/* ===========================
   Reset and Base Styles
   =========================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #ffffff; /* clean white base */
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===========================
   Hero Section (Landing Page)
   =========================== */
.hero {
    min-height: 100vh;
    background: linear-gradient(135deg, #6a4c93 0%, #b57edc 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px 20px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.15) 0%, transparent 70%);
    animation: pulse 15s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1) rotate(0deg); opacity: 0.3; }
    50% { transform: scale(1.1) rotate(180deg); opacity: 0.5; }
}

.hero-container {
    max-width: 1400px;
    width: 100%;
    display: grid;
    grid-template-columns: 45% 55%;
    gap: 60px;
    align-items: center;
    position: relative;
    z-index: 1;
}

/* Left Side: Mobile App Image */
.hero-left {
    display: flex;
    justify-content: center;
    align-items: center;
    animation: floatAnimation 6s ease-in-out infinite;
}

@keyframes floatAnimation {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-20px); }
}

.hero-mobile-img {
    max-height: 500px;
    width: auto;
    height: auto;
    object-fit: contain;
    filter: drop-shadow(0 20px 40px rgba(0,0,0,0.3));
    transition: transform 0.3s ease;
}

.hero-mobile-img:hover {
    transform: scale(1.05);
}

/* Right Side: Title and Buttons */
.hero-right {
    color: white;
    animation: fadeInRight 1s ease-out;
}

@keyframes fadeInRight {
    from { opacity: 0; transform: translateX(50px); }
    to { opacity: 1; transform: translateX(0); }
}

.hero-badge {
    display: inline-block;
    background: rgba(255,255,255,0.2);
    padding: 8px 20px;
    border-radius: 50px;
    font-size: 0.9em;
    margin-bottom: 20px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.3);
}

.hero-title {
    font-size: 4em;
    font-weight: 800;
    margin-bottom: 15px;
    line-height: 1.1;
    text-shadow: 1px 1px 6px rgba(0,0,0,0.2);
    color: #fff;
}

.hero-subtitle {
    font-size: 1.6em;
    font-weight: 400;
    margin-bottom: 20px;
    line-height: 1.4;
    opacity: 0.95;
    color: #f5e9ff; /* soft lavender */
}

.hero-authors,
.hero-university {
    font-size: 1.1em;
    margin-bottom: 8px;
    opacity: 0.9;
    color: #fce4f6;
}

/* Hero Buttons */
.hero-buttons {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 16px 40px;
    font-size: 1.1em;
    font-weight: 600;
    text-decoration: none;
    border-radius: 50px;
    transition: all 0.3s ease;
    cursor: pointer;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

.btn-primary {
    background: #6a4c93;
    color: white;
}
.btn-primary:hover {
    background: #5a3d7a;
}

.btn-secondary {
    background: white;
    color: #6a4c93;
    border: 2px solid #6a4c93;
}
.btn-secondary:hover {
    background: #b57edc;
    color: white;
}

/* ===========================
   Abstract Section
   =========================== */
.abstract {
    background: #ffffff;
    padding: 80px 20px;
    border-left: 4px solid #b57edc;
    border-right: 4px solid #b57edc;
}

.abstract h3 {
    color: #6a4c93;
    font-size: 2.5em;
    margin-bottom: 30px;
    font-weight: 700;
    text-align: center;
}

.abstract p {
    color: #333;
    font-size: 1.1em;
    line-height: 1.8;
    max-width: 1200px;
    margin: 0 auto 20px auto;
}

/* ===========================
   Content Grid
   =========================== */
.content-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 25px;
    max-width: 1200px;
    margin: 60px auto;
    padding: 0 20px;
}

.left-column, .right-column {
    display: flex;
    flex-direction: column;
}

/* ===========================
   Sections
   =========================== */
section {
    background: #ffffff;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    margin-bottom: 25px;
}

section h3 {
    color: #6a4c93;
    font-size: 1.8em;
    margin-bottom: 20px;
    border-bottom: 3px solid #b57edc;
    padding-bottom: 12px;
    font-weight: 700;
}

section h4 {
    color: #b57edc;
    font-size: 1.4em;
    margin: 20px 0 12px 0;
    font-weight: 600;
}

section p {
    margin-bottom: 12px;
    text-align: justify;
    line-height: 1.7;
}

/* ===========================
   Subsections
   =========================== */
.subsection {
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid #e6d9f5;
}

.subsection:last-child {
    border-bottom: none;
}

.feature-box {
    background: #f9f6ff;
    padding: 20px;
    border-radius: 8px;
    border-left: 4px solid #6a4c93;
    margin: 15px 0;
}

/* ===========================
   Images
   =========================== */
img:not(.hero-mobile-img) {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin: 20px 0;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

img:not(.hero-mobile-img):hover {
    transform: scale(1.02);
    box-shadow: 0 6px 20px rgba(0,0,0,0.2);
}

.caption {
    text-align: center;
    font-style: italic;
    color: #666;
    font-size: 0.95em;
    margin-top: -10px;
}

/* ===========================
   Tables
   =========================== */
table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    border-radius: 8px;
    overflow: hidden;
    background: #ffffff;
}

table th, table td {
    padding: 15px;
    text-align: left;
    border: 1px solid #ddd;
}

table thead {
    background-color: #6a4c93; /* deep muted purple */
    color: white;
}

table th {
    font-weight: 700;
    font-size: 1.1em;
}

table tbody tr {
    transition: background-color 0.3s ease;
}

table tbody tr:nth-child(even) {
    background-color: #f9f6ff; /* very light lavender */
}

table tbody tr:hover {
    background-color: #e6d9f5; /* soft lavender hover */
}

table td {
    font-size: 1em;
}

.performance-note {
    font-size: 0.95em;
    color: #555;
    font-style: italic;
    margin-top: 15px;
}

/* ===========================
   Lists
   =========================== */
ul {
    margin: 15px 0;
    padding-left: 25px;
}

li {
    margin: 10px 0;
    line-height: 1.7;
}

.feature-list li {
    position: relative;
    padding-left: 10px;
}

.feature-list li::before {
    content: '✓';
    color: #6a4c93; /* purple checkmark */
    font-weight: bold;
    position: absolute;
    left: -20px;
}

/* ===========================
   Pipeline Sections
   =========================== */
.pipeline-section {
    margin: 20px 0;
    padding: 15px;
    background: #ffffff;
    border-radius: 8px;
    border-left: 4px solid #b57edc; /* lavender accent */
}

.pipeline-section h4 {
    margin-top: 0;
    color: #6a4c93;
}

.pipeline-section ul {
    margin-top: 10px;
}

/* ===========================
   Model Performance Section
   =========================== */
.model-performance {
    max-width: 1200px;
    margin: 60px auto;
    padding: 40px 30px;
    background: #ffffff; /* clean white base */
    border-left: 4px solid #b57edc;
    border-right: 4px solid #b57edc;
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
}

.model-performance h3 {
    color: #6a4c93;
    font-size: 2em;
    margin-bottom: 20px;
    border-bottom: 3px solid #b57edc;
    padding-bottom: 12px;
}

/* ===========================
   Conclusion Section
   =========================== */
.conclusion {
    background: #ffffff;
    padding: 80px 20px;
    margin: 0;
    border-top: 1px solid #e6d9f5;
    border-left: 4px solid #b57edc;
    border-right: 4px solid #b57edc;
}

.conclusion h3 {
    color: #6a4c93;
    font-size: 2.5em;
    margin-bottom: 30px;
    font-weight: 700;
    text-align: center;
}

.conclusion p {
    font-size: 1.1em;
    line-height: 1.8;
    margin-bottom: 20px;
    text-align: justify;
    color: #333;
}

/* ===========================
   Footer
   =========================== */
footer {
    background: linear-gradient(135deg, #6a4c93 0%, #b57edc 100%);
    color: white;
    text-align: center;
    padding: 30px 20px;
    box-shadow: 0 -4px 10px rgba(0,0,0,0.1);
}

footer p {
    margin: 5px 0;
    font-size: 1em;
}

/* ===========================
   Scroll-to-Top Button
   =========================== */
#scrollToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: #6a4c93; /* purple button */
    color: white;
    border: none;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    font-size: 24px;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(0,0,0,0.3);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1000;
}

#scrollToTop.visible {
    opacity: 1;
    visibility: visible;
}

#scrollToTop:hover {
    background: #5a3d7a; /* darker purple hover */
    transform: translateY(-5px);
}