:root {
    --UI-color: #00000066;
    --background-image: url(../image/background.jpg);
    --back-filter: 20px;
    --back-filter-color: #00000030;
    --font-color: white;
    --purple-text-color: #747bff;
    --main-p-size: 22px;
    --card-bg: #00000055;
    --card-border: #ffffff15;
    --glow-color: #747bff66;
    --section-gap: 80px;
}

/* smooth scroll */
html {
    scroll-behavior: smooth;
}

@font-face {
    font-family: "default";
    src: url();
    font-display: swap;
}
@font-face {
    font-family: "ubuntu";
    src: url(../fonts/Ubuntu-Regular.ttf);
    font-display: swap;
}
* {
    padding: 0;
    margin: 0;
    font-family: "ubuntu","default";
}

/* ========== Rainbow Animation ========== */
@keyframes rainbow {
    0%   { background-position: 0% 50%; }
    50%  { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}
@keyframes rainbow-border {
    0%   { border-color: #ff6b6b; box-shadow: 0 0 15px #ff6b6b44; }
    14%  { border-color: #ffa500; box-shadow: 0 0 15px #ffa50044; }
    28%  { border-color: #ffee00; box-shadow: 0 0 15px #ffee0044; }
    42%  { border-color: #51cf66; box-shadow: 0 0 15px #51cf6644; }
    57%  { border-color: #339af0; box-shadow: 0 0 15px #339af044; }
    71%  { border-color: #5c7cfa; box-shadow: 0 0 15px #5c7cfa44; }
    85%  { border-color: #cc5de8; box-shadow: 0 0 15px #cc5de844; }
    100% { border-color: #ff6b6b; box-shadow: 0 0 15px #ff6b6b44; }
}
.rainbow-text {
    background: linear-gradient(
        270deg,
        #ff6b6b, #ffa500, #ffee00, #51cf66,
        #339af0, #5c7cfa, #cc5de8, #ff6b6b
    );
    background-size: 400% 100%;
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: rainbow 4s linear infinite;
    font-weight: 900;
}
.section-title {
    font-size: 36px;
    text-align: center;
    margin-bottom: 40px;
    position: relative;
    display: inline-block;
}
.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 100%;
    height: 3px;
    border-radius: 2px;
    background: linear-gradient(
        270deg,
        #ff6b6b, #ffa500, #ffee00, #51cf66,
        #339af0, #5c7cfa, #cc5de8, #ff6b6b
    );
    background-size: 400% 100%;
    animation: rainbow 4s linear infinite;
}

/* ========== Floating Particles ========== */
@keyframes float-up {
    0% {
        transform: translateY(100vh) scale(0);
        opacity: 0;
    }
    10% {
        opacity: 1;
    }
    90% {
        opacity: 1;
    }
    100% {
        transform: translateY(-10vh) scale(1);
        opacity: 0;
    }
}
.particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    pointer-events: none;
    z-index: -1;
    overflow: hidden;
}
.particle {
    position: absolute;
    bottom: -20px;
    border-radius: 50%;
    background: var(--purple-text-color);
    opacity: 0.3;
    animation: float-up linear infinite;
}
.particle:nth-child(1)  { left: 5%;  width: 8px;  height: 8px;  animation-duration: 12s; animation-delay: 0s;  background: #ff6b6b; }
.particle:nth-child(2)  { left: 15%; width: 12px; height: 12px; animation-duration: 15s; animation-delay: 2s;  background: #ffa500; }
.particle:nth-child(3)  { left: 25%; width: 6px;  height: 6px;  animation-duration: 10s; animation-delay: 4s;  background: #51cf66; }
.particle:nth-child(4)  { left: 35%; width: 10px; height: 10px; animation-duration: 18s; animation-delay: 1s;  background: #339af0; }
.particle:nth-child(5)  { left: 45%; width: 14px; height: 14px; animation-duration: 13s; animation-delay: 3s;  background: #cc5de8; }
.particle:nth-child(6)  { left: 55%; width: 7px;  height: 7px;  animation-duration: 16s; animation-delay: 5s;  background: #ffee00; }
.particle:nth-child(7)  { left: 65%; width: 9px;  height: 9px;  animation-duration: 11s; animation-delay: 6s;  background: #5c7cfa; }
.particle:nth-child(8)  { left: 75%; width: 11px; height: 11px; animation-duration: 14s; animation-delay: 0.5s; background: #ff6b6b; }
.particle:nth-child(9)  { left: 85%; width: 5px;  height: 5px;  animation-duration: 17s; animation-delay: 3.5s; background: #51cf66; }
.particle:nth-child(10) { left: 92%; width: 13px; height: 13px; animation-duration: 19s; animation-delay: 1.5s; background: #cc5de8; }

/* ========== Section Divider ========== */
.section-divider {
    width: 60%;
    max-width: 600px;
    height: 2px;
    border: none;
    border-radius: 1px;
    background: linear-gradient(
        90deg,
        transparent,
        #747bff88,
        #cc5de888,
        #747bff88,
        transparent
    );
    margin: 0 auto;
}

/* backfilter */
body{
    color: var(--font-color);
    width: 100vw;
    height: 100vh;
    background-image: var(--background-image);
    background-repeat: no-repeat;
    background-size: cover;
    background-position: 0 0;
    background-attachment: fixed;
}
.backfilter {
    position: fixed;
    width: 100vw;
    height: 100vh;
    backdrop-filter: blur(var(--back-filter));
    background-color: var(--back-filter-color);
    z-index: -1145;
}

/* header */
header {
    background-color: var(--UI-color);
    height: 60px;
    width: 100%;
    position: fixed;
    z-index: 100;
}
#logo_in_header {
    position: absolute;
    left: 50px;
}
header h1 {
    display: inline;
    position: absolute;
    top: 0;
    line-height: 60px;
}
header a {
    color: white;
    text-decoration: none;
}
header a:hover {
    text-decoration: underline;
}
header ul {
    position: absolute;
    top: 0;
    right: 5vw;
    line-height: 60px;
}
header li {
    display: inline;
    margin-right: 4vw;
}
header ul li a {
    font-size: 18px;
}

/* main */
main {
    display: flex;
    padding: 60px 0 0 0;
    flex-direction: column;
    align-items: center;
    gap: var(--section-gap);
    min-height: calc(100vh - 120px);
}
main p{
    font-size: var(--main-p-size);
}

/* welcome */
.welcome {
    text-align: center;
    padding-top: 40px;
}
.welcome h1{
    font-size: 55px;
    color: white;
}
.welcome p {
    font-size: var(--main-p-size);
    margin-top: 10px;
}
.purpletext {
    color: var(--purple-text-color);
    font-weight: 800;
}
.textbackground {
    font-weight: 800;
    background: var(--UI-color);
    border-radius: 5px;
    font-size: var(--main-p-size);
    padding: 2px 4px;
}

/* about */
.about {
    display: flex;
    flex-direction: column;
    align-items: center;
}
.about h1 {
    font-size: 36px;
    margin-bottom: 30px;
}
.about div {
    display: flex;
    padding: 30px;
    border-radius: 10px;
    background-color: var(--UI-color);
    gap: 8vw;
    flex-wrap: wrap;
    justify-content: center;
}
.about span {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-size: 20px;
    color: var(--font-color);
}
.about span h3 {
    font-size: 28px;
    color: var(--purple-text-color);
    margin-bottom: 20px;
}
.about span p {
    font-size: 24px;
    color: var(--font-color);
}
.about i {
    margin-bottom: 20px;
}
.about a {
    color: gray;
    text-decoration: none;
}
.about a:hover {
    color: var(--text-color);
}

/* ========== Skills Section ========== */
.skills {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 80%;
    max-width: 900px;
}
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 24px;
    width: 100%;
}
.skill-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 28px 24px;
    text-align: center;
    transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}
.skill-card:hover {
    transform: translateY(-6px);
    border-color: var(--purple-text-color);
    box-shadow: 0 8px 30px var(--glow-color);
}
.skill-card .skill-icon {
    font-size: 48px;
    margin-bottom: 12px;
    display: block;
}
.skill-card h3 {
    font-size: 20px;
    margin-bottom: 14px;
    color: var(--purple-text-color);
}
.skill-bar-bg {
    background: #ffffff22;
    border-radius: 10px;
    height: 10px;
    overflow: hidden;
}
.skill-bar-fill {
    height: 100%;
    border-radius: 10px;
    background: linear-gradient(90deg, var(--purple-text-color), #cc5de8);
    animation: fill-bar 1.5s ease-out forwards;
    transform-origin: left;
}
@keyframes fill-bar {
    from { transform: scaleX(0); }
    to   { transform: scaleX(1); }
}

/* ========== Projects Section ========== */
.projects {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 80%;
    max-width: 900px;
}
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
    width: 100%;
}
.project-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 28px 24px;
    transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
    text-decoration: none;
    color: var(--font-color);
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
}
.project-card:hover {
    transform: translateY(-6px);
    animation: rainbow-border 3s linear infinite;
}
.project-card .project-icon {
    font-size: 40px;
}
.project-card h3 {
    font-size: 22px;
    color: var(--purple-text-color);
}
.project-card p {
    font-size: 16px;
    opacity: 0.85;
    line-height: 1.5;
}
.project-card .project-tag {
    display: inline-block;
    background: #747bff33;
    color: var(--purple-text-color);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
}

/* ========== Goals Section ========== */
.goals {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 80%;
    max-width: 700px;
    margin-bottom: 20px;
}
.goals-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
    width: 100%;
}
.goal-item {
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 18px 24px;
    transition: transform 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}
.goal-item:hover {
    transform: translateX(8px);
    border-color: var(--purple-text-color);
    box-shadow: 0 4px 20px var(--glow-color);
}
.goal-check {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    border: 2px solid var(--purple-text-color);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 14px;
    transition: background 0.3s ease, border-color 0.3s ease;
}
.goal-item.done .goal-check {
    background: #51cf66;
    border-color: #51cf66;
    color: white;
}
.goal-item.done .goal-text {
    text-decoration: line-through;
    opacity: 0.6;
}
.goal-text {
    font-size: 20px;
}
.goal-emoji {
    font-size: 24px;
    flex-shrink: 0;
}

/* ========== Back to Top ========== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 46px;
    height: 46px;
    border-radius: 50%;
    background: var(--purple-text-color);
    color: white;
    border: none;
    cursor: pointer;
    font-size: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.3s ease, transform 0.3s ease, background 0.3s ease;
    pointer-events: none;
    z-index: 200;
    box-shadow: 0 4px 15px #747bff55;
}
.back-to-top.visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}
.back-to-top:hover {
    background: #5c6cf0;
    box-shadow: 0 6px 24px #747bff88;
    transform: translateY(-3px);
}

/* footer */
footer {
    background-color: var(--UI-color);
    color: white;
    height: 60px;
    width: 100vw;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 16px;
    margin-top: auto;
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
    .welcome h1 {
        font-size: 36px;
    }
    .skills, .projects, .goals {
        width: 90%;
    }
    .skills-grid, .projects-grid {
        grid-template-columns: 1fr;
    }
    .about div {
        gap: 30px;
    }
    header ul {
        right: 2vw;
    }
    header li {
        margin-right: 3vw;
    }
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 40px;
        height: 40px;
        font-size: 18px;
    }
}