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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333;
    line-height: 1.7;
}

/* ── Navigation ── */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 100;
    background: rgba(26, 35, 64, 0.95);
    backdrop-filter: blur(8px);
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
    transition: box-shadow 0.3s;
}

nav.scrolled {
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

nav .logo {
    color: #fff;
    font-weight: 700;
    font-size: 1.1rem;
    letter-spacing: 1px;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 2rem;
}

nav ul li a {
    color: #ccc;
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 500;
    transition: color 0.2s;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

nav ul li a:hover,
nav ul li a.active {
    color: #fff;
}

/* ── Hamburger (mobile) ── */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    background: none;
    border: none;
    padding: 5px;
}

.hamburger span {
    display: block;
    width: 25px;
    height: 2px;
    background: #fff;
    transition: transform 0.3s, opacity 0.3s;
}

/* ── Hero Section ── */
.hero {
    position: relative;
    height: 100vh;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: #fff;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    inset: 0;
    background: url('cek.jpg') center/cover no-repeat;
    filter: brightness(0.35);
    z-index: -1;
}

.hero-content {
    max-width: 800px;
    padding: 2rem;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: 2px;
}

.hero-content .edition {
    font-size: 1.1rem;
    opacity: 0.85;
    margin-bottom: 1.5rem;
    font-style: italic;
}

.hero-content .details {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    line-height: 1.8;
}

.hero-content .details strong {
    display: block;
    font-size: 1.4rem;
    margin-bottom: 0.3rem;
}

.btn {
    display: inline-block;
    padding: 0.8rem 2.5rem;
    background: #c0392b;
    color: #fff;
    text-decoration: none;
    border-radius: 4px;
    font-weight: 600;
    font-size: 1rem;
    transition: background 0.2s, transform 0.2s;
    letter-spacing: 0.5px;
}

.btn:hover {
    background: #e74c3c;
    transform: translateY(-2px);
}

/* ── Sections ── */
section {
    padding: 5rem 2rem;
}

.container {
    max-width: 900px;
    margin: 0 auto;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: #1a2340;
    margin-bottom: 0.5rem;
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: #c0392b;
    margin-top: 8px;
}

.section-subtitle {
    color: #777;
    font-size: 1rem;
    margin-bottom: 2.5rem;
}

/* ── Home / Aims ── */
#home, #keynote {
    background: #f8f9fa;
}

.aims-text {
    font-size: 1.05rem;
    color: #555;
    line-height: 1.9;
}

/* ── Registration ── */
#registration {
    background: #fff;
}

.fee-cards {
    display: flex;
    gap: 1.5rem;
    margin: 2rem 0;
    flex-wrap: wrap;
}

.fee-card {
    flex: 1;
    min-width: 220px;
    background: #f8f9fa;
    border: 2px solid #e9ecef;
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
    transition: border-color 0.2s, transform 0.2s;
}

.fee-card:hover {
    border-color: #c0392b;
    transform: translateY(-3px);
}

.fee-card .price {
    font-size: 2.5rem;
    font-weight: 700;
    color: #1a2340;
}

.fee-card .label {
    font-size: 0.95rem;
    color: #777;
    margin-top: 0.5rem;
}

.info-block {
    background: #f8f9fa;
    border-left: 4px solid #1a2340;
    padding: 1.2rem 1.5rem;
    margin: 1.5rem 0;
    border-radius: 0 4px 4px 0;
}

.info-block p {
    margin-bottom: 0.5rem;
}

.info-block p:last-child {
    margin-bottom: 0;
}

.bank-info {
    background: #fff8f0;
    border-left: 4px solid #e67e22;
    padding: 1.2rem 1.5rem;
    margin: 1.5rem 0;
    border-radius: 0 4px 4px 0;
    font-family: 'Courier New', monospace;
}

.reg-note {
    color: #555;
    margin: 1rem 0;
    line-height: 1.8;
}

.deadline {
    color: #c0392b;
    font-weight: 700;
}

a.link {
    color: #2980b9;
    text-decoration: none;
    border-bottom: 1px solid transparent;
    transition: border-color 0.2s;
}

a.link:hover {
    border-bottom-color: #2980b9;
}

/* ── Program ── */
#program {
    background: #f8f9fa;
}

.tba {
    font-size: 1.5rem;
    color: #999;
    text-align: center;
    padding: 3rem 0;
    font-style: italic;
}

/* ── Travel ── */
#travel {
    position: relative;
    background: #1a2340;
    color: #fff;
    overflow: hidden;
}

#travel::before {
    content: '';
    position: absolute;
    inset: 0;
    background: url('1sala-A.jpg') center/cover no-repeat;
    opacity: 0.15;
    z-index: 0;
}

#travel .container {
    position: relative;
    z-index: 1;
}

#travel .section-title {
    color: #fff;
}

#travel .section-subtitle {
    color: #aaa;
}

.venue-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(4px);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
}

.venue-card h3 {
    font-size: 1.3rem;
    margin-bottom: 0.8rem;
    color: #f0c040;
}

.venue-card p {
    color: #ccc;
    line-height: 1.8;
}

.venue-card a {
    color: #74b9ff;
    text-decoration: none;
}

.venue-card a:hover {
    text-decoration: underline;
}

.transport-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.transport-item {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(4px);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 8px;
    padding: 1.5rem;
}

.transport-item h4 {
    color: #f0c040;
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.transport-item p {
    color: #bbb;
    font-size: 0.95rem;
}

.transport-item a {
    color: #74b9ff;
    text-decoration: none;
}

.transport-item a:hover {
    text-decoration: underline;
}

.travel-grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.travel-grid-2 .venue-card {
    margin-bottom: 0;
}

ul.hotel-list {
    columns: 2;
    -webkit-columns: 2;
    -moz-columns: 2;
    column-gap: 2rem;
}

/* ── Footer ── */
footer {
    background: #111;
    color: #888;
    text-align: center;
    padding: 2rem;
    font-size: 0.9rem;
}

footer a {
    color: #aaa;
    text-decoration: none;
}

/* ── Responsive ── */
@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2rem;
    }

    .hero-content .details {
        font-size: 1rem;
    }

    nav ul {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: rgba(26, 35, 64, 0.98);
        flex-direction: column;
        align-items: center;
        padding: 1.5rem 0;
        gap: 1.2rem;
        transform: translateY(-120%);
        transition: transform 0.3s ease;
    }

    nav ul.open {
        transform: translateY(0);
    }

    .hamburger {
        display: flex;
    }

    .transport-grid, .travel-grid-2 {
        grid-template-columns: 1fr;
    }

    ul.hotel-list {
        columns: 1;
        -webkit-columns: 1;
        -moz-columns: 1;
    }
}