:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #e74c3c;
    --light: #ecf0f1;
    --dark: #2c3e50;
    --success: #2ecc71;
    --warning: #f39c12;
    --danger: #e74c3c;
    --success-light: #d5f5e3;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f5f7fa;
    color: var(--dark);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
}

header {
    background-color: var(--primary);
    padding: 1.5rem;
    border-bottom: 1px solid #eaeaea;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 2rem;
}

.logo-container {
    width: 150px;
}

.zoho-logo {
    width: 100%;
    height: auto;
    object-fit: contain;
}

.title-container {
    text-align: left;
    border-left: 1px solid #e0e0e0;
    padding-left: 2rem;
}

header h1 {
    font-size: 1.8rem;
    color: white;
    font-weight: 600;
}

header p {
    font-size: 1rem;
    color: var(--light);
    margin: 0;
}

.main-container {
    display: flex;
    max-width: 1400px;
    margin: 2rem auto;
    padding: 0 1rem;
    gap: 2rem;
}

.content-container {
    flex: 0 0 70%;
}

.intro {
    background-color: white;
    padding: 2rem;
    border-radius: 8px;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
    margin-bottom: 2rem;
    border-left: 4px solid var(--secondary);
    transition: all 0.3s ease;
}

.intro h2 {
    font-size: 1.5rem;
    color: var(--primary);
}

.intro p {
    font-size: 1rem;
    color: #7f8c8d;
}

.intro ul li {
    padding: 0.6rem 0.8rem;
    font-size: 0.95rem;
}

.intro-header {
    display: flex;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 1px solid #e0e0e0;
}

.intro-header h2 {
    margin: 0;
    font-weight: 600;
}

.intro-icon {
    margin-left: 15px;
    color: var(--secondary);
    font-size: 22px;
}

/* Intro Cards */
.intro-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.intro-card {
    background-color: white;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    display: flex;
    align-items: flex-start;
}

.intro-card:hover {
    box-shadow: 0 6px 15px rgba(0, 0, 0, 0.1);
}

.card-icon {
    margin-right: 15px;
    color: var(--secondary);
    font-size: 24px;
    margin-top: 3px;
}

.card-content h4 {
    margin: 0 0 8px 0;
    color: var(--primary);
    font-size: 16px;
    font-weight: 600;
}

.card-content p {
    margin: 0;
    font-size: 14px;
    line-height: 1.5;
}

/* Video Section */
.intro-video {
    grid-column: 1 / -1;
    background-color: #e3f2fd;
    border-radius: 8px;
    padding: 20px;
    margin-top: 10px;
}

.intro-video h4 {
    margin: 0 0 10px 0;
    color: var(--primary);
    font-size: 18px;
}

.intro-video p {
    margin: 0 0 15px 0;
    color: var(--dark);
    font-size: 14px;
}

.video-link-btn {
    display: inline-flex;
    align-items: center;
    padding: 10px 20px;
    background-color: var(--secondary);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    font-weight: 500;
    transition: background-color 0.3s ease;
}

.video-link-btn:hover {
    background-color: var(--primary);
}

.video-link-btn i {
    margin-right: 8px;
    font-size: 18px;
}


.problem-section {
    background: white;
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    border-left: 4px solid var(--secondary);
}

.problem-section h2 {
    color: var(--primary);
    border-bottom: 2px solid var(--light);
    padding-bottom: 0.5rem;
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
}

.problem {
    position: relative;
    background-color: var(--light);
    padding: 1.5rem;
    border-radius: 6px;
    margin-bottom: 1.5rem;
    transition: all 0.3s;
}

.problem.solved {
    border-left: 4px solid var(--success);
    background: rgba(46, 204, 113, 0.05);
}

.problem h3 {
    color: var(--primary);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.problem h4 {
    color: var(--dark);
    margin: 1.5rem 0 0.5rem;
    font-size: 1.1rem;
}

.requirements {
    margin: 1rem 0;
    padding-left: 1.5rem;
}

.requirements li {
    margin-bottom: 0.8rem;
    position: relative;
    list-style: none;
    line-height: 1.6;
}

.requirements li::before {
    font-weight: bold;
    display: inline-block;
    width: 1em;
    margin-left: -1em;
}

.requirements li strong {
    color: var(--primary);
}

.requirements ul {
    margin-top: 0.5rem;
    padding-left: 1.5rem;
    list-style-type: circle;
}

.requirements ul li {
    margin-bottom: 0.3rem;
    font-size: 0.95rem;
}

.solution-container {
    margin-top: 1.5rem;
    border-top: 1px dashed #ddd;
    padding-top: 1.5rem;
}

.solution-toggle {
    background: var(--secondary);
    color: white;
    border: none;
    padding: 0.8rem 1.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
}

.solution-toggle:hover {
    background: #2980b9;
}

.solution-toggle i {
    transition: transform 0.3s;
}

.solution-toggle.active i {
    transform: rotate(180deg);
}

.solution-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    margin-top: 0;
    padding: 0 1rem;
    background: #f0f7ff;
    border-radius: 0 0 4px 4px;
}

.solution-content.show {
    max-height: 8000px;
    padding: 1rem;
    margin-top: 0.5rem;
    transition: max-height 0.5s ease-in;
}

.code-block {
    position: relative;
    background: #151515;
    color: #f8f8f2;
    padding: 2.5rem 1rem 2.5rem 1rem;
    border-radius: 4px;
    overflow-x: auto;
    margin: 1.5rem 0;
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.code-block pre {
    margin: 0;
    white-space: pre-wrap;
    tab-size: 4;
}

.code-block::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 30px;
    background: #1e1e1e;
    border-radius: 4px 4px 0 0;
}

.code-block::after {
    content: '•••';
    position: absolute;
    top: 8px;
    left: 15px;
    color: #555;
    font-size: 1.2rem;
    letter-spacing: 2px;
}

.copy-btn {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: none;
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    transition: all 0.3s;
    display: flex;
    align-items: center;
    gap: 0.3rem;
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
}

.copy-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

.copy-btn i {
    font-size: 0.8rem;
}

.progress-btn {
    background: var(--success);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    margin-top: 1rem;
    transition: all 0.3s;
}

.progress-btn:hover {
    background: #27ae60;
}

.progress-checkmark {
    color: var(--success);
    margin-right: 0.5rem;
}

.video-sidebar {
    flex: 0 0 28%;
    position: sticky;
    top: 20px;
    height: fit-content;
    max-height: 100vh;
    overflow-y: auto;
    padding: 1rem;
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 15px rgba(0, 0, 0, 0.05);
}

.video-container {
    margin-top: 10px;
    position: relative;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    overflow: hidden;
}

.video-link {
    display: block;
    position: relative;
    text-decoration: none;
    color: inherit;
}

.video-thumbnail {
    width: 100%;
    display: block;
    border-radius: 8px;
}

.play-button {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 40px;
    background-color: rgba(255, 0, 0, 0.8);
    border-radius: 10px;
    transition: all 0.3s ease;
}

.play-button::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-40%, -50%);
    width: 0;
    height: 0;
    border-top: 12px solid transparent;
    border-bottom: 12px solid transparent;
    border-left: 15px solid white;
}

.video-link:hover .play-button {
    background-color: rgba(255, 0, 0, 1);
    transform: translate(-50%, -50%) scale(1.1);
}

.channel-info {
    text-align: center;
    margin-top: 1rem;
    padding: 1rem;
    background-color: var(--light);
    border-radius: 8px;
}

.channel-link {
    color: var(--secondary);
    text-decoration: none;
    font-weight: bold;
    display: inline-block;
    margin: 0.5rem 0;
    transition: color 0.3s ease;
}

.channel-info img {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    margin: 10px 0;
}

.channel-link:hover {
    color: var(--accent);
}

footer {
    text-align: center;
    padding: 1.5rem;
    background-color: var(--primary);
    color: white;
    margin-top: 2rem;
    width: 100%;
}

.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.7);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background-color: white;
    padding: 2rem;
    border-radius: 8px;
    max-width: 500px;
    width: 90%;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    animation: modalFadeIn 0.3s ease-out;
}

@keyframes modalFadeIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-content h2 {
    color: var(--primary);
    margin-bottom: 1rem;
}

.modal-content p {
    margin-bottom: 1.5rem;
    color: var(--dark);
}

.subscribe-btn {
    background-color: #ff0000;
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 4px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    text-decoration: none;
    font-weight: 600;
    box-shadow: 0 2px 10px rgba(255, 0, 0, 0.3);
}

.subscribe-btn:hover {
    background-color: #cc0000;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(255, 0, 0, 0.4);
}

.subscribe-btn:active {
    transform: translateY(0);
}

.youtube-icon {
    width: 20px;
    height: 20px;
}

.already-subscribed {
    margin-top: 1rem;
    color: rgb(196, 196, 196);
    cursor: pointer;
    text-decoration: none;
    font-size: 0.7rem;
    transition: color 0.2s;
}

.already-subscribed:hover {
    color: var(--secondary);
    text-decoration: underline;
}

.locked-content {
    background-color: #f8f9fa;
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
    margin-bottom: 2rem;
    border: 2px dashed #ddd;
}

.locked-icon {
    font-size: 3rem;
    color: var(--accent);
    margin-bottom: 1rem;
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}

.hidden {
    display: none;
}

.return-message {
    background-color: var(--success-light);
    color: var(--dark);
    padding: 1.5rem;
    text-align: center;
    margin: 1rem 0;
    border-radius: 8px;
    display: none;
    border-left: 4px solid var(--success);
    animation: slideIn 0.5s ease-out;
    position: relative;
    overflow: hidden;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.return-message::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    animation: shine 2s infinite;
}

@keyframes shine {
    0% {
        transform: translateX(-100%);
    }
    100% {
        transform: translateX(100%);
    }
}

.return-message h3 {
    color: var(--success);
    margin-bottom: 0.5rem;
    font-size: 1.3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.return-message p {
    color: var(--dark);
    margin-bottom: 0;
    font-size: 1rem;
}

.checkmark {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background-color: var(--success);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: bold;
}

.confetti {
    position: fixed;
    width: 10px;
    height: 10px;
    background-color: #f00;
    opacity: 0;
    z-index: 9999;
    animation: confetti 3s ease-out;
}

@keyframes confetti {
    0% {
        transform: translateY(0) rotate(0deg);
        opacity: 1;
    }
    100% {
        transform: translateY(100vh) rotate(720deg);
        opacity: 0;
    }
}

.mobile-menu-toggle {
    display: none;
    background: var(--primary);
    color: white;
    border: none;
    padding: 1rem;
    width: 100%;
    text-align: center;
    margin-bottom: 1rem;
    border-radius: 4px;
    cursor: pointer;
}

/* ==================== */
/* RESPONSIVE BREAKPOINTS */
/* ==================== */

/* Large tablets and small laptops (1024px and below) */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
    }

    .content-container,
    .video-sidebar {
        flex: 1 1 100%;
    }

    .video-sidebar {
        position: static;
        max-height: none;
        margin-top: 2rem;
    }

    .modal-content {
        max-width: 90%;
        padding: 1.5rem;
    }
}

/* Tablets (768px and below) */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        text-align: center;
        gap: 1rem;
    }

    .title-container {
        text-align: center;
        border-left: none;
        padding-left: 0;
        border-top: 1px solid #e0e0e0;
        padding-top: 1rem;
    }

    .logo-container {
        width: 100px;
    }

    header h1 {
        font-size: 1.5rem;
    }

    header p {
        font-size: 0.9rem;
    }

    .intro {
        padding: 1.2rem;
    }
    
    .intro-content {
        grid-template-columns: 1fr;
    }

    .intro-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .intro-icon {
        margin-left: 0;
        margin-top: 10px;
    }

    .problem-section {
        padding: 1.5rem;
    }
    
    .problem {
        padding: 1.2rem;
    }
    
    .requirements {
        padding-left: 1rem;
    }
    
    .requirements ul {
        padding-left: 1rem;
    }
    
    .code-block {
        font-size: 0.8rem;
        padding: 2rem 1rem 1rem 1rem;
    }

    .code-block::before {
        height: 25px;
    }

    .mobile-menu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 0.5rem;
    }
    
    .sidebar {
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.3s ease-out;
        padding: 0;
    }
    
    .sidebar.mobile-open {
        max-height: 1000px;
        padding: 1rem;
        transition: max-height 0.5s ease-in;
    }

    .video-container {
        margin-bottom: 1rem;
    }

    .play-button {
        width: 50px;
        height: 35px;
    }

    .play-button::before {
        border-top: 10px solid transparent;
        border-bottom: 10px solid transparent;
        border-left: 14px solid white;
    }

    .channel-info img {
        width: 100px;
        height: 100px;
    }
}

/* Mobile devices (480px and below) */
@media (max-width: 480px) {
    header {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.3rem;
    }
    
    .problem h3 {
        font-size: 1.1rem;
    }

    .problem h4 {
        font-size: 1rem;
    }
    
    .solution-toggle {
        padding: 0.6rem 1rem;
        font-size: 0.9rem;
    }
    
    .channel-info img {
        width: 80px;
        height: 80px;
    }

    .video-sidebar {
        padding: 0.8rem;
    }

    .channel-info {
        padding: 0.8rem;
    }

    .subscribe-btn {
        padding: 10px 18px;
        font-size: 0.9rem;
    }

    .locked-icon {
        font-size: 2.5rem;
    }

    .locked-content {
        padding: 1.5rem;
    }

    .return-message {
        padding: 1rem;
    }

    .return-message h3 {
        font-size: 1.1rem;
    }
}

/* Small mobile devices (360px and below) */
@media (max-width: 360px) {
    .main-container {
        padding: 0 0.5rem;
    }

    .intro, 
    .problem-section {
        padding: 1rem;
    }

    .video-link-btn,
    .solution-toggle,
    .progress-btn {
        width: 100%;
        text-align: center;
    }

    .play-button {
        width: 40px;
        height: 30px;
    }

    .play-button::before {
        border-top: 8px solid transparent;
        border-bottom: 8px solid transparent;
        border-left: 12px solid white;
    }

    .channel-info img {
        width: 70px;
        height: 70px;
    }
}