow: 0 -2px 10px rgba(0,0,0,0.1); }
body.dark-mode #cookie-consent-banner { background-color: var(--dark-surface); border-top-color: var(--dark-border); }
#cookie-consent-banner p { margin: 0; }
#cookie-consent-banner a { color: var(--primary-color); font-weight: 600; text-decoration: none;}
body.dark-mode #cookie-consent-banner a { color: var(--glow-cyan); }

/* Footer */
footer { background: var(--light-surface); border-top: 1px solid var(--light-border); color: var(--light-secondary-text); text-align: center; padding: 1.5rem; margin-top: auto; }
 body.dark-mode footer { background-color: var(--dark-surface); border-top-color: var(--dark-border); }