/**
 *    Copyright (c) ppy Pty Ltd <contact@ppy.sh>.
 *
 *    This file is part of osu!web. osu!web is distributed with the hope of
 *    attracting more community contributions to the core ecosystem of osu!.
 *
 *    osu!web is free software: you can redistribute it and/or modify
 *    it under the terms of the Affero GNU General Public License version 3
 *    as published by the Free Software Foundation.
 *
 *    osu!web is distributed WITHOUT ANY WARRANTY; without even the implied
 *    warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *    See the GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with osu!web.  If not, see <http://www.gnu.org/licenses/>.
 */

.landing-middle-buttons {
  padding: 20px;
  text-align: center;

  &__button {
    .default-box-shadow();
    border-radius: @border-radius-large;
    margin: 5px;
    display: inline-block;
    width: 250px;
    height: 75px;
    transition: all 120ms;
    background-size: cover;

    &:hover {
      .thicker-box-shadow();
    }

    &--blog {
      .at2x-simple("/images/landing/button-blog.png");
    }
  }
}

/**
 *    Copyright (c) ppy Pty Ltd <contact@ppy.sh>.
 *
 *    This file is part of osu!web. osu!web is distributed with the hope of
 *    attracting more community contributions to the core ecosystem of osu!.
 *
 *    osu!web is free software: you can redistribute it and/or modify
 *    it under the terms of the Affero GNU General Public License version 3
 *    as published by the Free Software Foundation.
 *
 *    osu!web is distributed WITHOUT ANY WARRANTY; without even the implied
 *    warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *    See the GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with osu!web.  If not, see <http://www.gnu.org/licenses/>.
 */

.landing-middle-buttons {
  padding: 20px;
  text-align: center;

  &__button {
    .default-box-shadow();
    border-radius: @border-radius-large;
    margin: 5px;
    display: inline-block;
    width: 250px;
    height: 75px;
    transition: all 120ms;
    background-size: cover;

    &:hover {
      .thicker-box-shadow();
    }

    &--blog {
      .at2x-simple('/images/landing/button-blog.png');
    }
  }
}

Use single quotes instead of doubles
Use single quotes instead of doubles
