:root {
    --primary-blue: #3b82f6;
    --dark-blue: #1e3a8a;
    --light-blue: #60a5fa;
    --accent-cyan: #22d3ee;
    --bg-dark: #0f172a;
    --bg-card: rgba(255, 255, 255, 0.08);
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --input-bg: rgba(255, 255, 255, 0.1);
    --input-border: rgba(255, 255, 255, 0.2);
    --input-text: #f1f5f9;
    --input-placeholder: #94a3b8;
    --gradient-1: linear-gradient(135deg, #3b82f6 0%, #1e40af 100%);
    --gradient-2: linear-gradient(135deg, #22d3ee 0%, #3b82f6 100%);
    --gradient-3: linear-gradient(135deg, #1e3a8a 0%, #0f172a 100%);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Outfit', sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
    transition: background-color 0.5s ease, color 0.5s ease;
}

body.light-mode {
    background: #f1f5f9;
    color: #1e293b;
    --bg-card: rgba(255, 255, 255, 0.9);
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --input-bg: rgba(0, 0, 0, 0.05);
    --input-border: rgba(0, 0, 0, 0.2);
    --input-text: #1e293b;
    --input-placeholder: #64748b;
}

/* Background Shapes */
.shape {
    position: fixed;
    border-radius: 50%;
    filter: blur(80px);
    z-index: -1;
    animation: float 20s ease-in-out infinite;
}

.shape-1 {
    width: 400px;
    height: 400px;
    background: var(--primary-blue);
    top: -100px;
    left: -100px;
    opacity: 0.4;
}

.shape-2 {
    width: 300px;
    height: 300px;
    background: var(--accent-cyan);
    top: 50%;
    right: -100px;
    opacity: 0.3;
    animation-delay: -5s;
}

.shape-3 {
    width: 350px;
    height: 350px;
    background: var(--dark-blue);
    bottom: -100px;
    left: 30%;
    opacity: 0.35;
    animation-delay: -10s;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(30px, -30px) scale(1.1); }
    50% { transform: translate(-20px, 20px) scale(0.95); }
    75% { transform: translate(20px, 30px) scale(1.05); }
}

/* Navigation Bar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.navbar.light {
    background: rgba(255, 255, 255, 0.95);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 16px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 8px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 1rem;
    padding: 10px 20px;
    border-radius: 10px;
    transition: all 0.3s ease;
}

.nav-link:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.08);
}

.nav-link.active {
    color: white;
    background: var(--gradient-1);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 100px 24px 40px;
}

/* Page Sections */
.page-section {
    margin-bottom: 80px;
    scroll-margin-top: 100px;
}

/* Header Section */
.header {
    text-align: center;
    margin-bottom: 60px;
    position: relative;
}

.title {
    font-size: 3rem;
    font-weight: 700;
    background: var(--gradient-2);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 16px;
    letter-spacing: -1px;
}

.subtitle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    color: var(--text-secondary);
    font-size: 1.1rem;
    font-weight: 300;
    margin-bottom: 30px;
}

.divider {
    width: 60px;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--light-blue), transparent);
}

.profile {
    display: inline-block;
    padding: 16px 32px;
    background: var(--bg-card);
    border-radius: 50px;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.profile .name {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.profile .course {
    font-size: 0.9rem;
    color: var(--light-blue);
    font-weight: 400;
}

/* Intro Grid (Home Page) */
.intro-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 24px;
    max-width: 800px;
    margin: 0 auto;
}

.intro-card {
    background: var(--bg-card);
    border-radius: 24px;
    padding: 32px;
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    display: flex;
    align-items: center;
    gap: 20px;
    text-decoration: none;
    cursor: pointer;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.intro-card:hover {
    transform: translateY(-8px);
    background: rgba(255, 255, 255, 0.15);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
}

.intro-number {
    font-size: 3rem;
    font-weight: 700;
    color: rgba(59, 130, 246, 0.2);
    font-family: 'Outfit', sans-serif;
}

.intro-content {
    flex: 1;
}

.intro-content h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.intro-content p {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 300;
}

.intro-arrow {
    font-size: 2rem;
    color: var(--light-blue);
    transition: transform 0.3s ease;
}

.intro-card:hover .intro-arrow {
    transform: translateX(8px);
}

/* Activities Grid */
.activities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
    justify-content: center;
    max-width: 1000px;
    margin: 0 auto;
}

/* Activity Card */
.activity-card {
    background: var(--bg-card);
    border-radius: 24px;
    padding: 28px;
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    position: relative;
    overflow: hidden;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.activity-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-1);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.activity-card:hover {
    transform: translateY(-8px);
    background: rgba(255, 255, 255, 0.12);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
}

.activity-card:hover::before {
    opacity: 1;
}

.activity-number {
    font-size: 3rem;
    font-weight: 700;
    color: rgba(59, 130, 246, 0.2);
    line-height: 1;
    margin-bottom: 16px;
    font-family: 'Outfit', sans-serif;
}

.activity-content {
    margin-bottom: 24px;
}

.activity-content h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    line-height: 1.4;
}

.activity-content p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 300;
}

/* Run Button */
.run-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
    padding: 14px 24px;
    background: var(--gradient-1);
    border: none;
    border-radius: 12px;
    color: white;
    font-family: 'Outfit', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.run-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s ease;
}

.run-btn:hover::before {
    left: 100%;
}

.run-btn:hover {
    transform: scale(1.02);
    box-shadow: 0 10px 30px rgba(59, 130, 246, 0.4);
}

.run-btn:active {
    transform: scale(0.98);
}

.run-btn svg {
    width: 18px;
    height: 18px;
    transition: transform 0.3s ease;
}

.run-btn:hover svg {
    transform: translateX(4px);
}

/* Lab 3 Demo Styles */
.lab3-demo {
    margin-top: 16px;
}

.lab3-demo .run-btn {
    padding: 12px 20px;
}

/* Input Fields */
.input-group {
    display: flex;
    gap: 10px;
    margin-bottom: 12px;
}

.input-group input {
    flex: 1;
    padding: 12px 16px;
    border: 2px solid var(--input-border);
    border-radius: 10px;
    background: var(--input-bg);
    color: var(--input-text);
    font-family: 'Outfit', sans-serif;
    font-size: 0.95rem;
    outline: none;
    transition: all 0.3s ease;
}

.input-group input:focus {
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.input-group input::placeholder {
    color: var(--input-placeholder);
}

.small-btn {
    padding: 12px 20px !important;
    white-space: nowrap;
}

/* Demo Input */
.demo-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--input-border);
    border-radius: 10px;
    background: var(--input-bg);
    color: var(--input-text);
    font-family: 'Outfit', sans-serif;
    font-size: 0.95rem;
    outline: none;
    transition: all 0.3s ease;
    margin-bottom: 10px;
}

.demo-input:focus {
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.demo-input::placeholder {
    color: var(--input-placeholder);
}

/* Demo Lists */
.demo-list {
    list-style: none;
    max-height: 150px;
    overflow-y: auto;
    background: var(--input-bg);
    border-radius: 10px;
    padding: 10px;
    border: 1px solid var(--input-border);
}

.demo-list li {
    padding: 10px 14px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    margin-bottom: 8px;
    font-size: 0.95rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-primary);
}

.demo-list li:last-child {
    margin-bottom: 0;
}

.delete-btn {
    background: #ef4444;
    color: white;
    border: none;
    width: 24px;
    height: 24px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 1rem;
    line-height: 1;
    transition: all 0.3s ease;
}

.delete-btn:hover {
    background: #dc2626;
    transform: scale(1.1);
}

/* Character Counter */
.char-count {
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-top: 8px;
}

.char-count span {
    color: var(--light-blue);
    font-weight: 600;
}

/* Calculator */
.operator {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--light-blue);
}

.result {
    margin-top: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent-cyan);
    text-align: center;
}

/* Demo Image */
.demo-image {
    width: 100%;
    max-width: 150px;
    height: auto;
    border-radius: 12px;
    margin-bottom: 12px;
    display: block;
    margin-left: auto;
    margin-right: auto;
    border: 3px solid var(--primary-blue);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.3);
    background: white;
}

.todo-list {
    max-height: 180px;
}

/* =========================
   Lab 4 Demo - Inputs & Buttons
   ========================= */
.lab4-demo input {
    width: 100%;
    padding: 12px 16px;
    border-radius: 12px;
    border: 2px solid var(--input-border);
    background: var(--input-bg);
    color: var(--input-text, var(--text-primary));
    font-size: 1rem;
    outline: none;
    transition: all 0.3s ease;
    box-sizing: border-box;
}

.lab4-demo input:focus {
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.lab4-demo .button-group {
    margin-top: 10px;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.lab4-demo .button-group button {
    flex: 1 1 45%;
    padding: 12px 20px;
    border-radius: 12px;
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--gradient-1);
    color: white;
}

.lab4-demo .button-group button:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 20px rgba(59, 130, 246, 0.4);
}

.lab4-demo .button-group button:active {
    transform: scale(0.98);
    box-shadow: 0 4px 10px rgba(59, 130, 246, 0.3);
}

/* =========================
   Lab 4 Demo - Inputs & Buttons
   ========================= */
.lab4-demo input {
    width: 100%;
    padding: 12px 16px;
    border-radius: 12px;
    border: 2px solid var(--input-border);
    background: var(--input-bg);
    color: var(--input-text, var(--text-primary));
    font-size: 1rem;
    outline: none;
    transition: all 0.3s ease;
    box-sizing: border-box;
}

.lab4-demo input:focus {
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.lab4-demo .button-group {
    margin-top: 10px;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

.lab4-demo .button-group button {
    flex: 1 1 45%;
    padding: 12px 20px;
    border-radius: 12px;
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--gradient-1);
    color: white;
}

.lab4-demo .button-group button:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 20px rgba(59, 130, 246, 0.4);
}

.lab4-demo .button-group button:active {
    transform: scale(0.98);
    box-shadow: 0 4px 10px rgba(59, 130, 246, 0.3);
}

/* =========================
   Lab 4 – Averages & Final Grade Panel
   ========================= */

.lab4-demo .averages-panel {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 20px;
    padding: 20px;
    margin-top: 20px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.lab4-demo .averages-panel h4 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 8px;
}

.lab4-demo .averages-panel .average-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 12px;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.08);
    font-weight: 500;
    color: var(--text-primary);
    transition: all 0.3s ease;
}

.lab4-demo .averages-panel .average-item span {
    font-weight: 600;
    color: var(--accent-cyan);
}

.lab4-demo .averages-panel .final-grade {
    margin-top: 12px;
    padding: 10px 0;
    border-radius: 12px;
    font-size: 1.2rem;
    font-weight: 700;
    text-align: center;
    background: var(--gradient-2);
    color: white;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
}

.lab4-demo .button-group .compute-btn {
    background: var(--gradient-2);
    color: white;
    font-weight: 600;
    transition: all 0.3s ease;
}

.lab4-demo .button-group .compute-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 20px rgba(34, 211, 238, 0.4);
}

.lab4-demo .button-group .compute-btn:active {
    transform: scale(0.98);
    box-shadow: 0 4px 10px rgba(34, 211, 238, 0.3);
}

/* Mobile responsiveness */
@media (max-width: 480px) {
    .lab4-demo .averages-panel {
        padding: 16px;
    }

    .lab4-demo .averages-panel .average-item {
        flex-direction: column;
        gap: 4px;
        text-align: center;
    }
}

.lab4-card {
  background-color: rgba(255,255,255,0.1);
  padding: 20px;
  border-radius: 15px;
  margin: 15px 0;
}
.lab4-inputs input {
  width: 100px;
  margin: 5px;
  padding: 8px;
  border-radius: 5px;
  border: none;
}
.lab4-card button {
  margin-top: 10px;
}
.lab4-card {
  background-color: rgba(255, 255, 255, 0.1);
  padding: 20px;
  border-radius: 15px;
}
.lab4-inputs input {
  width: 120px;
  margin: 5px;
  padding: 8px;
  border-radius: 5px;
  border: none;
}
.lab4-card {
  background-color: rgba(255, 255, 255, 0.08);
  padding: 20px;
  border-radius: 15px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.lab4-inputs input {
  width: 120px;
  margin: 5px;
  padding: 8px;
  border-radius: 5px;
  border: none;
  background-color: rgba(255,255,255,0.1);
  color: #fff;
}

.button-group {
  display: flex;
  gap: 10px;
}

.button-group .run-btn {
  padding: 10px 20px;
  border-radius: 10px;
  border: none;
  background-color: #3b82f6;
  color: #fff;
  cursor: pointer;
}

.lab4-results p {
  font-weight: 600;
  color: #f1f5f9;
}


/*