@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;600;800&family=Tajawal:wght@400;500;700&display=swap');

:root {
    /* Sleek, Professional Modern UI */
    --primary-color: #4F46E5;   /* Indigo */
    --primary-dark: #3730A3;
    --secondary-color: #10B981; /* Emerald */
    --secondary-dark: #059669;
    --accent-color: #F59E0B;    /* Amber */
    --accent-dark: #D97706;
    --bg-color: #F8FAFC;        /* Slate 50 */
    --card-bg: #FFFFFF;
    --text-main: #1E293B;       /* Slate 800 */
    --text-muted: #64748B;      /* Slate 500 */
    --glass-blur: blur(16px);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}

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

body {
    font-family: 'Outfit', 'Tajawal', sans-serif;
    background-color: #f0f9ff;
    background-image: 
        radial-gradient(#38bdf8 3px, transparent 3px), 
        radial-gradient(#f43f5e 3px, transparent 3px),
        radial-gradient(#facc15 3px, transparent 3px);
    background-size: 60px 60px, 60px 60px, 60px 60px;
    background-position: 0 0, 20px 20px, 40px 40px;
    color: var(--text-main);
    min-height: 100vh;
    overflow-x: hidden;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* --- Header Styles --- */
.main-header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: var(--glass-blur);
    border-bottom: 5px solid;
    border-image: linear-gradient(to right, #ef4444, #f59e0b, #10b981, #3b82f6, #8b5cf6) 1;
    padding: 1rem 2.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.logo-text {
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

.subject-tag {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    background: #F1F5F9;
    padding: 0.2rem 0.6rem;
    border-radius: 6px;
    display: inline-block;
    margin-top: 0;
    margin-left: 10px;
    vertical-align: middle;
}

.main-nav {
    display: flex;
    gap: 0.5rem;
}

.nav-btn {
    padding: 0.6rem 1.2rem;
    border: 3px solid transparent;
    background: #f1f5f9;
    border-radius: 12px;
    font-weight: 800;
    font-size: 1rem;
    color: #475569;
    cursor: pointer;
    transition: all 0.2s ease;
}

.nav-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.nav-btn.active {
    background: linear-gradient(135deg, #3b82f6, #2563eb);
    color: white;
    border-color: #1d4ed8;
    box-shadow: 0 4px 10px rgba(59, 130, 246, 0.4);
}

#home-btn.active { background: linear-gradient(135deg, #ef4444, #dc2626); border-color: #b91c1c; box-shadow: 0 4px 10px rgba(239, 68, 68, 0.4); }
#alphabet-btn.active { background: linear-gradient(135deg, #f59e0b, #d97706); border-color: #b45309; box-shadow: 0 4px 10px rgba(245, 158, 11, 0.4); }
#units-btn.active { background: linear-gradient(135deg, #10b981, #059669); border-color: #047857; box-shadow: 0 4px 10px rgba(16, 185, 129, 0.4); }

/* --- Content Area --- */
#content-area {
    flex: 1;
    padding: 2.5rem;
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

.welcome-screen {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 70vh;
}

.welcome-content {
    background: var(--card-bg);
    padding: 3rem;
    border-radius: 24px;
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(226, 232, 240, 0.8);
    width: 100%;
    max-width: 900px;
}

/* --- Buttons --- */
button {
    font-family: inherit;
    outline: none;
}

.btn-back {
    background: transparent !important;
    color: var(--text-muted) !important;
    border: 1px solid #cbd5e1 !important;
    border-radius: 8px !important;
    padding: 0.5rem 1rem !important;
    font-size: 1rem !important;
    transition: all 0.2s ease !important;
}

.btn-back:hover {
    background: #f1f5f9 !important;
    color: var(--text-main) !important;
}

/* --- Tracing Canvas --- */
#tracing-canvas, #dotCanvas {
    background-image: linear-gradient(#e2e8f0 1px, transparent 1px), linear-gradient(90deg, #e2e8f0 1px, transparent 1px);
    background-size: 20px 20px;
    background-color: #ffffff;
    border: 1px solid #cbd5e1 !important;
    border-radius: 12px;
}

/* --- Responsive Design --- */
@media (max-width: 768px) {
    .main-header {
        flex-direction: column;
        gap: 1rem;
        padding: 1rem;
    }
    #content-area {
        padding: 1rem;
    }
    .welcome-content {
        padding: 1.5rem;
    }
}