/* General Styles */
body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #000000 0%, #333333 100%); /* Black to dark grey gradient */
    color: #f0f0f0; /* Light grey text */
    margin: 0;
    line-height: 1.6;
    overflow-x: hidden; /* Prevent horizontal scroll */
}

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

/* Header */
header {
    background: radial-gradient(ellipse at bottom, #330033 0%, #000000 100%); /* Black hole effect with purple */
    color: white;
    padding: 60px 20px;
    text-align: center;
    border-bottom-left-radius: 150px; /* Increased curve */
    border-bottom-right-radius: 150px; /* Increased curve */
    box-shadow: 0 15px 40px rgba(128, 0, 128, 0.8); /* Purple glow */
    position: relative;
    overflow: hidden;
}

header h1 {
    margin: 0;
    font-size: 3.5em;
    font-weight: 700;
    text-shadow: 2px 2px 10px rgba(255, 255, 255, 0.5); /* White text shadow */
    position: relative;
    z-index: 1;
}

header .subtitle {
    margin: 15px 0 0;
    font-size: 1.4em;
    font-weight: 300;
    opacity: 0.8;
    position: relative;
    z-index: 1;
}

/* Introduction */
.introduction {
    background: #1a1a1a; /* Dark background */
    padding: 40px;
    border-radius: 20px;
    margin: 40px auto;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5); /* Darker shadow */
    text-align: center;
    border-left: 10px solid #666666; /* Grey accent */
    font-size: 1.1em;
    line-height: 1.8;
    position: relative;
    overflow: hidden;
    color: #f0f0f0; /* Light text */
}

.introduction::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(45deg, rgba(0, 0, 0, 0.05), rgba(50, 50, 50, 0.05)); /* Subtle dark grey gradient */
    z-index: 0;
}

.introduction strong {
    color: #cccccc; /* Lighter grey accent */
}

/* Roadmap Timeline */
#roadmap-container {
    position: relative;
    padding: 40px 0;
}

.timeline-thread {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1;
}

#roadmap-container::before {
    content: '';
    position: absolute;
    top: 0;
    bottom: 0;
    left: 50%;
    width: 2px; /* Thinner line */
    background: linear-gradient(to bottom, rgba(100, 100, 100, 0.3), rgba(200, 200, 200, 0.3)); /* Subtle grey gradient */
    transform: translateX(-50%);
    z-index: -1;
    border-radius: 1px;
}

.year-card {
    position: relative;
    margin-bottom: 80px;
    width: 45%;
    padding: 30px 40px;
    box-sizing: border-box;
    border-radius: 20px;
    background: #1a1a1a; /* Dark background */
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5); /* Darker shadow */
    border: 2px solid transparent; /* Default transparent border */
    transition: transform 0.4s ease, box-shadow 0.4s ease, border-color 0.4s ease;
    animation: fade-in 1s ease-out forwards;
    opacity: 0;
    color: #e0e0e0; /* Light text */
}

.year-card:nth-child(3n+1) {
    border-color: #ff0000; /* Red */
}

.year-card:nth-child(3n+2) {
    border-color: #ff69b4; /* Pink */
}

.year-card:nth-child(3n) {
    border-color: #0000ff; /* Blue */
}

.year-card:nth-child(odd) {
    left: 55%;
    transform: translateX(100%);
}

.year-card:nth-child(even) {
    left: 0;
    transform: translateX(-100%);
}

.year-card.in-view {
    transform: translateX(0%);
    opacity: 1;
}

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

.year-card:hover {
    transform: translateY(-15px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.6); /* Even darker shadow on hover */
}

.year-card::before {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: #000000; /* Black background for the hole */
    border-radius: 50%;
    box-shadow: inset 0 0 5px rgba(255, 255, 255, 0.3), 0 0 10px rgba(255, 255, 255, 0.2); /* Inner glow and subtle outer glow */
    z-index: 2; /* Ensure it's above the timeline */
    top: 15px; /* Position from the top */
}

.year-card:nth-child(odd)::before {
    left: 15px; /* Position on the top-left for odd cards (now on right) */
}

.year-card:nth-child(even)::before {
    right: 15px; /* Position on the top-right for even cards (now on left) */
}

.year-card h2 {
    color: #cccccc; /* Grey accent */
    font-size: 2.2em;
    margin-top: 0;
    border-bottom: 4px solid #999999; /* Grey border */
    padding-bottom: 15px;
    display: inline-block;
    margin-bottom: 20px;
}

.year-card h3 {
    font-weight: 500;
    margin-top: 10px;
    color: #b0b0b0; /* Lighter grey */
    font-size: 1.5em;
}

/* Sections */
.sections-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 25px;
    margin-top: 30px;
}

.section-card {
    background: #2a2a2a; /* Dark background */
    padding: 25px;
    border-radius: 15px;
    border: 2px solid transparent; /* Increased border width from 1px to 2px */
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2); /* Darker shadow */
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275); /* Smoother, more bouncy transition */
    color: #e0e0e0; /* Light text */
    transform-origin: center; /* Ensure scaling happens from center */
}

.section-card:hover {
    transform: translateY(-8px) scale(1.03); /* Added slight scale effect */
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.4); /* Increased shadow */
    border-color: inherit; /* This will use the border color set by the year-card:nth-child rules */
}

/* Custom glow effects for each year's section cards */
.year-card:nth-child(1) .section-card:hover {
    filter: drop-shadow(0 0 10px rgba(255, 59, 59, 0.4)); /* Red glow */
}

.year-card:nth-child(2) .section-card:hover {
    filter: drop-shadow(0 0 10px rgba(162, 89, 255, 0.4)); /* Purple glow */
}

.year-card:nth-child(3) .section-card:hover {
    filter: drop-shadow(0 0 10px rgba(0, 230, 118, 0.4)); /* Green glow */
}

.year-card:nth-child(4) .section-card:hover {
    filter: drop-shadow(0 0 10px rgba(255, 105, 180, 0.4)); /* Pink glow */
}
.section-card h4 {
    margin-top: 0;
    color: #00ffff; /* Cyan accent */
    font-size: 1.4em;
    margin-bottom: 15px;
}

.section-card ul {
    padding-left: 0;
    list-style: none;
    margin: 0;
}

/* Skills */
.skill-item {
    display: flex;
    flex-direction: column;
    padding: 12px 0;
    border-bottom: 1px dashed #444444; /* Darker dashed border */
    cursor: pointer;
    transition: all 0.3s ease;
    border-radius: 8px; /* Rounded corners */
    border: 1px solid transparent; /* Default transparent border */
}

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

.skill-item:hover {
    background-color: transparent; /* Transparent background on hover */
    border-color: inherit; /* This will use the border color set by the year-card:nth-child rules */
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.skill-name {
    display: flex;
    align-items: center;
    font-weight: 500;
    color: #c0c0c0; /* Lighter grey */
}

.skill-name input[type="checkbox"] {
    /* This will be removed or hidden */
    display: none;
}

.skill-name .pin-icon { /* New class for the pin icon */
    margin-right: 10px;
    font-size: 1.2em;
    color: #ffffff; /* Changed from cyan to white */
    cursor: pointer;
    transition: transform 0.2s ease;
}

.skill-name .pin-icon:hover {
    transform: scale(1.2);
}

.skill-resources {
    margin-top: 10px;
    padding-left: 37px; /* Align with pin icon */
    display: none; /* Initially hidden */
    animation: slide-down 0.3s ease-out forwards;
}

.skill-item.active {
    background-color: transparent; /* Transparent background when active */
}

.skill-item.active .skill-resources {
    display: block;
}

@keyframes slide-down {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}

.skill-resources ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
}

.skill-resources li {
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    position: relative;
    padding-left: 20px;
    transition: all 0.3s ease;
    border-radius: 5px;
    padding: 5px 5px 5px 20px;
    border: 1px solid transparent;
}

.skill-resources li:hover {
    border-color: inherit; /* This will use the border color set by the year-card:nth-child rules */
    transform: translateY(-2px);
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.2);
}

.skill-resources li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: #90ee90;
}

.skill-resources li.external::before {
    background-color: #ff6b6b;
}

.skill-resources a {
    color: #90ee90; /* Light green for links */
    text-decoration: none;
    transition: color 0.3s ease;
    font-size: 0.95em;
    margin-left: 5px;
}

.skill-resources a:hover {
    color: #00ffff; /* Cyan on hover */
    text-decoration: underline;
}

.skill-resources .emoji {
    font-size: 1.1em;
    margin-right: 5px;
}

/* Progress Bar */
#progress-container {
    position: sticky;
    top: 0;
    left: 0;
    width: 100%;
    background-color: #1a1a1a; /* Dark background */
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3); /* Darker shadow */
}

#progress-bar {
    width: 0%;
    height: 10px;
    background: linear-gradient(90deg, #00aaff, #00ffff); /* Blue to cyan gradient */
    transition: width 0.3s ease-out;
    border-radius: 0 5px 5px 0;
}

/* Go to Top Button */
#go-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: #00aaff; /* Blue */
    color: white;
    border: none;
    border-radius: 50%;
    width: 55px;
    height: 55px;
    font-size: 28px;
    cursor: pointer;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.4); /* Darker shadow */
    display: none; /* Hidden by default */
    transition: background-color 0.3s ease, transform 0.3s ease;
    z-index: 999;
}

#go-to-top:hover {
    background: #00ffff; /* Cyan on hover */
    transform: translateY(-5px);
}

/* Responsive Design - Adjust colors for dark theme */
@media (max-width: 992px) {
    header h1 {
        font-size: 2.8em;
    }
    header .subtitle {
        font-size: 1.2em;
    }
    .year-card {
        width: 90%;
        left: 5%;
        padding: 25px;
    }
    .year-card:nth-child(odd)::after,
    .year-card:nth-child(even)::after {
        left: -15px; /* Adjust for single column */
        top: 20px;
    }
    #roadmap-container::before {
        left: 20px;
    }
    .year-card:nth-child(odd),
    .year-card:nth-child(even) {
        transform: translateX(0%); /* No horizontal animation on small screens */
    }
}

@media (max-width: 768px) {
    header {
        padding: 40px 15px;
    }
    header h1 {
        font-size: 2.2em;
    }
    .introduction {
        margin: 30px auto;
        padding: 30px;
    }
    .year-card {
        padding: 20px;
        margin-bottom: 60px;
    }
    .year-card h2 {
        font-size: 1.8em;
    }
    .year-card h3 {
        font-size: 1.3em;
    }
    .sections-container {
        gap: 20px;
    }
    .section-card {
        padding: 20px;
    }
    .section-card h4 {
        font-size: 1.2em;
    }
    .skill-name input[type="checkbox"] {
        width: 20px;
        height: 20px;
    }
    .skill-resources {
        padding-left: 35px;
    }
    #go-to-top {
        width: 50px;
        height: 50px;
        font-size: 24px;
        bottom: 20px;
        right: 20px;
    }
}

@media (max-width: 480px) {
    header h1 {
        font-size: 1.8em;
    }
    header .subtitle {
        font-size: 1em;
    }
    .introduction {
        padding: 20px;
        font-size: 0.95em;
    }
    .year-card {
        width: 95%;
        left: 2.5%;
    }
    .year-card h2 {
        font-size: 1.5em;
    }
    .year-card h3 {
        font-size: 1.1em;
    }
    .skill-name {
        font-size: 0.9em;
    }
    .skill-resources a {
        font-size: 0.85em;
    }
}
.year-card:nth-child(1),
.year-card:nth-child(1) .section-card,
.year-card:nth-child(1) .skill-resources li::before {
    border-color: #ff3b3b !important; /* Red */
    box-shadow: 0 0 0 2px #ff3b3b33;
    background-color: #1a1a1a;
}
.year-card:nth-child(2),
.year-card:nth-child(2) .section-card,
.year-card:nth-child(2) .skill-resources li::before {
    border-color: #a259ff !important; /* Purple */
    box-shadow: 0 0 0 2px #a259ff33;
    background-color: #1a1a1a;
}
.year-card:nth-child(3),
.year-card:nth-child(3) .section-card,
.year-card:nth-child(3) .skill-resources li::before {
    border-color: #00e676 !important; /* Green */
    box-shadow: 0 0 0 2px #00e67633;
    background-color: #1a1a1a;
}
.year-card:nth-child(4),
.year-card:nth-child(4) .section-card,
.year-card:nth-child(4) .skill-resources li::before {
    border-color: #ff69b4 !important; /* Pink */
    box-shadow: 0 0 0 2px #ff69b433;
    background-color: #1a1a1a;
}

/* Remove default border colors for year-cards */
.year-card {
    border: 2px solid transparent;
}
.section-card {
    border: 1px solid transparent;
}
.skill-resources li::before {
    background-color: inherit;
}
/* Remove this extra closing brace as it's not matching any opening brace */

@media (max-width: 480px) {
    header h1 {
        font-size: 1.8em;
    }
    header .subtitle {
        font-size: 1em;
    }
    .introduction {
        padding: 20px;
        font-size: 0.95em;
    }
    .year-card {
        width: 95%;
        left: 2.5%;
    }
    .year-card h2 {
        font-size: 1.5em;
    }
    .year-card h3 {
        font-size: 1.1em;
    }
    .skill-name {
        font-size: 0.9em;
    }
    .skill-resources a {
        font-size: 0.85em;
    }
}