/* --- Reset & Base --- */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Instrument Sans', 'Segoe UI', Arial, sans-serif;
    background: #f7f7f9;
    color: #232323;
    line-height: 1.7;
    font-size: 1.08rem;
    min-height: 100vh;
}

/* --- Navigation --- */
nav {
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    background: rgba(20,20,20,0.82);
    box-shadow: 0 2px 16px rgba(0,0,0,0.07);
    z-index: 100;
    transition: background 0.3s, backdrop-filter 0.3s;
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 68px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    position: relative;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: #fff;
    letter-spacing: 1px;
    text-shadow: 0 2px 8px rgba(0,0,0,0.12);
}

.nav-links {
    display: flex;
    gap: 24px;
    list-style: none;
}

.nav-links a {
    color: #fff;
    text-decoration: none;
    font-weight: 500;
    padding: 8px 0;
    position: relative;
    transition: color 0.2s;
    letter-spacing: 0.5px;
}

.nav-links a::after {
    content: '';
    display: block;
    height: 2px;
    width: 0;
    background: linear-gradient(90deg, #fff, #888);
    transition: width 0.3s;
    border-radius: 2px;
    margin-top: 3px;
}

.nav-links a:hover,
.nav-links a:focus {
    color: #ffd700;
}

.nav-links a:hover::after,
.nav-links a:focus::after {
    width: 100%;
}

.dropdown-content {
    display: none;
    position: absolute;
    background: #232323;
    min-width: 180px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.13);
    border-radius: 8px;
    top: 100%;
    left: 0;
    z-index: 10;
    padding: 10px 0;
}

.nav-links li {
    position: relative;
}

.nav-links li:hover .dropdown-content {
    display: block;
}

.dropdown-content a {
    color: #fff;
    padding: 10px 24px;
    display: block;
    text-decoration: none;
    font-size: 1rem;
    transition: background 0.2s;
}

.dropdown-content a:hover {
    background: #111;
    color: #ffd700;
}

/* --- Hamburger --- */
.nav-toggle {
    display: none;
    flex-direction: column;
    justify-content: center;
    width: 36px;
    height: 36px;
    cursor: pointer;
    margin-left: 12px;
    z-index: 200;
}
.nav-toggle span {
    height: 4px;
    width: 100%;
    background: #fff;
    margin: 5px 0;
    border-radius: 2px;
    transition: all 0.3s;
    display: block;
}

/* --- Hero Section --- */
.hero {
    min-height: 100vh;
    background: 
        linear-gradient(120deg, rgba(20,20,20,0.92) 0%, rgba(20,20,20,0.7) 100%),
        url('../img/gedung-fmipa.jpg') center/cover no-repeat;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    position: relative;
    padding-top: 90px;
    color: #fff;
    overflow: hidden;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 700px;
    margin: 0 auto;
    padding: 40px 18px 36px 18px;
    background: rgba(30,30,30,0.55);
    border-radius: 24px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.13);
    backdrop-filter: blur(2px);
}

.hero h1 {
    font-size: 2.3rem;
    font-weight: 800;
    margin-bottom: 18px;
    letter-spacing: 0.5px;
    color: #fff;
    text-shadow: 0 2px 16px rgba(0,0,0,0.13);
}

.hero .hero-subtitle {
    font-size: 1.18rem;
    margin-bottom: 18px;
    color: #ffd700;
    font-weight: 500;
}

.hero-date {
    font-size: 1.08rem;
    font-weight: 600;
    background: rgba(255,255,255,0.10);
    padding: 12px 28px;
    border-radius: 32px;
    display: inline-block;
    margin-bottom: 32px;
    color: #fff;
    box-shadow: 0 2px 12px rgba(0,0,0,0.07);
}

.cta-button {
    background: linear-gradient(90deg, #ffd700, #232323);
    color: #232323;
    padding: 15px 38px;
    border: none;
    border-radius: 32px;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    box-shadow: 0 4px 16px rgba(0,0,0,0.13);
    transition: background 0.2s, color 0.2s, transform 0.2s;
    display: inline-block;
    margin-top: 10px;
}

.cta-button:hover {
    background: linear-gradient(90deg, #232323, #ffd700);
    color: #ffd700;
    transform: translateY(-2px) scale(1.04);
}

/* --- Section General --- */
.section {
    padding: 80px 0 60px 0;
    background: #fff;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 48px;
    color: #232323;
    letter-spacing: 0.5px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, #ffd700, #232323);
    margin: 18px auto 0 auto;
    border-radius: 2px;
}

/* --- About Section --- */
.about {
    background: #f7f7f9;
}

.about-content {
    display: flex;
    flex-wrap: wrap;
    gap: 48px;
    align-items: flex-start;
    justify-content: center;
}

.about-text {
    flex: 1 1 320px;
    min-width: 280px;
    font-size: 1.08rem;
    color: #444;
}

.about-features {
    flex: 1 1 320px;
    min-width: 280px;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.feature {
    background: #fff;
    border-radius: 16px;
    padding: 28px 18px;
    text-align: center;
    box-shadow: 0 4px 16px rgba(0,0,0,0.07);
    transition: transform 0.2s, box-shadow 0.2s;
}

.feature:hover {
    transform: translateY(-4px) scale(1.03);
    box-shadow: 0 8px 32px rgba(0,0,0,0.11);
}

.feature-icon {
    font-size: 2.2rem;
    color: #ffd700;
    margin-bottom: 10px;
}

.feature h3 {
    font-size: 1.5rem;
    color: #232323;
    margin-bottom: 6px;
}

.feature p {
    color: #666;
    font-weight: 500;
}

/* --- Speakers & Conferences --- */
.speakers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 32px;
    justify-items: center;
}

.speaker-card {
    position: relative;
    overflow: hidden;
    background: #fff;
    border-radius: 18px;
    padding: 32px 20px 24px 20px;
    text-align: center;
    box-shadow: 0 4px 16px rgba(0,0,0,0.08);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 340px;
}

.speaker-card:hover {
    transform: translateY(-4px) scale(1.03);
    box-shadow: 0 8px 32px rgba(0,0,0,0.13);
}

.speaker-avatar img {
    width: 90px;
    height: 90px;
    border-radius: 50%;
    background: linear-gradient(135deg, #232323 60%, #ffd700 100%);
    margin: 0 auto 18px auto;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2.2rem;
    color: #fff;
    box-shadow: 0 2px 8px rgba(0,0,0,0.10);
}

.speaker-name {
    font-size: 1.15rem;
    font-weight: 700;
    color: #232323;
    margin-bottom: 6px;
}

.speaker-title {
    color: #ffd700;
    font-weight: 500;
    margin-bottom: 8px;
}

.speaker-bio {
    color: #666;
    font-size: 0.98rem;
    margin-bottom: 0;
}

/* Conference Card Hover Reveal */
.speaker-card ul {
    opacity: 0;
    pointer-events: none;
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    margin: 0;
    padding: 40px 24px 24px 24px;
    background: rgba(20, 20, 20, 0.96);
    color: #fff;
    border-radius: 18px;
    box-shadow: 0 8px 32px rgba(0,0,0,0.13);
    z-index: 10;
    display: flex;
    flex-direction: column;
    justify-content: center;
    transition: opacity 0.4s cubic-bezier(.4,0,.2,1);
    font-size: 1rem;
    text-align: left;
}

.speaker-card:hover ul,
.speaker-card:focus-within ul {
    opacity: 1;
    pointer-events: auto;
}

.speaker-card ul li {
    margin-bottom: 10px;
    font-size: 1rem;
    letter-spacing: 0.1px;
    list-style: disc inside;
}
.speaker-card ul li:last-child {
    margin-bottom: 0;
}

/* Conference CTA Button */
.conference-btn {
    margin-top: 18px;
    background: linear-gradient(90deg, #ffd700 60%, #232323 100%);
    color: #232323;
    padding: 13px 32px;
    border: none;
    border-radius: 24px;
    font-size: 1.08rem;
    font-weight: 700;
    cursor: pointer;
    text-decoration: none;
    box-shadow: 0 4px 16px rgba(0,0,0,0.13);
    transition: background 0.2s, color 0.2s, transform 0.2s;
    display: inline-block;
    position: relative;
    z-index: 2;
}

.conference-btn:hover,
.conference-btn:focus {
    background: linear-gradient(90deg, #232323 60%, #ffd700 100%);
    color: #ffd700;
    transform: translateY(-2px) scale(1.04);
    outline: none;
}

/* --- Timeline Section --- */
.timeline {
    background: linear-gradient(120deg, #232323 0%, #111 100%);
    color: #fff;
}

.timeline-container {
    margin-top: 32px;
}

.timeline-item {
    display: flex;
    align-items: flex-start;
    margin-bottom: 32px;
    gap: 28px;
}

.timeline-date {
    background: rgba(255,255,255,0.13);
    padding: 14px 24px;
    border-radius: 8px;
    font-weight: 600;
    min-width: 160px;
    text-align: center;
    font-size: 1.05rem;
    color: #fff;
    box-shadow: 0 2px 8px rgba(0,0,0,0.07);
}

.timeline-content {
    flex: 1;
}

.timeline-title {
    font-size: 1.15rem;
    font-weight: 700;
    margin-bottom: 6px;
    color: #ffd700;
}

.timeline-desc {
    opacity: 0.93;
    line-height: 1.6;
    color: #eaf6fb;
}

/* --- Contact Section --- */
.contact {
    background: #f7f7f9;
}

.contact-content {
    display: flex;
    justify-content: flex-end;
}

.contact-info {
    display: flex;
    flex-direction: row;
    gap: 32px;
    background: none;
    box-shadow: none;
    padding: 0;
    max-width: 100%;
}

.contact-item {
    background: #fff;
    border-radius: 16px;
    box-shadow: 0 4px 16px rgba(0,0,0,0.07);
    padding: 24px 18px;
    display: flex;
    align-items: center;
    margin-bottom: 0;
    min-width: 220px;
}

.contact-icon {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, #232323 60%, #ffd700 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 1.3rem;
    margin-right: 16px;
}

.contact-text h4 {
    font-size: 1.08rem;
    margin-bottom: 3px;
    color: #232323;
}

.contact-text p {
    color: #444;
    font-size: 0.98rem;
}

/* --- Footer --- */
footer {
    background: #232323;
    color: #fff;
    padding: 32px 0 18px 0;
    text-align: center;
    font-size: 1rem;
    letter-spacing: 0.2px;
}

footer .footer-title {
    font-size: 1.1rem;
    font-weight: 600;
    letter-spacing: 1px;
    margin-bottom: 8px;
    color: #ffd700;
}

footer .footer-desc {
    font-size: 0.98rem;
    color: #bbb;
}

/* --- Responsive --- */
@media (max-width: 1024px) {
    .nav-container, .container {
        padding: 0 12px;
    }
    .about-content, .contact-content {
        gap: 28px;
    }
}

@media (max-width: 900px) {
    .about-content,
    .contact-content {
        flex-direction: column;
        gap: 32px;
    }
    .about-features {
        grid-template-columns: 1fr 1fr;
    }
    .nav-toggle {
        display: flex;
        margin-left: 0;
    }
    .nav-links {
        position: absolute;
        top: 60px;
        left: 0;
        width: 100vw;
        background: #232323 !important;
        flex-direction: column;
        align-items: flex-start;
        gap: 0;
        box-shadow: 0 8px 32px rgba(0,0,0,0.13);
        padding: 12px 0;
        display: none;
        z-index: 150;
    }
    .nav-links.open {
        display: flex;
    }
    .nav-links a {
        color: #fff;
        width: 100%;
        display: block;
        padding: 14px 24px;
    }
    .dropdown-content {
        position: static;
        box-shadow: none;
        background: #232323;
        min-width: 100%;
        border-radius: 0;
        padding: 0;
    }
    .logo {
        font-size: 1.2rem;
    }
    .nav-container {
        flex-direction: row;
        height: 60px;
        padding: 0 10px;
    }
}

@media (max-width: 700px) {
    .about-features {
        grid-template-columns: 1fr;
    }
    .speakers-grid {
        grid-template-columns: 1fr;
    }
    .hero-content {
        padding: 18px 4px;
    }
    .section {
        padding: 38px 0 28px 0;
    }
    .section-title {
        font-size: 1.3rem;
    }
}

@media (max-width: 600px) {
    .container {
        padding-left: 10px;
        padding-right: 10px;
    }
    .timeline-item {
        flex-direction: column;
        gap: 10px;
    }
    .timeline-date {
        min-width: 0;
        width: 100%;
    }
    .contact-info {
        flex-direction: column;
        gap: 16px;
        align-items: stretch;
    }
    .contact-item {
        min-width: 0;
        width: 100%;
    }
}

/* Keynote Speakers Grid: 4 items, last item centered on new row */
@media (min-width: 900px) {
    #speakers .speakers-grid {
        grid-template-columns: repeat(3, 1fr);
    }
    #speakers .speakers-grid .speaker-card:nth-child(4) {
        grid-column: 2 / 3;
    }
}
@media (max-width: 900px) {
    #speakers .speakers-grid {
        grid-template-columns: 1fr !important;
    }
    #speakers .speakers-grid .speaker-card:nth-child(4) {
        grid-column: auto;
    }
}

/* Tambahkan atau pastikan aturan ini */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding-left: 24px;
    padding-right: 24px;
    width: 100%;
    box-sizing: border-box;
}