/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

.hide-scrollbar::-webkit-scrollbar {
    display: none;
}
.hide-scrollbar {
    -ms-overflow-style: none;
    scrollbar-width: none;
}

/* Static Book Cover & Layout Utilities (No 3D tilt animation) */
.perspective-1000 { perspective: none; }
.preserve-3d { transform-style: flat; }
.backface-hidden { backface-visibility: visible; }
.book-inner {
    transform: none !important;
    transition: box-shadow 0.25s ease;
}
.book-container:hover .book-inner {
    transform: none !important;
}

.font-siliguri { font-family: 'Hind Siliguri', sans-serif; }

/* Clean Professional Theme Base (Soft Light Mode + Previous Deep Dark Mode #0b0f19) */
body {
    background-color: #f9fafb;
    color: #111827;
    transition: background-color 0.3s, color 0.3s;
}
html.dark body {
    background-color: #0b0f19;
    color: #f3f4f6;
}

/* Animation System */
.fade-up, .fade-left, .fade-right, .scale-in {
    opacity: 0;
    transition: all 0.6s cubic-bezier(0.2, 0.8, 0.2, 1);
    will-change: transform, opacity;
}

.fade-up { transform: translateY(20px); }
.fade-left { transform: translateX(-24px); }
.fade-right { transform: translateX(24px); }
.scale-in { transform: scale(0.96); }

.is-visible {
    opacity: 1 !important;
    transform: translate(0, 0) scale(1) !important;
}

/* Stagger Delays */
.delay-100 { transition-delay: 100ms; }
.delay-200 { transition-delay: 200ms; }
.delay-300 { transition-delay: 300ms; }
.delay-400 { transition-delay: 400ms; }
.delay-500 { transition-delay: 500ms; }

/* Language Toggle Logic */
[data-lang="en"] .bn-text { display: none !important; }
[data-lang="bn"] .en-text { display: none !important; }

/* FAQ Accordion */
.faq-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.25s ease-out;
    opacity: 0;
}
.faq-item.open .faq-content {
    opacity: 1;
}
.faq-item.open .faq-icon {
    transform: rotate(180deg);
}

/* Signature Gold Underline Accent (#f3ca34) */
.about-heading-underline {
    border-bottom: 4px solid #f3ca34;
    padding-bottom: 0.5rem;
}

.about-text-underline {
    text-decoration: underline;
    text-decoration-color: #f3ca34;
    text-decoration-thickness: 2.5px;
    text-underline-offset: 5px;
}

/* About Page Profile Card */
.about-profile-card {
    background: linear-gradient(180deg, #059669 0%, #065f46 58%, #0b0f19 100%);
    transform: none;
    transition: box-shadow 0.3s ease;
}

/* Custom Selection */
::selection {
    background-color: #10b981;
    color: #ecfdf5;
}

/* Tech Stack Pill Hover */
.tech-pill {
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
.tech-pill:hover {
    transform: translateY(-2px);
}