:root {
    --bg: #0f172a;
    --card-bg: #1e293b;
    --card-bg-hover: #334155;
    --text: #f8fafc;
    --text-muted: #94a3b8;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    --accent: #8b5cf6;
    --danger: #ef4444;
    --border: #334155;
}

:root.light-mode {
    --bg: #f8fafc;
    --card-bg: #e2e8f0;
    --card-bg-hover: #cbd5e1;
    --text: #1e293b;
    --text-muted: #64748b;
    --border: #cbd5e1;
}

* {
    box-sizing: border-box; /* Fondamentale per il mobile */
}

/* Reset globale bottoni */
button {
    font-family: inherit;
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    overflow-x: hidden; /* Evita scroll laterale indesiderato */
}

/* --- HEADER --- */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px; /* Ridotto leggermente */
    background-color: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}
.logo { display: flex; align-items: center; gap: 10px; }
.nav-group { display: flex; align-items: center; gap: 10px; }

/* Buttons */
.nav-btn {
    background: transparent;
    border: 1px solid transparent;
    color: var(--text);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 8px 14px;
    border-radius: 10px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    font-family: inherit;
    font-size: 14px;
    font-weight: 500;
    white-space: nowrap;
    position: relative;
    overflow: hidden;
}
.nav-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: rgba(255, 255, 255, 0.1);
    transition: left 0.3s ease;
    z-index: -1;
}
.nav-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.1);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}
.nav-btn:hover::before { left: 0; }
.nav-btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.nav-btn.primary, .btn-primary {
    background: linear-gradient(135deg, var(--primary), #1d4ed8);
    color: white;
    border: none;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}
.nav-btn.primary:hover, .btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-hover), #1e40af);
    box-shadow: 0 8px 20px rgba(59, 130, 246, 0.4);
    transform: translateY(-3px);
}
.nav-btn.primary:active, .btn-primary:active {
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(59, 130, 246, 0.3);
}

.nav-btn.danger {
    color: var(--danger);
    background: rgba(239, 68, 68, 0.08);
    border: 1px solid rgba(239, 68, 68, 0.2);
}
.nav-btn.danger:hover {
    background: rgba(239, 68, 68, 0.15);
    border-color: rgba(239, 68, 68, 0.4);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.2);
}

/* Bottoni utility */
.btn-primary.full-width {
    width: 100%;
    padding: 12px 16px;
    font-size: 15px;
    font-weight: 600;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
}
.btn-primary.full-width:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(59, 130, 246, 0.4);
}

/* --- HERO & FILTERS --- */
.hero { text-align: center; padding: 40px 20px 30px; }
.hero h1 { 
    font-size: 2.5em; 
    margin: 0; 
    line-height: 1.2;
    background: linear-gradient(90deg, #3b82f6, #8b5cf6); 
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent; 
}
.hero p { margin-top: 10px; color: var(--text-muted); }

.filters { display: flex; justify-content: center; margin-bottom: 20px; padding: 0 20px; flex-wrap: wrap; gap: 10px; }
#searchInput { 
    width: 100%; 
    max-width: 500px; 
    padding: 12px 18px;
    border-radius: 50px;
    border: 1px solid var(--border);
    background: rgba(255, 255, 255, 0.05);
    color: white;
    font-family: inherit;
    transition: all 0.3s ease;
    font-size: 15px;
}
#searchInput:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: var(--primary);
}
#searchInput:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

input, select, textarea {
    padding: 12px;
    border-radius: 8px;
    border: 1px solid var(--border);
    background: var(--card-bg);
    color: white;
    font-family: inherit;
    width: 100%; /* Fix per mobile */
    transition: all 0.3s ease;
}
input:focus, select:focus, textarea:focus {
    outline: none;
    border-color: var(--primary);
    background: var(--card-bg);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}
input::placeholder {
    color: var(--text-muted);
}

/* --- GRIGLIA APPUNTI --- */
.container { 
    max-width: 1200px; 
    margin: 0 auto; 
    padding: 10px 20px; 
    flex: 1; 
    width: 100%; 
}

.grid {
    display: grid;
    /* Responsive automatico: minimo 300px, altrimenti 1 colonna */
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); 
    gap: 20px;
}

/* Horizontal carousel for appunti */
.carousel-wrapper { position: relative; }
.carousel {
    display: flex;
    gap: 20px;
    overflow-x: auto;
    scroll-behavior: smooth;
    padding: 10px 6px;
}
.carousel::-webkit-scrollbar { height: 8px; }
.carousel::-webkit-scrollbar-thumb { background: rgba(148,163,184,0.12); border-radius: 10px; }
.carousel .card { min-width: 300px; flex: 0 0 auto; }
.carousel .request-card { min-width: 320px; flex: 0 0 auto; }
.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(0,0,0,0.5);
    color: var(--text);
    border: none;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 10;
}
.carousel-btn.left { left: 6px; }
.carousel-btn.right { right: 6px; }
.carousel-btn:hover { background: rgba(0,0,0,0.7); }

/* Cards */
.card {
    background: rgba(30, 41, 59, 0.7);
    border: 1px solid rgba(148, 163, 184, 0.1);
    border-radius: 12px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    backdrop-filter: blur(10px);
}
.card:hover {
    transform: translateY(-4px);
    background: rgba(30, 41, 59, 0.85);
    border-color: rgba(59, 130, 246, 0.2);
    box-shadow: 0 12px 24px rgba(59, 130, 246, 0.15);
}
.card:active { transform: translateY(-2px); } /* Feedback tocco su mobile */
.card-header { display: flex; justify-content: space-between; font-size: 0.85em; }
.badge { padding: 4px 8px; border-radius: 6px; font-weight: 600; font-size: 11px; text-transform: uppercase; display: inline-block; }
.badge.Appunti { background: rgba(59, 130, 246, 0.2); color: #60a5fa; border: 1px solid rgba(59, 130, 246, 0.3); }
.badge.Schema { background: rgba(16, 185, 129, 0.2); color: #34d399; border: 1px solid rgba(16, 185, 129, 0.3); }
.badge.Esercizi { background: rgba(245, 158, 11, 0.2); color: #fbbf24; border: 1px solid rgba(245, 158, 11, 0.3); }
.card h3 { margin: 5px 0; font-size: 1.2em; word-wrap: break-word; } /* Evita testo lunghissimo */
.meta-info { font-size: 0.9em; color: var(--text-muted); }

/* Card Footer */
.card-footer {
    display: flex;
    justify-content: space-between;
    padding-top: 15px;
    border-top: 1px solid rgba(148, 163, 184, 0.1);
    gap: 10px;
    flex-wrap: wrap;
}
.btn-action {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    padding: 10px;
    border-radius: 10px;
    border: 1px solid rgba(148, 163, 184, 0.1);
    background: rgba(255, 255, 255, 0.03);
    color: var(--text-muted);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}
.btn-action:hover {
    background: rgba(148, 163, 184, 0.08);
    color: var(--text);
    border-color: rgba(148, 163, 184, 0.2);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}
.btn-action:active {
    transform: translateY(0);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}
.btn-action.like-btn.liked {
    color: #ff6b6b;
    background: rgba(239, 68, 68, 0.12);
    border-color: rgba(239, 68, 68, 0.3);
}
.btn-action.like-btn.liked:hover {
    background: rgba(239, 68, 68, 0.2);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.2);
}

.btn-action.fav-btn.active {
    color: #fbbf24;
    background: rgba(245, 158, 11, 0.12);
    border-color: rgba(245, 158, 11, 0.3);
}
.btn-action.fav-btn.active:hover {
    background: rgba(245, 158, 11, 0.2);
    box-shadow: 0 4px 12px rgba(245, 158, 11, 0.2);
}

/* --- MODALS --- */
.modal { 
    display: none; 
    position: fixed; 
    z-index: 200; 
    left: 0; 
    top: 0; 
    width: 100%; 
    height: 100%; 
    background-color: rgba(0,0,0,0.85); 
    backdrop-filter: blur(5px); 
    overflow-y: auto; /* Permette scroll se modale troppo alta */
}

.modal-content {
    background-color: rgba(30, 41, 59, 0.95);
    margin: 5% auto;
    padding: 25px;
    border: 1px solid rgba(148, 163, 184, 0.1);
    width: 90%;
    max-width: 500px;
    border-radius: 16px;
    position: relative;
    color: var(--text);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(10px);
    animation: fadeIn 0.3s ease;
}
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.close { position: absolute; right: 20px; top: 15px; font-size: 28px; cursor: pointer; color: var(--text-muted); padding: 5px; transition: all 0.2s ease; }
.close:hover { color: white; transform: scale(1.1); }

/* Anteprima Layout Specifico */
#modalAnteprima .modal-content {
    max-width: 1100px;
    height: 85vh; /* Altezza fissa */
    display: flex;
    flex-direction: column;
    padding: 0;
    overflow: hidden;
}

.preview-layout { display: flex; height: 100%; width: 100%; }
.preview-pdf { flex: 2; position: relative; display: flex; flex-direction: column; background: #000; height: 100%; }
.preview-chat { flex: 1; border-left: 1px solid var(--border); display: flex; flex-direction: column; background: var(--card-bg); max-width: 350px; min-width: 250px; }

/* Chat */
.chat-box { flex: 1; overflow-y: auto; padding: 15px; display: flex; flex-direction: column; gap: 10px; }
.chat-msg {
    font-size: 13px;
    line-height: 1.4;
    padding: 10px 12px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 10px;
    word-break: break-word;
    transition: all 0.2s ease;
}
.chat-msg:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.12);
}
.chat-input-area {
    padding: 15px;
    border-top: 1px solid var(--border);
    display: flex;
    gap: 10px;
}
.chat-input-area button {
    min-width: 80px;
    padding: 10px 14px;
}

/* Locked Overlay */
.locked-overlay { position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; background: rgba(15, 23, 42, 0.95); z-index: 10; text-align: center; padding: 20px; }

/* Blur Content (per locked preview) */
.blur-content { filter: blur(8px); pointer-events: none; opacity: 0.5; }

/* Tab Buttons */
.admin-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--border);
    flex-wrap: wrap;
}
.tab-btn {
    background: transparent;
    border: none;
    color: var(--text-muted);
    padding: 12px 16px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: all 0.3s ease;
    font-family: inherit;
    position: relative;
}
.tab-btn:hover {
    color: var(--text);
    background: rgba(255, 255, 255, 0.05);
}
.tab-btn.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
    box-shadow: 0 2px 8px rgba(59, 130, 246, 0.2);
}

/* Danger Button */
.btn-danger {
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.9), rgba(220, 38, 38, 0.9));
    border: none;
    color: white !important;
    box-shadow: 0 4px 15px rgba(239, 68, 68, 0.3);
}
.btn-danger:hover {
    background: linear-gradient(135deg, var(--danger), #b91c1c);
    box-shadow: 0 8px 20px rgba(239, 68, 68, 0.4);
    transform: translateY(-3px);
}
.btn-danger:active {
    transform: translateY(-1px);
    box-shadow: 0 4px 8px rgba(239, 68, 68, 0.3);
}

/* Admin Dashboard */
#adminDashboard .modal-content { max-width: 900px; height: 85vh; display: flex; flex-direction: column; }
.modal-body { overflow-y: auto; flex: 1; }

/* Stat Cards */
.stat-card {
    background: rgba(59, 130, 246, 0.1);
    border: 1px solid rgba(59, 130, 246, 0.2);
    border-radius: 12px;
    padding: 20px;
    text-align: center;
    transition: all 0.3s ease;
}
.stat-card:hover {
    background: rgba(59, 130, 246, 0.15);
    border-color: rgba(59, 130, 246, 0.4);
    transform: translateY(-4px);
}
.stat-number {
    font-size: 32px;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 8px;
}
.stat-label {
    font-size: 12px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.admin-list-item { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; padding: 10px; background: var(--bg); border-radius: 8px; margin-bottom: 8px; border: 1px solid var(--border); gap: 10px; }

/* Footer */
footer {
    background-color: #0f172a;
    border-top: 1px solid var(--border);
    padding: 20px 0;
    margin-top: 40px;
    font-size: 13px;
    color: var(--text-muted);
}
.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.footer-right { display: flex; align-items: center; gap: 6px; cursor: pointer; padding: 8px 12px; border-radius: 8px; transition: all 0.2s ease; }
.footer-right:hover { background: rgba(255, 255, 255, 0.05); transform: scale(1.05); }

/* Toast */
.toast {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: linear-gradient(135deg, #10b981, #059669);
    color: white;
    padding: 14px 24px;
    border-radius: 12px;
    z-index: 300;
    max-width: 90%;
    box-shadow: 0 8px 24px rgba(16, 185, 129, 0.3);
    font-weight: 500;
    animation: slideIn 0.3s ease;
}
.toast.error {
    background: linear-gradient(135deg, var(--danger), #dc2626);
    box-shadow: 0 8px 24px rgba(239, 68, 68, 0.3);
}
@keyframes slideIn {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ==========================================================================
   📱 MOBILE FIX & RESPONSIVE (IL CUORE DELLE CORREZIONI)
   ==========================================================================
*/
@media (max-width: 768px) {
    
    /* 1. Header Semplificato */
    header { padding: 15px; }
    .logo span:last-child { display: none; } /* Nasconde scritta ShareNotes se troppo stretto */
    .desktop-only { display: none !important; } /* Nasconde testi pulsanti "Carica", "Admin" */
    
    /* 2. Griglia a 1 Colonna */
    .grid { 
        grid-template-columns: 1fr; /* Una sola colonna piena */
        gap: 15px;
    }
    .card { padding: 15px; } /* Meno padding interno */

    /* 3. Fix Modale Upload (Form Input impilati) */
    /* Questo forza i div che hanno display:grid (quelli delle select) a diventare block */
    #uploadForm div[style*="grid-template-columns"] {
        display: flex !important;
        flex-direction: column;
        gap: 10px;
    }

    /* 4. Fix Modale Anteprima (PDF sopra, Chat sotto) */
    #modalAnteprima .modal-content {
        height: 100vh; /* A tutto schermo su mobile */
        margin: 0;
        width: 100%;
        max-width: 100%;
        border-radius: 0;
    }
    .preview-layout { flex-direction: column; }
    .preview-pdf { flex: 1; height: 50%; border-bottom: 1px solid var(--border); }
    .preview-chat { 
        flex: 1; 
        max-width: 100%; 
        border-left: none; 
        max-height: 50%; /* Chat prende metà schermo */
    }
    
    /* 5. Admin Panel Mobile */
    #adminDashboard .modal-content { width: 100%; height: 100%; margin: 0; border-radius: 0; }
    .admin-tabs { overflow-x: auto; white-space: nowrap; padding-bottom: 5px; } /* Tabs scrollabili */
    .admin-list-item { flex-direction: column; align-items: flex-start; }
    .admin-actions { width: 100%; display: flex; justify-content: flex-end; margin-top: 10px; }

    /* 6. Footer */
    .footer-content { flex-direction: column; gap: 15px; text-align: center; }

    /* 7. Typography */
    .hero h1 { font-size: 2em; }
    
    /* 8. Fix vari */
    .modal-content { margin: 10% auto; width: 95%; } /* Modali standard più larghe */
}

/* Fix per la X su iPhone/Android con Notch */
@media (max-width: 768px) {
    #modalAnteprima .close {
        top: 15px !important;     /* Scende un po' */
        right: 15px !important;
        background: rgba(0,0,0,0.5); /* Sfondo scuro per vederla meglio */
        width: 40px;
        height: 40px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        z-index: 999; /* Assicura che stia sopra a tutto */
    }
}

.advanced-filter {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
    padding: 10px;
    background: rgba(100, 150, 255, 0.05);
    border-radius: 8px;
    border: 1px solid var(--border);
}

.advanced-filter select, .advanced-filter input {
    padding: 8px 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--secondary);
    color: var(--text);
    font-size: 13px;
    font-family: inherit;
}

.advanced-filter select:focus, .advanced-filter input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(100, 150, 255, 0.1);
}

.rating-stars {
    display: flex;
    gap: 5px;
    justify-content: center;
    padding: 10px;
    background: rgba(100, 150, 255, 0.1);
    border-radius: 6px;
    animation: slideIn 0.2s ease-out;
}

.rating-stars .star {
    cursor: pointer;
    font-size: 24px;
    opacity: 0.5;
    transition: all 0.2s ease;
}

.rating-stars .star:hover {
    opacity: 1;
    transform: scale(1.2);
}