.fade-in {
    opacity: 0;
    transform: translateY(52px) scale(0.985);
    transition:
        opacity 0.75s ease-out,
        transform 0.95s cubic-bezier(0.22, 1, 0.36, 1);
}

.fade-in.show {
    opacity: 1;
    transform: translateY(0) scale(1);
}

@media (max-width: 576px) {
    .fade-in {
        transform: translateY(42px) scale(0.99);
    }
}

@media (prefers-reduced-motion: reduce) {
    .fade-in,
    .fade-in.show {
        opacity: 1;
        transform: none;
        transition: none;
    }
}
  
/* Display controls: language and color theme */
#particles-js {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
}

.display-controls {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1200;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px;
    border: 1px solid rgba(0, 234, 255, 0.28);
    border-radius: 999px;
    background: rgba(13, 13, 18, 0.78);
    box-shadow:
        0 8px 30px rgba(0, 0, 0, 0.28),
        0 0 20px rgba(0, 234, 255, 0.08);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
}

.display-control {
    min-height: 38px;
    border: 0;
    border-radius: 999px;
    color: #dce7ee;
    background: transparent;
    cursor: pointer;
    transition:
        color 0.2s ease,
        background-color 0.2s ease,
        transform 0.2s ease;
}

.display-control:hover {
    color: #00eaff;
    background: rgba(0, 234, 255, 0.1);
}

.display-control:focus-visible {
    outline: 2px solid #00eaff;
    outline-offset: 2px;
}

.display-control:active {
    transform: scale(0.96);
}

.language-control {
    display: flex;
    align-items: center;
    gap: 7px;
    padding: 0 12px;
    font-family: 'Noto Sans TC', sans-serif;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.04em;
}

.language-option {
    color: #75838d;
    text-shadow: none;
    transition: color 0.2s ease;
}

.language-option.active {
    color: #00eaff;
}

.control-divider {
    width: 1px;
    height: 14px;
    background: rgba(220, 231, 238, 0.25);
}

.theme-control {
    display: grid;
    width: 38px;
    padding: 0;
    place-items: center;
    font-size: 0.95rem;
}

.theme-control i {
    transition: transform 0.3s ease;
}

.theme-control:hover i {
    transform: rotate(16deg);
}

/* Light-mode version */
.light-mode .display-controls {
    border-color: rgba(111, 78, 55, 0.24);
    background: rgba(248, 241, 231, 0.82);
    box-shadow: 0 8px 30px rgba(90, 70, 55, 0.14);
}

.light-mode .display-control {
    color: #5a4637;
}

.light-mode .display-control:hover {
    color: #8b5a2b;
    background: rgba(139, 90, 43, 0.1);
}

.light-mode .language-option {
    color: #9a897b;
}

.light-mode .language-option.active {
    color: #6f4e37;
}

.light-mode .control-divider {
    background: rgba(90, 70, 55, 0.22);
}

.light-mode .display-control:focus-visible {
    outline-color: #8b5a2b;
}

@media (max-width: 576px) {
    .display-controls {
        top: 14px;
        right: 14px;
        gap: 4px;
        padding: 5px;
    }

    .language-control {
        min-height: 34px;
        padding: 0 9px;
    }

    .theme-control {
        width: 34px;
        min-height: 34px;
    }
}