:root {
    --bg-color: #1a5b78;
    --tab-bg-color: #113c50;
    --gap: 2vw;
    --card-width: 48vw;
    --header-height: 70px;
    --circle-mobile: 75vw;
    --circle-desktop: 25vw;
    --cutout-radius-mobile: calc((var(--circle-mobile) / 2) + var(--gap));
    --cutout-radius-desktop: calc((var(--circle-desktop) / 2) + var(--gap));
}

body, html {
    margin: 0;
    padding: 0;
    background-image: url('background.webp');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    font-family: "PingFang TC", "Heiti TC", "Microsoft JhengHei", sans-serif;
    overflow-x: hidden;
}

.wrapper {
    position: relative;
    margin: 25px auto;
    width: 100%;
    max-width: 100vw;
    padding-top: calc(var(--circle-mobile) / 2);
}

.hero-circle {
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    transform-origin: bottom center;
    width: var(--circle-mobile);
    height: var(--circle-mobile);
    background-color: var(--bg-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    z-index: 100;
    overflow: hidden;
    transition: width 0.6s cubic-bezier(0.19, 1, 0.22, 1),
                height 0.6s cubic-bezier(0.19, 1, 0.22, 1),
                border-radius 0.6s cubic-bezier(0.19, 1, 0.22, 1),
                background-color 0.4s ease,
                top 0.6s cubic-bezier(0.19, 1, 0.22, 1);
}

.hero-content {
    font-size: 1.5rem;
    font-weight: bold;
    transition: opacity 0.3s ease, transform 0.3s ease;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.hero-content img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 50%;
}

/* Navbar */
.main-nav {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 40px;
    box-sizing: border-box;
    opacity: 0;
    pointer-events: none;
    transform: translateY(20px);
    transition: opacity 0.4s ease 0.2s, transform 0.4s ease 0.2s;
}

.brand {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -1px;
}

.main-nav a {
    color: white;
    text-decoration: none;
    margin-left: 25px;
    font-weight: 500;
    opacity: 0.8;
    transition: 0.3s;
}

.main-nav a:hover {
    opacity: 1;
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

.hero-circle.is-header {
    position: fixed;
    top: 20px;
    width: 92vw;
    max-width: 1200px;
    height: var(--header-height);
    border-radius: 24px;
    transform: translateX(-50%) !important;
    background-color: rgba(26, 91, 120, 0.25);
    backdrop-filter: blur(15px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
}

.hero-circle.is-header .hero-content {
    opacity: 0;
    transform: scale(0.5);
}

.hero-circle.is-header .main-nav {
    color: white;
    mix-blend-mode: exclusion;
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
}

/* Card */
.cards-wrapper {
    position: relative;
    width: 92vw;
    margin: 0 auto;
    background-color: var(--tab-bg-color);
    border-radius: 24px;
    mask-image: radial-gradient(circle at 50% 0px, transparent var(--cutout-radius-mobile), black calc(var(--cutout-radius-mobile) + 1px));
    -webkit-mask-image: radial-gradient(circle at 50% 0px, transparent var(--cutout-radius-mobile), black calc(var(--cutout-radius-mobile) + 1px));
    padding-top: calc(var(--cutout-radius-mobile) + 15px);
    display: flex;
    flex-direction: column;
}

/* Mobile Tabs */
.tabs-mobile {
    display: flex;
    justify-content: center;
    align-items: flex-end;
    padding: 0 20px;
    gap: 8px;
}

.tab-btn {
    padding: 10px 24px;
    margin-bottom: 8px;
    background-color: transparent;
    color: rgba(255, 255, 255, 0.5);
    border: none;
    border-radius: 999px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    position: relative;
    z-index: 1;
    transition: color 0.3s ease, background-color 0.3s ease;
}

.tab-btn:not(.active):hover {
    background-color: rgba(255, 255, 255, 0.12);
    color: rgba(255, 255, 255, 0.9);
}

.tab-btn.active {
    padding: 12px 30px 16px;
    margin-bottom: 0;
    background-color: var(--bg-color);
    color: white;
    z-index: 2;
    border-radius: 20px 20px 0 0;
}

.tab-btn.active::before,
.tab-btn.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    width: 20px;
    height: 20px;
    pointer-events: none;
}

.tab-btn.active::before {
    left: -20px;
    background: radial-gradient(circle at 0 0, transparent 19.5px, var(--bg-color) 20px);
}

.tab-btn.active::after {
    right: -20px;
    background: radial-gradient(circle at 100% 0, transparent 19.5px, var(--bg-color) 20px);
}

/* Panel */
.panels-wrapper, .panels {
    background-color: var(--bg-color);
    flex-grow: 1;
    border-radius: 0 0 24px 24px;
}

.card {
    display: none;
    padding: 30px 20px;
    color: white;
    box-sizing: border-box;
    font-size: 1.1rem;
    line-height: 1.6;
}

.card.active { 
    display: block; 
    animation: fadeIn 0.4s ease; 
}

.card-header {
    text-align: center;
    font-size: 3rem;
    font-weight: 900;
    margin-bottom: 10px;
    -webkit-text-stroke: 0.5px currentColor;
}

.right {
    text-align: right;
}

.desktop-only { display: none; }

.social-links {
    display: flex;
    gap: 15px;
    align-items: center;
    margin-top: 20px;
    justify-content: center;
}

.social-links img {
    width: 40px;
    transition: transform 0.3s ease;
    cursor: pointer;
}

.social-links img:hover { transform: scale(1.2); }

.placeholder-text { text-align: center; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Desktop Layout */
@media (min-width: 768px) {
    .wrapper { padding-top: calc(var(--circle-desktop) / 2); }
    .hero-circle { width: var(--circle-desktop); height: var(--circle-desktop); }
    .cards-wrapper {
        width: 100%;
        background-color: transparent;
        mask-image: none;
        -webkit-mask-image: none;
        padding-top: 0;
        flex-direction: row;
        justify-content: center;
        gap: var(--gap);
    }
    .card-header { text-align: left; }
    .tabs-mobile { display: none; }
    .panels { display: contents; }
    .card {
        display: block !important;
        width: var(--card-width);
        min-height: 80vh;
        background-color: var(--bg-color);
        border-radius: 24px;
        padding: 40px 20px;
        animation: none;
    }
    .card-about {
        -webkit-mask-image: radial-gradient(circle at calc(100% + var(--gap)/2) 0, transparent var(--cutout-radius-desktop), black calc(var(--cutout-radius-desktop) + 1px));
        mask-image: radial-gradient(circle at calc(100% + var(--gap)/2) 0, transparent var(--cutout-radius-desktop), black calc(var(--cutout-radius-desktop) + 1px));
    }
    .card-placeholder {
        -webkit-mask-image: radial-gradient(circle at calc(var(--gap)/-2) 0, transparent var(--cutout-radius-desktop), black calc(var(--cutout-radius-desktop) + 1px));
        mask-image: radial-gradient(circle at calc(var(--gap)/-2) 0, transparent var(--cutout-radius-desktop), black calc(var(--cutout-radius-desktop) + 1px));
    }
    .desktop-only { display: unset; }
    .social-links {
        justify-content: flex-start;
    }
    .placeholder-text {
        text-align: right;
    }
}

.extra-content {
    height: 200vh;
    padding: 100px 10%;
    color: #444;
    text-align: center;
    background: linear-gradient(to bottom, #f0f2f5, #ffffff);
}