/* ===== CSS Variables ===== */
:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #0ea5e9;
    --accent: #f43f5e;
    --dark: #0f172a;
    --dark-light: #1e293b;
    --gray: #64748b;
    --gray-light: #94a3b8;
    --light: #f1f5f9;
    --white: #ffffff;
    --gradient: linear-gradient(135deg, #6366f1 0%, #0ea5e9 100%);
    --shadow: 0 10px 40px rgba(0, 0, 0, 0.15);
    --shadow-sm: 0 4px 20px rgba(0, 0, 0, 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--dark);
    color: var(--white);
    line-height: 1.6;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

/* ===== Floating Header ===== */
.floating-header {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    width: calc(100% - 60px);
    max-width: 1200px;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 50px;
    padding: 15px 30px;
    z-index: 1000;
    box-shadow: var(--shadow);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--white);
}

.logo i {
    color: var(--primary);
    font-size: 1.6rem;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 35px;
}

.nav-links a {
    font-weight: 500;
    color: var(--gray-light);
    transition: color 0.3s ease;
    position: relative;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--white);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient);
    transition: width 0.3s ease;
}

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

.login-btn {
    background: var(--gradient);
    padding: 10px 25px !important;
    border-radius: 25px;
    color: var(--white) !important;
}

.login-btn::after {
    display: none !important;
}

.login-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(99, 102, 241, 0.4);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 2px;
    background: var(--white);
    transition: 0.3s;
}

/* ===== Hero Section ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 120px 60px 60px;
    max-width: 1400px;
    margin: 0 auto;
    gap: 60px;
}

.hero-content {
    flex: 1;
    max-width: 600px;
}

.hero-content h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 20px;
}

.gradient-text {
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-content p {
    font-size: 1.2rem;
    color: var(--gray-light);
    margin-bottom: 35px;
}

.hero-buttons {
    display: flex;
    gap: 20px;
}

.btn {
    padding: 15px 35px;
    border-radius: 30px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.btn-primary {
    background: var(--gradient);
    color: var(--white);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    background: transparent;
    border: 2px solid var(--gray);
    color: var(--white);
}

.btn-secondary:hover {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.hero-visual {
    flex: 1;
    position: relative;
    height: 500px;
}

.floating-card {
    position: absolute;
    background: rgba(30, 41, 59, 0.8);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 20px 30px;
    display: flex;
    align-items: center;
    gap: 15px;
    animation: float 6s ease-in-out infinite;
    box-shadow: var(--shadow-sm);
}

.floating-card i {
    font-size: 2rem;
    color: var(--primary);
}

.floating-card span {
    font-weight: 600;
}

.card-1 { top: 10%; left: 10%; animation-delay: 0s; }
.card-2 { top: 30%; right: 5%; animation-delay: 1s; }
.card-3 { bottom: 30%; left: 5%; animation-delay: 2s; }
.card-4 { bottom: 10%; right: 15%; animation-delay: 3s; }

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

/* ===== Features Section ===== */
.features {
    padding: 100px 60px;
    max-width: 1400px;
    margin: 0 auto;
}

.features h2,
.topics h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 60px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.feature-card {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    padding: 40px 30px;
    text-align: center;
    transition: all 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-10px);
    border-color: var(--primary);
    box-shadow: 0 20px 40px rgba(99, 102, 241, 0.15);
}

.feature-icon {
    width: 80px;
    height: 80px;
    background: var(--gradient);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 25px;
}

.feature-icon i {
    font-size: 2rem;
    color: var(--white);
}

.feature-card h3 {
    font-size: 1.4rem;
    margin-bottom: 15px;
}

.feature-card p {
    color: var(--gray-light);
}

/* ===== Stats Section ===== */
.stats {
    display: flex;
    justify-content: center;
    gap: 80px;
    padding: 80px 60px;
    background: linear-gradient(180deg, var(--dark-light) 0%, var(--dark) 100%);
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 3rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    color: var(--gray-light);
    font-size: 1.1rem;
}

/* ===== Topics Section ===== */
.topics {
    padding: 100px 60px;
    max-width: 1400px;
    margin: 0 auto;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 25px;
}

.topic-card {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 15px;
    padding: 30px;
    text-align: center;
    transition: all 0.3s ease;
    cursor: pointer;
}

.topic-card:hover {
    background: rgba(99, 102, 241, 0.1);
    border-color: var(--primary);
}

.topic-card i {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 15px;
}

.topic-card h4 {
    font-size: 1.1rem;
}

/* ===== Page Header ===== */
.page-header {
    padding: 150px 60px 60px;
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.page-header h1 {
    font-size: 3rem;
    margin-bottom: 20px;
}

.page-header p {
    font-size: 1.2rem;
    color: var(--gray-light);
}

/* ===== Resources Section ===== */
.resources-section {
    padding: 40px 60px 100px;
    max-width: 1400px;
    margin: 0 auto;
}

.filter-tabs {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 15px;
    margin-bottom: 50px;
}

.filter-btn {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--gray-light);
    padding: 12px 25px;
    border-radius: 25px;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: var(--white);
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.resource-card {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    overflow: hidden;
    display: flex;
    transition: all 0.3s ease;
}

.resource-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
}

.resource-icon {
    width: 120px;
    min-height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: var(--white);
}

.resource-icon.ml { background: linear-gradient(135deg, #6366f1, #8b5cf6); }
.resource-icon.dl { background: linear-gradient(135deg, #0ea5e9, #06b6d4); }
.resource-icon.math { background: linear-gradient(135deg, #f43f5e, #ec4899); }
.resource-icon.nlp { background: linear-gradient(135deg, #10b981, #14b8a6); }
.resource-icon.cv { background: linear-gradient(135deg, #f59e0b, #eab308); }

.resource-content {
    padding: 25px;
    flex: 1;
}

.resource-tag {
    display: inline-block;
    background: rgba(99, 102, 241, 0.2);
    color: var(--primary-light);
    padding: 5px 15px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.resource-content h3 {
    font-size: 1.2rem;
    margin-bottom: 10px;
}

.resource-content p {
    color: var(--gray-light);
    font-size: 0.95rem;
    margin-bottom: 15px;
}

.resource-meta {
    display: flex;
    gap: 20px;
    color: var(--gray);
    font-size: 0.85rem;
    margin-bottom: 15px;
}

.resource-meta i {
    margin-right: 5px;
}

.resource-link {
    color: var(--primary-light);
    font-weight: 600;
    font-size: 0.95rem;
    transition: color 0.3s;
}

.resource-link:hover {
    color: var(--white);
}

.resource-link i {
    margin-left: 5px;
    font-size: 0.8rem;
}

/* ===== IOAI Resources ===== */
.ioai-resources {
    padding: 80px 60px;
    background: var(--dark-light);
}

.ioai-resources h2 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 50px;
}

.ioai-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    max-width: 1200px;
    margin: 0 auto;
}

.ioai-card {
    background: var(--dark);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 40px;
    text-align: center;
    transition: all 0.3s ease;
}

.ioai-card:hover {
    border-color: var(--primary);
}

.ioai-card i {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 20px;
}

.ioai-card h3 {
    margin-bottom: 15px;
}

.ioai-card p {
    color: var(--gray-light);
    margin-bottom: 20px;
}

.ioai-card a {
    color: var(--primary-light);
    font-weight: 600;
}

/* ===== Practice Section ===== */
.practice-stats {
    display: flex;
    justify-content: center;
    gap: 50px;
    padding: 0 60px 60px;
    max-width: 1000px;
    margin: 0 auto;
}

.stat-card {
    display: flex;
    align-items: center;
    gap: 20px;
    background: var(--dark-light);
    padding: 25px 35px;
    border-radius: 20px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.stat-card i {
    font-size: 2.5rem;
    color: var(--primary);
}

.stat-card .number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
}

.stat-card .label {
    color: var(--gray-light);
}

.contest-section {
    padding: 40px 60px 100px;
    max-width: 1200px;
    margin: 0 auto;
}

.contest-tabs {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 50px;
}

.contest-tab {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--gray-light);
    padding: 15px 35px;
    border-radius: 30px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.contest-tab:hover,
.contest-tab.active {
    background: var(--primary);
    border-color: var(--primary);
    color: var(--white);
}

.contest-content {
    display: none;
}

.contest-content.active {
    display: block;
}

.contest-list {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.contest-card {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    padding: 30px;
    transition: all 0.3s ease;
}

.contest-card:hover {
    border-color: var(--primary);
}

.contest-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 25px;
}

.contest-badge {
    display: inline-block;
    padding: 6px 15px;
    border-radius: 15px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 10px;
}

.contest-badge.ioai {
    background: rgba(99, 102, 241, 0.2);
    color: var(--primary-light);
}

.contest-badge.kaggle {
    background: rgba(14, 165, 233, 0.2);
    color: var(--secondary);
}

.contest-info h3 {
    font-size: 1.4rem;
    margin-bottom: 10px;
}

.contest-info p {
    color: var(--gray-light);
    max-width: 600px;
}

.contest-meta {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 8px;
    color: var(--gray);
}

.contest-meta i {
    margin-right: 8px;
}

.contest-problems {
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    padding-top: 20px;
}

.problem-item {
    display: flex;
    align-items: center;
    padding: 15px 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.problem-item:last-child {
    border-bottom: none;
}

.problem-name {
    flex: 1;
    font-weight: 500;
}

.difficulty {
    padding: 5px 15px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
    margin-right: 20px;
}

.difficulty.easy {
    background: rgba(16, 185, 129, 0.2);
    color: #10b981;
}

.difficulty.medium {
    background: rgba(245, 158, 11, 0.2);
    color: #f59e0b;
}

.difficulty.hard {
    background: rgba(244, 63, 94, 0.2);
    color: #f43f5e;
}

.solve-btn {
    background: var(--primary);
    color: var(--white);
    padding: 8px 20px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.3s;
}

.solve-btn:hover {
    background: var(--primary-dark);
}

.kaggle-link {
    display: inline-block;
    background: var(--secondary);
    color: var(--white);
    padding: 12px 25px;
    border-radius: 25px;
    font-weight: 600;
    margin-top: 15px;
    transition: all 0.3s;
}

.kaggle-link:hover {
    background: #0284c7;
}

.kaggle-link i {
    margin-left: 8px;
}

/* Practice Problems Grid */
.practice-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.practice-category {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    padding: 30px;
}

.practice-category h3 {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 25px;
    font-size: 1.2rem;
}

.practice-category h3 i {
    color: var(--primary);
}

.problem-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.problem-row {
    display: flex;
    align-items: center;
    padding: 12px 15px;
    background: rgba(255, 255, 255, 0.02);
    border-radius: 10px;
    transition: all 0.3s;
}

.problem-row:hover {
    background: rgba(99, 102, 241, 0.1);
}

.problem-title {
    flex: 1;
    font-size: 0.95rem;
}

.problem-row .difficulty {
    margin-right: 15px;
    font-size: 0.75rem;
    padding: 3px 10px;
}

.problem-row a {
    color: var(--primary-light);
    font-weight: 600;
    font-size: 0.9rem;
}

/* ===== Auth Section ===== */
.auth-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 120px 60px 60px;
    position: relative;
}

.auth-container {
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 30px;
    padding: 50px;
    width: 100%;
    max-width: 450px;
    position: relative;
    z-index: 1;
}

.auth-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 35px;
}

.auth-tab {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--gray);
    padding: 15px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: all 0.3s;
}

.auth-tab.active {
    color: var(--white);
    border-color: var(--primary);
}

.auth-form {
    display: none;
}

.auth-form.active {
    display: block;
}

.auth-form h2 {
    font-size: 1.8rem;
    margin-bottom: 8px;
}

.auth-form > p {
    color: var(--gray-light);
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 22px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--gray-light);
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-wrapper i {
    position: absolute;
    left: 18px;
    color: var(--gray);
}

.input-wrapper input {
    width: 100%;
    background: var(--dark);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    padding: 15px 18px 15px 50px;
    color: var(--white);
    font-size: 1rem;
    transition: all 0.3s;
}

.input-wrapper input:focus {
    outline: none;
    border-color: var(--primary);
}

.toggle-password {
    position: absolute;
    right: 15px;
    background: none;
    border: none;
    color: var(--gray);
    cursor: pointer;
}

.form-options {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 25px;
}

.checkbox-wrapper {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    color: var(--gray-light);
    font-size: 0.9rem;
}

.checkbox-wrapper input {
    width: 18px;
    height: 18px;
    accent-color: var(--primary);
}

.checkbox-wrapper a {
    color: var(--primary-light);
}

.forgot-link {
    color: var(--primary-light);
    font-size: 0.9rem;
}

.auth-submit {
    width: 100%;
    background: var(--gradient);
    border: none;
    color: var(--white);
    padding: 16px;
    border-radius: 15px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.auth-submit:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 30px rgba(99, 102, 241, 0.3);
}

.divider {
    display: flex;
    align-items: center;
    margin: 30px 0;
    color: var(--gray);
}

.divider::before,
.divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: rgba(255, 255, 255, 0.1);
}

.divider span {
    padding: 0 20px;
    font-size: 0.9rem;
}

.social-login {
    display: flex;
    gap: 15px;
}

.social-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 14px;
    border-radius: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    border: 1px solid rgba(255, 255, 255, 0.1);
    background: var(--dark);
    color: var(--white);
}

.social-btn:hover {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.social-btn i {
    font-size: 1.2rem;
}

.auth-decoration {
    position: absolute;
    inset: 0;
    overflow: hidden;
    pointer-events: none;
}

.floating-shape {
    position: absolute;
    border-radius: 50%;
    background: var(--gradient);
    opacity: 0.1;
    animation: floatShape 15s ease-in-out infinite;
}

.shape-1 {
    width: 400px;
    height: 400px;
    top: -100px;
    right: -100px;
}

.shape-2 {
    width: 300px;
    height: 300px;
    bottom: -50px;
    left: -100px;
    animation-delay: 5s;
}

.shape-3 {
    width: 200px;
    height: 200px;
    top: 50%;
    left: 20%;
    animation-delay: 10s;
}

@keyframes floatShape {
    0%, 100% { transform: translate(0, 0) scale(1); }
    50% { transform: translate(30px, -30px) scale(1.1); }
}

/* ===== Footer ===== */
.footer {
    background: var(--dark-light);
    padding: 60px 60px 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    max-width: 1200px;
    margin: 0 auto;
    gap: 60px;
    margin-bottom: 40px;
}

.footer-brand {
    max-width: 300px;
}

.footer-brand i {
    font-size: 2rem;
    color: var(--primary);
}

.footer-brand span {
    font-size: 1.5rem;
    font-weight: 700;
    margin-left: 10px;
}

.footer-brand p {
    color: var(--gray-light);
    margin-top: 15px;
}

.footer-links h4 {
    margin-bottom: 20px;
    font-size: 1.1rem;
}

.footer-links a {
    display: block;
    color: var(--gray-light);
    margin-bottom: 12px;
    transition: color 0.3s;
}

.footer-links a:hover {
    color: var(--primary-light);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    color: var(--gray);
}

.heart-pulse {
    color: #f43f5e;
    animation: heartbeat 1.2s ease-in-out infinite;
    display: inline-block;
}

@keyframes heartbeat {
    0% {
        transform: scale(1);
    }
    14% {
        transform: scale(1.3);
    }
    28% {
        transform: scale(1);
    }
    42% {
        transform: scale(1.3);
    }
    70% {
        transform: scale(1);
    }
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {
    .hero {
        flex-direction: column;
        text-align: center;
        padding: 120px 40px 60px;
    }

    .hero-content {
        max-width: 100%;
    }

    .hero-buttons {
        justify-content: center;
    }

    .hero-visual {
        display: none;
    }

    .stats {
        flex-wrap: wrap;
        gap: 40px;
    }
}

@media (max-width: 768px) {
    .floating-header {
        width: calc(100% - 30px);
        padding: 12px 20px;
    }

    .nav-links {
        position: fixed;
        top: 80px;
        left: 50%;
        transform: translateX(-50%);
        width: calc(100% - 30px);
        background: rgba(15, 23, 42, 0.95);
        backdrop-filter: blur(20px);
        border-radius: 20px;
        flex-direction: column;
        padding: 30px;
        gap: 20px;
        opacity: 0;
        visibility: hidden;
        transition: all 0.3s;
    }

    .nav-links.active {
        opacity: 1;
        visibility: visible;
    }

    .hamburger {
        display: flex;
    }

    .hero-content h1 {
        font-size: 2.5rem;
    }

    .features,
    .topics,
    .resources-section,
    .contest-section {
        padding: 60px 20px;
    }

    .page-header {
        padding: 120px 20px 40px;
    }

    .page-header h1 {
        font-size: 2rem;
    }

    .practice-stats {
        flex-direction: column;
        align-items: center;
    }

    .contest-header {
        flex-direction: column;
    }

    .contest-meta {
        align-items: flex-start;
        flex-direction: row;
        gap: 20px;
        margin-top: 15px;
    }

    .problem-item {
        flex-wrap: wrap;
        gap: 10px;
    }

    .problem-name {
        width: 100%;
    }

    .auth-container {
        padding: 30px 25px;
    }

    .footer-content {
        flex-direction: column;
        gap: 40px;
    }

    .resources-grid {
        grid-template-columns: 1fr;
    }

    .resource-card {
        flex-direction: column;
    }

    .resource-icon {
        width: 100%;
        height: 100px;
    }
}

/* ===== Toast Notifications ===== */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    padding: 15px 25px;
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 10000;
    opacity: 0;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast-success {
    border-color: #10b981;
}

.toast-success i {
    color: #10b981;
}

.toast-error {
    border-color: #f43f5e;
}

.toast-error i {
    color: #f43f5e;
}

.toast-info i {
    color: var(--secondary);
}

/* ===== User Dropdown ===== */
.user-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    margin-top: 10px;
    background: var(--dark-light);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    padding: 10px 0;
    min-width: 180px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
    z-index: 1001;
}

.user-dropdown.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 20px;
    color: var(--gray-light);
    transition: all 0.3s;
}

.dropdown-item:hover {
    background: rgba(99, 102, 241, 0.1);
    color: var(--white);
}

.dropdown-item i {
    width: 20px;
}

/* ===== Nav Avatar ===== */
.nav-avatar {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    object-fit: cover;
}

.login-btn.user-logged-in {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 8px 20px !important;
}

.nav-username {
    max-width: 100px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* ===== Kaggle Dashboard ===== */
.kaggle-dashboard {
    padding: 0 60px 80px;
    max-width: 1300px;
    margin: 0 auto;
}

/* Auth required */
.auth-required-msg {
    text-align: center;
    padding: 80px 20px;
}
.auth-required-msg i {
    font-size: 4rem;
    color: var(--gray);
    margin-bottom: 20px;
}
.auth-required-msg h2 {
    margin-bottom: 12px;
}
.auth-required-msg p {
    color: var(--gray-light);
    margin-bottom: 30px;
}

/* Credentials card */
.credentials-setup {
    display: flex;
    justify-content: center;
}
.credentials-card {
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 24px;
    padding: 50px;
    max-width: 520px;
    width: 100%;
    text-align: center;
}
.credentials-icon {
    width: 80px;
    height: 80px;
    background: var(--gradient);
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 25px;
}
.credentials-icon i {
    font-size: 2rem;
    color: var(--white);
}
.credentials-card h2 {
    margin-bottom: 12px;
}
.credentials-card > p {
    color: var(--gray-light);
    margin-bottom: 30px;
    font-size: 0.95rem;
    line-height: 1.7;
}
.credentials-card a {
    color: var(--primary-light);
}
.credentials-form {
    text-align: left;
}
.credentials-form .btn {
    width: 100%;
    margin-top: 10px;
}

/* Status bar */
.kaggle-status-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 16px;
    padding: 16px 24px;
    margin-bottom: 30px;
}
.status-badge {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.95rem;
}
.status-badge.connected i {
    color: #10b981;
}

/* Small buttons */
.btn-sm {
    padding: 10px 20px;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    border: none;
}
.btn-gradient {
    background: var(--gradient);
    color: var(--white);
}
.btn-gradient:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99,102,241,0.35);
}
.btn-outline {
    background: transparent;
    border: 1px solid rgba(255,255,255,0.15);
    color: var(--gray-light);
}
.btn-outline:hover {
    border-color: var(--primary);
    color: var(--white);
    background: rgba(99,102,241,0.1);
}

/* Dashboard tabs */
.kaggle-tabs {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
}
.kaggle-tab {
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.1);
    color: var(--gray-light);
    padding: 14px 28px;
    border-radius: 25px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 8px;
}
.kaggle-tab:hover,
.kaggle-tab.active {
    background: var(--primary);
    border-color: var(--primary);
    color: var(--white);
}
.kaggle-tab-content {
    display: none;
}
.kaggle-tab-content.active {
    display: block;
}

/* Search bar */
.kaggle-search-bar {
    display: flex;
    gap: 12px;
    margin-bottom: 30px;
}
.search-input-wrapper {
    flex: 1;
    position: relative;
    display: flex;
    align-items: center;
}
.search-input-wrapper i {
    position: absolute;
    left: 18px;
    color: var(--gray);
}
.search-input-wrapper input {
    width: 100%;
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 15px;
    padding: 14px 18px 14px 48px;
    color: var(--white);
    font-size: 1rem;
    transition: border-color 0.3s;
}
.search-input-wrapper input:focus {
    outline: none;
    border-color: var(--primary);
}

/* Competition cards grid */
.api-competition-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 24px;
    margin-bottom: 30px;
}
.api-comp-card {
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 20px;
    padding: 28px;
    transition: all 0.3s;
}
.api-comp-card:hover {
    border-color: var(--primary);
    transform: translateY(-4px);
}
.api-comp-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 14px;
}
.api-comp-status {
    font-size: 0.8rem;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 12px;
}
.api-comp-status.active {
    background: rgba(16,185,129,0.2);
    color: #10b981;
}
.api-comp-status.ended {
    background: rgba(100,116,139,0.2);
    color: var(--gray-light);
}
.api-comp-title {
    font-size: 1.15rem;
    margin-bottom: 10px;
    line-height: 1.4;
}
.api-comp-desc {
    color: var(--gray-light);
    font-size: 0.9rem;
    margin-bottom: 16px;
    line-height: 1.6;
}
.api-comp-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    color: var(--gray);
    font-size: 0.85rem;
    margin-bottom: 18px;
}
.api-comp-meta i {
    margin-right: 5px;
    color: var(--primary-light);
}
.api-comp-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    border-top: 1px solid rgba(255,255,255,0.05);
    padding-top: 18px;
}
.api-comp-actions a {
    text-decoration: none;
}

/* Pagination */
.kaggle-pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px;
    margin-top: 10px;
}
.page-indicator {
    color: var(--gray-light);
    font-weight: 600;
}

/* Loading spinner */
.loading-spinner {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
    padding: 60px 0;
    color: var(--gray-light);
}
.spinner {
    width: 42px;
    height: 42px;
    border: 4px solid rgba(99,102,241,0.2);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Empty state */
.empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 14px;
    padding: 60px 0;
    color: var(--gray);
    text-align: center;
}
.empty-state i {
    font-size: 3rem;
    opacity: 0.5;
}

/* Submissions lookup */
.submissions-lookup {
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.05);
    border-radius: 20px;
    padding: 30px;
    margin-bottom: 30px;
}
.submissions-lookup h3 {
    margin-bottom: 8px;
}
.submissions-lookup > p {
    color: var(--gray-light);
    margin-bottom: 20px;
    font-size: 0.95rem;
}
.submissions-lookup code {
    background: rgba(99,102,241,0.15);
    padding: 2px 8px;
    border-radius: 6px;
    color: var(--primary-light);
    font-size: 0.9rem;
}
.submissions-search-row {
    display: flex;
    gap: 12px;
}

/* Submission competition cards */
.submission-comp-card {
    background: var(--dark-light);
    border: 1px solid rgba(255,255,255,0.06);
    border-radius: 20px;
    margin-bottom: 20px;
    overflow: hidden;
    transition: border-color 0.3s;
}
.submission-comp-card:hover {
    border-color: rgba(99,102,241,0.3);
}
.submission-comp-card.highlight-flash {
    animation: flashHighlight 1.5s ease;
}
@keyframes flashHighlight {
    0%, 100% { border-color: rgba(255,255,255,0.06); }
    30% { border-color: rgba(99,102,241,0.6); box-shadow: 0 0 20px rgba(99,102,241,0.2); }
}
.sub-card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    padding: 24px 28px 16px;
    gap: 16px;
    flex-wrap: wrap;
}
.sub-card-info h3 {
    font-size: 1.1rem;
    margin-bottom: 8px;
    color: var(--white);
}
.sub-card-meta {
    display: flex;
    gap: 16px;
    align-items: center;
    flex-wrap: wrap;
    font-size: 0.88rem;
    color: var(--gray-light);
}
.sub-card-meta .api-comp-status {
    font-size: 0.75rem;
}
.sub-card-meta i {
    margin-right: 4px;
    color: var(--primary-light);
}
.sub-card-meta .fa-trophy {
    color: #f59e0b;
}
.sub-card-actions {
    display: flex;
    gap: 8px;
    flex-shrink: 0;
}
.sub-card-body {
    padding: 0 28px 24px;
}
.sub-card-body .table-wrapper {
    margin-top: 0;
}
.kaggle-table.compact th {
    padding: 10px 14px;
    font-size: 0.82rem;
}
.kaggle-table.compact td {
    padding: 8px 14px;
    font-size: 0.85rem;
}
.sub-error {
    color: #ef4444;
    font-size: 0.9rem;
    padding: 12px 0;
}
.sub-error i {
    margin-right: 6px;
}
.sub-none {
    color: var(--gray-light);
    font-size: 0.9rem;
    padding: 12px 0;
    font-style: italic;
}
.sub-more {
    color: var(--gray-light);
    font-size: 0.82rem;
    text-align: right;
    margin-top: 8px;
    font-style: italic;
}

/* Kaggle tables */
.table-wrapper {
    overflow-x: auto;
    border-radius: 16px;
    border: 1px solid rgba(255,255,255,0.05);
}
.kaggle-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.92rem;
}
.kaggle-table thead {
    background: rgba(99,102,241,0.12);
}
.kaggle-table th {
    padding: 14px 18px;
    text-align: left;
    font-weight: 600;
    color: var(--primary-light);
    white-space: nowrap;
}
.kaggle-table td {
    padding: 12px 18px;
    border-bottom: 1px solid rgba(255,255,255,0.03);
    color: var(--gray-light);
}
.kaggle-table tbody tr:hover {
    background: rgba(99,102,241,0.06);
}
.rank-cell {
    font-weight: 700;
    color: var(--white);
}
.score-cell {
    color: #10b981;
    font-weight: 600;
}
.sub-status {
    padding: 4px 12px;
    border-radius: 10px;
    font-size: 0.8rem;
    font-weight: 600;
}
.status-complete {
    background: rgba(16,185,129,0.2);
    color: #10b981;
}
.status-pending {
    background: rgba(245,158,11,0.2);
    color: #f59e0b;
}

/* Modal */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.7);
    backdrop-filter: blur(6px);
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}
.modal-content {
    background: var(--dark);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: 24px;
    width: 100%;
    max-width: 900px;
    max-height: 80vh;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}
.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 24px 30px;
    border-bottom: 1px solid rgba(255,255,255,0.05);
}
.modal-header h2 {
    font-size: 1.3rem;
}
.modal-close {
    background: none;
    border: none;
    color: var(--gray-light);
    font-size: 2rem;
    cursor: pointer;
    transition: color 0.3s;
    line-height: 1;
}
.modal-close:hover {
    color: var(--white);
}
.modal-body {
    padding: 24px 30px;
    overflow-y: auto;
}

/* Responsive */
@media (max-width: 768px) {
    .kaggle-dashboard {
        padding: 0 20px 60px;
    }
    .credentials-card {
        padding: 30px 24px;
    }
    .kaggle-status-bar {
        flex-direction: column;
        gap: 14px;
        text-align: center;
    }
    .kaggle-tabs {
        flex-wrap: wrap;
    }
    .api-competition-grid {
        grid-template-columns: 1fr;
    }
    .api-comp-actions {
        flex-direction: column;
    }
    .api-comp-actions .btn-sm {
        width: 100%;
        text-align: center;
    }
    .submissions-search-row {
        flex-direction: column;
    }
    .sub-card-header {
        flex-direction: column;
    }
    .sub-card-actions {
        width: 100%;
    }
    .sub-card-actions .btn-sm {
        flex: 1;
        text-align: center;
    }
    .modal-content {
        max-height: 90vh;
    }
    .modal-header,
    .modal-body {
        padding: 18px 20px;
    }
    .kaggle-search-bar {
        flex-direction: column;
    }
}