:root {
    --primary: #6366f1;
    --primary-hover: #4f46e5;
    --secondary: #06b6d4;
    --accent: #f43f5e;
    --bg: #f8fafc;
    --bg-rgb: 248, 250, 252;
    --card-bg: #ffffff;
    --card-bg-rgb: 255, 255, 255;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --header-h: 64px;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --radius: 8px;
}

/* Dark Mode - Professional Matte Aesthetic */
body.dark {
    --primary: #e2ff8d;
    --primary-hover: #d4f86a;
    --secondary: #ffffff;
    --bg: #111111;
    --bg-rgb: 17, 17, 17;
    --card-bg: #1a1a1a;
    --card-bg-rgb: 26, 26, 26;
    --text-main: #ffffff;
    --text-muted: #888888;
    --border: #2a2a2a;
    --header-bg: #000000;
    --shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
    --radius: 12px;
}

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

body {
    font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg);
    color: var(--text-main);
    line-height: 1.5;
    min-height: 100vh;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    width: 95%;
    max-width: 1100px;
    margin: 0 auto;
}

#header {
    background-color: var(--card-bg);
    border-bottom: 1px solid var(--border);
    height: var(--header-h);
    display: flex;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 1px 2px 0 rgb(0 0 0 / 0.05);
}

body.dark #header {
    background-color: #000000;
}

#header h1 a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 800;
    letter-spacing: -1px;
    font-size: 1.5rem;
}

nav a {
    color: var(--text-main);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: color 0.2s;
    margin-left: 20px;
}

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

.user-greeting {
    font-size: 0.8rem;
    opacity: 0.8;
    margin-left: 20px;
}

.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-main);
    font-size: 1.5rem;
    cursor: pointer;
}

body.dark .menu-toggle {
    color: white;
}

#main-content {
    padding: 2.5rem 0;
}

.row {
    display: grid;
    grid-template-columns: 1fr 320px;
    gap: 2.5rem;
}

.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 2rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
}

.col-side .card {
    margin-bottom: 2rem;
}

/* Responsive Puzzle */
#puzzle-container {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 0;
}

#puzzle {
    position: relative;
    width: min(90vw, 500px);
    aspect-ratio: 1/1;
    background-color: #cbd5e1;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 10px 15px -3px rgb(0 0 0 / 0.1);
}

body.dark #puzzle {
    background-color: #1e293b;
    box-shadow: 0 20px 25px -5px rgb(0 0 0 / 0.3);
}

.puzzle-piece {
    position: absolute;
    box-sizing: border-box;
    border: 1px solid rgba(255,255,255,0.2);
    border-radius: 4px;
    cursor: pointer;
    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.puzzle-piece:hover {
    z-index: 10;
    transform: scale(1.02);
    filter: brightness(1.1);
}

/* Standardised Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius);
    font-weight: 700;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s;
    border: 1px solid transparent;
    font-family: inherit;
    text-decoration: none;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

body.dark .btn-primary {
    color: #111111;
    font-weight: 800;
    box-shadow: 0 4px 14px rgba(226, 255, 141, 0.2);
}

.alert {
    padding: 1rem;
    border-radius: var(--radius);
    margin-bottom: 1rem;
}

.alert.success {
    background-color: rgba(34, 197, 94, 0.1);
    color: #22c55e;
    border: 1px solid rgba(34, 197, 94, 0.2);
}

.alert.info {
    background-color: rgba(59, 130, 246, 0.1);
    color: #3b82f6;
    border: 1px solid rgba(59, 130, 246, 0.2);
}

body.dark .alert.info {
    background-color: #222222;
    color: var(--primary);
    border-color: #333333;
}

/* Footer */
#footer {
    background: var(--card-bg);
    padding: 3rem 0;
    border-top: 1px solid var(--border);
    margin-top: 4rem;
    text-align: center;
}

/* Theme Toggle Button */
#theme-toggle {
    background: var(--bg);
    border: 1px solid var(--border);
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--text-main);
    display: flex;
    align-items: center;
    gap: 8px;
    cursor: pointer;
}

body.dark #theme-toggle {
    background: #222222;
    border-color: #333333;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.85);
    overflow-y: auto;
    backdrop-filter: blur(4px);
}

.modal-content {
    background-color: var(--card-bg);
    margin: 2rem auto;
    padding: 2rem;
    width: 90%;
    max-width: 600px;
    border-radius: var(--radius);
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
}

.btn-secondary {
    background-color: var(--bg);
    border: 1px solid var(--border);
    color: var(--text-main);
}

body.dark .btn-secondary {
    color: var(--text-muted);
}

body.dark .btn-secondary:hover {
    color: var(--text-main);
}

#hint-btn {
    background-color: var(--bg);
    border: 1px solid var(--border);
    color: var(--text-main);
}

body.dark #hint-btn {
    color: var(--text-muted);
}

body.dark #hint-btn:not(:disabled) {
    color: var(--text-main);
}

body.dark #hint-btn:disabled {
    opacity: 0.6;
}

.cropper-container {
    max-height: 70vh;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    overflow: hidden;
}

#crop-preview {
    max-width: 100%;
    display: block;
}

/* Mobile Adjustments */
@media (max-width: 900px) {
    .row {
        grid-template-columns: 1fr;
    }
    .col-side { order: 2; }
    .col-main { order: 1; }

    .menu-toggle {
        display: block;
    }

    #nav-menu {
        display: none;
        position: absolute;
        top: var(--header-h);
        left: 0;
        width: 100%;
        background-color: var(--card-bg);
        border-bottom: 1px solid var(--border);
        padding: 1rem 0;
        flex-direction: column;
        align-items: center;
        gap: 1.5rem;
        box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    }

    #nav-menu.show {
        display: flex;
    }

    nav a {
        margin-left: 0;
        font-size: 1.1rem;
        width: 100%;
        text-align: center;
        padding: 0.5rem 0;
    }

    .user-greeting {
        margin-left: 0;
        margin-bottom: 0.5rem;
    }

    .modal-content {
        margin: 1rem auto;
        padding: 1.5rem;
    }
}

.bmc-button {
    width: 100% !important;
    border-radius: 12px !important;
}