:root {
    --footer-height: 100px;
    --color-text: #ffffff;
    --color-paragraph: #cccccc;
    --color-subcategory: #aaaaaa;
    --color-body: #0b0b0f;
    --color-first: #0072ff;
    --color-second: #00c6ff;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', sans-serif;
    color: var(--color-text);
    background: var(--color-body);
    overflow-x: hidden;
}

.navbar {
    position: fixed;
    top: 20px;
    left: 50%;
    padding: 12px 28px;
    display: flex;
    gap: 25px;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 40px;
    transform: translateX(-50%);
    z-index: 1000;
}

.navbar a {
    font-size: 15px;
    font-weight: 500;
    text-decoration: none;
    color: var(--color-paragraph);
    transition: 0.3s;
}

.navbar a:hover {
    color: var(--color-text);
    transform: translateY(-2px);
}

section {
    min-height: 100vh;
    padding: 120px 20px 80px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    text-align: center;
}

section:last-of-type {
    min-height: calc(100vh - var(--footer-height));
}

section > h1 {
    margin-bottom: 20px;
}

h1 {
    font-size: 64px;
    font-weight: 800;
    background: linear-gradient(90deg, var(--color-second), var(--color-first));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h2 {
    margin-top: 10px;
    font-size: 26px;
    color: var(--color-subcategory);
}

p {
    max-width: 700px;
    margin-top: 20px;
    line-height: 1.6;
    color: var(--color-paragraph);
}

.glass {
    width: min(1100px, 100%);
    padding: 40px;
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
}

.glass.experience, .glass.hobby, .glass.contacts {
    display: flex;
    flex-direction: column;
    align-items: center;
}

button, #scrollTopBtn {
    margin-top: 40px;
    padding: 16px 40px;
    font-size: 18px;
    color: var(--color-text);
    background: linear-gradient(135deg, var(--color-first), var(--color-second));
    border: none;
    border-radius: 40px;
    transition: 0.4s;
    cursor: pointer;
}

button:hover {
    box-shadow: 0 0 40px var(--color-first);
    transform: scale(1.08);
}

/* skills */
.skills {
    width: 100%;
    display: grid;
    grid-template-columns:repeat(auto-fit, minmax(150px, 1fr));
    gap: 20px;
}

.skill {
    padding: 18px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 14px;
    transition: 0.3s;
}

.skill:hover {
    transform: translateY(-8px) scale(1.05);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
}

/* portfolio */
.portfolio {
    width: 100%;
    margin-top: 50px;
    display: grid;
    grid-template-columns:repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.card {
    padding: 40px;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 15px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    transition: 0.4s;
}

.card:hover {
    box-shadow: 0 40px 80px rgba(0, 0, 0, 0.6);
    transform: scale(1.05) rotateX(4deg);
}

.card a {
    font-size: 20px;
    text-decoration: none;
    color: var(--color-text);
}

/* courses */
.courses {
    max-width: 900px;
    margin-top: 40px;
    display: grid;
    gap: 20px;
}

.course {
    padding: 20px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 12px;
}

.course a, .contacts a { /* contacts */
    text-decoration: none;
    color: var(--color-second);
}

footer {
    width: 100%;
    padding: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 50px;
    text-align: center;
    color: #777;
}

/* background blobs */
.blob {
    position: fixed;
    width: 500px;
    height: 500px;
    border-radius: 50%;
    filter: blur(120px);
    opacity: 0.4;
    z-index: -1;
}

.blob1 {
    top: -200px;
    left: -200px;
    background: var(--color-first);
}

.blob2 {
    bottom: -200px;
    right: -200px;
    background: var(--color-second);
}

#scrollTopBtn {
    position: fixed;
    bottom: 40px;
    right: 40px;
    width: 35px;
    height: 35px;
    padding: 16px 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 3px 18px rgba(0, 0, 0, 0.5);
    opacity: 0;
    visibility: hidden;
}

#scrollTopBtn:hover {
    transform: scale(1.15);
    box-shadow: 0 0 20px var(--color-second), 0 0 40px var(--color-first);
}

#scrollTopBtn.show {
    opacity: 1;
    visibility: visible;
}

/* ================= */
/* MOBILE ADAPTATION */
/* ================= */

@media (max-width: 900px) {
    h1 {
        font-size: 48px;
    }

    h2 {
        font-size: 22px;
    }

    p {
        font-size: 16px;
    }

    section {
        padding: 80px 20px;
    }

    .glass {
        padding: 30px;
    }
}

.menu-toggle {
    display: none;
    font-size: 22px;
    cursor: pointer;
}

.nav-links {
    display: flex;
    gap: 25px;
}

/* mobile */

@media (max-width: 768px) {
    .navbar {
        left: unset;
        right: 20px;
        padding: 8px 16px;
        gap: 15px;
        border-radius: 16px;
        transform: unset;
    }

    .menu-toggle {
        display: block;
    }

    .nav-links {
        position: absolute;
        top: 60px;
        right: 0;
        width: calc(100vw - 40px);
        padding: 25px;
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 20px;
        text-transform: uppercase;
        background: rgba(0, 0, 0, 0.8);
        backdrop-filter: blur(20px);
        border-radius: 20px;
        opacity: 0;
        pointer-events: none;
        transition: 0.3s;
    }

    .nav-links.active {
        opacity: 1;
        pointer-events: auto;
    }
}

@media (max-width: 600px) {
    h1 {
        font-size: 36px;
    }

    h2 {
        font-size: 20px;
    }

    p {
        font-size: 15px;
    }

    .skills {
        grid-template-columns:repeat(2, 1fr);
        gap: 15px;
    }

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

    .skill {
        padding: 14px;
        font-size: 14px;
    }

    .card {
        padding: 25px;
    }

    .course {
        padding: 16px;
        font-size: 14px;
    }

    button {
        padding: 14px 30px;
        font-size: 16px;
    }

    footer {
        flex-direction: column;
        gap: 10px;
    }

    .blob {
        width: 300px;
        height: 300px;
        filter: blur(100px);
    }

    #scrollTopBtn {
        bottom: 80px;
        right: 20px;
    }
}

.card:active, .skill:active {
    transform: scale(0.97);
}